Enzymatically curdled milk product with extended shelf life

Abstract

A method of manufacture of an extended shelf life milk curd product includes heating milk to a temperature to denature whey proteins of the milk then cooling the milk to an enzyme temperature of less than 72°C. After which a proteolytic enzyme is introduced to form a coagulant with a smooth pudding form and the coagulant is again heated to deactivate the enzyme.

Description

ENZYMATICALLY CURDLED MILK PRODUCT WITH EXTENDED SHELF LIFECROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of US provisional application 63 / 541,932 filed October 2, 2023, and hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTION

[0002] The present invention relates to milk curd products and, in particular, to a product and method of making an enzymatically curdled milk product with improved shelflife.

[0003] Milk curd products are well known and include a variety of products such as cheeses and yogurts. Curdling, which produces curd, make use of enzymes such as rennet, bacterial cultures, or edible acids such as lemon juice. In enzymatic curdling, the enzyme operates to cleave the K-caseins on the surface of the milk casein micelles, causing the destabilized micelles to aggregate. Ginger milk curd is a curdled milk product originating from the Guangdong province in southern China. The traditional ginger milk curd recipe calls for hot milk to be poured over ginger concentrate, allowing the ginger protease enzyme to act as a curdling agent that turns heated milk into a soft pudding. This soft pudding has a texture that is smooth and a flavor that is slightly spiced by ginger and is consumed while still warm.SUMMARY OF THE INVENTION

[0004] The present invention provides a curdled milk product using a protease enzyme that may be refrigerated to maintain a shelflife suitable for modem food distribution.

[0005] Specifically the invention provides a method of making a milk product with extended shelflife including the steps of (a) heating milk to a temperature to denature whey proteins of the milk;(b) cooling the milk to an enzyme temperature of less than 72°C; (c) introducing a proteolytic enzyme to milk at the enzyme temperature to form a coagulant with a smooth pudding form; and (d) heating the coagulant to deactivate the enzyme.

[0006] It is thus a feature of at least one embodiment of the invention to provide a milk curd product that remains palatable over a period of time consistent with modem food distribution by terminating enzyme action determined to produce bitterness.

[0007] In some embodiments the additional step of cooling the product and whipping it to a smooth consistency, for example, using a high shear mixer, may be performed.

[0008] It is thus a feature of at least one embodiment of the invention to moderate theincreased firmness of the product that occurs during the deactivation of the enzyme while reducing syneresis (water / solid separation).

[0009] The method may further include the step of adding milk protein concentrate prior to step (b).

[0010] It is thus a feature of at least one embodiment of the invention to control the structural firmness of the product.

[0011] The proteolytic enzyme may be zingibain, for example, extracted from ginger root as a juice.

[0012] It is thus a feature of one embodiment of the invention to provide a proteolytic enzyme from a natural source which adds flavor to the product.

[0013] The ginger root may be free from refrigeration prior to step (c).

[0014] It is thus a feature of at least one embodiment of the invention to improve the activity of the zingibain.

[0015] The ginger root may be processed to provide ginger juice subject to low temperature, long time pasteurization prior to step (c) and / or the milk may be ultra pasteurized.

[0016] It is thus a feature of at least one embodiment of the invention to extend shelf life by further reducing bacterial action.

[0017] In some embodiments the milk may be ultrafiltered prior to step (a) and / or treated with an enzyme to reduce lactose prior to step (a).

[0018] It is thus a feature of at least one embodiment of the invention to provide a milk curd product that is acceptable to lactose intolerant individuals.

[0019] In some embodiments lavender flavoring may be added, for example, through the introduction of lavender flowers.

[0020] It is thus a feature of one embodiment of the invention to provide for the comforting qualities of lavender fragrance in the above described milk product while providing improved shelf stability. It is another feature of this embodiment to provide natural ingredients in a milk curd product with extended shelf life.

[0021] These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Fig. 1 is a flowchart showing the steps of producing a milk curd product according tothe present invention.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023] The formulation for one embodiment of the milk curd product and the composition of the present invention is shown in Table 1 below. The main ingredients of the milk curd product are ultra-filtered milk, ~85% milk protein concentrate, ginger juice, lavender, and white granulated sugar (sucrose).Table 1 - formulation.

[0024] The main ingredient in the milk curd product is ultra-filtered milk followed by 85% milk protein concentrate (MPC-85 / MPC). There is an approximately 89% dairy ingredient composition in the milk curd product. In both the ultra-filtered milk and MPC, the main functional components are the casein and whey proteins. The ultra-filtered milk and MPC provide the proteins for the coagulated matrix described below. Casein proteins make up about 80% of the proteins in milk and include a-sl-, a-s2-, 0-, and K-caseins. In milk, casein proteins exist primarily as structures called casein micelles, which are spherical structures with extruding K-caseins on the surface.

[0025] The present invention uses a proteolytic enzyme (i.e. , zingibain) found in ginger / ginger juice to coagulate milk proteins into a pudding-like structure by cleaving the K- caseins on the surface of the casein micelles, causing the destabilized micelles to aggregate. To make a smooth coagulum with whey retention, instead of a curd-like cheese product, whey proteins must be denatured for interaction with casein micelles prior to enzyme addition (similar to yogurt production).

[0026] Zingibain is temperature sensitive, being most active at 63°C and inactivated at 70°C. These temperatures are very close and must be managed to prevent inactivating the enzyme and prevent the coagulum from forming. To denature whey proteins and prevent enzyme inactivation, the product is heated above the denaturation temperature of whey proteins (approximately 70°C), and then cooled to < 70°C prior to enzyme addition. Done correctly, the enzyme fully impacts the casein proteins with attached whey proteins, which causes a soft and smooth pudding to form.

[0027] With casein and whey proteins being functional components of the coagulum, the MPC acts as an extra structural component and increases the protein content. Although ultrafiltered milk has a higher protein content than regular milk, the structure that is formed in making the product uses only ultra-filtered milk which is not extremely strong. By adding the milk protein concentrate, more proteins are added into the protein matrix created by the enzyme. The higher concentration of proteins (approximately 20 g per 6 ounce serving) from the powder allows the structure to become more firm and structurally sound.

[0028] In addition to containing the proteolytic enzyme zingibain, ginger juice has the health benefits of being anti-inflammatory, easing anxiety, and relieving nausea. Ginger has been shown to increase the blood flow to the brain. Lavendar is added for its flavor and calming effects. Lavendar has been shown to improve depressive symptoms. Sugar is added for sweetness.

[0029] Referring to FIG. 1 , in one embodiment, raw milk may be received as indicated by process block 10 which may be then subject to ultra pasteurization per process block 12, for example, at approximately 128°C for two seconds. The ultra pasteurized milk may then be ultrafiltered to remove water and boost protein weight concentration per process block 14 and then treated with a lactase enzyme per process block 16 to be substantially lactose free.

[0030] Milk satisfying these requirements may be purchased commercially, for example, from Fairlife, LLC of Chicago, Illinois, under the tradename Fairlife milk.

[0031] At process box 18 milk protein concentrate may be added. The milk protein concentrate may be MPC-85 (MPI-85) typically processed using pasteurized skim milk and a low-heat membrane filtration process so that the protein is not denatured.

[0032] At process block 20, flavorings such as lavender flavoring (from lavender flowers) may be added. Lavender is optional and may be substituted with other flavors.

[0033] At process block 22 a non-lactose sweetener such as sucrose may be added to provide additional sweetness.

[0034] At process block 24, the mixture is heated to the protein denaturing temperature of approximately 88 °C for about 15 seconds to denature the whey proteins in milk to allow for a continuous coagulum.

[0035] At process block 26, after denaturing, the mixture is cooled down to < 63 °C (below the enzyme inactivation temperature) while being maintained above 60°C to preserve enzyme efficiency. The optimal temperature for the ginger enzyme (zingibain) is 63 °C as this enzyme starts inactivation at 70°C. After this step, the lavender flowers are strained out and, per process block 28, the liquid poured onto fully stirred ginger juice (1 :5.5 ratio of fresh grinded ginger juice to ultra-filtered milk and MPC), and then allowed to sit (i.e., coagulate) for about 20 mins per process block 30.

[0036] The ginger juice may be prepared ahead of time using a continuous washing line equipped with a brush washing machine to wash and then peel ginger, and an electric automatic ginger extractor can be used to obtain fresh, filtered ginger juice. In one embodiment, the ginger juice may be subject to a low-temperature, long-time pasteurization (LTLT, approximately 63°C for about 30 minutes). Then, fully stirred ginger juice can be separated into different containers in a vibrating conveyor waiting for the heated milk.

[0037] Heated milk, cooled to the proper temperature, can then be poured into the containers with ginger juice with covers / lids that can hold the optimal temperature for zingibain to react with milk, which takes about 20 minutes. Following this incubation, the product can be steamed at approximately 68°C for about 15 minutes to inactivate the zingibain per process block 32. Without this step, the enzyme would continue proteolysis, causing the product to develop a bitter flavor during storage. This steaming process causes the coagulum to become unpleasantly firm. To combat this, the product is cooled to approximately 4°C and whipped using a high shear mixer to get a creamy and smooth texture per process block 34.

[0038] The product formulation is about 79.5% w / w ultra-filtered milk, about 9% w / w MPC, about 5% w / w ginger juice, and about 6.5% w / w sugar per batch.

[0039] The final product may be stored in a septic process in aseptic packaging per process block 36. The packaging containers can be designed like pudding cups or cups with separate compartments for toppings. After packaging, the final product goes to refrigerated storage.When the product is stored in aseptic packages and sealed (similar to single-serve pudding), the shelf life of this product can be significantly improved.

[0040] Shelf-Life and Safety

[0041] Due to the product being composed of five ingredients, two of those being liquids, the product is very high in liquid content. It also has an almost neutral pH of approximately 6.50, thus its low acid properties will not aid in eliminating biological hazards and elongating the overall shelf-life. These properties, high moisture content and high pH, deem the product to be susceptible to the growth of pathogenic and spoilage microorganisms.

[0042] After multiple trials, it was determined that the product remains palatable for a period of 21 days with refrigerated storage. It is to be noted, however, that on an industrial scale with proper equipment, shelf-life may be longer.Table 3. Shelf-life of the product through three weeks of storage.Length of Storage Palatable? (yes / no) pH1 day Yes 6.517 days Yes 6.5114 days Yes 6.5021 days Yes 6.52

[0043] Shelf-life may be maintained using aseptic packaging with a hot seal. Ultra-high temperatures (UHT) paired with aseptic packaging with a hot seal, similar to that of a shelfstable pudding cup, removes contaminants from both the product and the packaging, while doing so in a sterile environment. In combination, UHT and aseptic packaging are cost-efficient and work to improve shelf-life and create a safe product. In one embodiment, the present invention is packaged in individual 6 oz. (170 g) containers. A single container contains approximately 89% dairy ingredients and has 20 g of protein per serving (approximately 12% protein per serving). The present invention contains 20 g of dairy protein, thus has an abundance of BCAAs to provide health benefits to consumers.

[0044] "Extended Shelf Life" as used herein refers to a food product that can be manufactured remotely and shipped to stores or restaurants for consumption more than one day later possibly including intervening refrigeration and / or a food product that remains palatable with refrigeration in excess of 15 days. "Ultrafiltered milk" is milk that has been passed through a membrane to reduce lactose and water content. "Ultra pasteurized milk" is milk that is heatedto a minimum of 280°F or 128°C for a minimum of two seconds to kill virtually all of the bacteria therein. "Low-temperature pasteurization" refers to pasteurization at a temperature between 63° and 65° C for over 30 minutes. "Aseptic packaging" is packaging using a processing and container preventing microorganisms from entering during or after packaging. "Refrigeration" refers to storage at temperatures below 5°C for a period of time in excess of one hour.

[0045] Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as "upper", "lower", "above", and "below" refer to directions in the drawings to which reference is made. Terms such as "front", "back", "rear", "bottom" and "side", describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms "first", "second" and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.

[0046] When introducing elements or features of the present disclosure and the exemplary embodiments, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of such elements or features. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0047] It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.

[0048] To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any ofthe appended claims or claim elements to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.

Claims

CLAIMSWhat we claim is:

1. A method of making an extended shelf life milk product comprising:(a) heating milk to a temperature to denature whey proteins of the milk;(b) subsequent to (a), cooling the milk to an enzyme temperature of less than 72°C;(c) subsequent to (b), introducing a proteolytic enzyme to milk at the enzyme temperature to form a coagulant with a smooth pudding form; and(d) heating the coagulant to deactivate the enzyme.

2. The method of claim 1 further including the step subsequent to step (d) of cooling the product and whipping it to a smooth consistency.

3. The method of claim 2 where the whipping employs a shear mixer.

4. The method of claim 1 further including the step of adding milk protein concentrate prior to step (b).

5. The method of claim 4 where the added milk concentrate has a concentration of greater than 70% over raw milk by weight and is added in a weight percentage with respect to the milk of greater than 8%.

6. The method of claim 1 where the enzyme temperature is greater than 60°C.

7. The method of claim 1 where the proteolytic enzyme is zingibain.

8. The method of claim 7 wherein the zingibain is extracted from ginger root free from refrigeration prior to step (c).

9. The method of claim 7 wherein the ginger root is processed to provide ginger juice subject to low-temperature, long-time pasteurization prior to step (c).

10. The method of claim 1 wherein the milk is ultrafiltered prior to step (a).

11. The method of claim 1 wherein the milk is treated with an enzyme to reduce lactose prior to step (a).

12. The method of claim 1 wherein the milk is ultra pasteurized prior to step (a).

13. The method of claim 1 including the step of sealing the coagulant in an aseptic package.

14. The method of claim 1 further including the step of adding a non-lactose sweetener.

15. The method of claim 14 wherein the non-lactose sweetener is sucrose.

16. The method of claim 1 further including the step of adding lavender flavoring.

17. The method of claim 16 wherein the step of adding lavender flavoring includes the addition of lavender flowers into the milk and then removal of the lavender flowers from the milk.

18. An extended shelf life milk product produced using the steps of:(a) heating milk to a temperature to denature whey proteins of the milk;(b) subsequent to (a), cooling the milk to an enzyme temperature of less than 72°C;(c) subsequent to (b), introducing a proteolytic enzyme to milk at the enzyme temperature to form a coagulant with a smooth pudding form; and(d) heating the coagulant to deactivate the enzyme; the shelf stable milk product remaining palatable for a period of excess of 10 days with refrigerated storage.

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