Antimicrobial compositions and methods thereof

Abstract

The present disclosure concerns antimicrobial compositions comprising alpha hops acid and nisin and having a pH of between about 7.0 to about 9.0, processes for making the antimicrobial compositions and methods of using the antimicrobial compositions for limiting microbial contamination in a medium.

Description

[0001] Antimicrobial compositions and methods thereof Field of the Invention The present disclosure relates to antimicrobial compositions. More particularly, the present dislosure relates to liquid antimicrobial compositions, to methods for preparing the compositions, and to methods of preventing or limiting microbial contamination in a medium using the antimicrobial compositions described herein. Background of the Invention Microbial contamination in the bioethanol industry is pervasive and can inhibit yeast performance and reduce ethanol yield. Estimates (based upon 2016 industry values) place the yearly cost of the yield loss in the U.S. alone to be more than $200 million USD. To minimize these losses, the industry has become heavily reliant on the use of antibiotics during fermentation. Not surprisingly, the dependence on antibiotics in bioethanol production has been found to promote the emergence of antibiotic-resistant strains that undermine the effectiveness of this control measure. Additionally, antibiotic residues can carry over into animal feed via dried distiller grains. The presence of antibiotics and / or antibiotic- resistant bacteria in animal feed has raised concerns among regulators and consumers, leading to a growing interest in the U.S. bioethanol industry for cost effective antibiotic-free solutions to control microbial contamination in their fermentation process. Novel antibiotic-free products for controlling microbial contamination are therefore highly desirable. In addition, the beer and distilled spirits industry also have problems with microbial contamination, particularly bacterial contamination, as they cannot use antibiotics as a means of controlling contamination. Novel antibiotic-free products for controlling microbial contamination are therefore highly desirable. Means of preventing or limiting microbial contamination without the use of antibiotics in medium are therefore highly desirable. Summary The shortcomings of the prior art are generally mitigated by the antimicrobial compositions and methods described herein. According to a first aspect, the present disclosure provides an antimicrobial composition (i) comprising alpha hops acid and nisin, and (ii) having a pH of between about 7.0 to about 9.0. In an embodiment, the alpha hops acid comprises at least one humulone, adhumulone, cohumulone, posthumulone, prehumulone, adprehumulone, derivative thereof, or any combination thereof. In another embodiment, the alpha hops acid derivative comprises an iso alpha acid, a rhoiso alpha acid, a tetrahydroiso alpha acid, or a hexahydroiso alpha acid. In another embodiment, the iso alpha acid comprises at least one isocohumulone, isohumulone, isoprehumulone, isoposthumulone, isoadhumulone, isoadprehumulone, derivative thereof, or any combination thereof. In still another embodiment, the iso alpha hops acid derivative comprises the tetrahydroiso alpha acid. In additional embodiments, the tetrahydroiso alpha acid comprises tetrahydroiso cohumulone, tetrahydroiso humulone, tetrahydroiso prehumulone, tetrahydroiso posthumulone, tetrahydroiso adhumulone, tetrahydroiso adprehumulone, or any combination thereof. In some embodiments, the antimicrobial composition comprises at least 2,000 ppm of alpha hops acid. In some embodiments, the nisin comprises nisin A and / or nisin Z. In specific embodiments, the nisin is nisin Z. In additional embodiments, the antimicrobial composition comprises at least 100 ppm of nisin. In further embodiments, the antimicrobial composition exhibits a synergistic antimicrobial activity in a medium compared to the antimicrobial activity of equivalent amounts of nisin and alpha hops acid added separately to the medium. In some embodiments, the antimicrobial composition comprises less than 60 mM of sodium (Na2+). In a further embodiment, the antimicrobial composition is in a liquid form. In some embodiments, the antimicrobial composition is an aqueous solution or an aqueous suspension. In some specific embodiments, the antimicrobial composition further comprises a buffer, which could be, for example, a potassium phosphate buffer, a HEPES buffer, an ammonium chloride buffer, and / or a glycylglycine buffer. In some embodiments, the antimicrobial composition is capable of retaining antimicrobial activity for at least 10 days at 4°C. In further embodiments, the antimicrobial composition comprises a stabilizer. In some embodiments, the stabilizer is xanthan gum, guar gum, locust bean gum, starch, maltodextrin, pectin, agar, carrageenan, sodium pyrophosphate, collagen, lecithin, or a combination thereof. In specific embodiments, the stabilizer is xantham gum (which can, in some additional embodiments, be present in the antimicrobial composition at a concentration of at least 0.1% w / v). According to a second aspect, the present disclosure provides a medium comprising the antimicrobial composition described herein. Embodiments of the antimicrobial composition, including the alpha hops acids, the nisin and the buffer have been described above and apply herein. According to a third aspect, the present disclosure provides a process for making the antimicrobial composition described herein. Embodiments of the antimicrobial composition, including the alpha hops acids, the nisin and the buffer have been described above and apply herein. The process comprises a) combining an alpha hops acid solution with a nisin solution, wherein the nisin solution has a pH of between about 7.0 to about 9.0. In some embodiments, the process further comprises, before a), providing the nisin solution by (i) adding nisin to water to obtain a first solution and (ii) adjusting the pH of the first solution between about 7.0 to about 9.0 with a base and / or a buffer. In additional embodiments, the process further comprises, before a), providing the nisin solution by (i) providing a second solution comprising nisin and (ii) adjusting the pH of the second solution between about 7.0 to about 9.0 with a base and / or a buffer. In yet further embodiments, the process further comprises, before a), providing the nisin solution by (i) adjusting the pH of a third solution to a pH between about 7.0 and 9.0 with a base and / or a buffer and (ii) adding nisin to the third solution. In some embodiments, the buffer is a potassium phosphate buffer, a HEPES buffer, an ammonium chloride buffer, and / or a glycylglycine buffer. In some specific embodiments, the buffer is the ammonium chloride buffer. In further embodiments, the process comprises b) adding a stabilizer in at least one of the alpha hops acid solution, the nisin solution, the first solution, the second solution, the third solution or the antimicrobial composition. In some embodiments, the process further comprises, before i), adding a stabilizer to water to obtain a stabilizer solution and adding nisin to the stabilizer solution to obtain the first solution. In some embodiments, the stabilizer is xanthan gum, guar gum, locust bean gum, starch, maltodextrin, pectin, agar, carrageenan, sodium pyrophosphate, collagen, lecithin, or a combination thereof. In specific embodiments, the stabilizer is xantham gum (which can, in some additional embodiments, be present in the antimicrobial composition at a concentration of at least 0.1% w / v).In additional embodiments, the process further comprises c) storing the antimicrobial composition at a temperature of between about 2°C to about 10°C. In some embodiments, the process further comprises determining the antimicrobial activity of the antimicrobial composition before and / or after step b). The present disclosure also provides the antimicrobial composition obtainable or obtained by performing the process described herein. The present disclosure also provides an antimicrobial composition obtainable or obtained by performing the process described herein. According to a fourth aspect, the present disclosure provides a method of preventing or limiting microbial contamination in a medium. The method comprises (i) adding the antimicrobial composition described herein or obtainable / obtained by the process described herein to a medium. In an embodiment, the medium is a liquefaction medium, a propagation medium, a fermentation medium, a food, a food ingredient, a feed, a feed ingredient, a beverage, and / or a beverage ingredient. In some embodiments, the method is for preventing or limiting bacterial contamination and / or fungal contamination in the medium. In additional embodiments, the method is for substantially limiting the acidification of the medium. In yet further embodiments, the method further comprises, before i), diluting the antimicrobial composition to a desired concentration. According to a sixth aspect, the present disclosure provides a kit for preventing or limiting microbial contamination in a medium with an antimicrobial composition. The kit comprises nisin, alpha hops acid, optionally a base, a buffer and / or a stabilizer; and instructions to make the antimicrobial composition according to the process described herein and / or to perform the method described herein. Embodiments of the antimicrobial composition, including the alpha hops acids, the nisin, the base, the buffer and the stabilizer have been described above and apply herein. Other and further aspects and advantages of the present invention will be better understood upon the reading of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. Brief Description of the Drawings The above and other aspects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which: Figures 1A and 1B show the influence of various hop alpha acid extracts on the pH (1A) and lactate production (1B g / L) in corn mash challenged by a three-strain cocktail of bioethanol contaminants after a 15 hour incubation at 33°C. Results are shown in function of the concentration of the different hop α-acid extracts compared to controls (+cont = indicator bacteria only with no hop alpha acids added; -cont = no bacteria, no hop alpha acids). Figure 2 shows the growth of the indicator strain Lactiplantibacillus (Lb.) paracasei in MRS broth (pH 5.8) alone (MRS control, left curve), supplemented with 20 ppm iso α-acid hops preparation (aHops, middle curve), or supplemented with a mixture of 20 ppm iso α-acid hops and 4 ppm nisin (aHops + nisin, right curve) with the pH of the nisin preparation adjusted to pH 8.0 before blending with iso α-acid hops. Results are shown as the growth of Lb. paracasei as a function of absorbance at 600 nm (OD600) over time (hh:mm.ss). Figure 3 shows the growth of the hops and nisin indicator strain Lb. plantarum in MRS broth (pH 6.0) supplemented with nisin, tetrahydroiso α-acid hops (THIA), or combinations of the two ingredients (tH-N blend) described in Table 5. Results are shown in function of the growth of the indicator strain absorbance at 600 nm (OD600) in function of time (hh:mm.ss) and the formulations added to the MRS culture medium (No inhibition: control; 2 ppm nisin; tH-N blend 1; 5 ppm THIA; tH-N blend 2; THIA and nisin dosed separately (5 ppm THIA, 2 ppm nisin added individually to MRS broth, see Table 5)). Figure 4 shows the final organic acids (lactate (white bars), acetate (grey bars), and formate (black bars) all in g / L) and pH content (•) of experimentally contaminated corn mash supplemented with a tetrahydroiso α-acid hops (10 ppm) / nisin (4 ppm) blend (tH-N blend) or a comparable levels of tetrahydroiso α-acid hops and nisin dosed separately. Figure 5 shows the growth of the indicator strain Lb. plantarum in MRS broth (pH 6.0) supplemented with the samples described in Table 7. Results are shown as a function of absorbance at 600 nm (OD600) over time (hh:mm.ss) and the formulation tested. Figures 6A and B show the growth of the indicator strain Lb. plantarum in MRS broth (pH 6.0) supplemented with nisin only (1 ppm Nisin), tetrahydroiso α-acid hops only (THIA, 5 ppm), or blends (tH-N) of the two ingredients as described in Table 8 having been adjusted to (A) pH 6.5 to 8.5 and (B) 8 to 10 prior to their supplementation to the culture medium. Results are shown as a function of absorbance at 600 nm (OD600) over time (hh:mm.ss) and the formulation tested. Figure 7 shows the number of hours that each of the blends from Figures 6A and 6B took to reach an optical density of at least 0.7 after storing the blends for either 9 days (white bars) or 15 days (grey bars) at 30°C. Figures 8A and 8B show the growth of the indicator strain Lb. plantarum in MRS broth (pH 6.0) supplemented with nisin only (1 ppm), β-acid hops only (bHops, 5 ppm), pH adjusted blends of β-acid hops / nisin (bH + N) as described in Table 9 or various controls (No inhibition: no inhibitors; tetrahydroiso α-acid hops / nisin blend (tH + N); or tetrahydroiso α-acid hops only (5 ppm THIA). Blends of the two ingredients having been adjusted to (A) pH 6.5 to 8.5 and (B) 8 to 10 prior to their supplementation to the culture medium. Results are shown as a function of absorbance at 600 nm (OD600) over time (hh:mm.ss) and the formulation tested. Figure 9 shows the stability of nisin (2 ppm) and tetrahydroiso α-acid hops (5ppm) blends (initially formulated at pH 8.0) at 4°C, 21°C or 37°C. Results are shown as the concentration of nisin (g / L) as a function of time after a storage period of 140 days. Figure 10 shows the changes in pH of the tetrahydroiso α-acid hops (5ppm) / nisin (2 ppm) blend (initially formulated at pH 8.0) in function of time (days) when stored at 4°C. Figures 11A to 11D shows growth of the indicator strain Lb. plantarum in MRS broth (pH 6.0) supplemented with nisin (1ppm Nisin), tetrahydroiso α-acid hops (5ppm THIA), nisin and tetrahydroiso α-acid hops dosed separately (in A and B only), nisin (1ppm) and tetrahydroiso α-acid hops (5ppm) blend with no buffer (tH + N blend), or the nisin and tetrahydroiso α-acid hops blends with different buffers: KH2PO4(tH + N blend KH2PO4) (A), HEPES (tH + N blend HEPES) (B), ammonium chloride (tH + N blend NH4Cl) (C), or diglycine (tH + N blend diglycine) (D). Results are shown as absorbance at 600 nm (OD600) in function of time (hh:mm.ss) and and blends composition tested are described in Table 11. Figure 12 shows growth of the indicator strain Lb. plantarum in MRS broth (pH 6.0) supplemented with nisin (1.5ppm Nisin), tetrahydroiso α-acid hops (7.5ppm THIA), nisin and tetrahydroiso α-acid hops blend buffered with 10mM ammonium chloride with no stabilizer (tH + N blend), or the nisin and tetrahydroiso α-acid hops blend buffered with 10mM ammonium chloride and supplemented with 0.0375% (tH + N blend 0.0375% Xan Gum), 0.05% (tH + N blend 0.05% Xan Gum), 0.075 (tH + N blend 0.075% Xan Gum) or 0.1% (tH + N blend 0.1% Xan Gum) xanthan gum. Results are shown as absorbance at 600 nm (OD600) in function of time (hh:mm.ss) and blends composition tested are described in Table 13. Detailed Description The present disclosure provides an antimicrobial composition comprising alpha hops acids and nisin. In some embodiments, the antimicrobial composition exhibits activity towards bacteria. In some embodiments, the antimicrobial composition exhibits bacteriostatic and / or bactericidal activity. The antimicrobial composition can exhibit activity towards a Gram-negative and / or a Gram-positive bacterium. For example, the antimicrobial composition can have activity against bacteria from the genus Escherichia (such as for example, from the species Escherichia coli) or from the genus Zymomonas (such as, for example, from the species Zymomonas mobilis). In another example, the antimicrobial composition can have activity against a Gram-positive bacterium, such as, for example, lactic acid bacteria or LAB. LAB are a group of Gram-positive bacteria, non-respiring non-spore- forming, cocci or rods, which produce lactic acid as the major end product of the fermentation of carbohydrates. Bacterial genuses of LAB include, but are not limited to, Lactobacillus, Leuconostoc, Pediococcus, Lactococcus, Streptococcus, Aerococcus, Carnobacterium, Enterococcus, Oenococcus, Sporolactobacillus, Tetragenococcus, Vagococcus, and Weissella. Bacterial species of LAB include, but are not limited to, Lactococcus lactis, Lactococcus garviae, Lactococcus raffinolactis, Lactococcus pentosus, Oenococcus oeni, Pediococcus pentosaceus, Pediococcus acidilactici,, Carnococcus allantoicus, Carnobacterium gallinarum,, Vagococcus fessus, Streptococcus thermophilus, Enterococcus phoeniculicola, Enterococcus plantarum, Enterococcus raffinosus, Enterococcus avium, Enterococcus pallens Enterococcus hermanniensis, Enterococcus faecalis, and Enterococcus faecium. In an embodiment, the LAB is a Lactobacillus sp. and, include, without limitation the following genera Lactobacillus delbrueckii group, Paralactobacillus, Holzapfelia, Amylolactobacillus, Bombilactobacillus, Companilactobacillus, Lapidilactobacillus, Agrilactobacillus, Schleiferilactobacillus, Loigolactobacilus, Lacticaseibacillus, Latilactobacillus, Dellaglioa, Liquorilactobacillus, Ligilactobacillus, Lactiplantibacillus, Furfurilactobacillus, Paucilactobacillus, Limosilactobacillus, Fructilactobacillus, Acetilactobacillus, Apilactobacillus, Levilactobacillus, Secundilactobacillus and Lentilactobacillus. In some additional embodiments, the Lactobacillus species is L. acetotolerans, L. acidifarinae, L. acidipiscis, L. acidophilus, L. agilis, L. algidus, L. alimentarius, L. amylolyticus, L. amylophilus, L. amylotrophicus, L. amylovorus, L. animalis, L. antri, L. apodemi, L. aviarius, L. bifermentans, L. brevis, L. buchneri, L. camelliae, L. casei, L. catenaformis, L. ceti, L. coleohominis, L. collinoides, L. composti, L. concavus, L. coryniformis, L. crispatus, L. crustorum, L. curvatus, L. delbrueckii (including L. delbrueckii subsp. bulgaricus, L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. lactis), L. dextrinicus, L. diolivorans, L. equi, L. equigenerosi, L. farraginis, L. farciminis, L. fermentum, L. fornicalis, L. fructivorans, L. frumenti, L. fuchuensis, L. gallinarum, L. gasseri, L. gastricus, L. ghanensis, L. graminis, L. ammesii, L. hamsteri, L. harbinensis, L. hayakitensis, L. helveticus, L. hilgardii, L. omohiochii, L. iners, L. ingluviei, L. intestinalis, L. jensenii, L. johnsonii, L. kalixensis, L. efiranofaciens, L. kefiri, L. kimchii, L. kitasatonis, L. kunkeei, L. leichmannii, L. lindneri, L. alefermentans, L. mali, L. manihotivorans, L. mindensis, L. mucosae, L. murinus, L. nagelii, L. namurensis, L. nantensis, L. oligofermentans, L. oris, L. panis, L. pantheris, L. parabrevis, L. parabuchneri, L. paracasei, L. paracollinoides, L. parafarraginis, L. parakefiri, L. aralimentarius, L. paraplantarum, L. pentosus, L. perolens, L. plantarum, L. pontis, L. protectus, L. psittaci, L. rennini, L. reuteri, L. rhamnosus, L. rimae, L. rogosae, L. rossiae, L. ruminis, L. saerimneri, L. sakei, L. salivarius, L. sanfranciscensis, L. satsumensis, L. secaliphilus, L. sharpeae, L. siliginis, L. spicheri, L. suebicus, L. thailandensis, L. ultunensis, L. vaccinostercus, L. vaginalis, L. versmoldensis, L. vini, L. vitulinus, L. zeae or L. zymae. In some embodiments, the bacterial host cell is from the genus Lactiplantibacillus sp., and in some further embodiments, from the species Lactiplantibacillus pentosus (which was previously referred to as Lactobacillus plantarum or Lactiplantibacillus plantarum). Since the antimicrobial composition is intended to be used in a medium allowing yeast growth and / or yeast fermentation, the antimicrobial composition of the present disclosure does not exhibit a substantial effect on the growth and / or fermentation properties of yeasts. As used in the present disclosure, the expression “does not exhibit a substantial effect on the growth and / or fermentation properties of yeasts” indicates that the presence of the antimicrobial composition in the propagation or fermentation medium does not reduce by more than 25%, 20%, 15%, 10%, 5% or less the ability of a yeast to propagate or to make a fermentation product (when compared to the ability of a yeast in a propagation or fermentation medium lacking the antimicrobial composition). In some embodiments, the presence of the antimicrobial composition in the propagation or in the fermentation medium increases the ability of a yeast to propagate or to make a fermentation product (when compared to the ability of a yeast in a propagation or fermentation medium lacking the antimicrobial composition). The antimicrobial composition of the present disclosure has a pH of between about 7.0 to about 9.0 and, in some embodiments, between about 7.1 and about 8.9, between about 7.2 and about 8.8, between about 7.3 and about 8.7, between about 7.4 and about 8.6 or between about 7.5 and about 8.5. In some specific embodiments, the antimicrobial composition has a pH between about 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.18.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, or 8.9 and about 9.0, 8.9, 8.8, 8.7, 8.6, 8.5, 8.4, 8.3, 8.2, 8.1, 8.0, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7.3, 7.2 or 7.1. As used in the context of the present disclosure, the term “about” indicates that the recited value can vary within a certain range depending on the margin of error of the method or device used to evaluate or measure. A margin of error of 10% is generally accepted. Hops acid Hops acids are obtained from the flowers (“cones”) of the hop plant (Humulus lupulus) and have been a component of human and animal food for centuries. The term "hops acids" as known in the art means the bitter acid components of the hops. Hops acids include alpha hops acids, beta hops acids, their corresponding salts, their corresponding analogs, and derivatives, as well as extracts comprising same. Hops acids can be prepared by extraction and purification from natural hops or by chemical synthesis. For instance, producers of hop extracts isolate the alpha and beta hops acids commercially via various chromatographic techniques and have developed a technique to separate the two acid fractions using liquid carbon dioxide under supercritical conditions. Both alpha and beta hops acid show bacteriostatic activity against Gram-positive bacteria, and this activity has been linked to the prenyl group side chains on both types of hop acids. It was previously reported that stronger bacteriostatic action is associated with a greater number of these prenyl groups. The formulae for alpha hops acids (I) and beta hops acids (II) are the following: There are many analogs of alpha hops acids (also generally referred to as “humulones”) including, but not limited to cohumulones, humulones, prehumulones, posthumulones, adhumulones, and adprehumulones. Embodiments of alpha hops acids analogs can have formula (III): limited to lupulones, colupulones, adlupulones, prelupulones, and postlupulones. The term "hops acid derivatives" and "hops acid analogs" as used herein means compounds that are chemically derived from alpha hops acids, or beta hops acids, either through natural biosynthetic processes or synthetic processes using human intervention. Heating hops acids promotes, amongst other things, thermal isomerization of alpha hops acids into iso alpha hops acids (as depicted below, see Scheme I). Examples of iso alpha hops acids include, but are not limited to, isocohumulone, isohumulone, isoprehumulone, isoposthumulone, isoadhumulone, and isoadprehumulone, Scheme I Individual alpha hops acids give rise to two epimeric iso alpha hops acid derivatives (cis- and trans-). As such, iso alpha hops acids derivatives include, but are not limited, cis-isocohumulone, trans- isocohumulone, cis-isohumulone, trans-isohumulone, cis-isoprehumulone, trans-isoprehumulone, cis- isoposthumulone, trans-isoposthumulone, cis-isoadhumulone, trans-isoadhumulone, cis- isoadprehumulone, and trans-isoadprehumulone. Scheme II provides an embodiment of the epimeric iso alpha hops acids derivatives obtained from the alpha hops acid humulone. Iso alpha hops acid derivatives also include hydrogenated derivatives which include, but are not limited to rhoiso alpha acids, tetrahydroiso alpha acids and hexahydroiso alpha acids. Rhoiso alpha acids include, without limitation, rhoiso cohumulone, rhoiso humulone, rhoiso prehumulone, rhoiso posthumulone, rhoiso adhumulone, and rhoiso adprehumulone. Tetrahydroiso alpha acids include, without limitations, tetrahydroiso cohumulone, tetrahydroiso humulone, tetrahydroiso prehumulone, tetrahydroiso posthumulone, tetrahydroiso adhumulone, and tetrahydroiso adprehumulone. Hexahydroiso alpha acids include, without limitation, hexahydroiso cohumulone, hexahydroiso humulone, hexahydroiso prehumulone, hexahydroiso posthumulone, hexahydroiso adhumulone, and hexahydroiso adprehumulone. Embodiments of hydrogenated derivatives of iso alpha hops acids can have, for example, formulae IV, V or VI (in which R has the same definitions as the R in formula II): The antimicrobial composition of the present disclosure comprises alpha hops acids. For example, the antimicrobial composition of the present disclosure comprises at least one of cohumulone, humulone, prehumulone, posthumulone, adhumulone, adprehumulone as well as derivatives thereof. The cohumulone can be provided, at least in part, as a derivative which include, but is not limited to isocohumulone (cis-isocohumulone, trans-isocohumulone, or mixture thereof) as well as derivatives thereof. The isocohumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso cohumulone, tetrahydroiso cohumulone and hexahydroiso cohumulone. The humulone can be provided, at least in part as a derivative which include, but is not limited isohumulone (cis-isohumulone, trans-isohumulone, or mixture thereof). The isohumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso humulone, tetrahydroiso humulone and hexahydroiso humulone. The prehumulone can be provided, at least in part, as a derivative which include, but is not limited to isoprehumulone (cis-isoprehumulone, trans-isoprehumulone, or mixture thereof). The isoprehumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso prehumulone, tetrahydroiso prehumulone and hexahydroiso prehumulone. The posthumulone can be provided, at least in part, as a derivative which include, but is not limited to isoposthumulone (cis-isoposthumulone, trans-isoposthumulone, or mixture thereof). The isoposthumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso posthumulone, tetrahydroiso posthumulone and hexahydroiso posthumulone. The adhumulone can be provided, at least in part, as a derivative which include, but is not limited to isoadhumulone (cis-isoadhumulone, trans-isoadhumulone, or mixture thereof). The isoadhumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso adhumulone, tetrahydroiso adhumulone and hexahydroiso adhumulone. The adprehumulone can be provided, at least in part as a derivative which include, but is not limited to isoadprehumulone (cis-isoadprehumulone, trans- isoadprehumulone. or mixture thereof). The isoadprehumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso adprehumulone, tetrahydroiso adprehumulone and hexahydroiso adprehumulone. In some embodiments, the hops acid present in the antimicrobial composition consist essentially of alpha hops acids. The expression “hops acid consisting essentially of alpha hops acids” indicate that the antimicrobial composition only includes alpha hops acids as a source of hops acids. In some additional embodiments, the hops acids present in the antimicrobial composition exclude (e.g., do not include) beta hops acids (such as, for example lupulone, colupulone, adlupulone, prelupulone, and postlupulone or derivatives thereof). In some embodiments, the antimicrobial composition can comprise iso alpha acids. Iso alpha acids include, but are not limited to isocohumulone (cis-isocohumulone, trans-isocohumulone, or mixture thereof), isohumulone (cis-isohumulone, trans-isohumulone, or mixture thereof), isoprehumulone (cis- isoprehumulone, trans-isoprehumulone, or mixture thereof), isoposthumulone (cis-isoposthumulone, trans-isoposthumulone, or mixture thereof), isoadhumulone (cis-isoadhumulone, trans- isoadhumulone, or mixture thereof), and isoadprehumulone (cis-isoadprehumulone, trans- isoadprehumulone, or mixture thereof). The isocohumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso cohumulone, tetrahydroiso cohumulone and hexahydroiso cohumulone. The isohumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso humulone, tetrahydroiso humulone and hexahydroiso humulone. The isoprehumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso prehumulone, tetrahydroiso prehumulone and hexahydroiso prehumulone. The isoposthumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso posthumulone, tetrahydroiso posthumulone and hexahydroiso posthumulone. The isoadhumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso adhumulone, tetrahydroiso adhumulone and hexahydroiso adhumulone. The isoadprehumulone can be provided, at least in part, as a derivative which includes, without limitation, rhoiso adprehumulone, tetrahydroiso adprehumulone and hexahydroiso adprehumulone. In some embodiments, the hops acids present in the antimicrobial composition consist essentially of iso alpha hops acids. The expression “hops acids consisting essentially of iso alpha hops acids” indicate that the antimicrobial composition only includes iso alpha hops acids as a source of hops acids. In some embodiments, the antimicrobial composition can comprise tetrahydroiso alpha acids. Tetrahydroiso alpha acids include, but are not limited to tetrahydroiso cohumulone, tetrahydroiso humulone, tetrahydroiso prehumulone, tetrahydroiso posthumulone, tetrahydroiso adhumulone, and tetrahydroiso adprehumulone. In some embodiments, the hops acids present in the antimicrobial composition consist essentially of tetrahydroiso alpha hops acids. The expression “hops acids consisting essentially of tetrahydroiso alpha hops acids” indicate that the antimicrobial composition only includes tetrahydroiso alpha hops acids as a source of hops acids. In some additional embodiments, the antimicrobial composition excludes (e.g., does not include) rhoiso alpha acids or hexohydroiso alpha acids. It will be appreciated that the amount / concentration of alpha hops acids present in the antimicrobial composition can vary, especially in view of the intended use (the type of contamination of the medium, the level of contamination of the medium, the temperature of the medium, the size of the tank holding the medium, etc.). In some embodiments, the alpha hops acids (which can, in some embodiments, be tetrahydroiso alpha acids) can be provided to the medium in the antimicrobial composition to achieve a concentration of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 ppm or more. In some embodiments, the alpha hops acids (which can, in some embodiments be tetrahydroiso alpha acids) can be provided to the medium in the antimicrobial composition to achieve a concentration of at least 5 ppm or more. The antimicrobial composition can be provided in a concentrated form that may require dilution prior to being used. In some embodiments of a concentrated form of the antimicrobial composition, the alpha hops acids (which can, in some embodiments, be tetrahydroiso alpha acids) of the antimicrobial composition can be provided at a concentration of at least about 2,000, 2,100, 2,200, 2,300, 2,400, 2,500 ppm or more. In some additional embodiments of a concentrated form of the antimicrobial composition, the alpha hops acids (which can, in some embodiments, be tetrahydroiso alpha acids) of the antimicrobial composition can be provided at a concentration of at least about 2,500 ppm. Alternatively, the antimicrobial composition can be provided in a more diluted form. In some embodiments of a diluted form of the antimicrobial composition, the alpha hops acids (which can, in some embodiments, be tetrahydroiso alpha acids) of the antimicrobial composition can be provided at a concentration of at most about 2,000, 1,500, 1,000, 750, 500, 250, 100, 90, 80, 70, 60, 50, 40, 30, 20 ppm or less. Nisin composition of the present disclosure also comprises nisin. Nisin is a 34 amino acid- long polycyclic bacteriocin (antibacterial peptide) that is produced by some strains of the lactic acid bacterium Lactococcus lactis, a species that occurs naturally in fermented milk and vegetable products, including silage. Bacteriocins are ribosomally-derived proteins that many bacteria produce naturally to inhibit the growth of other bacteria. Nisin is a member of the lantibiotic class of bacteriocins, and displays broad-spectrum inhibition against Gram-positive bacteria, but has little to no activity against Gram-negatives, yeast, or molds. Of particular interest is the fact that nisin’s spectrum of inhibition enables its application to control contamination by lactic acid bacteria in fermentations where Saccharomyces cerevisiae is the primary biocatalyst. The nisin that is included in the antimicrobial composition can be nisin A, nisin Z, nisin J, nisin H, nisin Q or nisin U as well as any combinations thereof. In an embodiment, the antimicrobial composition comprises nisin A which has the amino acid sequence of SEQ ID NO: 1 (ITSISLCTPGCKTGALMGCNMKTATCHCSIHVSK) or is a variant of the amino acid sequence of SEQ ID NO: 1 (retaining, at least in part, the biological activity of nisin). In an embodiment, the antimicrobial composition comprises nisin Z which has the amino acid sequence of SEQ ID NO: 2 (ITSISLCTPGCKTGALMGCNMKTATCNCSIHVSK) or is a variant of the amino acid sequence of SEQ ID NO: 2 (retaining, at least in part, the biological activity of nisin Z). A nisin variant comprises at least one amino acid difference when compared to the amino acid sequence of the wildtype nisin. In some embodiments, the variant nisin comprises two, three, four, five or more amino acid differences when compared to the amino acid sequence of the wildtype nisin. The nisin “variants” have at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identity to the wildtype nisin described herein. The term “percent identity”, as known in the art, is a relationship between two or more sequences, as determined by comparing the sequences. The level of identity can be determined conventionally using known computer programs. Identity can be readily calculated by known methods, including but not limited to those described in: Computational Molecular Biology (Lesk, A. M., ed.) Oxford University Press, NY (1988); Biocomputing: Informatics and Genome Projects (Smith, D. W., ed.) Academic Press, NY (1993); Computer Analysis of Sequence Data, Part I (Griffin, A. M., and Griffin, H. G., eds.) Humana Press, NJ (1994); Sequence Analysis in Molecular Biology (von Heinje, G., ed.) Academic Press (1987); and Sequence Analysis Primer (Gribskov, M. and Devereux, J., eds.) Stockton Press, NY (1991). Preferred methods to determine identity are designed to give the best match between the sequences tested. Methods to determine identity and similarity are codified in publicly available computer programs. Sequence alignments and percent identity calculations may be performed using the Megalign program of the LASERGENE bioinformatics computing suite (DNASTAR Inc., Madison, Wis.). Multiple alignments of the sequences disclosed herein were performed using the Clustal method of alignment (Higgins and Sharp (1989) CABIOS. 5:151-153) with the default parameters (GAP PENALTY=10, GAP LENGTH PEN ALT Y= 10). Default parameters for pairwise alignments using the Clustal method were KTUPLB 1, GAP PENALTY=3, WINDOW=5 and DIAGONALS SAVED=5. The nisin variants exhibit the biological activity (antimicrobial activity) associated with the wildtype nisin. In an embodiment, the nisin variant exhibits at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% of the biological activity of the wildtype nisin. In some embodiments, the biological activity of the nisin variant is higher than the biological activity of the wildtype nisin. The biological activity of the wildtype and nisin variants can be determined by methods and assays known in the art. The variant can be a fragment of the wildtype nisin or fragment of a nisin variant. A fragment comprises at least one less amino acid residue when compared to the amino acid sequence of the wildtype nisin or the nisin variant. In some embodiments, nisin “fragments” have at least 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 2930, 31, 32, or 33 consecutive amino acids of the wildtype nisin or the nisin variant. In some embodiments, the fragment corresponds to the wildtype nisin or the nisin variant to which the signal sequence was removed. In some embodiments, the “fragment” has at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9% identity to the wildtype nisin or to the nisin variant. The fragments of the wildtype nisin or of the nisin variants exhibit the biological activity (antimicrobial activity) of the wildtype nisin or of the nisin variant. In an embodiment, the fragment enzyme exhibits at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% of the biological activity of the heterologous enzyme or variant thereof. It will be appreciated that the amount / concentration of nisin present in the antimicrobial composition can vary, especially in view of the intended use (the type of contamination of the medium, the level of contamination of the medium, the temperature of the medium, the size of the tank holding the medium, etc.). In some embodiments, nisin (which can, in some embodiments be nisin Z) can be provided to the medium in the antimicrobial composition to achieve a concentration of at least 1, 2, 3, 4, 5 ppm or more. In some embodiments, the nisin (which can, in some embodiments nisin Z) can be provided to the medium in the antimicrobial composition to achieve a concentration of at least 1 ppm or more. The antimicrobial composition can be provided in a concentrated form that may require dilution prior to being used. In some embodiments of a concentrated form of the antimicrobial composition, the nisin (which can, in some embodiments, be nisin Z) of the antimicrobial composition can be provided at a concentration of at least 100, 110, 120, 130, 140, 140, 160, 170, 180, 190, 200 ppm or more. In some additional embodiments of a concentrated form of the antimicrobial composition, the nisin (which can, in some embodiments, be nisin Z) of the antimicrobial composition can be provided at a concentration of at least about 100 ppm. Alternatively, the antimicrobial composition can be provided in a more diluted form. In some embodiments of a diluted form of the antimicrobial composition, the nisin (which can, in some embodiments, be nisin Z) of the antimicrobial composition can be provided at a concentration of at most 100, 90, 80, 70, 60, 50, 40, 30, 20 ppm or less. Antimicrobial composition and process for making same The present disclosure provides an antimicrobial composition comprising alpha hops acids and nisin which exhibit an unexpected advantage of having a higher antimicrobial activity when being admixed together prior to being added to a medium (when compared to the same amount of alpha hops acids and nisin added separately to the medium). The expression “antimicrobial composition” and the term “blend” are used herein interchangeably throughout the present disclosure. The antimicrobial activity of a composition can be determined by the person skilled in the art in various ways. In some embodiments, it is possible to determine the antimicrobial activity of a composition or a component of a composition by adding same to a medium which has been, is simultaneously and / or will be supplemented with, an indicator strain (e.g., an indicator bacterial strain). By monitoring the growth of the indicator strain in the medium, it is possible to ascertain if the presence of the antimicrobial composition or its components influence the growth rate / viability of the indicator strain (which are proxies for the bacteriostatic / bactericidal activities of the composition or its components). In some additional embodiments, the growth and / or viability of the indicator strain is sensitive to the presence of the components of the antimicrobial composition. The indicator strain may be a single genus / species of bacteria or may be a combination of different genus / species bacteria. In some specific embodiments, the indicator strain comprises bacteria from the genus Lacticaseibacillus sp., and in some further embodiments, from the species Lacticaseibacillus paracasei. In some specific embodiments, the indicator strain comprises bacteria from the genus Lactiplantibacillus sp., and in some further embodiments, from the species Lactiplantibacillus plantarum. In some specific embodiments, the indicator strain comprises bacteria from the genus Limosilactobacillus sp., and in some further embodiments, from the species Limosilactobacillus fermentum. In some specific embodiments, the indicator strain comprises bacteria from the genus Lactobacillus sp., and in some further embodiments, from the species Lactobacillus amylovorus. Alternatively, it is possible to approximate the antimicrobial activity of the composition by determining the amount of undegraded nisin present in the antimicrobial composition. As it will be appreciated from the examples, during storage, nisin can be degraded which can, ultimately reduce the antimicrobial properties of the composition. As such, by measuring the amount of nisin present in the antimicrobial composition prior to and during storage antimicrobial composition, it is possible to approximate the antimicrobial activity of the composition. As used in the context of the present disclosure, an antimicrobial composition is considered to “retain activity” during storage when at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% of the nisin that was included in the initial antimicrobial composition (prior to storage) remains present (in an undegraded form) in the stored antimicrobial composition. Alternatively, an antimicrobial composition is considered to “retain activity” during storage when the antimicrobial properties of the antimicrobial composition in a medium are higher than the antimicrobial activities of alpha hops acids and nisin added separately to a corresponding control medium. It will be understood that the period at which the antimicrobial composition will retain its activity will depend at least in part, on the temperature at which it has been stored. In some embodiments, the antimicrobial composition will retain some of its activity, when stored at a temperature of about 4°C, for at least about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130 or 140 days. In some embodiments, the antimicrobial composition will retain some of its activity, when stored at a temperature of about 21°C, for at least about 10, 20, 30, 40 or 50 days. In some embodiments, the antimicrobial composition will retain some of its activity, when stored at a temperature of about 37°C, for at least 10, 20 or 30 days. In embodiments of the antimicrobial composition of the present disclosure, the concentration of alpha hops acids (which can be tetrahydro isomerized alpha acids) is higher than the concentration of nisin (which can be nisin Z). In some embodiments, the ratio of the parts per million (ppm) of alpha hops acids (which can be tetrahydro isomerized alpha acids) to the ppm of nisin (which can be nisin Z) can be 1.1:1, 1.2: 1, 1.3: 1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2: 1, 2.3: 1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2: 3, 3.3: 1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1, 4.1:1, 4.2: 1, 4.3: 1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1, 5:1, 5.1:1, 5.2: 1, 5.3: 1, 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1, 6:1, 6.1:1, 6.2: 1, 6.3: 1, 6.4:1, 6.5:1, 6.6:1, 6.7:1, 6.8:1, 6.9:1, 7:1, 7.1:1, 7.2: 1, 7.3: 1, 7.4:1, 7.5:1, 7.6:1, 7.7:1, 7.8:1, 7.9:1, 8:1, 8.1:1, 8.2: 1, 8.3: 1, 8.4:1, 8.5:1, 8.6:1, 8.7:1, 8.8:1, 8.9:1, 9:1, 9.1:1, 9.2: 1, 9.3: 1, 9.4:1, 9.5:1, 9.6:1, 9.7:1, 9.8:1, 9.9:1, or 10:1. The antimicrobial composition of the present disclosure can include, in some embodiments, a buffer. In some embodiments, the buffer can be used to facilitate the method of making the antimicrobial composition and / or to improve the antimicrobial properties of the composition during storage. Without wishing to be bound to theory, the presence of a buffer in the antimicrobial composition can limit or delay the acidification of the antimicrobial composition during storage. In some embodiments of the antimicrobial composition, it was shown that acidification of a buffer-less antimicrobial composition can occur during storage which ultimately reduced the antimicrobial activity of the stored antimicrobial composition. By preventing acidification of the antimicrobial composition during storage, its antimicrobial properties can be maintained for a longer period during storage. The antimicrobial composition can therefore comprise a buffer to stabilize the blend and help retain the antimicrobial properties of its components. Any buffering system that is able to maintain a composition in a pH range between about 7.0 to about 9.0 can be used in the antimicrobial composition of the present disclosure. In some embodiment, the pKa of the buffer that can be included in the antimicrobial composition is between about 7.0 and about 9.0. For example, the buffer can be potassium phosphate, ammonium chloride, BES (N,N-Bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, N,N-Bis(2- hydroxyethyl)taurine), MOBS (4-(N-Morpholino)butanesulfonic acid), TEA (2,2′,2′′-Nitrilotriethanol, Tris(2-hydroxyethyl)amine), HEPBS (N-(2-Hydroxyethyl)piperazine-N′-(4-butanesulfonic acid)), TABS (N-tris(Hydroxymethyl)methyl-4-aminobutanesulfonic acid), MOPS (3-(N- Morpholino)propanesulfonic acid, 4-Morpholinepropanesulfonic acid), BEC, phosphoric acid, TES (2-[(2-Hydroxy-1,1-bis(hydroxymethyl)ethyl)amino]ethanesulfonic acid, N- [Tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid,), HEPES (4-(2-hydroxyethyl)-1- piperazineethanesulfonic acid), DIPSO (3-(N,N-Bis[2-hydroxyethyl]amino)-2- hydroxypropanesulfonic acid, N,N-Bis(2-hydroxyethyl)-3-amino-2-hydroxypropanesulfonic acid), TAPSO (2-Hydroxy-3-[tris(hydroxymethyl)methylamino]-1-propanesulfonic acid, N- [Tris(hydroxymethyl)methyl]-3-amino-2-hydroxypropanesulfonic acid), triethanolamine (YEA), N- ethylmorpholine, POPSO (Piperazine-1,4-bis(2-hydroxypropanesulfonic acid) dihydrate, Piperazine- N,N′-bis(2-hydroxypropanesulfonic acid)), EPPS or HEPPS (4-(2-Hydroxyethyl)-1- piperazinepropanesulfonic acid, 4-(2-Hydroxyethyl)piperazine-1-propanesulfonic acid, N-(2- Hydroxyethyl)piperazine-N′-(3-propanesulfonic acid)), HEPPSO (2-Hydroxy-3-(4-(2- hydroxyethyl)piperazin-1-yl)propane-1-sulfonic acid), tris, tricine, glycylglycine (also referred to as diglycine), bicine, TAPS (N-[Tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid, [(2- Hydroxy-1,1-bis(hydroxymethyl)ethyl)amino]-1-propanesulfonic acid), morpholine, N- methyldiethanolamine, AMPD (2-amino-2-methyl-1,3-propanediol), and / or diethanolamine. In some embodiments, the buffer that can be included in the antimicrobial composition can have the generally recognized as safe (GRAS) status. For example, the buffer included in the antimicrobial composition can be approved to be used in food and / or feed. It is to be understood that any suitable buffer that does not show any deleterious effect on the formulation process, antimicrobial composition stability, or antimicrobial activity may be used while still remaining within the scope of the invention. In some embodiments, the antimicrobial composition may comprise a potassium phosphate buffer, a HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer, an ammonium chloride buffer, a glycylglycine buffer or a combination thereof. In some specific embodiments, the antimicrobial composition may comprise a HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer. In some specific embodiments, the antimicrobial composition may comprise an ammonium chloride buffer. In some specific embodiments, the antimicrobial composition may comprise a glycylglycine buffer. The concentration of the buffer in the medium can be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mM or more. When potassium phosphate is used as the buffer, its concentration in the antimicrobial composition can be of at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mM or more. When HEPES is used as the buffer, its concentration in the antimicrobial composition can be of at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50 mM or more. When ammonium chloride is used as the buffer, its concentration in the antimicrobial composition can be of at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50 mM or more. When glycylclycine is used as the buffer, its concentration in the antimicrobial composition can be of at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50 mM or more. In some embodiments, the antimicrobial composition has a maximal amount of sodium ions of 60 mM or less. As shown in the examples below, the concentration of alpha hops acid in the antimicrobial composition can be increased by limiting the sodium content in the nisin preparation. For example, the antimicrobial composition can have a maximal amount of sodium ions equal to or less than 60, 50, 40, 30, 20, 10 mM or less. In some specific embodiments, the antimicrobial composition does not include sodium ions. The antimicrobial composition can be provided in a liquid form, such as, for example, as an aqueous suspension or solution. Each of the components of the antimicrobial composition can be provided as a solution or a suspension. In some embodiments, the antimicrobial composition can be provided in a concentrated dose that requires dilution before adding it to the medium. Alternatively, the antimicrobial composition can be provided in a “ready-to-use” form that does not require dilution before adding it to the medium. The antimicrobial composition of the present disclosure can also include, in some embodiments, a stabilizer. In some embodiments, the stabilizer can be used to facilitate the method of making the antimicrobial composition and / or to improve the antimicrobial properties of the composition during storage. Without wishing to be bound to theory, the presence of a stabilizer in the antimicrobial composition can limit or delay the precipitation of the antimicrobial composition during storage. In some embodiments of the antimicrobial composition, it was shown that precipitation of a stabilizer- less antimicrobial composition can occur during storage that may ultimately reduce the antimicrobial activity of the stored antimicrobial composition. By preventing precipitation of the antimicrobial composition during storage, its antimicrobial properties can be maintained for a longer period during storage. The antimicrobial composition can therefore comprise a stabilizer to stabilize the blend and help retain the antimicrobial properties of its components. Any stabilizer system that is able to prevent precipitation without affecting the antimicrobial activity can be used in the antimicrobial composition of the present disclosure. For example, the stabilizer can be xanthan gum, guar gum, locust bean gum, starch, maltodextrin, pectin, agar, carrageenan, sodium pyrophosphate, collagen, lecithin, or a combination thereof. In some embodiments, the stabilizer that can be included in the antimicrobial composition can have the generally recognized as safe (GRAS) status. For example, the stabilizer included in the antimicrobial composition can be approved to be used in food and / or feed. It is to be understood that any suitable stabilizer that does not show any deleterious effect on the formulation process, antimicrobial composition stability, or antimicrobial activity may be used while still remaining within the scope of the invention. In some embodiments, the antimicrobial composition may comprise xanthan gum, guar gum, locust bean gum, starch, maltodextrin, pectin, agar, carrageenan, sodium pyrophosphate, collagen, lecithin, or a combination thereof. In some specific embodiments, the antimicrobial composition may comprise xanthan gum. The concentration of the stabilizer in the medium can be at least about 0.01, 0.02, 0.03, 0.04, 0.05, 0.075, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10% or more. When xanthan gum is used as the stabilizer, its concentration in the antimicrobial composition can be of at least about 0.03, 0.04, 0.05, 0.075, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10% or more. It is to be understood that several other additives well known in the art could be added to the antimicrobial composition to help solubilize the hops acid and / or nisin in the presence of higher concentrations of sodium while still remaining within the scope of the invention, as selecting a suitable additive would fall well within the reach of the person of ordinary skill in the art. For example, additional of stabilizers, excipients or other additives may be added to the composition to help stabilize the ingredients, thereby helping to retain the antimicrobial properties of the blend. It is also to be understood that the additives could be added to the antimicrobial composition to help solubilize the hops acid and / or nisin even at low concentrations or in the absence or of sodium while still remaining within the scope of the invention. The present disclosure also provides a process for making the antimicrobial composition described herein. The process comprises combining an alpha hops acid solution with a nisin solution or a nisin suspension. The nisin solution / suspension used to prepare the antimicrobial composition (prior to the addition of the alpha hops acids) has a pH of between about 7.0 to about 9.0. In the process of the present disclosure, it is important that the alpha hops acids be added to a nisin solution / suspension that already has a pH of between about 7.0 to about 9.0. As it will be shown in the Examples section, adding alpha hops acids to an acidic solution comprising nisin does not provide satisfactory results. The process of the present disclosure can comprise, in some embodiments, a step of providing the nisin solution / suspension having a pH between about 7.0 and about 9.0. For example, the nisin solution / suspension can be obtained by adding nisin (which can be in a powdered form or as a concentrated solution) to water to obtain a first solution / suspension and then adjusting the pH of the first solution / suspension between about 7.0 and about 9.0. A base, a buffer or a combination of both a base and a buffer can be used to adjust the pH of the first solution / suspension. In some embodiments, the pH of the first solution / suspension can be adjusted with a base and afterwards stabilized with a buffer. In another example, the nisin solution / suspension can be obtained by providing a second solution / suspension comprising nisin (which in some embodiments can be acidic) and adjusting the pH of the second solution / suspension between about 7.0 and about 9.0. A base, a buffer or a combination of both a base and a buffer can be used to adjust the pH of the second solution / suspension. In some embodiments, the pH of the second solution / suspension can be adjusted with a base and afterwards stabilized with a buffer. In still another example, the nisin solution / suspension can be obtained by adding nisin (which can be in a powdered form or as a concentrated solution) to a third solution / suspension having a pH between about 7.0 to about 9.0. Prior to the addition of the nisin, the pH of the third solution / suspension can be adjusted using a base and / or a buffer. A base, a buffer or a combination of both a base and a buffer can be used to adjust the pH of the third solution / suspension. In some embodiments, the pH of third solution / suspension can be adjusted with a base and afterwards stabilized with a buffer. Bases that can be used to adjust the pH of the first, second and / or third solution / suspension include, without limitations, sodium hydroxide, potassium hydroxide, calcium carbonate, sodium carbonate and ammonium hydroxide. The process of the present disclosure can comprise, in some embodiments, a step of adding a stabilizer. The stabilizer can be added to the alpha hops acid solution or to the nisin solution, before or after adjusting the pH. The stabilizer can also be added to the antimicrobial composition as the last step of the process before storage. The stabilizer can also be added to water as the first step of the process, before adding nisin. In an embodiment, the nisin solution / suspension can be obtained by first adding a stabilizer to water and then adding nisin (which can be in a powdered form or as a concentrated solution) to obtain a first solution / suspension comprising the stabilizer and nisin, and then adjusting the pH of the first solution / suspension to between about 7.0 and about 9.0 with a base and / or a buffer. A base, a buffer or a combination of both a base and a buffer can be used to adjust the pH of the first solution / suspension. In another embodiment the stabilizer can be added in the first solution. In another embodiment, the stabilizer can be added to a second solution / suspension comprising nisin before or after adjusting the pH to between about 7.0 and about 9.0. For example, the pH of the second solution / suspension comprising nisin can be adjusted to between about 7.0 and about 9.0 with a base and / or a buffer and the stabilizer subsequently added to the pH-adjusted second solution / suspension comprising nisin. A base, a buffer or a combination of both a base and a buffer can be used to adjust the pH of the second solution / suspension. In yet another embodiment, the stabilizer can be added to a third solution which has been pH-adjusted to between about 7.0 and 9.0 with a base and / or a buffer before adding nisin to the third solution. A base, a buffer or a combination of both a base and a buffer can be used to adjust the pH of the third solution / suspension. In some embodiments, the pH of the first, second and / or third solution / suspension can be adjusted with a base and afterwards stabilized with a buffer. In another embodiment, the stabilizer can be added to the antimicrobial composition. In yet another embodiment, the stabilizer can be added to the source of alpha hops acid and then mixed with the nisin solution / suspension. Once the nisin solution / suspension has been obtained, it can be mixed with the source of alpha hops acid. In some embodiments, the source of alpha hops acids is iso hops acids. In yet another embodiment, the source of alpha hops acids is tetrahydroiso alpha acids. The alpha hops acid solution / suspension may be obtained commercially in solution or may be prepared by dissolving alpha hops acid to a desired concentration. Since alpha hops acids are usually provided in a basic solution (so as to maximize their stability), there is usually no need to adjust the pH of the alpha hops acids solution prior to adding them to the nisin solution. However, in instances in which alpha hops acids are provided in solution having a pH below about 7.0 or above about 9.0, the process can include an optional step of adjusting the pH of the alpha hops acids solution to between about 7.0 and about 9.0. This can be done, for example, with a base and / or a buffer (which may be the same or different than the one used to provide the nisin solution / suspension). Optionally, after the alpha hops acids solution have been combined with the nisin solution / suspension, the pH of the resulting mixture can be adjusted or re-adjusted to a pH of between about 7.0 and about 9.0 to provide the antimicrobial composition. In some embodiments, this pH adjustment step can be done by using a base, a buffer or a combination of both (which may be the same or different than the one used to provide the nisin solution / suspension or the alpha hops acids). In some embodiments, the pH of the antimicrobial composition can be adjusted with a base and afterwards stabilized with a buffer. Bases that can be used to adjust the pH of the antimicrobial composition include, without limitations, sodium hydroxide, potassium hydroxide, calcium carbonate, sodium carbonate and ammonium hydroxide. In some embodiments, the process can also include adding excipients or other additives may be added to the antimicrobial composition to help stabilize the ingredients, limit sedimentation of the solution, and / or increase or prolong the antimicrobial properties of the blend. Depending on the required need, the process may further comprise storing the antimicrobial composition at a temperature of between about 2°C to about 10°C. In some additional embodiments, the process may further comprise determining the antimicrobial activity of the antimicrobial composition before and / or after storing the antimicrobial composition at a temperature of between about 2°C to about 10°C. This determination may be done after 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 days or more. Determining the antimicrobial activity of the antimicrobial may be performed as a quality assurance after a batch has been produced and following storage before usage and / or shipment to determine whether antimicrobial activity of the composition has been lost. Method of preventing or limiting microbial contamination in a medium The present disclosure provides a method of preventing or limiting microbial contamination in a medium. Broadly, the method comprises contacting the antimicrobial composition described herein with a medium. In some embodiments, the medium is intended for the propagation and / or the fermentation by a fungus, such as a yeast. The method includes adding a single dose of the antimicrobial composition described herein or a plurality of doses of the antimicrobial composition described herein. In some embodiments, the medium can be suspected to be contaminated or at risk of being contaminated. In other embodiments, the medium can be known to be contaminated (and the method can optionally include a step of determining qualitatively or quantitatively the contamination). In some embodiments, the medium is at risk of being contaminated and the method is performed so as to limit or delay contamination. The method can be used to prevent or limit contamination caused by bacteria (bacterial contamination). The method can be used to prevent or limit contamination caused by fungi (fungal contamination). In some embodiments, the method can include a step of determining the presence / absence or amount of contamination prior to contacting the medium with the antimicrobial composition. Alternatively or in combination, the method can include a step of determining the presence / absence or amount of contamination after the medium has been contacted with the antimicrobial composition. This latter determination step can be used to determine if the initial dose of the antimicrobial composition was sufficient to prevent or limit microbial contamination and, if not, it can inform that additional dose(s) can or should be added. Advantageously, the method described herein can be used to limit, reduce or avoid the use of antibiotics. The present disclosure also provides a medium comprising the antimicrobial composition as described herein (which could have been provided as a single dose or as a plurality of doses in the medium). Any other medium prone to microbial contamination (such as bacterial contamination) or that could otherwise benefit from controlling microbial contamination (such as bacterial contamination) is contemplated and would fall well within the scope of the present disclosure. The medium could be a propagation medium, which could, in some embodiments be a yeast propagation medium. The medium could be a liquefaction medium which could, in some embodiments, be used in a following fermentation. The medium could be a fermentation medium, which could be, in some embodiments, be a yeast fermentation medium. The medium could be food or a food ingredient, which could be a food or a food ingredient obtained from the fermentation of a yeast. The medium could be feed or a feed ingredient, which could be a feed or a feed ingredient obtained from the fermentation of a yeast. The medium could be a beverage (including an alcoholic beverage) or a beverage ingredient (including an alcoholic beverage ingredient), which could be a beverage or a beverage ingredient obtained from the fermentation of a yeast. In some embodiments, the medium that is contacted with the antimicrobial composition can be used to make a food, a feed and / or a beverage. According to an embodiment, the method further comprises, before adding the antimicrobial composition to a medium, diluting the antimicrobial composition to a desired concentration. Since bacterial contamination, especially lactic acid bacteria contamination, can cause the accumulation of organic acids in the medium, the method of the present disclosure can be used to prevent or limit the acidification of the medium. In this specific embodiment, the method can optionally include a step of determining the pH of the medium prior and / or after the addition of the antimicrobial composition to the medium. In an embodiment, the antimicrobial composition is used to substantially limit the acidification of the medium. As indicated above, the antimicrobial composition can be added to a propagation medium to prevent or limit microbial contamination of the propagation medium. A “propagation medium” refers to a medium allowing the accumulation of biomass of a target microorganism (which can be a yeast). A microbial contamination in a propagation medium refers to a microorganism (which can be a lactic acid bacteria) that is not the target microorganism and that, in some embodiments, whose presence can reduce the accumulation of the target microorganism. In some embodiments, during propagation, the target microorganism is placed in contact with a source of metabolizable carbon sources which can include, for example, C5 carbohydrates or C6 carbohydrates (which can include, for example) glucose, fructose, glycerol), or a combination thereof which can optionally be supplemented with the antimicrobial composition. In an embodiment, the propagation is performed using a propagation medium comprising glucose, such as, for example, molasses (which can be supplemented with the antimicrobial composition). In a specific embodiment, during propagation, the propagation medium comprises glucose as the sole source of metabolizable carbohydrate (which can be supplemented with the antimicrobial composition). In another specific embodiment, the propagation medium comprises glycerol as the sole source of metabolizable carbohydrate (which can be supplemented with the antimicrobial composition). In still another embodiment, the propagation medium comprises fructose as the sole source of metabolizable carbohydrate (which can be supplemented with the antimicrobial composition). In some embodiments, the propagation is performed as a continuous fermentation. In alternative embodiments, the propagation is performed as a batch fermentation. In yet further embodiments, the propagation is performed as a fed-batch fermentation. The propagation can, at least in part, be conducted in aerobic conditions. In some embodiments, the target microorganism (which can be Saccharomyces cerevisiae) can be conducted according to a traditional baker’s yeast production method. The propagation can be a continuous method, a batch method or a fed-batch method. The propagation medium can comprise a carbon source (such as, for example, molasses, sucrose, glucose, dextrose syrup, ethanol, corn, glycerol, corn steep liquor and / or a lignocellulosic biomass), a nitrogen source (such as, for example, ammonia or another inorganic source of nitrogen), a phosphorous source (such as, for example, phosphoric acid or another inorganic source of phosphorous), and optionally the antimicrobial composition. The propagation medium can further comprise additional micronutrients such as vitamins and / or minerals to support the propagation of the propagating microorganism. In the traditional baker’s yeast production method, the target microorganism is placed in a propagation medium which can, in some embodiments, allow for a specific growth rate of 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16 or 0.15 h-1or less. In order to limit the growth rate of the target microorganism, in some embodiments, the method can further comprise controlling the addition of nutriments, such as carbohydrates. Limiting the growth rate of the target microorganism during propagation can be achieved by maintaining the concentration of carbohydrates below 0.1, 0.01, 0.001 or 0.0001 weight % with respect to the volume of the propagation medium. Controlling the concentration of the carbohydrates of the propagation medium can be done by various means known in the art and can involve sampling the propagation medium at various intervals, determining the carbohydrate concertation, alcohol concentration and / or gas (CO2) concentration in those samples and adding or refraining from adding, if necessary additional carbohydrates in the propagation medium to accelerate or decelerate the growth of the target microorganism. In some embodiments, the propagation provides for adding nitrogen and / or phosphorous to match / support the growth rate of the target microorganism. The traditional baker’s yeast production method is preferably conducted under high aeration conditions. For example, in some embodiments, the method can include controlling the aeration of the vessel to achieve a specific aeration rate, for example, of at least 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2 or 1.3 air volume / vessel volume / minute. The traditional baker’s yeast production method can be conducted at a specific pH and / or a specific temperature which is optimal for the growth and viability of the target microorganism. As such, in embodiments in which the target yeast is from the genus Saccharomyces, the method can comprise controlling the pH of the propagation medium to between about 3.0 to about 6.0, about 3.5 to about 5.5 or about 4.0 to about 5.5. In a specific embodiment, the pH is controlled at about 4.5. In another example, in embodiments in which the target yeast is from the genus Saccharomyces, the method can comprise controlling the temperature of the propagation medium between about 20°C to about 40°C, about 25°C to about 30°C or about 30°C to about 35°C. In a specific embodiment, the temperature is controlled at between about 30°C to about 35°C (32°C for example). At the end of the traditional baker’s yeast production method, a specific concentration can be sought or achieved. In some embodiments, the concentration of the propagated target microorganism in the propagation medium is at least about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 or more weight % with respect to the volume of the propagation medium. In a specific embodiment in which the target microorganism is propagated using a fed-batch method, the concentration of the propagated target microorganism in the propagation medium is at least about 0.25 weight % with respect to the volume of the propagation medium. After propagation, the propagated target microorganism can be used in a subsequent process (which can include a fermentation process) to make a food / a feed / a beverage, a food / a feed / a beverage ingredient, a food / a feed / a beverage additive. As indicated above, the antimicrobial composition can be added to a fermentation medium to prevent or limit microbial contamination of the propagation medium. A “fermentation medium” refers to a medium allowing the production of one or more fermentation products from a target microorganism (which can be a yeast). A microbial contamination in a fermentation medium refers to a microorganism (which can be a lactic acid bacteria) that is not the target microorganism and that, in some embodiments, whose presence can reduce the production of the one or more fermentation products from the target microorganism. In some embodiments, the fermentation medium can be inoculated with a target microorganism that has been propagated in a propagation medium comprising the antimicrobial composition. In some embodiments, the antimicrobial composition can be added to a liquefaction medium. As used herein, a “liquefaction medium” or “slurry” (when the biomass comprises corn) refers to a medium which is intended to be treated in order to render more easily fermentable by a target microorganism (like a fermenting yeast for example). In some embodiments, the liquefaction medium is mechanically treated to reduce the size of its particles of the medium. In such embodiment, the liquefaction medium is referred to as a raw liquefaction medium. In other embodiments, the liquefaction medium is thermally and enzymatically treated to cause hydrolysis (e.g., the liquefaction) of starch it contains. In such embodiment, after the liquefaction step, an hydrolyzed liquefaction medium will be obtained. Prior to liquefaction, the liquefaction medium can comprise starch (in a gelatinized or raw form). In some embodiments, the liquefaction medium is derived from a slurry such as a corn slurry (in a gelatinized or raw form). The starch present in the liquefaction medium can be provided in a raw form (e.g., non-gelatized) or a gelatinized form. The liquefaction medium or the slurry can be provided from various biomass sources. For example, the biomass from which the mass can be obtained can include, but is not limited to, starch, sugar and lignocellulosic materials. Starch materials can include, but are not limited to, slurries such as corn, wheat, rye, barley, rice, or milo. Sugar materials can include, but are not limited to, sugar beets, artichoke tubers, sweet sorghum, molasses or cane. The terms “lignocellulosic material”, “lignocellulosic substrate” and “cellulosic biomass” mean any type of biomass comprising cellulose, hemicellulose, lignin, or combinations thereof, such as but not limited to woody biomass, forage grasses, herbaceous energy crops, non-woody-plant biomass, agricultural wastes and / or agricultural residues, forestry residues and / or forestry wastes, paper-production sludge and / or waste paper sludge, waste -water-treatment sludge, municipal solid waste, corn fiber from wet and dry mill corn ethanol plants and sugar-processing residues. The terms “hemicellulosics”, “hemicellulosic portions” and “hemicellulosic fractions” mean the non-lignin, non-cellulose elements of lignocellulosic material, such as but not limited to hemicellulose (i.e., comprising xyloglucan, xylan, glucuronoxylan, arabinoxylan, mannan, glucomannan and galactoglucomannan), pectins (e.g., homogalacturonans, rhamnogalacturonan I and II, and xylogalacturonan) and proteoglycans (e.g., arabinogalactan-protein, extensin, and pro line -rich proteins). In a non-limiting example, the lignocellulosic material can include, but is not limited to, woody biomass, such as recycled wood pulp fiber, sawdust, hardwood, softwood, and combinations thereof; grasses, such as switch grass, cord grass, rye grass, reed canary grass, miscanthus, or a combination thereof; sugar-processing residues, such as but not limited to sugar cane bagasse; agricultural wastes, such as but not limited to rice straw, rice hulls, barley straw, corn cobs, cereal straw, wheat straw, canola straw, oat straw, oat hulls, and corn fiber; stover, such as but not limited to soybean stover, corn stover; succulents, such as but not limited to, agave; and forestry wastes, such as but not limited to, recycled wood pulp fiber, sawdust, hardwood (e.g., poplar, oak, maple, birch, willow), softwood, or any combination thereof. Lignocellulosic material may comprise one species of fiber; alternatively, lignocellulosic material may comprise a mixture of fibers that originate from different lignocellulosic materials. Other lignocellulosic materials are agricultural wastes, such as cereal straws, including wheat straw, barley straw, canola straw and oat straw; corn fiber; stovers, such as corn stover and soybean stover; grasses, such as switch grass, reed canary grass, cord grass, and miscanthus; or combinations thereof. It will be appreciated that suitable lignocellulosic material may be any feedstock that contains soluble and / or insoluble cellulose, where the insoluble cellulose may be in a crystalline or non-crystalline form. In various embodiments, the lignocellulosic biomass comprises, for example, wood, corn, corn stover, sawdust, bark, molasses, sugarcane, leaves, agricultural and forestry residues, grasses such as switchgrass, ruminant digestion products, municipal wastes, paper mill effluent, newspaper, cardboard or combinations thereof. Paper sludge is also a viable feedstock for lactate or acetate production. Paper sludge is solid residue arising from pulping and paper-making, and is typically removed from process wastewater in a primary clarifier. The cost of disposing of wet sludge is a significant incentive to convert the material for other uses, such as conversion to ethanol. Processes provided by the present invention are widely applicable. Moreover, the fermentation products may be used to produce ethanol or higher value-added chemicals, such as organic acids, aromatics, esters, acetone and polymer intermediates. In some embodiments, in order to favor or optimize the hydrolysis of starch during liquefaction process, it is possible to include, one or more further exogenous enzyme having amylolytic activity in the liquefaction medium or slurry. In some embodiments, the antimicrobial composition is contacted with a liquefaction medium or a slurry which has not been submitted to a heat treatment step (and in some embodiments which is not intended to be submitted to a heat treatment step). In some embodiments, the antimicrobial composition is contacted with a liquefaction medium or a slurry which has not yet been submitted to a heat treatment step but is intended to be submitted to such heat treatment step. In other embodiments, the antimicrobial composition is contacted with a liquefaction medium or a slurry which has already been submitted to a previous heat treatment step. In additional embodiments, the antimicrobial composition is contacted with a liquefaction medium or a slurry before and after it has already been submitted to a heat treatment step. In embodiments in which liquefaction includes a heat treatment of the liquefaction medium, the heat treatment step can include submitting the liquefaction medium (which may or may not include the antimicrobial composition) to a liquefaction temperature and for a liquefaction time period. In some embodiments, the liquefaction temperature is at least about 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 95°C, 100°C, 105°C or more can be used. In some further embodiments, the liquefaction temperature is between about 60°C to 85°C. In some further embodiments, the liquefaction temperature is between about 70°C to 75°C. In some further embodiments, the liquefaction temperature is between about 80°C to 85°C. When the liquefaction temperature is between about 60°C to 85°C it can be maintained for a liquefaction time of about 60 minutes or more. In some additional embodiments, a jet cooker can be used to provide the heat treatment step. In such embodiments, the liquefaction temperature can be at least about 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C or more. Still in such embodiment, the liquefaction temperature can be maintained for a liquefaction time of about 1 minute or more. The antimicrobial composition can be added to a fermentation medium including any type of biomass known in the art which allows the production of a fermentation product from a target microorganism (e.g., a fermenting yeast for example). In an embodiment, the fermentation medium is obtained from a liquefied medium. The fermentation product that obtained during the fermentation process can be an alcohol, such as, for example, ethanol, isopropanol, n-propanol, 1-butanol, methanol, acetone, 1,3- propanediol and / or 1,2-propanediol. The antimicrobial composition can be added to the fermentation medium prior to, during and / or after fermentation. The fermentation can be performed at temperatures of at least about 25°C, about 28°C, about 30°C, about 31°C, about 32°C, about 33°C, about 34°C, about 35°C, about 36°C, about 37°C, about 38°C, about 39°C, about 40°C, about 41°C, about 42°C, or about 50°C. In some embodiments, the fermentation is conducted under anaerobic conditions. As used herein, “anaerobic conditions” means that the liquefaction medium is under an oxygen-poor environment. An oxygen-poor environment may have an oxygen concentration below that of air. For example, the concentration of oxygen may be below 21%, 20%, 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1% by volume. Components of the fermentation medium may include a carbohydrate source, a phosphorous source and a nitrogen source. The medium can optionally include micronutrients (such as vitamins and minerals), fatty acids, nitrogen, amino acids or a combination thereof. A “fermentation medium” comprises a raw or a hydrolyzed liquefaction medium and the fermenting yeast, optionally in combination with other components. In some embodiments, the fermentation medium includes nutrients used by the fermenting yeast during the fermentation process. Components of the fermentation medium may include a carbohydrate source, a phosphorous source and a nitrogen source. The medium can optionally include micronutrients (such as vitamins and minerals), fatty acids, nitrogen, amino acids or a combination thereof. For example, the fermentation medium can include, but is not limited to, starch (including starch material derived from grains), sugar and lignocellulosic materials. Starch materials can include, but are not limited to, mashes such as corn, wheat, rye, barley, rice, or milo. Starch, when present, can be provided in a raw or a gelatinized form. Sugar materials can include, but are not limited to, sugar beets, artichoke tubers, sweet sorghum, molasses or cane. The terms “lignocellulosic material”, “lignocellulosic substrate” and “cellulosic biomass” mean any type of biomass comprising cellulose, hemicellulose, lignin, or combinations thereof, such as but not limited to woody biomass, forage grasses, herbaceous energy crops, non-woody-plant biomass, agricultural wastes and / or agricultural residues, forestry residues and / or forestry wastes, paper-production sludge and / or waste paper sludge, waste-water-treatment sludge, municipal solid waste, corn fiber from wet and dry mill corn ethanol plants and sugar-processing residues. The terms “hemicellulosics”, “hemicellulosic portions” and “hemicellulosic fractions” mean the non-lignin, non-cellulose elements of lignocellulosic material, such as but not limited to hemicellulose (i.e., comprising xyloglucan, xylan, glucuronoxylan, arabinoxylan, mannan, glucomannan and galactoglucomannan), pectins (e.g., homogalacturonans, rhamnogalacturonan I and II, and xylogalacturonan) and proteoglycans (e.g., arabinogalactan-protein, extensin, and pro line -rich proteins). In a non-limiting example, the lignocellulosic material can include, but is not limited to, woody biomass, such as recycled wood pulp fiber, sawdust, hardwood, softwood, and combinations thereof; grasses, such as switch grass, cord grass, rye grass, reed canary grass, miscanthus, or a combination thereof; sugar-processing residues, such as but not limited to sugar cane bagasse; agricultural wastes, such as but not limited to rice straw, rice hulls, barley straw, corn cobs, cereal straw, wheat straw, canola straw, oat straw, oat hulls, and corn fiber; stover, such as but not limited to soybean stover, corn stover; succulents, such as but not limited to, agave; and forestry wastes, such as but not limited to, recycled wood pulp fiber, sawdust, hardwood (e.g., poplar, oak, maple, birch, willow), softwood, or any combination thereof. Lignocellulosic material may comprise one species of fiber; alternatively, lignocellulosic material may comprise a mixture of fibers that originate from different lignocellulosic materials. Other lignocellulosic materials are agricultural wastes, such as cereal straws, including wheat straw, barley straw, canola straw and oat straw; corn fiber; stovers, such as corn stover and soybean stover; grasses, such as switch grass, reed canary grass, cord grass, and miscanthus; or combinations thereof. Substrates for cellulose activity assays can be divided into two categories, soluble and insoluble, based on their solubility in water. Soluble substrates include cellodextrins or derivatives, carboxymethyl cellulose (CMC), or hydroxyethyl cellulose (HEC). Insoluble substrates include crystalline cellulose, microcrystalline cellulose (Avicel), amorphous cellulose, such as phosphoric acid swollen cellulose (PASC), dyed or fluorescent cellulose, and pretreated lignocellulosic biomass. These substrates are generally highly ordered cellulosic material and thus only sparingly soluble. It will be appreciated that suitable lignocellulosic material may be any feedstock that contains soluble and / or insoluble cellulose, where the insoluble cellulose may be in a crystalline or non-crystalline form. In various embodiments, the lignocellulosic biomass comprises, for example, wood, corn, corn stover, sawdust, bark, molasses, sugarcane, leaves, agricultural and forestry residues, grasses such as switchgrass, ruminant digestion products, municipal wastes, paper mill effluent, newspaper, cardboard or combinations thereof. Paper sludge is also a viable feedstock for lactate or acetate production. Paper sludge is solid residue arising from pulping and paper-making, and is typically removed from process wastewater in a primary clarifier. The cost of disposing of wet sludge is a significant incentive to convert the material for other uses, such as conversion to ethanol. Processes provided by the present invention are widely applicable. Moreover, the saccharification and / or fermentation products may be used to produce ethanol or higher value-added chemicals, such as organic acids, aromatics, esters, acetone and polymer intermediates. Further examples of biomasses that can be included in the fermentation medium can comprise, for example, a fruit (apple, grape, pears, plums, cherries, peaches), a plant (sugar cane, agave, cassava, ginger), a starchy material (rice, rye, corn, Sorghum, millet, barley, wheat) or a derived product (grape must, apple mash, malted grain, crushed fruit, fruit puree, fruit juice, fruit must, plant mash, gelatinized and saccharified starch from different plant origins as corn, rye, wheat, barley). In some embodiments, the process can be used to produce ethanol at a particular rate. For example, in some embodiments, ethanol is produced at a rate of at least about 0.1 mg per hour per liter, at least about 0.25 mg per hour per liter, at least about 0.5 mg per hour per liter, at least about 0.75 mg per hour per liter, at least about 1.0 mg per hour per liter, at least about 2.0 mg per hour per liter, at least about 5.0 mg per hour per liter, at least about 10 mg per hour per liter, at least about 15 mg per hour per liter, at least about 20.0 mg per hour per liter, at least about 25 mg per hour per liter, at least about 30 mg per hour per liter, at least about 50 mg per hour per liter, at least about 100 mg per hour per liter, at least about 200 mg per hour per liter, or at least about 500 mg per hour per liter. The antimicrobial composition can be used in a cell recycling process having an initial fermentation cycle and a plurality of further fermentation cycles. The antimicrobial composition can be added to the initial fermentation cycle and / or in at least one of the further fermentation cycles. In the cell recycling process, the biomass obtained after fermentation (referred to the “fermented population” or the “substantially isolated fermented population”) is recycled, at least in part, between two fermentation cycles. In the context of the present disclosure, the expression “the biomass is recycled between two fermentation cycles” refers to the fact that the biomass present at the end of a fermentation cycle is used (at least in part) in another following fermentation cycle. This means that the biomass obtained at the end of the initial fermentation cycle recycled and used in a following further fermentation cycle. This also means that the biomass obtained at the end of a further fermentation cycle is used in a following further fermentation cycle. The cell recycling process can refer to a batch fermentation (e.g., a batch fermentation cycle) in which the fermenting yeast population is pitched in a single fermenter and the biomass, after fermentation, is recycled and used in the following fermentation cycle. The cell recycling process can refer to a continuous fermentation (e.g., a continuous fermentation cycle) in which the fermenting yeast population is pitched in a first fermenter and sequentially used in a series of additional and distinct fermenters to conduct a series of sequential fermentations. In such embodiment, the biomass, between sequential fermenters, is not substantially isolated. In such embodiment, the biomass, after the series of sequential fermentations, is recycled and used in the following fermentation cycle. In specific embodiments, the process of the present disclosure only includes continuous fermentation cycles. In still additional embodiments, the processes of the present disclosure can include both fermentation and continuous fermentation cycles. The cell recycling process can include an initial fermentation cycle at least one, two, three, four, five, six, seven, eight, nine, 10, 15, 20, 25, 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, 380, 385, 390, 395, 400, 405, 410, 415, 420, 425, 430, 435, 440, 445, 450, 455, 460, 465, 470, 475, 480, 485, 490, 495, 500 or more further fermentation cycles. Each fermentation cycle (irrespective of its type) comprises a step of contacting the fermentation medium with a fermenting population (optionally in the presence of the antimicrobial composition). The fermenting population will ferment (e.g., convert some of the biomass into a fermentation product) the fermentation medium to generate a fermented medium. After the fermentation, a fermented medium will be obtained, and it comprises a fermentation product and a fermented population. In a process comprising a batch fermentation cycle, the fermenting population is contacted (e.g., pitched) with a fermentation medium in a fermenter. The fermenting population can be added to the fermenter prior to, at the same time and / or after the fermentation medium has been added. In a process comprising a continuous fermentation cycle, the fermenting population can be added to the series of fermenters prior to, at the same time and / or after the fermentation medium has been added. In the cell recycling process, the fermentation step can be performed, for example, at temperatures of at least about 30°C, about 31°C, about 32°C, about 33° , about 34°C, about 35°C, about 36°C, about 37°C, about 38°C, about 39°C, about 40°C, about 41°C, about 42°C, about 43°C, about 44°C, about 45°C, about 46°C, about 47°C, about 48°C, about 49°C, or about 50°C. In some embodiments, the fermentation step can be performed, for example, at temperatures above about 30°C, about 31°C, about 32°C, about 33°C, about 34°C, about 35°C, about 36°C, about 37°C, about 38°C, about 39°C, about 40°C, about 41°C, about 42°C, or about 43°C, or about 44°C, or about 45°C, or about 50°C. In some embodiments, the fermentation step can be performed at temperatures from about 30°C to 60°C, about 30°C to 55°C, about 30°C to 50°C, about 40°C to 60°C, about 40°C to 55°C or about 40°C to 50°C. During a cycle, the fermentation step can be performed for a period between about 1 to about 20 hours, and in some embodiments, for a period between about 8 to 12 hours. In an embodiment, the fermentation step is performed for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 hours or more. In another embodiment, the fermentation step is performed for a period of at most 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 hour or less. In an embodiment, the fermentation step is performed for at least 8, 9, 10, 11, 12 hours or more. In another embodiment, the fermentation step is performed for a period of at most 12, 11, 10, 9, 8 hours or less. Once the fermented medium has been obtained, the fermentation cycle comprises a step of substantially isolating the fermented population from the fermented medium (which will comprise the fermented product). As used in the context of the present disclosure, the expression “substantially isolating the fermented population from the fermented medium” refers to the dissociation of the majority of the fermented population from the fermented medium and / or to the removal of the majority of the components of the fermented medium from the fermented population. In some embodiments, “substantially isolating” refers to concentrating the fermented population to at least 5, 10, 15, 20, 25, 30, 35, 45% or more when compared to the concentration of the fermented population in the fermented medium. This substantial isolation can be obtained, for example, by centrifuging and / or filtering the fermented medium and recuperating the fraction enriched in the fermented population. Cell separation and recovery in the fuel ethanol process can be carried out using stacked-disk, nozzle discharge type centrifuges. In these machines, the feed-broth from the end of fermentation, often referred to in the process as “vinho bruto” or “beer” is introduced into the top of the machine, circulates to the bottom, and is then forced upward through a set of rotating disks. The rotation of these disks imparts a centrifugal force on the total feed, and particles. Yeast cells and other solids are forced downward and to the side of the machine. The cells then exit through nozzles at the outer edge of the machine creating a concentrated yeast cream. Clarified liquid, often called “vinho,”, “vinho delevurado” or “wine” exits the machine out the top. The substantial isolation of the fermented population from the fermented medium will generate a depleted fermentation medium (which can be optionally supplemented with the antimicrobial composition). As used in the context of the present disclosure, the expression “depleted fermentation medium” refers to a fermented medium which was treated to substantially remove the fermented population which was present at the end of the previous fermentation cycle. In a process comprising a batch fermentation cycle, the substantial isolation will occur after the end of the fermentation in the single fermenter. In a process comprising a continuous fermentation cycle, the substantial isolation will occur after the end of the sequential fermentations. Once the depleted fermentation medium has been obtained, it can be submitted to a further step of substantially isolating the fermentation product. As used in the context of the present disclosure, the expression, the expression “substantially isolating the fermentation product from the depleted fermentation medium” refers to the dissociation of the majority of the fermentation product from the depleted fermentation medium. When the fermentation product is an alcohol, like ethanol, the step of substantially isolating the fermentation product from the depleted fermentation medium can be carried out by distilling the depleted fermentation medium. In a process comprising a batch fermentation cycle and / or a continuous fermentation cycle, the substantial isolation of the fermentation product will occur after the depleted medium will have been obtained. Because the fermentation process is a cell-recycling one, the process also includes using a fermenting population that has been obtained from a previous fermentation cycle. Once the fermented population has been substantially isolated from the fermented medium, it can be directly submitted to a further fermentation cycle, or it can be treated prior before submitted to a further fermentation cycle. The fermented population can be, for example, concentrated, diluted, washed with an aqueous solution (including water) and / or treated to reduce the bacterial contamination it may contain. Since the process of the present disclosure comprises more than one fermentation cycle, the fermented population is susceptible of containing bacterial contaminants. The presence of such bacterial contaminants should be limited so as not to affect the fermentation yield. For example, bacterial contaminants capable of generating organic acid, such as lactic acid (e.g., lactic acid bacteria), may be detrimental to the growth and fermentation performances of the fermenting population. As such, in some embodiments, it may be useful to include, in the process, a step of treating the fermented population to reduce / limit bacterial contamination. This can be achieved, for example, by treating the fermented population with the antimicrobial composition, an acidic solution and / or one or more antibiotics. In some embodiment, the reduction / limitation of the bacterial contamination can be achieved by treating the fermented population with an acidic solution, optionally in combination with an antibiotic treatment. In other embodiment, the reduction / limitation of the bacterial contamination can be achieved by treating the fermented population with one or more antibiotic, optionally in combination with an acid treatment. In the acid treatment step, an acid or an acidic solution is put into contact with the substantially isolated fermented population. In some embodiments, the acid or the acidic solution has a pH of between 2 and 3, and in some additional embodiments, between 2.0 and 2.2. In some embodiments, the contact between the substantially isolated fermented population and the acid / acidic solution is maintained so as to reduce the contaminating bacterial population that may be present. For example, the contact between the substantially isolated fermented population and the acid or the acidic solution can last at least 30, 40, 50, 60, 70, 80, 90, 100, 110, 120 minutes or more. In certain embodiments, the acid is sulphuric acid and / or the acidic solution comprises sulphuric acid. After the acid treatment step, the pH of the acid-treated fermented population can be adjusted prior to the further fermentation cycle. In some embodiments, the pH of the acid-treated fermented population is not adjusted prior to the further fermentation cycle. The fermentation medium used in the cell recycling process of the present disclosure can comprise considerable amounts of readily fermentable sugars (e.g., sucrose, glucose and fructose). In an embodiment, the fermentation medium comprises sugarcane or a sugarcane derivative (optionally in combination with the antimicrobial composition). In another embodiment, the fermentation medium comprises sugar beets or a sugar beet derivative (optionally in combination with the antimicrobial composition). In still a further embodiment, the fermentation medium comprises sweet sorghum or a sweet sorghum derivative (optionally in combination with the antimicrobial composition). In yet a further embodiment, the fermentation medium comprises sugarcane, sugar beets, sweet sorghum, derivatives thereof as well as combinations thereof (optionally in combination with the antimicrobial composition). In specific embodiments, the fermentation medium comprises sugarcane or a sugarcane derivative. After it has been harvested, the sugarcane is pressed or diffused to generate sugarcane juice and a solid fibrous residue, the cane bagasse. In the context of the present disclosure, sugarcane juice is considered to be a sugarcane derivative. The sugarcane juice can be clarified and concentrated by evaporation until sucrose crystallization is observed. The clarified sugarcane juice and the concentrated sugarcane juice are considered sugarcane derivatives. The sucrose crystals obtained after crystallization can be collected by centrifugation, generating a sucrose saturated viscous phase, called “cane molasses”. Cane molasses, which is also considered to be a sugarcane derivative, can include between 45 to 60 % sucrose and 5 to 20 % glucose plus fructose. In some embodiments, the fermentation medium comprises, as a sugarcane derivative, a sugarcane juice. In another embodiment, the fermentation medium comprises, as a sugarcane derivative, a cane molasses. In still another embodiment, the fermentation medium comprises, as a sugarcane derivative, both sugarcane juice and a cane molasses. In some embodiments, the cell recycling processes of the present disclosure comprise producing ethanol at a particular rate. For example, in some embodiments, ethanol is produced at a rate of at least about 0.1 mg per hour per liter, at least about 0.25 mg per hour per liter, at least about 0.5 mg per hour per liter, at least about 0.75 mg per hour per liter, at least about 1.0 mg per hour per liter, at least about 2.0 mg per hour per liter, at least about 5.0 mg per hour per liter, at least about 10 mg per hour per liter, at least about 15 mg per hour per liter, at least about 20.0 mg per hour per liter, at least about 25 mg per hour per liter, at least about 30 mg per hour per liter, at least about 50 mg per hour per liter, at least about 100 mg per hour per liter, at least about 200 mg per hour per liter, at least about 300 mg per hour per liter, at least about 400 mg per hour per liter, at least about 500 mg per hour per liter, at least about 600 mg per hour per liter, at least about 700 mg per hour per liter, at least about 800 mg per hour per liter, at least about 900 mg per hour per liter, at least about 1 g per hour per liter, at least about 1.5 g per hour per liter, at least about 2 g per hour per liter, at least about 2.5 g per hour per liter, at least about 3 g per hour per liter, at least about 3.5 g per hour per liter, at least about 4 g per hour per liter, at least about 4.5 g per hour per liter, at least about 5 g per hour per liter, at least about 5.5 g per hour per liter, at least about 6 g per hour per liter, at least about 6.5 g per hour per liter, at least about 7 g per hour per liter, at least about 7.5 g per hour per liter, at least about 8 g per hour per liter, at least about 8.5 g per hour per liter, at least about 9 g per hour per liter, at least about 9.5 g per hour per liter, at least about 10 g per hour per liter, at least about 10.5 g per hour per liter, at least about 11 g per hour per liter, at least about 11.5 g per hour per liter, at least about 12 g per hour per liter, at least about 12.5 g per hour per liter, at least about 13 g per hour per liter, at least about 13.5 g per hour per liter, at least about 14 g per hour per liter, at least about 14.5 g per hour per liter or at least about 15 g per hour per liter. Ethanol production can be measured using any method known in the art. For example, the quantity of ethanol in fermentation samples can be assessed using HPLC analysis. Many ethanol assay kits are commercially available that use, for example, alcohol oxidase enzyme-based assays. As indicated above, the antimicrobial composition can be added to a food ingredient or to a food to prevent or limit microbial contamination of the food ingredient or the food. In some embodiments, the food ingredient or the food can be fermented by a target microorganism (which can be a yeast). In other embodiments, the food ingredient or the food does not necessarily include the antimicrobial composition but can be obtained from a propagated medium and / or a fermentation medium that has received at least one dose of the antimicrobial composition. In some embodiments, the food or the food ingredient includes the antimicrobial composition. In embodiments in which the food or the food ingredient is obtained by propagation and optionally fermentation, the antimicrobial composition of the present disclosure can be included in a propagation medium used to propagate the target microorganism intended to be used to make the food or the food ingredient. Alternatively, or in combination, the antimicrobial composition of the present disclosure can be included in a fermentation medium fermented by the target microorganism to generate the food or the food ingredient. In some embodiments, the antimicrobial composition can be added directly to a food or a food ingredient. As indicated above, the antimicrobial composition can be added to a feed ingredient or to a feed to prevent or limit microbial contamination of the feed ingredient or the feed. In some embodiments, the feed ingredient or the feed can be fermented by a target microorganism (which can be a yeast). In other embodiments, the feed ingredient or the feed does not necessarily include the antimicrobial composition but can be obtained from a propagated medium and / or a fermentation medium that has received at least one dose of the antimicrobial composition. In some embodiments, the feed or the feed ingredient includes the antimicrobial composition. In embodiments in which the feed or the feed ingredient is obtained by propagation and optionally fermentation, the antimicrobial composition of the present disclosure can be included in a propagation medium used to propagate the target microorganism intended to be used to make the feed or the feed ingredient. Alternatively, or in combination, the antimicrobial composition of the present disclosure can be included in a fermentation medium fermented by the target microorganism to generate the feed or the feed ingredient. In some embodiments, the antimicrobial composition can be added directly to a feed or a feed ingredient. One example of a feed that can be obtained from a fermented medium supplemented with the antimicrobial composition can be distiller’s dried grains and associated derivatives. Once fermentation of a fermentation medium (which can, in some embodiments, comprise corn or be derived from corn) has been completed and that some of the fermentation product has been removed from the fermented biomass, the solid and the liquid fraction of whole stillage can be separated. This can be achieved by submitting whole stillage to a centrifuging step or a filtration step. The solid fraction of whole stillage is referred to as a wet cake. The wet cake can be used without further modification as a feed or a feed additive as distillers wet grains (DWG). Alternatively, the wet cake can be submitted to a drying step to provide dried distillers grains (DDG). The DWG and the DDG can be used as a feed or a feed additive. The liquid fraction of whole stillage is referred to as thin sillage. Thin sillage can be submitted to an evaporating step to provide a syrup. The syrup can be added to the wet cake to make distillers wet grains with solubles (DWGS). Alternatively, the wet cake supplemented with the syrup can be dried to provide dried distillers grains with solubles (DDGS). The DWGS and the DDGS can be used as a feed or a feed additive. The syrup can be used without further modifications as condensed distillers solubles (CDS). The syrup can also be dried to obtain dried solubles (DS). The CDS and the DS can be used as a feed or a feed additive. As indicated above, the antimicrobial composition can be added to a beverage ingredient or to a beverage to prevent or limit microbial contamination of the beverage ingredient or the beverage. In some embodiments, the beverage ingredient or the beverage can be fermented by a target microorganism (which can be a yeast). In other embodiments, the beverage ingredient or the beverage does not necessarily include the antimicrobial composition but can be obtained from a propagated medium and / or a fermentation medium that has received at least one dose of the antimicrobial composition. In some embodiments, the beverage or the beverage ingredient includes the antimicrobial composition. As used herein, a “beverage” refers to a potable liquid for human consumption. In an embodiment, the beverage is an alcoholic beverage. In some embodiment, the alcoholic beverage has between 1 to 99 %ABV, between 1 to 80 %ABV, between 5 to 99 %ABV, between 5 to 80 %ABV, between 5 to 60 %ABV, between 5 to 40 %ABV, between 20 to 80 %ABV, between 30 to 80 %ABV, or between 35 to 80 %ABV. Examples of alcoholic beverage products include, but are not limited to beer, brandy, cachaça, Cognac, mezcal, whisky, whiskey, gin, tequila, rum, wine, mead, sake, baiju, shochu, soju, cider, perry, arrack, jenever, vermouth, Armangnac, korn, raki, pulque, basi, vodka, poitin, akvavit, aquavit, absinthe, spirits, new-make spirit, white dog, and moonshine. In embodiments in which the beverage (including the alcoholic beverage) is obtained by fermentation (and optionally distillation), the antimicrobial composition of the present disclosure can be included in a propagation medium used to propagate the target microorganism intended to be used to make the beverage. Alternatively, or in combination, the antimicrobial composition of the present disclosure can be included in a fermentation medium fermented by the target microorganism to generate the beverage (or a medium which will be submitted to distillation to generate the beverage). In some embodiments, the antimicrobial composition can be added to a distillate intended to be used to make the beverage (after distillation and / or during maturation). The fermentation medium that can be used to make a beverage, can comprise, without limitation, a plant (including a cereal), a carbohydrate (or a combination thereof), a fruit, and / or a vegetable. In an embodiment, the substrate of the fermentation medium includes fermentable materials which contain C6 sugar as for example fructose, glucose, galactose, sucrose, maltose or starch, as well as their degradation products. As an example, the fermentable material can comprise a fruit (apple, grape, pears, plums, cherries, peaches), a plant (sugar cane, agave, cassava, ginger), a sugar material (honey, molasses), a starchy material (rice, rye, corn, sorghum, millet, barley, wheat, potatoes) or a derived product (grape must, apple mash, malted grain (or cereal), crushed fruit, fruit puree, fruit juice, fruit must, plant mash, gelatinized and saccharified starch from different plant origins as rice, corn, sorghum, wheat, barley). In another embodiment, the fermentation medium can comprise a starchy material. In the context of the present disclosure, a “starchy material” refers to a material that contains starch that could be converted into alcohol by a yeast during alcoholic fermentation. Starchy material could be for example, gelatinized and saccharified starch from cereals, grains (wheat, barley, rice, buckwheat) or grain derived-products (malted grain or a wort) or vegetable (potatoes, beets). In yet another embodiment, the fermentation medium can comprise, but is not limited to, barley, wheat, rye, oats, corn, maize, buckwheat, millet, rice, sorghum, including variants of these cereals that have been subject to the malting, cooking (torrefaction) or micronization process, or a combination thereof. In one embodiment, the malted grain (or cereal) are malted barley, malted wheat, malted rye, malted oats, malted corn, malted buckwheat, malted millet, malted rice, and malted sorghum. In another embodiment, the torrefied grain (or cereal) are torrefied barley, torrefied wheat, torrefied rye, torrefied oatas, torrefied corn, torrefied buckwheat, torrefied millet, torrefied rice and torrefied sorghum. In yet another embodiment, the micronized grain (or cereal) are micronized barley, micronized wheat, micronized rye, micronized oats, micronized corn, micronized buckwheat, micronized millet, micronized rice and micronized sorghum The target microorganism that can be used in the methods of the present disclosure can be a yeast. In some embodiments, the yeast is a budding yeast. In other embodiments, the yeast is methylotrophic (e.g., yeast able to utilize methanol as the sole carbon and energy source). Embodiments of methylotrophic yeasts include, but are not limited to Komagataella sp. and Ogataea sp. In some embodiments, the yeast is an oleaginous yeast (e.g., a yeast capable of accumulating more than 20% of its dry cell weight as lipids or triglycerides). In an embodiment, the target microorganism is from Blastobotrys sp. In another embodiment, the target microorganism is from Blastobotrys adeninivorans (basonym Trichosporon adeninivorans). In an embodiment, the target microorganism is from Candida sp. In another embodiment, the target microorganism is from Candida albicans. In an embodiment, the target microorganism is from Cyberlindnera sp. In another embodiment, the target microorganism is from Cyberlindnera jadinii (basonym Saccharomyces jadinii). In an embodiment, the target microorganism is from the Debaryomyces sp. In another embodiment, the target microorganism is from Debaryomyces hansenii. In another embodiment, the target microorganism is from Debaryomyces hansenii. In an embodiment, the target microorganism is from Hanseniaspora sp. (also known as Kloeckera sp.). In another embodiment, the target microorganism is from Hanseniaspora guilliermondii. In another embodiment, the target microorganism is from Hanseniaspora pseudoguilliermondii. In an embodiment, the target microorganism is from the Kazachstania sp. In another embodiment, the target microorganism is from Kazachstania bulderi (basonym Saccharomyces bulderi). In another embodiment, the target microorganism is from Kazachstania barnettii (basonym Saccharomyces barnettii). In another embodiment, the target microorganism is from Kazachstania exigua (basonym Saccharomyces exiguus). In an embodiment, the target microorganism is from Kluyveromyces sp. In another embodiment, the target microorganism is from Kluyveromyces lactis (basonym Torulaspora lactis). In another embodiment, the target microorganism is from Kluyveromyces marxianus also known as Kluyveromyces fragilis (basonym Saccharomyces marxianus). In an embodiment, the target microorganism is from Komagataella sp. In another embodiment, the target microorganism is from Komagataella phaffii. In an embodiment, the target microorganism is from Limtongozyma sp. In another embodiment, the target microorganism is from Limtongozyma cylindracea (basonym Candida cylindracea). In an embodiment, the target microorganism is from Lipomyces sp. In an embodiment, the target microorganism is from Metschnikowia sp. In another embodiment, the target microorganism is from Metschnikowia sinensis. In another embodiment, the target microorganism is from Metschnikowia fructicola. In another embodiment, the target microorganism is from Metschnikowia pulcherrima. In another embodiment, the target microorganism is from Metschnikowia zobellii. In another embodiment, the target microorganism is from Metschnikowia shanxiensis. In an embodiment, the target microorganism is from Ogataea sp. In another embodiment, the target microorganism is from Ogataea polymorpha (basonym Hansenula polymorpha). In another embodiment, the target microorganism is from Ogataea methanolica (basonym Pichia methanolica). In an embodiment, the target microorganism is from Pichia sp. (also known as Hansenula sp.). In an embodiment, the target microorganism is from Rasamsonia sp. In another embodiment, the target microorganism is from Rasamsonia emersonii. In an embodiment, the target microorganism is from Saccharomyces sp. In another embodiment, the target microorganism is from Saccharomyces cerevisiae. In yet another embodiment, the target microorganism is from Saccharomyces cerevisiae var. diastaticus. In another embodiment, the target microorganism is from Saccharomyces uvarum. In another embodiment, the target microorganism is from Saccharomyces boulardii. In an embodiment, the target microorganism is from Scheffersomyces sp. In another embodiment, the target microorganism is from Scheffersomyces stipitis (basonym Pichia stipitis). In an embodiment, the target microorganism is from Schwanniomyces sp. In another embodiment, the target microorganism is from Schwanniomyces polymorphus (basonym Pichia polymorpha). In another embodiment, the target microorganism is from Schwanniomyces occidentalis. In an embodiment, the target microorganism is from Wickerhamomyces sp. In another embodiment, the target microorganism is from Wickerhamomyces anomalus. In an embodiment, the target microorganism is from Yarrowia sp. In another embodiment, the target microorganism is from Yarrowia lipolytica. Additional target yeasts can be, for example, from the genus Saccharomyces, Kluyveromyces, Arxula, Debaryomyces, Candida, Pichia, Phaffia, Schizosaccharomyces, Hansenula, Kloeckera, Schwanniomyces or Yarrowia. Suitable yeast species can include, for example, S. cerevisiae, S. bulderi, S. barnetti, S. exiguus, S. uvarum, S. diastaticus, K. lactis, K. marxianus or K. fragilis. In some embodiments, the yeast is selected from the group consisting of Saccharomyces cerevisiae, Schizzosaccharomyces pombe, Candida albicans, Pichia pastoris, Pichia stipitis, Yarrowia lipolytica, Hansenula polymorpha, Phaffia rhodozyma, Candida utilis, Arxula adeninivorans, Debaryomyces hansenii, Debaryomyces polymorphus, Schizosaccharomyces pombe and Schwanniomyces occidentalis. In one particular embodiment, the yeast is Saccharomyces cerevisiae. In some embodiments, the yeast cell can be an oleaginous yeast. For example, the oleaginous yeast can be from the genus Blakeslea, Candida, Cryptococcus, Cunninghamella, Lipomyces, Mortierella, Mucor, Phycomyces, Pythium, Rhodosporidum, Rhodotorula, Trichosporon or Yarrowia. In some alternative embodiments, the yeast can be an oleaginous microalgae (e.g., for example, from the genus Thraustochytrium or Schizochytrium). In an embodiment, the yeast is from the genus Saccharomyces and, in some embodiments, from the species Saccharomyces cerevisiae. Kits The present disclosure provides a kit for preventing or limiting microbial contamination in a medium. The kit provides the components to be included in the antimicrobial composition used to prevent or limit contamination in the medium. The kit comprises nisin. The embodiments with respect to the type of nisin that can be used and the amount of nisin that can be present in the antimicrobial composition have been provided above and can be used in the kit. The kits also comprise alpha hops acid. The embodiments with respect to the type of alpha hops acids that can be used and the amount of alpha hops acids that can be present in the antimicrobial composition have been provided above and can be used in the kit. In some embodiments, the kit comprises a buffer. The embodiments with respect to the type of buffer that can be used and the amount of buffer that can be present in the antimicrobial composition have been provided above and can be used in the kit. The kit can include instructions to make the antimicrobial composition according to the process described herein. Alternatively, or in combination, the kit can include instructions to perform the method described herein. In some embodiments, the kit can also comprise a base or an acid to adjust the pH of the solution(s) used to make the antimicrobial composition or to adjust the pH of the antimicrobial composition. In some embodiments, the base can be, for example, sodium hydroxide (NaOH). It is to be understood that any other suitable base that does not show any deleterious effect on the formulation process, stability, or antimicrobial activity of the composition may be used while still remaining within the scope of the invention. The present invention will be further illustrated in the following examples. Although the invention is described in terms of specific illustrative embodiments, it is to be understood that the embodiments described herein are by way of example only and that the scope of the invention is not intended to be limited thereby. Examples Example 1: Relative antimicrobial activity of different alpha hops acids Experiments were conducted to assess the relative antimicrobial activity of commercially available formulations of hops acid comprising either iso-alpha hops acids or tetrahydroiso-alpha hops acids on strains of Lactobacilli contaminating bacteria from fuel ethanol plants in corn mash. Lactate production and a drop in pH during ethanol production are good indicators of bacterial contamination as Lactobacilli are common contaminating bacteria during corn mash fermentation and different species may produce lactic acid, acetic acid and formic acid, all of which reduce the pH of a contaminated medium.

[0002] Table 1: Materials and Formulations. Material Components Final concentration in the medium Commercial α-hops acid (IsostabTM) - 25,000 ppm 40-100 ppm hops acid Tetrahydroiso α-hops acid 10-80 ppm (LactostabTM, ProtemostoTM) - 25,000 Medium Corn Mash pH 5.0, 30% total solids Glucose 1% Challenge Lb. plantarum - 1.0 x 109CFU / ml 1.0 x 106CFU / ml bacteria Lb. fermentum - 1.0 x 109CFU / ml 1.0 x 106CFU / ml Lb. amylovorus - 1.0 x 109CFU / ml 1.0 x 106CFU / ml Activity was assessed in 20 mL of commercially sourced corn mash (pH 5.0, 30% total solids) supplemented with different concentrations of different alpha hops acid formulations comprising either iso alpha hops acids or tetrahydroiso alpha hops acids and 1% glucose to support bacterial growth. The three-strain cocktail consisted of three bacteria strains: Lb. plantarum (now classified as Lactiplantibacillus plantarum), Lb. fermentum (now classified as Limosilactobacillus fermentum) and Lb. amylovorus). The iso alpha hops acid preparation consisted of the commercial preparation IsostabTMand was assessed at concentrations ranging from 40 ppm to 100 ppm. The tetrahydroiso α- acid hops preparations consisted of the commercial preparations LactostabTMor ProtemostoTMand were assessed at concentrations ranging from 10 ppm to 80 ppm (Figure 1). The medium was also supplemented with 10 ppm of cycloheximide, which inhibits protein synthesis in eukaryotic cells, thereby preventing yeast contamination. The alpha hops acid formulations were spiked into the corn mash, which was experimentally challenged (i.e., contaminated) with the three-strain cocktail of bioethanol contaminants. The challenge cocktail was prepared by propagating the bacteria separately in MRS broth (medium), washed, standardized to an optical density of 2.0 at 600 nm (~1.0 x 109CFU / ml) and each strain was mixed at equal volume. The three-strain cocktail was then inoculated at 0.1% (~1.0 x 106CFU / ml of each strain) into each corn mash sample. Control samples contained no added alpha hops acid (-cont) whereas the positive control (+cont) did not receive the cocktail challenge. The corn mash was incubated for 15 hours at 33°C with shaking (100 rpm) to prevent sedimentation and contamination was assessed by measuring the pH and the lactate concentration which was determined by high-performance liquid chromatography (HPLC). Figure 1 shows that tetrahydroiso alpha hops acid (Lactostab EP20-2442 and Protemosto EP22-23676) was approximately twice as effective as iso alpha hops acid (Isostab EP20-1356) in preventing pH drop (Figure 1A) and lactate production (Figure 1B) by biofuel contaminants inoculated in corn mash. Example 2: Antimicrobial composition comprising alpha hops acid and nisin Hops and nisin are most stable at opposing sides of pH neutrality with concentrated iso alpha hops acid and tetrahydroiso alpha hops acid extracts stabilized in liquid form at high pH (pH 8-10) while precipitating when acidified or diluted. In contrast, nisin activity, stability and solubility are very high at low pH, and each of these features will reportedly diminish as the pH is raised. Various formulations were made in which pH was adjusted to determine if such pH adjustments could have an impact on antimicrobial activity. Table 2: Materials and Formulations Sample Components Final concentration in the medium Control MRS broth N / A MRS bppm MRS broth Blend Blend: (nisin (100 ppm) at pH 8.0 + 30% Nisin - 4 ppm α-hops acid at pH8.0 α-hops acid - 20 ppm Challenge Lb. paracasei - 1.0 x 109CFU / ml pH adjustment after blending. Formulations were obtained by first combining 20 g / L of α-hops acids (30% solution) and 4 g / L of nisin (100 ppm) and then adjusting the pH to 6.0, 7.0, 8.0, 8.5, or 9.0. The formulations, hops only or nisin only were added to a MRS broth comprising the indicator strain Lb. paracasei (now classified as Lacticaseibacillus paracasei). The broth was cultured, and bacterial growth was spectrophotometrically monitored at 600 nm (OD600). Medium comprising the formulations (at all pHs) allowed faster microbial growth compared to the medium comprising hops only (data not shown). These results indicate that the antimicrobial activity of the α-hops acids was detrimentally affected in formulations in which pH was adjusted after blending. pH adjustment before blending. Additional formulations were obtained by adjusting the pH of the nisin solution before blending it with α-hops acids. Initially, the pH of the nisin solution was adjusted to 8.0  and then α-hops acids were added to the nisin solution to provide a blend. Adjusting the pH of the nisin solution to pH 8.0 before blending with the α-hops acids yielded an antimicrobial composition with increased antimicrobial activity compared to an equivalent composition without nisin, indicating that at least some nisin activity was retained in the blend (Figure 2). Indeed, the blend comprising 20 g / L hops (~ 2,500 ppm) and 4 g / L nisin (~100 ppm) depicted in Figure 2 exhibited greater antimicrobial activity with respect to the indicator strain Lb. paracasei compared to the same concentration of an hops only control preparation. Thus, these experiments show that pH adjustment of the nisin preparation to pH 8.0 before blending it with α-hops acids allowed the resulting formulation to retain the antimicrobial properties of the hops acid. Example 3: Effect of sodium on solubility of the alpha hops acid Mineral content in the blend and its starting material. The mineral content of iso alpha acids (IsostabTM), tetrahydroiso α-acids (THIA, two sources) and nisin was conducted as, as indicated in Table 3, sodium levels were very high in the nisin solution (Table 3). The blends (tH + N) were made by adjusting the pH of the nisin solution to 8.0 before adding the iso alph acids. Table 3: Mineral content of hops and nisin solutions.Hops acids and nisin concentrations are provided as g / L. Minerals are provided as mg / L (ppm). Nisin in water solution formulated to contain 60 ppm nisin preparation and adjusted to pH 8.0. Product Hop Acids Nisin Prep P Ca Mg Mn K Na Iso a-acid hops 300 0 <2.5 <5.0 <2.5 <5.0 40 88 THIA-acid hops 1 100 0 <0.5 <1.0 <0.5 <0.1 9,6 19 THIA-acid hops 2 100 0 <0.5 <1.0 <0.5 <0.1 12 32 Nisin solution 0 60 19.0 4.50 8.70 0.11 83 20 tH + N blend (calculated values) 100 20 6.33 1.50 2.90 0.036 13,368 6,699 tH + N blend (measured values) 100 20 5.40 <1.0 <0.5 <0.1 11 4,3 Sodium concentration and hops solubility. In order to determine if the sodium present could influence the stability / antimicrobial activity of hops, an increasing amount of sodium chloride was added to a solution containing alpha hops acid. Experimental addition of NaCl to an iso alpha hops acid preparation (i.e., IsostabTM) confirmed that as little as 7.5 ppm of NaCl was sufficient to cause precipitation of the hops acids (Table 4). Table 4: Stability of α-acid hop preparations after NaCl addition Sample NaCl mM NaCl Precipitation? Added (g / L) 1 15 256.67 Yes 2 7.5 128.34 Yes 3 3.75 64.17 Cloudy 4 3.125 53.47 No 5 2.5 42.78 No Example 4: Synergistic effect of THIA and nisin in the blend A biological assay based on growth inhibition of an indicator strain, Lb. plantarum, was developed to determine the stability of various formulations. A threshold was established and defined as being able to suppress growth of Lb. plantarum to a degree of at least equal to an equivalent blended formulation containing only 60% of the nisin in the blend. Thus, two blended compositions were prepared comprising either 0.1 g / L of nisin (the blend) or 0.06 g / L of nisin (60% blend). Both formulations comprised 25 ml / L (2,500 ppm) of tetrahydroiso alpha-hops acid (THIA). The tetrahydroiso alpha hops were added to nisin solutions having a pH adjusted to 8.0. The growth of Lb. plantarum was assessed by measuring the optical density at 600 nm (OD600) of the growth medium containing MRS broth, Lb. plantarum and each of the samples defined in Table 5 below. The samples were first prepared at the indicated concentration and blended, when applicable, before added to the medium whereas the components of the “separate” sample (nisin and hops) were added separately to the medium. The final concentration in the medium was equivalent to 20% of a full dose that is able to kill the indicator strain, Lb. plantarum. Table 5: Materials and Formulations. Sample Components Final concentration in the medium Control MRS broth N / A Nisin MRS broth0.01% nisin (100 ppm)2 ppmHopsMRS broth10% THIA 5 ppmMRS broth tH-N 1 Blend: (0.01% nisin (100 ppm) at pH 8.0 + 10% THIA) at Nisin - 2 ppm pH 8.0 THIA - 5 ppm MRS broth tH-N 2 60% Blend: (0.006% nisin (60 ppm) at pH 8.0 + 10% Nisin - 1.2 ppm THIA) at pH 8.0 THIA - 5 ppm MRS broth Separate 0.01% nisin (100 ppm) Nisin - 2 ppm 10% THIA THIA - 5 ppm As shown in Figure 3, growth of Lb. plantarum was inhibited by both 2 ppm nisin or 5 ppm hops alone, and strongly inhibited by the blends. Unexpectedly, Figure 3 also shows that the antimicrobial activity of the blend was higher compared to when hops and nisin were added separately to the medium, thereby demonstrating a synergistic effect of the blend. Example 6: pH adjustment associated with the synergistic effect of THIA and nisin Conditions in a typical yeast propagation tank were replicated to determine whether the synergistic effect of the blend could be observed in corn mash fermentation. Table 6: Materials and Formulations Samples Components Final concentration in the medium Blend Corn mash Corn mash (17% total solids) Glucose Glucose - 2% Cycloheximide Cycloheximide - 10 ppm Blend: (0.01% nisin (100 ppm) at pH 8.0 + Nisin - 4 ppm 10% THIA) at pH 8.0 THIA - 10 ppm pH: 5.0 Separate Corn mash Corn mash (17% total solids) Glucose Glucose - 2% Cycloheximide Cycloheximide - 10 ppm 0.01% nisin (100 ppm) Nisin - 4 ppm 10% THIA THIA - 10 ppm pH: 5.0 Challenge Lb. plantarum - 1.0 x 106CFU / ml 1.0 x 106CFU / ml Lb. fermentum - 1.0 x 106CFU / ml 1.0 x 106CFU / ml Lb. amylovorus - 1.0 x 106CFU / ml 1.0 x 106CFU / ml Corn mash samples were spiked with the blend to a final concentration of 0.4X (10 ppm tetrahydroiso alpha hops acids and 4 ppm nisin), or with 10 ppm tetrahydroiso alpha hops acids and 4 ppm nisin added separately (separate condition). Each sample was also supplemented with 10 ppm of cycloheximide to prevent yeast contamination and then inoculated with the same three-strain cocktail of bioethanol isolates (Lb. plantarum, Lb. fermentum, and Lb. amylovorus) described in Example 1. The corn mash samples were incubated overnight (~18 h) at 33°C, then analyzed by HPLC and the pH was measured (Figure 4). The concentration of lactate, acetate and formate in the challenged medium was also measured to assess bacteria growth since Lactobacilli are common contaminating bacteria during corn mash fermentation and different species may produce lactic acid, acetic acid and formic acid. Bacterial activity was more effectively suppressed in corn mash samples spiked with the blend than the suppression observed in corn mash to which the same concentration of hops and nisin was added separately, confirming the synergistic effect of the blend (Figure 4). The antibacterial activity of nisin, hops, and nisin-hop blends that did or did not include a pH adjustment step of the nisin solution was also assessed (Table 7 and Figure 5). The activity of each formulation was assessed using the hops and nisin indicator strain Lb. plantarum in MRS broth (pH 6.0). Table 7: Materials and Formulations Final Samples Components concentration in the medium ControlMRS brothMRS broth - pH H2O6.0 isin only MRS brMRS broth - pH NothNisin - 0.2 g in 20 mL H2O6.0 Nisin - 2 ppm MRS broMRS broth - pH Nisin-pH thNisin - 0.2 g in 20 mL H2O (pH 8.0 - 8.5)6.0 Nisin - 2 ppm MRMRS broth - pH THIA S brothTHIA - 10% solution6.0 THIA - 5 ppm MRS brMRS broth - pH THIA-pH othTHIA - 10% solution at pH 8.0 - 8.56.0 THIA - 5 ppm MRS broth MRS broth - pH tH-N Blend: (Nisin - 0.2 g in 20 mL H2O) + (THIA - 10% 6.0 solution) Nisin - 2 ppm THIA - 5 ppm MRS broth MRS broth - pH tH-N-pH Blend: (Nisin - 0.2 g in 20 mL H2O at pH 8.0 - 8.5) + 6.0 (THIA - 10% solution) pH adjusted to 8.0-8.5 after Nisin - 2 ppm blending THIA - 5 ppm MRS broth MRS broth - pH Separate Nisin - 0.2 g in 20 mL H2O 6.0 THIA - 10% solution Nisin - 2 ppm THIA - 5 ppm The formulations comprising nisin, hops acid or combinations thereof optionally included a step of adjusting the pH to 8.0. Thus, the “nisin-pH” and “Protemosto-pH” samples were adjusted to pH 8.0 - 8.5, and the “blend-pH” sample only included a pH adjustment of the nisin solution to pH 8.0 before blended with the hops, and a second pH adjustment to 8.0-8.5 after blending. The “blend” sample did not involve pH adjustment at either step. All samples with tetrahydroiso alpha acids (THIA) were prepared using the commercial THIA product, Protemosto. As depicted in Figure 5, each of the nisin only (samples with and without pH adjustment) or THIA only (samples with and without pH adjustment) treatments produced a similar, ingredient-specific degree of growth inhibition. This shows that pH adjustment or dilution had little effect on the individual components of the blend. In contrast, the “blend-pH” sample wherein THIA and nisin were blended after the nisin had been pH-adjusted to 8.0, and then pH adjusted again to 8.0 after blending, was more effective in suppressing growth of Lb. plantarum than the “blend” in which neither the nisin or hops had been pH-adjusted before blended (Figure 5). The “blend-pH” was also more effective at suppressing growth of Lb. plantarum than when the nisin and hops were dosed separately into the MRS broth (Figure 5). Example 7: Influence of pH adjustment on the antimicrobial activity of the blend The nisin solution and the blend were adjusted to different pHs to determine the optimal value for optimizing the bacterial growth inhibition. All samples contained Lactiplantibacillus plantarum as indicator strain. Table 8: Materials and Formulations Samples ComponentsFinal concentration inthe mediumControlMRS brothH2OMRS broth - pH 6.0 Nisin MRS brothMRS broth - pH 6.0 Nisin - 50 g / L in H2O, pH 3.4Nisin - 1 ppm THIA MRS brothMRS broth - pH 6.0 10% THIA (Protemosto) pH 8.4THIA - 5 ppm tH-N-pH 7.0- MRS broth MRS broth - pH 6.0 10.0 Blend: (Nisin - 50 g / L in H2O, pH 7.0-10.0) + Nisin - 1 ppm (10% THIA ) at pH 7.0-10.0 THIA - 5 ppm Results show that a pH ranging from 7.0 to 10.0 provided growth inhibition to a similar extent (Figure 6) whereas nisin and THIA alone were less effective at inhibiting bacterial growth. However, when stored for 9 days or 15 days, the blends at pH 7.0-9.0 showed greater bacterial growth inhibition than the blends at pH 6.5, 9.5 and 10.0, indicating a loss of hops and / or nisin activity for these blends (Figure 7). Example 8: Formulations comprising β-hops acids and nisin Several formulations comprising nisin and β-hops acids were made, and their pH was adjusted prior to blending to determine the effect of pH on antimicrobial activity.

[0003] Table 9: Materials and Formulations Samples ComponentsFinal concentrationin the mediumControlMRS brothH2OMRS broth - pH 6.0 1ppm Nisin MRS brothMRS broth - pH 6.0 Nisin - 50 g / L in H2O, pH 3.4Nisin - 1 ppm 5ppm THIA MRS brothMRS broth - pH 6.0 10% THIA , pH 8.4THIA - 5 ppm 5ppm bHops MRS brothMRS broth - pH 6.0 10% β-hops, pH 10.02β-hops - 5 ppm MRS broth MRS broth - pH 6.0 bH + N Blend: ((Nisin - 0.2 g 20 mL H2O at pH 8.0) + (10% Nisin - 1 ppm THIA)) at pH 8.0 THIA - 5 ppm bH + N-pH MRS broth MRS broth - pH 6.0 6.5-10.0 Blend: ((Nisin - 0.2 g 20 mL H2O at pH 6.5-10.0) + Nisin - 1 ppm (10% β-hops)) at pH 6.5-10.0 β-hops - 5 ppm The blend was prepared using the commercial THIA product, Protemosto, whereas the β-blend was prepared using β-hops acid obtained from Hopsteiner. All samples contained Lactiplantibacillus plantarum as indicator strain. As depicted in Figure 8, the blend comprising THIA was clearly the most effective at suppressing growth of Lb. plantarum, as shown by the increased lag phase and the lower stationary phase. Although the β-blend comprising nisin and β-hops with a pH adjustment to 9.0-10.0 showed some inhibition, most β-blend samples showed no inhibition. Only the medium wherein nisin and β-hops were dosed separately showed a synergistic effect on growth inhibition, as shown by the increased lag phase compared to the nisin-only and β-hops-only samples (Figure 8). Precipitation of the β-hops acid likely accounted for the lack of growth inhibition of the β-blend formulation. In contrast, the sample with the strongest growth inhibition was the blend described above comprising THIA and nisin wherein the nisin solution and the blend are pH-adjusted to 8.0, thereby confirming the superiority of THIA in a blended formulation comprising nisin and hops acids. Example 9: Stability of nisin in the antimicrobial composition Blend. A blend has been made and included 25,000 ppm alpha hop acids, 10,000 ppm nisin prep. The pH of the nisin solution was adjusted to 8.0 prior to adding the hops acids. Temperature stability studies. Quantitative analysis of nisin in the blend at different temperatures over time was thus performed. The different blends were then stored at 4°C, 21°C or 37°C. Samples were obtained for up to 140 days and the amount of nisin present in such samples was determined. Figure 9 shows that storage at 37°C and 21°C is deleterious to the stability of nisin in the blend. In contrast, nisin appeared to be stable for at least 84 days at 4°C. Results also indicated that alpha hops acids, particularly THIA, were stable for at least 100 days at 4°C (data not shown). pH stability studies. The pH adjustment step required to obtain the blend can be time consuming as the nisin solution is unbuffered and slow to equilibrate to the desired pH. Additionally, the unbuffered final product is also prone to pH “drift” over time, and typically becomes more acidic (data not shown). Product acidification is undesirable as it may affect stability or activity of the blend. The pH of the of the blend was therefore measured periodically for over 200 days (when stored at 4°C) to monitor the stability of the pH and determine whether acidification could be an issue for long term storage. In these studies, the blend comprised nisin (2 ppm) and THIA (5 ppm) was prepared as described above, with the pH of nisin (prior to blending) and of the final blend adjusted to pH 8.0. Figure 10 shows that the pH fell to below pH 7.65 within 30 days and continued to undergo slow acidification over time. Example 10: Effect of different buffers on the antimicrobial activity of the hops acid / nisin blend A series of buffers was tested for their ability to stabilize the pH of the blend. Nisin was first added to the buffered solution and then the tetrahydroiso alpha acids were added to the mix. Potassium phosphate (KH2PO4) is "generally recognized as safe" (GRAS) as a food additive by the U.S. Food and Drug Administration (FDA) and was thus selected as a first candidate (Figure 11A). The widely used HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer was also tested in parallel (Figure 11B). Three different concentrations of KH2PO4 (1.0, 10, and 100 mM) and of HEPES buffer (0.42, 4.2, and 42 mM) were tested in the blend and the antimicrobial activity was measured as described above. Ammonium chloride (NH4Cl) and glycylglycine were also tested for their ability to stabilize the pH of the composition (Figure 11C and 11D). All samples contained Lactiplantibacillus plantarum as indicator strain.

[0004] Table 11: Materials and Formulations Sample ComponentsFinal concentration in themediumControlMRS brothH2OMRS broth - pH 6.0 Nisin MRS brothMRS broth - pH 6.0 Nisin - 50 g / L H2O, pH 3.4Nisin - 1 ppm 5ppm THIA MRS brothMRS broth - pH 6.0 10% THIA (2,500 ppm)THIA - 5 ppm MRS broth MRS broth - pH 6.0 tH + N blend Blend: ((Nisin - 0.2 g in 20 mL H2O at pH 8.0) + Nisin - 1 ppm (10% THIA)) at pH 8.0THIA - 5 ppmMRS MRS broth - pH 6.0 tH + N blend broth Blend: ((Nisin - 0.2 g in 20 mL H O at pH 8.0 Nisin - 1 ppm KH2PO24) + (10% THIA)) in KH2PO4at pH 8.0 THIA - 5 ppm KH2PO4- 1.0, 10, or 100 mM MRS broth MRS broth - pH 6.0 tH + N blend Blend: (( Nisin - 1 ppm   HEPES Nisin - 0.2 g in 20 mL H2O at pH 8.0) + (10% THIA)) in HEPES at pH 8.0 THIA - 5 ppm HEPES 0.42, 4.2, or 42 mM end MRS bro MRS broth - pH 6.0 tH + N bl th 4 Blend: ((Nisin - 0. Nisin - 1 ppm NH Cl 2 g in 20 mL H2O at pH 8.0) + (10% THIA)) in NH4Cl at pH 8.0 THIA - 5 ppm NH4Cl - 1.0, 10, or 100 mM MRS broth MRS broth - pH 6.0 tH + N blend Blend: ((Nisin - 0.2 g in 20 mL Nisin - 1 ppm glycylglycine H2O at pH 8.0) + (10% THIA)) in glycylglycine at pH 8.0 THIA - 5 ppm Glycylglycine - 1 or 10 mM Figure 11 shows that formulations made with 10 and 100 mM of KH2PO4, ammonium chloride or any of the three HEPES concentrations showed greater antimicrobial activity than the equivalent unbuffered formulation (i.e., “fresh blend”), suggesting that the buffered antimicrobial composition does not show any deleterious effect with respect to antimicrobial activity and may even increase the antimicrobial activity. Since the pH of the buffered composition should be stabilized over time compared to an equivalent unbuffered composition, the buffered composition is predicted to be stabilized over time. Blends comprising the ammonium chloride or the diglycine buffers were submitted to an accelerated aging study (2.5 weeks at 30°C). Table 12 indicates that blends made with an ammonium chloride or a diglycine buffer exhibited the same or a higher antimicrobial activity when compared to blends made without a buffer during this period. Table 12: Comparison of the antimicrobial activity of blends prepared with an ammonium chloride buffer (1 mM or 10 mM) or a diglycine buffer (1 or 10 mM) when compares to blends that do not have a buffer. Dark grey: better than blend with no buffer, lighter grey: not significantly different from blend with no buffer. Prep Name: Inhibition Ammonium Cl 1mM (3) Ammonium Cl 1mM (2) Ammonium Cl 1mM (1) Ammonium Cl 10mM (3) Ammonium Cl 10mM (2) Ammonium Cl 10mM (1) 6 / 2 Diglycine 10mM (3) 6 / 2 Diglycine 10mM (2) 6 / 2 Diglycine 10mM (1) 6 / 2 Diglycine 1mM (3) 6 / 2 Diglycine 1mM (2) 6 / 2 Diglycine 1mM (1) Example 11: Effect of a stabilizer at preventing precipitation of the antimicrobial composition A small amount of precipitate was observed at the bottom of the storage container during storage, which prompted investigation into means of preventing, reducing and / or eliminating precipitation. A recirculation system equipped with a pump was thus installed onto the storage container in order to prevent the accumulation of precipitate by maintaining a certain flow of the antimicrobial composition in the container during storage. This approach minimized precipitate formation and did not interfere with the antimicrobial activity of the composition. However, the addition of a pump recirculation system onto each storage container increased costs not only through the cost of the pump recirculation system itself but also by increasing shipping costs, as the pump recirculation system increased the weight of each container. Other means of preventing and / or eliminating precipitation was thus explored. The addition of a stabilizer was tested as a means of preventing, reducing and / or eliminating precipitation during storage in order to replace the pump recirculation system. Several stabilizers, particularly food-grade stabilizers, were investigated, for example, xanthan gum, guar gum, locust bean gum, starch, maltodextrin, pectin, agar, carrageenan, sodium pyrophosphate, collagen and lecithin. Xanthan gum was selected for further testing as it was already being used in Stabilized Liquid Yeast (SLY) and was one of the least expensive stabilizer for use at large scale. A series of concentrations was tested for the ability of xanthan gum to prevent, reduce and / or eliminate precipitation of the antimicrobial composition during storage. A xanthan gum stock solution of 0.133% was first prepared and refrigerated to remove a majority of bubbles. The stock solution was then removed from the fridge and centrifuged for 30 seconds. The samples were then prepared with varying concentrations of xanthan gum using the following modified procedure described below. The 0.133% xanthan gum stock was first diluted in water according to a desired final concentration. Ammonium chloride was then added to the diluted xantham gum and the pH was adjusted to between 8.20 and 8.40 to obtain a buffered xanthan gum solution. Nisin was then added. The resulting xanthan gum / nisin buffered solution was pH-adjusted to between 8.29 and 8.39. Finally, tetrahydroiso alpha acids were added to the xanthan gum / nisin buffered solution to obtain a stabilized and buffered antimicrobial composition. The samples were then stored for 10 days at 4°C. The antimicrobial activity was measured as described above (Figure 12) but without mixing (i.e., vortexing) the samples to account for the effect of any precipitate that may have formed during the days of storage. All samples contained Lactiplantibacillus plantarum as indicator strain. The samples were prepared as summarized in Table 13 and as described below. Antimicrobial composition without stabilizer ^ 10.7mg of ammonium chloride was added to 15mL of water and the pH was adjusted to between 8.20 and 8.40 to obtain a buffered solution. ^ 0.1g of nisin powder was added to the buffered solution and the pH was adjusted to between 8.29 and 8.39 to obtain a buffered nisin solution. ^ 5mL of THIA (10%) was added to the buffered nisin solution to obtain 20 mL of the buffered antimicrobial composition. Antimicrobial composition with xanthan gum as stabilizer ^ Different amounts of the 0.133% xanthan gum stock solution was added to 15 mL of water according to the final concentration of xanthan gum described in Table 13 to obtain a xanthan solution. ^ 10.7mg of ammonium chloride was added to the xanthan solution and the pH was adjusted to between 8.20 and 8.40 to obtain a buffered xanthan solution. ^ 0.1g of nisin powder was added to the buffered xanthan solution and the pH was adjusted to between 8.29 and 8.39 to obtain a buffered xanthan / nisin solution. ^ 5mL of THIA (10%) was added to the buffered xanthan / nisin solution to obtain 20 mL of the stabilized buffered antimicrobial composition (i.e., tH + N blend Xan Gum). Table 13: Materials and Formulations Sample ComponentsFinal concentration in themediumControlMRS brothH2OMRS broth - pH 6.0 Nisin MRS brothMRS broth - pH 6.0 Nisin - 50 g / L H2O, pH 3.4Nisin – 1.5 ppm THIA MRS brothMRS broth - pH 6.0 10% THIA (2,500 ppm)THIA – 7.5 ppm MRS broth MRS broth - pH 6.0 tH + N blend Blend: ((Nisin - 0.1 g) + (10% THIA)) in NH4Cl Nisin – 1.5 ppm at pH 8.29-8.39 THIA – 7.5 ppm NH4Cl - 10 mM MRS broth - pH 6.0 tH + N blend MRS broth Nisin – 1.5 ppm 0.0375% Xan Blend: ((0.133% xanthan gum) + (Nisin - 0.1 g) + THIA – 7.5 ppm Gum (10% THIA)) in NH4Cl at pH 8.29-8.39 NH4Cl - 10 mM Xanthan gum – 0.0375% MRS broth - pH 6.0 tH + N blend MRS broth Nisin – 1.5 ppm 0.05% Xan Blend: ((0.133% xanthan gum) + (Nisin - 0.1 g) + THIA – 7.5 ppm Gum (10% THIA)) in NH4Cl at pH 8.29-8.39 NH4Cl - 10 mM Xanthan gum – 0.05% MRS broth - pH 6.0 tH + N blend MRS broth Nisin – 1.5 ppm 0.075% Xan Blend: ((0.133% xanthan gum) + (Nisin - 0.1 g) + THIA – 7.5 ppm Gum (10% THIA)) in NH4Cl at pH 8.29-8.39 NH4Cl - 10 mM Xanthan gum – 0.075% MRS broth - pH 6.0 tH + N blend MRS broth Nisin – 1.5 ppm 0.1% Xan Blend: ((0.133% xanthan gum) + (Nisin - 0.1 g) + THIA – 7.5 ppm Gum (10% THIA)) in NH4Cl at pH 8.29-8.39 NH4Cl - 10 mM Xanthan gum – 0.1% Qualitative testing was performed after 10 days of storage at 4°C to evaluate the extent of precipitation in the composition comprising different concentrations of xanthan gum. Additional samples having lower concentrations of xanthan gum were also tested to determine the minimal amount that would be feasible. All samples were centrifuged 4 minutes at 2000rcf and the resulting solutions were evaluated for any precipitates by observation (data not shown). It was determined that samples having at least 0.0375% of xanthan gum displayed less precipitates whereas samples with less than 0.0375% xanthan gum were indistinguishable from the “tH + N blend” sample having no xanthan gum. All samples with 0.0375% xanthan gum or above had progressively less precipitate with 0.1% xanthan gum being effective at completely preventing precipitation during the 10 days of storage. Figure 12 shows that all formulations made with xanthan gum displayed the same antimicrobial activity than the equivalent formulation without xanthan gum (i.e., tH + N blend), suggesting that xanthan gum does not show any deleterious effect with respect to antimicrobial activity and may even increase the antimicrobial activity when stored for longer periods of time. While illustrative and presently preferred embodiments of the invention have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.

Claims

What is claimed is:

1. An antimicrobial composition (i) comprising alpha hops acid and nisin, and (ii) having a pH of between about 7.0 to about 9.

0.

2. The antimicrobial composition of claim 1, wherein the alpha hops acid comprises at least one humulone, adhumulone, cohumulone, posthumulone, prehumulone, adprehumulone, derivative thereof, or any combination thereof.

3. The antimicrobial composition of claim 2, wherein the alpha hops acid derivative comprises an iso alpha acid, a rhoiso alpha acid, a tetrahydroiso alpha acid, or a hexahydroiso alpha acid.

4. The antimicrobial composition of claim 3, wherein the iso alpha acid comprises at least one isocohumulone, isohumulone, isoprehumulone, isoposthumulone, isoadhumulone, isoadprehumulone, derivative thereof, or any combination thereof.

5. The antimicrobial composition of claim 4, wherein the iso alpha hops acid derivative comprises the tetrahydroiso alpha acid.

6. The antimicrobial composition of claim 5, wherein the tetrahydroiso alpha acid comprises tetrahydroiso cohumulone, tetrahydroiso humulone, tetrahydroiso prehumulone, tetrahydroiso posthumulone, tetrahydroiso adhumulone, tetrahydroiso adprehumulone, or any combination thereof.

7. The antimicrobial composition of any one of claims 1 to 6 comprising at least 2,000 ppm of alpha hops acid.

8. The antimicrobial composition of any one of claims 1 to 7, wherein the nisin comprises nisin A and / or nisin Z.

9. The antimicrobial composition of claim 8, wherein the nisin is nisin Z.

10. The antimicrobial composition of any one of claims 1 to 9, comprising at least 100 ppm of nisin.

11. The antimicrobial composition of any one of claims 1 to 10 exhibiting a synergistic antimicrobial activity in a medium compared to the antimicrobial activity of equivalent amounts of nisin and alpha hops acid added separately to the medium.

12. The antimicrobial composition of any one of claims 1 to 11 comprising less than 60 mM of sodium (Na2+).

13. The antimicrobial composition of any one of claims 1 to 12 being in a liquid form.

14. The antimicrobial composition of claim 13 being an aqueous solution or an aqueous suspension.

15. The antimicrobial composition of any one of claims 1 to 14, further comprising a buffer.

16. The antimicrobial composition of claim 15, wherein the buffer is a potassium phosphate buffer, a HEPES buffer, an ammonium chloride buffer, and / or a glycylglycine buffer.

17. The antimicrobial composition of any one of claims 1 to 16 being capable of retaining antimicrobial activity for at least 10 days at 4°C.

18. The antimicrobial composition of any one of claims 1 to 17, further comprising a stabilizer.

19. The antimicrobial composition of claim 18, wherein the stabilizer is xanthan gum, guar gum, locust bean gum, starch, maltodextrin, pectin, agar, carrageenan, sodium pyrophosphate, collagen, lecithin, or a combination thereof.

20. The antimicrobial composition of claim 18 or 19, wherein the stabilizer is xanthan gum.

21. The antimicrobial composition of claim 20, comprising at least 0.1% w / v of the xantham gum.

22. A medium comprising the antimicrobial composition of any one of claims 1 to 21.

23. A process for making the antimicrobial composition of any one of claims 1 to 21, the process comprising: a) combining an alpha hops acid solution with a nisin solution, wherein the nisin solution has a pH of between about 7.0 to about 9.

0.

24. The process of claim 23, further comprising, before a), providing the nisin solution by (i) adding nisin to water to obtain a first solution and (ii) adjusting the pH of the first solution between about 7.0 to about 9.0 with a base and / or a buffer.

25. The process of claim 23, further comprising, before a), providing the nisin solution by (i) providing a second solution comprising nisin and (ii) adjusting the pH of the second solution between about 7.0 to about 9.0 with a base and / or a buffer.

26. The process of claim 23, further comprising, before a), providing the nisin solution by (i) adjusting the pH of a third solution to a pH between about 7.0 and 9.0 with a base and / or a buffer and (ii) adding nisin to the third solution.

27. The process of any one of claims 24 to 26, wherein the buffer is a potassium phosphate buffer, a HEPES buffer, an ammonium chloride buffer, and / or a glycylglycine buffer.

28. The process of claim 27, wherein the buffer is the ammonium chloride buffer.

29. The process of claim 23, further comprising: b) adding a stabilizer in at least one of the alpha hops acid solution, the nisin solution, the first solution, the second solution, the third solution or the antimicrobial composition.

30. The process of claim 24, further comprising, before i), adding a stabilizer to water to obtain a stabilizer solution and adding nisin to the stabilizer solution to obtain the first solution.

31. The process of claim 29 or 30, wherein the stabilizer is xanthan gum, guar gum, locust bean gum, starch, maltodextrin, pectin, agar, carrageenan, sodium pyrophosphate, collagen, lecithin, or a combination thereof.

32. The process of any one of claims 29 to 31, wherein the stabilizer is xanthan gum.

33. The process of any one of claims 23 to 32, further comprising: c) storing the antimicrobial composition at a temperature of between about 2°C to about 10°C.

34. The process of claim 33, further comprising determining the antimicrobial activity of the antimicrobial composition before and / or after step c).

35. A method of preventing or limiting microbial contamination in a medium comprising: i) adding the antimicrobial composition of any one of claims 1 to 21 or obtainable / obtained by the process of any one of claims 23 to 34 to a medium.

36. The method of claim 35, wherein the medium is a liquefaction medium, a propagation medium, a fermentation medium, a food, a food ingredient, a feed, a feed ingredient, a beverage, and / or a beverage ingredient.

37. The method of claim 35 or 36 for preventing or limiting bacterial contamination and / or fungal contamination in the medium.

38. The method of any one of claims 35 to 37 for substantially limiting the acidification of the medium.

39. The method of any one of claims 35 to 38, further comprising, before i), diluting the antimicrobial composition to a desired concentration.

40. A kit for preventing or limiting microbial contamination in a medium with an antimicrobial composition, the kit comprising:^ nisin, ^ alpha hops acid, ^ optionally a base, a buffer and / or a stabilizer; and ^ instructions to make the antimicrobial composition according to the process any one of claims 23 to 34 and / or to perform the method of any one of claim 35 to 39.

41. The kit of claim 40, wherein the alpha hops acids, the nisin, the base, the buffer, the stabilizer and / or the antimicrobial composition is defined in any one of claims 1 to 23.

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