Saccharomyces cerevisiae CMRC 1S strain and application thereof

Abstract

The invention relates to the technical field of food fermentation, in particular to a saccharomyces cerevisiae CMRC 1S strain and application thereof. The strain CMRC 1S is separated from a traditional farmyard old manure sample in Henan region, has relatively strong protease production and aroma production capabilities, is excellent in fermentation performance, and is an excellent strain for preparing a leavening agent for production. The saccharomyces cerevisiae strain is added as a leavening agent to prepare the fermented flavored dried meat slices, degradation of protein in meat and formation of flavor are promoted, and the problems that traditional dried meat slices are hard in taste and poor in chewiness are solved; various volatile flavor and taste substances generated by fermentation improve the flavor quality of the dried meat slice, so that the overall acceptance of the product is remarkably improved, and the saccharomyces cerevisiae CMRC 1S has huge potential for producing the fermented flavor dried meat slice.

Description

Technical Field

[0001] The invention relates to the technical field of food fermentation, in particular to a CMRC 1S strain of Saccharomyces cerevisiae and application thereof. Background Art

[0002] With the increase in people's travel, leisure and entertainment activities and the increase in demand for nutritious and healthy meat products, high-quality, healthy and nutritious specialty leisure meat products have a good market development space. Meat jerky has a long history. In the Southern and Northern Dynasties, there were five-flavored jerky, white jerky, and sweet and crispy jerky; in the Tang Dynasty, there were red and bright fragrant jerky, and in the Yuan and Ming Dynasties, there were thousand-mile jerky. Therefore, meat jerky has a history of more than 3,000 years. According to the different ways of processing raw materials, meat jerky can be divided into minced meat jerky and meat jerky. It is mainly made of livestock and poultry meat. It is a cooked jerky product made through seasoning, mixing, baking, drying and other processes. It is portable, convenient, nutritious and delicious. It is favored by consumers, especially in Jiangsu, Fujian, Sichuan and other regions. Meat jerky food has become a local specialty.

[0003] In traditional processes, meat jerky production often requires a long drying time and a short baking process, and the final moisture content of the product is controlled at about 20%. The low moisture content of meat jerky makes it storable and easy to carry, but it also makes the product harder, affecting its elasticity and chewiness. In addition, the main flavor of meat jerky products mainly comes from the added spices and the Maillard reaction during the baking process, resulting in a relatively simple flavor. Texture and flavor are important indicators that affect the quality of meat jerky. The harder taste often limits its consumer group to young people. How to improve the texture quality of meat jerky, enrich its flavor and taste, and develop meat jerky into a high-end snack food suitable for all ages with unique flavor is the future development direction with huge economic potential.

[0004] Microbial fermentation can not only optimize the sensory quality and nutritional value of meat products, but also effectively improve the organizational structure of meat products, increase their tenderness, and produce a strong fermented flavor, thereby improving their flavor quality. In the process of using meat products as fermentation substrates, microorganisms use their own proteases and other enzyme systems to convert and decompose components such as proteins in meat into small molecules. These substances themselves have certain flavor characteristics or serve as precursors of volatile flavor substances, which can not only effectively improve the problem of single flavor of the product, but also alleviate the problem of dry and hard taste. It has been reported that many yeasts, including Saccharomyces cerevisiae, Debaryomyces hansenii, Pichia pastoris, etc., can use their own proteases and other enzyme systems to produce obvious aromas during growth, among which esters and alcohols are the main aroma substances; at the same time, they can stabilize the red color of meat products. For example, CN108850856 A discloses a method for making meat jerky fermented by multiple strains of lactic acid bacteria, yeast and Staphylococcus xylosus; CN112869046 A discloses a fermented flavored horse meat jerky and its preparation method, using a composite fermentation agent strain. Most existing literature and patents use commercial fermentation strains, and there is relatively little research and application of yeast fermentation agents suitable for traditional meat jerky.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a CMRC 1S strain of Saccharomyces cerevisiae and applications thereof.

[0007] Specifically, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a kind of brewer's yeast ( Saccharomyces cerevisiae ) CMRC 1S strain, the cerevisiae CMRC 1S strain is deposited in the General Microbiological Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No. 30797.

[0008] In a second aspect, the present invention provides a bacterial agent, wherein the bacterial agent contains the Saccharomyces cerevisiae CMRC 1S strain.

[0009] Preferably, the bacterial agent is a bacterial liquid, and the content of Saccharomyces cerevisiae CMRC 1S strain in the bacterial liquid is ≥ 1.0×10 6 CFU / mL.

[0010] In another preferred embodiment, the bacterial agent is bacterial powder, and the content of Saccharomyces cerevisiae CMRC 1S strain in the bacterial powder is ≥ 1.0×10 8 CFU / g.

[0011] In a third aspect, the present invention provides a method for preparing the bacterial agent, comprising the following steps: S1, inoculating the CMRC 1S strain of Saccharomyces cerevisiae into a YPD broth medium for culturing to obtain a culture solution; S2, removing impurities from the culture solution in step S1 to obtain the bacterial agent.

[0012] Preferably, the culturing in step S1 comprises: culturing at 20-35° C. for 36-48 hours.

[0013] Preferably, the impurity removal in step S2 comprises: centrifuging and discarding the supernatant, resuspending with sterile saline, adding a lyophilization protectant and freeze-drying.

[0014] In a fourth aspect, the present invention provides the use of the Saccharomyces cerevisiae CMRC 1S strain, or the bacterial agent, or the preparation method in the production of meat jerky or fermented meat jerky products.

[0015] In a fifth aspect, the present invention provides a method for processing fermented meat jerky, comprising the steps of: slicing pre-cooled fresh meat, marinating and fermenting it, and then baking it twice; the bacterial agent used in the fermentation is the bacterial agent described in the second aspect above.

[0016] Preferably, the precooling temperature is -35±5°C; And / or, the fresh meat is selected from pork hind leg meat; and / or, the slice thickness is 3-5 mm; And / or, auxiliary materials are added during pickling, the content of the auxiliary materials accounting for 15.1%-45% of the weight of the pork slices; by weight, the auxiliary materials include 5-15 parts of sugar, 1-2 parts of salt, 1-5 parts of fish sauce, 1-5 parts of soy sauce, 5-10 parts of vegetable oil, 1-5 parts of cooking wine, 0.1-2 parts of spices and 1-5 parts of sesame seeds; And / or, additives are added during pickling, wherein the content of the additives accounts for 0.4%-2.8% of the weight of the pork slices; in parts by weight, the additives include 0.1-0.3 parts of tripolyphosphate, 0.1-1 parts of monascus red, 0.1-0.5 parts of sodium isoascorbate, and 0.1-1 parts of TG enzyme; and / or, adding the bacterial agent according to any one of claims 2 to 4 during pickling: first dissolving the bacterial agent in a glucose solution with a mass concentration of 1 to 5% and then pouring it into the meat slices; wherein the amount of the glucose solution is 5 to 10% of the total weight of the meat slices; the amount of the bacterial agent added is 10 3 -10 4 CFU / g raw meat; And / or, the fermentation is intermittent tumbling treatment, after each tumbling for 5-10 minutes, the mixture is allowed to stand for 50-60 minutes at a temperature of 15-35°C, and the total time is 12-36 hours; And / or, the first baking temperature is 60-90°C, and the processing time is 1-3h; the second baking temperature is 90-120°C, and the processing time is 5-15min.

[0017] Beneficial effects: The CMRC 1S strain of brewer's yeast provided by the present invention is separated from a traditional farmyard old manure sample in Henan Province, grows well on YPD liquid and solid culture media, has high protease production activity, strong aroma production ability, can effectively improve the quality texture and flavor characteristics of meat products, and is an excellent strain for preparing a starter for production.

[0018] The invention adds brewer's yeast CMRC 1S as a fermentation agent. Due to the fermentation effect of brewer's yeast, macromolecular substances such as protein and fat in the meat jerky are degraded into small molecular substances, which is more conducive to digestion and absorption, increases nutritional value, improves the chewiness and texture of the product, and produces unique aroma components such as esters, giving the meat jerky a special fragrance, and has good market prospects.

[0019] The fermented pork jerky processed and prepared according to the method provided by the present invention has moderate hardness and softness, strong aroma, good flavor and taste, and significantly improved overall acceptance. The application of brewer's yeast CMRC 1S in the production of meat jerky products has great potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be described below.

[0021] Figure 1 The colony morphology of Saccharomyces cerevisiae CMRC 1S of the present invention.

[0022] Figure 2 It is the strain morphology of the Saccharomyces cerevisiae CMRC 1S of the present invention.

[0023] Figure 3 This is the preliminary screening result of protease of some screening strains of the present invention.

[0024] Figure 4 These are the results of protease activity assay of some of the strains screened in the present invention.

[0025] Figure 5 This is the growth curve of the Saccharomyces cerevisiae CMRC 1S strain of the present invention.

[0026] Figure 6 It is the environmental (acetic acid concentration) tolerance of the Saccharomyces cerevisiae CMRC 1S strain of the present invention.

[0027] Figure 7 It is the environmental (ethanol concentration) tolerance of the Saccharomyces cerevisiae CMRC 1S strain of the present invention.

[0028] Figure 8 It is the environmental (sodium chloride concentration) tolerance of the Saccharomyces cerevisiae CMRC 1S strain of the present invention. DETAILED DESCRIPTION

[0029] The purpose of the present invention is to provide a CMRC 1S strain of Saccharomyces cerevisiae that produces both protease and aroma and its application, especially in meat jerky products. In order to achieve the purpose of the present invention, the present invention separates and screens a yeast strain suitable for production operation through primary screening and secondary screening, which can effectively improve the dry and hard texture of meat jerky, increase its tenderness and elasticity, and enrich its flavor and taste, and applies it to meat jerky production, which is of great significance for the development of high-end and high-quality leisure meat products.

[0030] Specifically, the present invention collects homemade fermented foods such as old fat, sour meat, cheese, and koji wine from all over the country, separates and purifies them, and screens and rescreens them for protease and aroma production, and further tests on biological characteristics and fermentation characteristics, and finally separates and purifies a strain of brewer's yeast (Saccharomyces cerevisiae) that produces protease and aroma and is suitable for traditional meat jerky products in my country from samples of old fat from traditional farmers in Henan Province. Saccharomyces cerevisiae ) CMRC 1S strain, which has been deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Postal Code 100101, with deposit number CGMCC No. 30797 and deposit date May 28, 2024.

[0031] The invention also provides a method for separating, screening and identifying the yeast strain.

[0032] The collected samples were enriched and cultured. After 10-fold serial gradient dilution, the sample solution of appropriate concentration was aspirated and inoculated on yeast peptone dextrose (YPD) agar medium using the pour plate method. The samples were cultured at 30°C for 48 h, and colonies with typical yeast colony characteristics were picked for plate streak isolation and purification, and stored for later use.

[0033] For the initial screening of protease-producing yeast strains, the isolated and purified yeast was cultured in a liquid shaker after strain activation. A sterile filter paper was dipped in the strain culture solution and inoculated into YPD agar medium supplemented with 4% skim milk powder. The culture was cultured at 30°C for 48 hours. The strain to be tested was observed to see whether it produced a transparent circle, the diameter of the transparent circle and the diameter of the strain were measured, and the strains with transparent circles were recorded.

[0034] Rescreening of protease-producing yeast strains, calculating the HC ratio of strains with transparent rings, HC = transparent ring diameter ÷ strain diameter, yeast strains with HC ratios > 1.5 were inoculated into liquid culture medium for activation, and the bacterial solution concentration was adjusted to 1.0 × 10 7CFU / mL, inoculated into the rescreening medium at a 2% inoculation rate, fermented for 48 h to determine the protease activity, and screened out strains with higher protease activity. The protease activity determination was carried out according to the Folin method in GB / T 23527-2009.

[0035] The yeast obtained above was screened for aroma production by inoculating them into YPD liquid medium and YPD agar medium, respectively. After culturing at 30°C for 48 hours, the strains were screened by olfactory method.

[0036] According to the results of the initial screening, re-screening of protease production ability and the screening of aroma production ability, the yeast strain CMRC 1S with good growth and strong enzyme and aroma production ability was comprehensively selected for subsequent identification and application research.

[0037] The colony morphology of the brewer's yeast CMRC 1S of the present invention is as follows: it grows well on a YPD agar medium, the colonies are milky white, round, convex, with smooth surfaces and edges, and the colony diameter is about 2-3 mm.

[0038] The colony morphology of Saccharomyces cerevisiae CMRC 1S is shown in Figure 1 , strain morphology see Figure 2 .

[0039] The strain was identified as Saccharomyces cerevisiae ( Saccharomyces cerevisiae ), the physicochemical identification and enzymatic characteristics of the strain are shown in Table 1.

[0040] Table 1

[0041] Molecular biological identification of strain CMRC 1S: The total DNA of the strain was extracted and its 26S rDNA was amplified. After the electrophoresis test was qualified, it was sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. The sequencing results were compared with the sequences in the GenBank database by Blast homology. The results showed that the strain sequence was consistent with the strain Saccharomyces cerevisiae The PE-2 gene sequence is highly homologous and was identified as Saccharomyces cerevisiae ( Saccharomyces cerevisiae ), the 26S rDNA gene sequence of strain CMRC 1S is as follows: (SEQ ID NO.1).

[0042] The present invention also provides application of the Saccharomyces cerevisiae CMRC 1S in the field of food (fermentation).

[0043] The present invention further provides a starter containing the brewer's yeast, or a starter prepared by the brewer's yeast. The starter can be prepared according to conventional methods in the art. Preferably, the starter is prepared by freeze-drying after submerged fermentation of a microbial liquid.

[0044] In order to make the fermentation agent more suitable for the processing of meat jerky. The present invention provides a better method for preparing the fermentation agent, and the preparation method is specifically as follows: after the strain is transferred and activated, it is inoculated into the YPD broth medium at an inoculation rate of 2-4%, cultured on a shaking table to obtain a bacterial suspension, centrifuged and discarded the supernatant, sterile physiological saline is added to re-suspend the bacteria, and then centrifuged again to discard the supernatant, a small amount of physiological saline is added to mix to obtain a concentrated bacterial solution, and a certain volume of freeze-drying protective agent is added and freeze-dried to obtain the fermentation agent. Among them, the number of activations, shaking table culture conditions and centrifugation conditions can adopt conventional laboratory methods.

[0045] The present invention provides a preferred preparation method based on the conventional method, which specifically comprises: transferring and activating the bacterial strain stored in the glycerol tube twice, inoculating the bacterial strain into the YPD broth culture medium at an inoculation ratio of 2-4%, and then culturing the bacterial suspension at 28°C on a shaking table for 36-48 hours, discarding the upper culture solution after centrifuging at 3000-5000 rpm for 10-15 minutes, adding sterile physiological saline to resuspend the bacterial bodies, centrifuging and discarding the supernatant, adding a small amount of physiological saline to mix well to obtain a concentrated bacterial solution, adding a certain volume of freeze-drying protective agent, and freeze-drying to obtain a starter.

[0046] Optionally, the second amount of physiological saline added is 1 / 5-1 / 10 of the volume of the initial bacterial suspension, so that the bacterial concentration in the concentrated bacterial solution reaches 10 9 CFU / ml.

[0047] Optionally, the mass ratio of the concentrated bacterial solution to the lyophilization protective agent is about 0.1-10:1.

[0048] Optionally, the lyoprotectant component may include skim milk, glycerol and sucrose.

[0049] As a preferred method, the content of the saccharomyces cerevisiae strain in the fermentation agent is 10 9 -10 10 CFU / g.

[0050] The present invention further provides the use of the CMRC 1S strain of Saccharomyces cerevisiae or a microbial agent containing the CMRC 1S strain of Saccharomyces cerevisiae in the production of meat jerky (fermented) products. The use of yeast and other fermentation agents to produce meat jerky products is an effective way to improve their texture and flavor. The present invention adds the Saccharomyces cerevisiae strain as a fermentation agent to produce fermented flavored meat jerky, thereby promoting the degradation of protein in the meat and the formation of flavor, thereby improving the problem of hard taste and poor chewiness of traditional meat jerky; the various volatile flavors and flavor substances produced by fermentation improve the flavor quality of the meat jerky, significantly improving the overall acceptance of the product. The use of Saccharomyces cerevisiae CMRC 1S in the production of fermented flavored meat jerky has great potential.

[0051] The present invention also provides a fermented meat jerky product prepared by fermentation of brewer's yeast CMRC 1S. The raw materials used to prepare the fermented meat jerky product include multiple materials selected from pork hind leg meat, vegetable oil, auxiliary materials and seasonings, additives, fermentation agents and water.

[0052] Preferably, the vegetable oil is selected from at least one of peanut oil, sunflower seed oil or other vegetable oils.

[0053] Preferably, the auxiliary materials and seasonings are selected from salt, sugar, five-spice powder, light soy sauce, yeast extract, fish sauce and the like.

[0054] Preferably, the additive is selected from tripolyphosphate, monascus red, sodium isoascorbate, TG enzyme and the like.

[0055] As a more specific and preferred embodiment, the present invention provides a method for processing fermented flavored meat jerky, comprising the following steps: 1) Pretreatment of raw meat: Select fresh pork hind leg meat, remove fat and fascia, trim it into pieces of appropriate size and put it into a -35℃ quick freezer for precooling.

[0056] 2) Slicing: Take out the pre-frozen meat and put it into the slicer to slice it in the direction of the natural texture of the meat. The thickness of the meat slices is 3-5mm; 3) Marinating: Add marinating ingredients, additives, yeast fermentation agents and water to the pork slices in sequence, stir evenly, and then tumble and marinate in a vacuum manner to make the pork slices tasty; 4) Fermentation: Put the marinated meat slices into a constant temperature box for rolling, kneading, and fermentation; 5) Baking: Flatten the marinated meat slices and bake at low temperature to obtain original pork jerky; 6) Baking: After the original cut pork jerky has cooled, trim it into pieces of jerky of suitable packaging size, brush both sides with honey water, and bake in the oven; 7) Packaging: After the roasted meat jerky is completely cooled, it is aseptically packaged.

[0057] Further preferably, in step 3), the content of the pickling auxiliary materials accounts for 15.1%-45% of the weight of the pork slices; it includes 5-15 parts of sugar, 1-2 parts of salt, 1-5 parts of fish sauce, 1-5 parts of light soy sauce, 5-10 parts of vegetable oil, 1-5 parts of cooking wine, 0.1-2 parts of spices and 1-5 parts of sesame seeds by weight.

[0058] Further preferably, in step 3), the content of the additives is 0.4%-2.8% of the weight of the pork slices; and includes, by weight, 0.1-0.3 parts of tripolyphosphate, 0.1-1 parts of monascus red, 0.1-0.5 parts of sodium isoascorbate, and 0.1-1 parts of TG enzyme.

[0059] Further preferably, in step 3), in order to ensure the uniform distribution of the starter in the raw meat, the starter can be first dissolved in a small amount of glucose solution and then poured into the meat slices, specifically: the starter is dissolved in a glucose solution with a mass concentration of 1-5% and then poured into the meat slices; wherein the amount of the glucose solution is 5-10% of the total weight of the meat slices. The amount of the yeast fermentation agent added is 10 3 -10 4 CFU / g raw meat.

[0060] More preferably, in step 3), the water is 5-20 parts. The vacuum tumbling treatment time is 30-90 minutes, and the temperature is 4-10°C.

[0061] Further preferably, in step 4), the fermentation is an intermittent tumbling treatment, specifically: after each tumbling for 5-10 minutes, the mixture is intermittently allowed to stand for 50-60 minutes, the temperature is 15-35°C, preferably 20-35°C, and the total time is 12-36 hours.

[0062] Further preferably, in step 5), the low-temperature baking temperature is 60-90° C., and the processing time is 1-3 hours.

[0063] More preferably, in step 6), the baking temperature is 90-120° C. and the processing time is 5-15 min.

[0064] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] The endpoints and any values ​​of the ranges disclosed in this specification are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "specific implementations", or "some specific implementations" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0067] In the examples provided in this specification, if no specific techniques or conditions are specified, the techniques or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased through regular channels.

[0068] The unit "portion" expressing weight in the present invention can be gram, kilogram, kilo, jin, liang, ton etc., depending on the production scale.

[0069] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0070] Example 1

[0071] Screening of protease-producing yeast

[0072] For the initial screening of protease-producing yeast strains, the isolated and purified yeast was cultured in a liquid shaker after strain activation. A sterile filter paper was dipped in the strain culture solution and inoculated into YPD agar medium supplemented with 4% skim milk powder. The culture was cultured at 30°C for 48 hours. The strain to be tested was observed to see whether it produced a transparent circle, the diameter of the transparent circle and the diameter of the strain were measured, and the strains with transparent circles were recorded.

[0073] Rescreening of protease-producing yeast strains, calculating the HC ratio of strains with transparent rings, HC = transparent ring diameter ÷ strain diameter, yeast strains with HC ratio ≥ 1.5 were inoculated into liquid culture medium for activation, and the bacterial solution concentration was adjusted to 1.0 × 10 7 CFU / mL, inoculated into the rescreening medium at a 2% inoculation rate, fermented for 48 h to determine the protease activity, and screened out strains with higher protease activity. The protease activity determination was carried out according to the Folin method in GB / T 23527-2009.

[0074] After the strains that can produce extracellular proteases grow on the primary screening plate, obvious proteolysis zones can be formed around their colonies. The HC ratios are calculated as shown in Table 2. The HC ratios of CMRC 1S and strains 3, 5, 6, 9, and 10 are relatively high. The hydrolysis zones of some strains are as follows: Figure 3 The protease activity was further determined by liquid culture method, and the results were as follows Figure 4 The protease activities of CMRC 1S and strains 3, 5, 6, 9, and 10 were 89.98, 76.66, 88.31, 85.48, 68.99, and 71.22 U / mL, respectively.

[0075] Table 2 Results of preliminary screening of protease-producing yeasts

[0076] Example 2

[0077] Fragrance screening

[0078] The yeast culture liquid frozen in the glycerol tube was aseptically inoculated into YPD liquid medium and YPD solid medium respectively. After culturing at 30℃ for 48h, the yeast with strong aroma production ability was screened by smelling the aroma. The aroma characteristics were described with reference to the common aroma types of yeast. The results were characterized by wine aroma, fruity aroma, ester aroma, floral aroma, fragrance, sour taste, pungent smell and overall aroma. There were five levels of intensity, from low to high, indicating that the sensory characteristics of the fermentation broth were from weak to strong, respectively weak (+), weak (++), medium (+++), strong (++++) and strong (+++++). The blank control of the experiment was sterilized YPD liquid medium and YPD agar.

[0079] Yeasts that can produce aroma by fermentation were screened by smell. The flavor characteristics and intensities are shown in Table 3. The results show that the flavors of fermented products from different yeast strains are significantly different. Combined with the screening results of protease-producing yeasts, the CMRC 1S strain has high protease activity and can produce ester aroma, fruit aroma, and wine aroma by fermentation. It has a strong aroma-producing ability and is suitable for use as a starter strain for making fermented meat jerky.

[0080] Table 3 Fragrance screening results

[0081] Example 3

[0082] Analysis of Volatile Flavor Compounds in CMRC 1S Yeast Fermentation Broth

[0083] Accurately weigh 10 mL of the sample to be tested and place it in a headspace sample bottle, add 1 µL of 2-methyl-3-heptanone with a concentration of 0.816 μg / µL, tighten the bottle cap, insert a 50 / 30 µm DVB / CAR / PDMS extraction head, place it in a 50°C water bath for 10 min, then push out the fiber head and start extraction for 30 min. Then insert the extraction head into the GC-MS injection port for desorption for 10 min, and start the instrument to collect data at the same time. Repeat each sample 3 times and take the average value. The culture medium without yeast inoculation is used as the control.

[0084] GC conditions: TG-WAX MS polar column (30 m×0.25 mm, 0.25 μm), high-purity nitrogen as carrier gas (>99.99%), flow rate 1.0 mL / min, no split; hold for 2 min.

[0085] MS conditions: interface temperature 260 °C, transfer line temperature 230 °C; voltage 1.2 kV; EI temperature 280 °C; electron energy 70 eV; scan range 40-600 m / z; full scan mode; scan time 2 s.

[0086] Qualitative analysis: Compare the compounds in the mass spectrum with databases such as NIST and Wiley, and delete high-boiling point compounds with retention times greater than 45 minutes and no odor. The determination of the compounds is based on the positive and negative similarity index greater than 800.

[0087] Quantitative analysis: The content of each flavor substance relative to the internal standard 2-methyl-3-heptanone is calculated by the peak area and content of the internal standard. The calculation formula is as follows:

[0088] In the formula: C is the content of the volatile substance to be measured / (μg / kg); Ax is the peak area of ​​the volatile substance to be measured / (AU·min); C0 is the concentration of the internal standard (0.816 μg / μL); A0 is the peak area of ​​the internal standard / (AU·min); V is the injection volume of the internal standard / μL; m is the mass of the sample to be measured / g.

[0089] Odour Activity Value (OAV) is calculated according to the following formula:

[0090] Where: C is the concentration of the flavor substance to be tested (µg / kg); T is the detection threshold of the substance in water (µg / kg).

[0091] HS-SPME-GC-MS was used to identify the volatile flavor substances in blank fermentation broth without yeast and CMRC 1S yeast fermentation broth, and a total of 88 volatile flavor substances were detected. Since the contribution of each volatile flavor substance to its overall flavor characteristics is determined by the concentration of the volatile flavor substance and its corresponding sensory threshold, generally, volatile flavor substances with OAV≥1 contribute more to the overall flavor, and volatile flavor substances with 0.1 ≤ OAV<1 have an important modifying effect on the overall flavor. Therefore, the OAV value of each volatile flavor substance was calculated, and 8 and 18 volatile flavor substances with OAV ≥ 0.1 were detected in the two groups of samples, respectively, which are called odor active substances. The results are shown in the following table. Among them, aldehydes, alcohols and esters are more numerous, with 13 species, followed by heterocyclics and phenolic acids. The total OAV of the fermentation broth of the control group was 23.42, which was much lower than the 256.98 of the fermentation broth of CMRC1S. In the fermentation broth inoculated with Saccharomyces cerevisiae CMRC 1S, the types and total amount of odor active substances increased significantly, specifically in the significant increase of esters and alcohols, such as whiskey-flavored isoamyl alcohol and banana-flavored isoamyl acetate, which play an important role in the formation of the overall flavor of the sample. It can be seen that Saccharomyces cerevisiae CMRC 1S can produce a variety of aroma substances during the fermentation process, and it has great potential for application in meat product production.

[0092] Table 4 OAV values ​​of odor active substances in different samples

[0093] Example 4

[0094] Determination of the Growth Curve of Saccharomyces cerevisiae CMRC 1S

[0095] The glycerol-preserved Saccharomyces cerevisiae CMRC 1S was inoculated into YPD liquid medium for activation twice, and fresh bacterial liquid was transferred to fresh YPD liquid medium at a 2% inoculation rate. The culture was shaken at 30°C and 100 r / min, and the absorbance value (OD 600 ) changes, and 3 replicates were performed at each time point ( Figure 5 ).

[0096] Example 5

[0097] Fermentation agent and preparation method thereof

[0098] The glycerol-preserved strain was transferred and activated twice and then inoculated into YPD liquid culture medium at an inoculation ratio of 2%. After being cultured at 30°C and 100 r / min for 24 hours, a bacterial suspension was obtained. After centrifugation at 3000 rpm for 15 minutes, the upper culture solution was discarded, an equal volume of sterile saline was added to resuspend the bacteria, and then centrifuged and the supernatant was discarded. After adding 1 / 10 of the volume of the bacterial suspension, a sterile saline was added and mixed to obtain a concentrated bacterial solution. A freeze-drying protective agent (10% skim milk) 5 times the volume of the concentrated bacterial solution was added and freeze-dried to obtain a starter. The bacterial activity in the dry powder starter was detected by gradient dilution and pour plate method. 9 CFU / g.

[0099] Example 6

[0100] This embodiment provides a fermented flavored meat jerky and a processing method thereof.

[0101] The specific steps of the processing method of the fermented flavor meat shop are as follows: (1) Pretreatment of raw meat: Select 1000g of fresh pork hind leg meat, remove the fat and fascia, trim it into pieces of appropriate size, and put it into a -35℃ quick freezer for precooling.

[0102] (2) Slicing: Take out the pre-frozen meat and put it into a slicer to slice it in the direction of the natural texture of the meat. The thickness of the meat slices should be 3 mm.

[0103] (3) Preparation of starter culture: Weigh 1 g of glucose and dissolve it in 50 g of water to prepare a glucose solution with a mass concentration of 2%. Weigh 0.005 g of freeze-dried starter culture powder and dissolve it in the above glucose solution.

[0104] (4) Marinating: Add marinating auxiliary materials, additives, the fermentation agent solution prepared in step 3 and 100 g of water to the pork slices in sequence and stir evenly for vacuum rolling and marinating. Auxiliary materials include: 100 g sugar, 15 g salt, 50 g fish sauce, 10 g soy sauce, 50 g vegetable oil, 10 g cooking wine, 2 g ginger powder, 5 g black pepper powder and 30 g sesame. Additives include: 1.5 g tripolyphosphate, 5 g red yeast rice, 2 g sodium isoascorbate and 3 g TG enzyme. The vacuum rolling treatment time is 60 min and the temperature is 5°C.

[0105] (5) Fermentation: The marinated meat slices are placed in a constant temperature box for rolling and kneading, and then left to ferment. The fermentation is an intermittent rolling and kneading process, specifically: after each 5-minute rolling and kneading, the meat slices are left to ferment for 55 minutes at a temperature of 25°C. The total fermentation time is 12 hours.

[0106] (6) Baking: Flatten the marinated meat slices and bake at 75° C. for 2 h to obtain raw pork jerky; (7) Baking: After the original pork jerky has cooled, trim it into pieces of jerky of suitable packaging size, brush both sides with honey water, and bake in the oven at 110°C for 10 minutes.

[0107] (8) Packaging: After the roasted meat jerky is completely cooled, it is packaged aseptically.

[0108] Comparative Example 1

[0109] This comparative example also provides a fermented flavored meat jerky and a processing method thereof. The fermented flavored meat jerky is processed according to the steps of Example 6, except that: Step (3) Preparation of starter culture: Weigh 1 g of glucose and dissolve it in 50 g of water to prepare a glucose solution with a mass concentration of 2%.

[0110] Step (4) marinating: add marinating auxiliary materials, additives, the glucose solution prepared in step 3 and 100 g of water to the pork slices in sequence and stir evenly to perform vacuum rolling and marinating. The auxiliary materials include: 100 g sugar, 15 g salt, 50 g fish sauce, 10 g soy sauce, 50 g vegetable oil, 10 g cooking wine, 2 g ginger powder, 5 g black pepper powder and 30 g sesame. The additives include: 1.5 g tripolyphosphate, 5 g red yeast rice, 2 g sodium isoascorbate and 3 g TG enzyme. The vacuum rolling treatment time is 60 min and the temperature is 5°C.

[0111] Experimental Example 1

[0112] Sensory evaluation

[0113] A sensory evaluation panel consisting of 15 experienced professionals aged 20 to 40 was selected to evaluate the color, smell, taste and mouthfeel of the flavored meat jerky obtained in Example 6 and Comparative Example 1 by blind scoring. The total score for each item was 25 points, and the acceptance was the sum of the scores of the above four items. The mouth was rinsed with clean water between the evaluations of each sample. The sensory evaluation standards are shown in Table 5, and the sensory evaluation results are shown in Table 6.

[0114] Table 5 Sensory evaluation standards

[0115] Table 6 Sensory evaluation results

[0116] As can be seen from Table 6, the fermented flavored meat jerky produced in Example 6 is significantly higher than that in Comparative Example 1 in terms of smell, flavor, mouthfeel and overall acceptance, which is specifically manifested as strong aroma, unique fermented aroma; palatable taste, mellow aftertaste; moderate hardness and good elasticity. Comparative Example 1 has a single flavor, average taste, and a hard mouthfeel, so Example 6 has a higher overall acceptance. There is no significant difference in color between Example 6 and Comparative Example 1. It can be seen that the present invention uses brewer's yeast (CMRC 1S) to prepare a starter and use it to prepare fermented flavored meat jerky, which can significantly improve the flavor characteristics of traditional meat jerky, enhance the taste and quality of meat jerky products, and make it easier for consumers to accept.

[0117] Experimental Example 2

[0118] Environmental tolerance test of Saccharomyces cerevisiae CMRC 1S

[0119] The strain's tolerance to acetic acid, ethanol and sodium chloride was determined: the strain was transferred and activated twice and then inoculated with 2% inoculation into YPD liquid medium with different concentrations of acetic acid, ethanol and sodium chloride. The acetic acid addition was 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1.0%; the ethanol addition was 0%, 3%, 6%, 9%, 12% and 15%; the sodium chloride addition was 0%, 2%, 4%, 6%, 8% and 10%; after culturing at 30°C for 24 hours, 200 μL of yeast fermentation liquid was aspirated into an ELISA plate, and the OD value was measured at 600 nm using an ELISA reader ( Figure 6 , Figure 7 and Figure 8 ).

[0120] According to the above experimental results, when the acetic acid concentration was 0.4%, the OD value of the culture solution of Saccharomyces cerevisiae CMRC 1S was 0.082, close to 0, and thereafter the OD value remained almost unchanged when the acetic acid concentration was increased, that is, when the acetic acid concentration was 0.4%, the strain had stopped growing and reproducing. Similarly, it can be seen that the tolerance concentration of ethanol for Saccharomyces cerevisiae CMRC 1S is 12%. When the NaCl concentration was above 8%, the growth of the CMRC 1S strain was severely inhibited, and even stopped growing, that is, the tolerance concentration of NaCl for the CMRC 1S strain was 8%.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Saccharomyces cerevisiae ( Saccharomyces cerevisiae ) CMRC 1S strain, characterized in that The CMRC 1S strain of Saccharomyces cerevisiae is deposited in the General Microbiological Center of China National Microbiological Culture Collection Administration with a deposit number of CGMCC No.30797.

2. A bacterial agent, characterized in that: The bacterial agent contains the CMRC 1S strain of Saccharomyces cerevisiae according to claim 1.

3. The bacterial agent according to claim 2, characterized in that The bacterial agent is a bacterial liquid, and the content of the CMRC1S strain of Saccharomyces cerevisiae in the bacterial liquid is ≥ 1.0×10 6 CFU / mL.

4. The bacterial agent according to claim 2, characterized in that The bacterial agent is bacterial powder, and the content of the CMRC1S strain of Saccharomyces cerevisiae in the bacterial powder is ≥ 1.0×10 8 CFU / g.

5. The method for preparing the bacterial agent according to any one of claims 2 to 4, characterized in that: The method comprises the following steps: S1, inoculating the CMRC 1S strain of the brewer's yeast into a YPD broth medium for cultivation to obtain a culture solution; S2, removing impurities from the culture solution in step S1 to obtain the bacterial agent.

6. The method for preparing the bacterial agent according to claim 5, characterized in that: The culturing in step S1 includes: culturing at 20-35° C. for 36-48 hours.

7. The method for preparing the bacterial agent according to claim 5 or 6, characterized in that: The impurity removal in step S2 includes: centrifuging and discarding the supernatant, resuspending with sterile saline, adding a lyophilization protectant and freeze-drying.

8. Use of the CMRC 1S strain of Saccharomyces cerevisiae according to claim 1, or the bacterial agent according to any one of claims 2 to 4, or the preparation method according to any one of claims 5 to 7 in the production of meat jerky or fermented meat jerky products.

9. A method for processing fermented meat jerky, characterized in that: The method comprises the following steps: slicing the pre-cooled fresh meat, marinating and fermenting the meat, and then roasting the meat twice; the bacterial agent used in the fermentation is the bacterial agent described in any one of claims 2 to 4.

10. The method for processing fermented meat jerky according to claim 9, characterized in that: Precooling temperature is -35±5℃; And / or, the fresh meat is selected from pork hind leg meat; and / or, the slice thickness is 3-5 mm; And / or, auxiliary materials are added during pickling, the content of the auxiliary materials accounting for 15.1%-45% of the weight of the pork slices; by weight, the auxiliary materials include 5-15 parts of sugar, 1-2 parts of salt, 1-5 parts of fish sauce, 1-5 parts of soy sauce, 5-10 parts of vegetable oil, 1-5 parts of cooking wine, 0.1-2 parts of spices and 1-5 parts of sesame seeds; And / or, additives are added during pickling, wherein the content of the additives accounts for 0.4%-2.8% of the weight of the pork slices; in parts by weight, the additives include 0.1-0.3 parts of tripolyphosphate, 0.1-1 parts of monascus red, 0.1-0.5 parts of sodium isoascorbate, and 0.1-1 parts of TG enzyme; and / or, adding the bacterial agent according to any one of claims 2 to 4 during pickling: first dissolving the bacterial agent in a glucose solution with a mass concentration of 1 to 5% and then pouring it into the meat slices; wherein the amount of the glucose solution is 5 to 10% of the total weight of the meat slices; the amount of the bacterial agent added is 10 3 -10 4 CFU / g raw meat; And / or, the fermentation is intermittent tumbling treatment, after each tumbling for 5-10 minutes, the mixture is allowed to stand for 50-60 minutes at a temperature of 15-35°C, and the total time is 12-36 hours; And / or, the first baking temperature is 60-90°C, and the processing time is 1-3h; the second baking temperature is 90-120°C, and the processing time is 5-15min.

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