Protectant composition and use thereof

Abstract

This invention provides a protective agent composition and its application. The protective agent composition includes trehalose and tremella polysaccharide, which can be added to cold chain products (such as lactic acid bacteria beverages) to maintain their microbial activity under refrigeration, freezing, or repeated freeze-thaw conditions, ensuring that the viable bacteria count in the lactic acid bacteria beverage does not decrease significantly. Results show that after refrigeration at 2–10°C for 28 days, the viable bacteria count can still remain >1×10⁻⁶. 8 CFU / mL, the frozen product can still maintain a viable bacterial count of ≥4×10⁻⁶ CFU / mL after being stored in a -18°C freezer for 14 days. 5 After three freeze-thaw cycles, the number of viable bacteria remained ≥4×10⁻⁶ CFU / mL. 4 The CFU / mL concentration indicates that the protective agent composition can effectively guarantee the quality of the lactic acid bacteria beverage. The resulting lactic acid bacteria beverage is both drinkable and edible, and after freezing, it does not form large ice crystals, exhibiting a crunchy ice texture, making it suitable for long-term daily consumption by the general population of all ages.

Description

Technical Field

[0001] This invention relates to the field of biotechnology, and more specifically to a protective agent composition and its application. Background Technology

[0002] Low-temperature preservation is a common method used to ensure the quality of food raw materials, processing, or finished products. Currently, low-temperature pre-prepared products, slightly frozen aquatic products, and frozen foods have a broad market. Among them, frozen lactic acid bacteria drinks are favored by consumers because they contain probiotics, which can produce one or more specific and proven functional health benefits to the host. However, repeated freeze-thaw cycles are unavoidable in the production and sales of frozen lactic acid bacteria drinks. This allows low-temperature resistant harmful microorganisms to slowly grow or even regain their pathogenicity under repeated freeze-thaw conditions, and the number of live lactic acid bacteria also decreases significantly with repeated freeze-thaw cycles, resulting in a serious decline in the quality of frozen lactic acid bacteria drinks.

[0003] Currently, the activity of lactic acid bacteria is generally maintained by adding a freeze-drying protectant to the freeze-dried lactic acid bacteria powder. CN105602875A discloses a freeze-drying protectant for lactic acid bacteria, comprising skim milk powder, monosodium glutamate, trehalose, maltitol, polydextrose, and fermentation waste liquid generated after concentrating lactic acid bacteria fermentation broth. This mixture is then freeze-dried to obtain the freeze-dried lactic acid bacteria powder. The number of viable bacteria in the freeze-dried lactic acid bacteria powder remained essentially unchanged after 6 months of storage at room temperature (24-26℃), and decreased by approximately 25-50% after 1 year of storage. However, this freeze-drying protectant primarily protects the number of viable bacteria in the freeze-dried lactic acid bacteria powder and only effectively protects the activity of lactic acid bacteria at room temperature. Its protective effect on lactic acid bacteria beverages under low-temperature conditions is currently unknown.

[0004] CN 108676720 A discloses a freeze-drying protectant for lactic acid bacteria and bifidobacteria, comprising pullulan, Tris-HCl buffer, and ferrous ammonium sulfate. After mixing and freeze-drying with a suspension of lactic acid bacteria or bifidobacteria, the corresponding freeze-dried powder is obtained. The survival rate of the lactic acid bacteria freeze-dried powder after 100 days of storage at a constant temperature of 37°C and 65% relative humidity reaches 72.6%–92.3%; under the same conditions, the survival rate of the bifidobacteria freeze-dried powder after 100 days of storage reaches 65.4%–69.6%. However, this freeze-drying protectant was only studied for its protective effect on the freeze-dried powder of lactic acid bacteria or bifidobacteria at 37°C, and its protective effect on the bacterial strains in lactic acid bacteria beverages under repeated freeze-thaw conditions during low-temperature storage is not disclosed. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a protective agent composition and its application. The protective agent composition can be added to cold chain products (such as lactic acid bacteria beverages) to maintain the number of live bacteria in the lactic acid bacteria beverage under refrigeration, freezing, or repeated freeze-thaw conditions, thereby ensuring the quality of the lactic acid bacteria beverage.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a protective agent composition comprising trehalose and tremella polysaccharide.

[0008] Preferably, the mass ratio of trehalose to tremella polysaccharide is (1-6):(0.5-4).

[0009] Secondly, the present invention provides an application of the protective agent composition involved in the above-mentioned technical solution in extending the shelf life of cold chain products under refrigeration, freezing or repeated freeze-thaw conditions.

[0010] Thirdly, the present invention provides a cold chain product comprising the protective agent composition involved in the above-mentioned technical solution.

[0011] Preferably, the cold chain product is a lactic acid bacteria beverage, which includes white lactic acid bacteria beverages or brown lactic acid bacteria beverages.

[0012] Preferably, the lactic acid bacteria beverage comprises, by weight: 30-60 parts milk, 0-0.25 parts stabilizer, 4-9 parts sweetener, 1.5-10 parts protective agent composition, 2-7 parts dietary fiber, and 0.001-0.1 parts fermenting agent.

[0013] Preferably, the milk includes any one or more of whole milk, low-fat milk, or skim milk.

[0014] Preferably, the sweetener includes granulated sugar and / or glucose.

[0015] Preferably, the fermenting agent includes any one or more of Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus bulgaricus, or Streptococcus thermophilus.

[0016] Preferably, the dietary fiber includes polydextrose and citrus fiber.

[0017] Preferably, the mass ratio of the polydextrose to citrus fiber is (1.5-4):(0.5-3).

[0018] Preferably, the stabilizer includes a thickener and an emulsifier.

[0019] Preferably, the thickener comprises any one or more of gellan gum, sodium carboxymethyl cellulose, propylene glycol alginate, locust bean gum, gelatin, agar, gum arabic, guar gum, xanthan gum, carrageenan, pectin, or hydroxypropyl starch.

[0020] Preferably, the emulsifier comprises any one or more of glyceryl monostearate, glyceryl distearate, polyglycerol ester, sucrose ester, sodium stearoyl lactylate, glyceryl monocitrate, glyceryl monotartrate, glyceryl monosuccinate, glyceryl monoacetate, or sodium caseinate.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) This invention provides a protective composition comprising trehalose and tremella polysaccharide, which can ensure the microbial activity of cold chain products (such as lactic acid bacteria drinks) under refrigeration, freezing or repeated freeze-thaw conditions, and maintain the viable count of lactic acid bacteria drinks. Studies have shown that after refrigeration at 2-10℃ for 28 days, the viable count can still be maintained at >1×10⁻⁶. 8 CFU / mL, with no unacceptable stratification or precipitation, no obvious off-odor, and the frozen product can maintain a viable count of ≥4×10⁻⁶ CFU / mL after being stored at -18°C for 14 days. 5 After repeated freeze-thaw cycles at -18℃ to 25℃ three times, the viable bacterial count remained ≥4×10⁻⁶ CFU / mL. 4 CFU / mL indicates that the protective agent composition can effectively guarantee the quality of lactic acid bacteria beverages;

[0023] (2) The lactic acid bacteria beverage has a good flavor, taste and texture, and the product has no large ice crystals after freezing, and has the taste of crushed ice. The present invention organically combines active lactic acid bacteria with frozen popsicles, which is suitable for ordinary people of all ages to consume as a daily diet for a long time, which is beneficial to human health. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] In view of the lack of reports in the prior art regarding the protection of microbial activity in cold chain products, this invention provides a protective agent composition comprising trehalose and Tremella fuciformis polysaccharide. Compared to existing reports that trehalose can be used as an antifreeze in frozen foods (mainly for the protection of bioactive substances such as proteins), the trehalose involved in this invention is primarily used to protect microbial activity. In this invention, the mass ratio of trehalose to Tremella fuciformis polysaccharide is (1-6):(0.5-4).

[0026] This invention uses trehalose and tremella polysaccharide, two functional sugars, as a protective agent to maintain the activity of microorganisms under low temperature conditions.

[0027] Based on this, the present invention also provides an application of the protective agent composition involved in the above technical solution in extending the shelf life of cold chain products under refrigeration, freezing or repeated freeze-thaw conditions.

[0028] This invention also provides a cold chain product, comprising the protective agent composition involved in the above-mentioned technical solution. The cold chain product can be any product containing microorganisms. In this invention, the cold chain product is a lactic acid bacteria beverage, which can be white fermented milk or white lactic acid bacteria drink, or it can be made into brown fermented milk or brown lactic acid bacteria beverage through Maillard reaction. The preparation process of the brown fermented milk or brown lactic acid bacteria beverage can be carried out according to techniques well known to those skilled in the art. Generally, it requires the addition of monosaccharides, which are selected from one or more of glucose, fructose, galactose, or high-fructose corn syrup. The amount of monosaccharides added is 2-5% of the total weight of the yogurt raw materials (i.e., in terms of monosaccharides, the amount of monosaccharides added accounts for 2-5% of the total weight of the fermented milk or lactic acid bacteria beverage raw materials). Browning treatment is carried out at 115°C for 5-10 minutes or in a water bath at 90°C or above for 2-4 hours. Alternatively, lactase can be used to hydrolyze the lactose in milk or reconstituted milk before browning treatment.

[0029] It should be noted that the protective agent composition described in this invention is added to lactic acid bacteria beverages, which differs from the prior art in using substances such as trehalose as freeze-drying protectants for lactic acid bacteria freeze-dried powders. The difference lies in the requirement that the overall water activity of the powder be low, and the upper limit must be strictly controlled to ensure the bacterial activity of the freeze-dried powder, mainly utilizing the high hydration capacity of trehalose. In contrast, this invention, in frozen beverages with high moisture content, primarily utilizes the synergistic effect of trehalose and tremella polysaccharide to increase the number of live bacteria in frozen ice cream; neither trehalose nor tremella polysaccharide alone possesses this effect.

[0030] In this invention, the lactic acid bacteria beverage comprises, by weight: 30-60 parts milk, 0-0.25 parts stabilizer, 4-9 parts sweetener, 1.5-10 parts of the protective agent composition involved in the above scheme, 2-7 parts dietary fiber, and 0.001-0.1 parts fermentation agent. The stabilizer is 0-0.25 parts, but can be 0 parts. Other values ​​within the weight range of the above components are all within the protection scope of this invention and will not be elaborated further here.

[0031] The milk mainly refers to fresh milk or reconstituted milk that meets my country's standards for the purchase of raw milk, and can be any one or more of whole milk, skim milk, or low-fat milk, preferably any one or more of whole milk, partially skimmed milk, or completely skimmed milk. The stabilizer includes a thickener and an emulsifier. The thickener is selected from any one or more of gellan gum, sodium carboxymethyl cellulose, propylene glycol alginate, locust bean gum, gelatin, agar, gum arabic, guar gum, xanthan gum, carrageenan, pectin, or hydroxypropyl starch. The emulsifier is selected from any one or more of glyceryl monostearate, glyceryl distearate, polyglycerol esters, sucrose esters, sodium stearoyl lactylate, glyceryl monocitrate, glyceryl monotartrate, glyceryl monosuccinate, glyceryl monoacetate, or sodium caseinate. The sweetener includes white sugar and / or glucose, and preferably, conventional sweeteners well known to those skilled in the art, such as sugar alcohols and other macromolecular substances, can also be added as needed. The dietary fiber includes polydextrose and citrus fiber, with a mass ratio of polydextrose to citrus fiber of (1.5–4):(0.5–3). Preferably, conventional dietary fibers well known to those skilled in the art, such as resistant dextrin and inulin, may also be added as needed. The starter culture includes one or more of Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus bulgaricus, or Streptococcus thermophilus. In one embodiment of the invention, Lactobacillus casei is preferably used as the starter culture. The inoculum amount of the starter culture, based on the total product, is preferably 0.006–0.08 wt%, more preferably 0.01–0.06 wt%.

[0032] In this invention, the lactic acid bacteria beverage preferably further includes any one or more of the following: compound nutrients, fruit and vegetable juices, edible flavorings, acidity regulators, conventional excipients, water, or flavorings, to provide the lactic acid bacteria beverage with richer nutrition or further improve its flavor, thereby increasing the variety of lactic acid bacteria beverages. The compound nutrients may be compound vitamins or compound minerals or a combination of vitamins and minerals; the acidity regulator is selected from one or more of lactic acid, citric acid, malic acid, tartaric acid, phosphoric acid, or NaOH, with a content of 0.005–0.06 wt% based on 100 parts by weight of raw materials; the conventional excipients include one or more of light cream, butter, anhydrous butter, condensed milk, sweetened condensed milk, concentrated whey protein, or concentrated milk protein; the flavorings include salt. The selection and amount of the aforementioned compound nutrients, fruit and vegetable juices, edible flavorings, acidity regulators, conventional excipients, water, or flavorings can be determined by those skilled in the art according to actual needs.

[0033] The equipment used in the production process of the lactic acid bacteria beverage involved in this invention, such as steam fumigation equipment, homogenizer for homogenization, mixing tank for mixing, fermentation tank for fermentation, and sterilization equipment, can all be equipment known in the art. The filling of the liquid dairy products of this invention can also be carried out in accordance with the existing liquid product filling technology in the art. Specific production equipment and filling processes will not be described in detail here.

[0034] The production process of the lactic acid bacteria beverage involved in this invention can be carried out according to conventional techniques well known to those skilled in the art. In this invention, the lactic acid bacteria beverage is prepared according to the following method:

[0035] (1) Preparation and hydration: Heat the reconstituted milk or milk to 40-65°C, then add some sweeteners, stabilizers or optional conventional excipients, and stir for 30-40 minutes to prepare the milk; if preparing a brown product, only reducing sugars need to be added.

[0036] (2) Homogenization: Homogenize the liquid material at a pressure of 15-30 MPa and preheat it to about 65°C before homogenization.

[0037] (3) Sterilize the homogenized liquid at 93-97℃ for 5-10 minutes; if it is a brown product, it can be directly browned at 95℃ for 3-4 hours.

[0038] (4) Cooling and inoculation: Cool the liquid to the inoculation temperature of 37-42℃ and then inoculate;

[0039] (5) Fermentation: Fermentation is terminated when the acidity reaches 70-180°T. The fermentation time is 4-72 hours. The temperature and fermentation time range is suitable for most freeze-dried direct-inoculation starter cultures.

[0040] (6) Homogenization and cooling: Cool the fermented liquid to room temperature and homogenize it under aseptic conditions. The homogenization pressure is 15-30 MPa, thereby obtaining the yogurt base material.

[0041] (7) Preparation of yogurt base diluent: Add the protective agent composition (trehalose and tremella polysaccharide), along with the remaining sweeteners and dietary fiber. If a stabilizer is needed, add it at this stage as well. Prepare the diluent, stir for 30-40 minutes to dissolve the material, then pasteurize at 95℃ for 300 seconds. After pasteurization, cool to below 30℃ for later use.

[0042] (8) Beverage preparation: The amount of yogurt base added is 30-70% of the total weight of the active lactic acid bacteria beverage. At the same time, the above-mentioned yogurt base dilution is added, and then the mixture is homogenized at low temperature with a homogenization pressure of 15-30 MPa to obtain the lactic acid bacteria beverage.

[0043] The above-mentioned lactic acid bacteria beverage is filled into 150g stand-up pouches and frozen in a deep freezer (refrigeration temperature < -60℃) for 1 to 2 hours to obtain active lactic acid bacteria crushed ice.

[0044] Studies have shown that the active lactic acid bacteria beverage and lactic acid bacteria crushed ice obtained by this invention can maintain a live bacteria count >1×10⁻⁶ even after being refrigerated at 2–10°C for 28 days. 8 CFU / mL, with no unacceptable stratification or precipitation, and no obvious off-odor. The lactic acid bacteria crushed ice, stored at -18℃ for 14 days, still maintains a viable bacterial count of ≥4×10⁻⁶. 5 CFU / mL. After three freeze-thaw cycles, the lactic acid bacteria crushed ice still maintained a viable count of ≥4×10⁻⁶. 4 CFU / mL.

[0045] It is important to note that in order to ensure that the lactic acid bacteria beverage still contains a high number of live bacteria after repeated freeze-thaw cycles, the freezing process must first involve deep freezing for 1 hour before transferring the deep-frozen sample to a -18°C freezer for storage. Otherwise, the number of live bacteria in the product will be affected.

[0046] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention can be purchased commercially or prepared according to conventional preparation methods well known to those skilled in the art.

[0047] Example 1

[0048] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 60kg of trehalose, 30kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0049] The preparation method is as follows:

[0050] (1) Preparation and hydration: Heat part of the pure water to 45°C, then add 40kg of skim milk powder and 20kg of edible glucose, and stir at 300 rpm for 30 minutes.

[0051] (2) Homogenization: The liquid obtained in step (1) is preheated to 65°C and then homogenized at a pressure of 15 MPa.

[0052] (3) Browning sterilization: The liquid obtained in step (2) is subjected to browning sterilization at 95°C for 3 hours;

[0053] (4) Cooling and inoculation: Cool the liquid obtained in step (3) to the inoculation temperature of 37°C and inoculate it;

[0054] (5) Fermentation: Fermentation is terminated when the acidity reaches 180°T, and the fermentation time is 75 hours.

[0055] (6) Homogenization and cooling: Cool the fermented liquid to room temperature and homogenize it under aseptic conditions at a pressure of 15 MPa to obtain yogurt base material.

[0056] (7) Preparation of yogurt base diluent: Take the above-mentioned mass of white sugar, trehalose, tremella polysaccharide, polydextrose and citrus fiber to prepare sugar water, pasteurize the sugar water at 95℃ for 300 seconds, and cool it down to below 20℃ for later use.

[0057] (8) Beverage preparation: The amount of yogurt base added is 40% of the total weight of the active lactic acid bacteria beverage. The remaining amount is made up with the prepared sugar water. Then the mixture is homogenized at low temperature with a homogenization pressure of 18 MPa.

[0058] Example 2

[0059] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 50kg of trehalose, 30kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0060] The preparation method is the same as in Example 1.

[0061] Example 3

[0062] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 40kg of trehalose, 30kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25kg of Lactobacillus casei, and the remainder of water.

[0063] The preparation method is the same as in Example 1.

[0064] Example 4

[0065] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 30kg of trehalose, 30kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0066] The preparation method is the same as in Example 1.

[0067] Example 5

[0068] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 20kg of trehalose, 30kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0069] The preparation method is the same as in Example 1.

[0070] Example 6

[0071] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 10kg of trehalose, 30kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0072] The preparation method is the same as in Example 1.

[0073] Example 7

[0074] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 30kg of trehalose, 40kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0075] The preparation method is the same as in Example 1.

[0076] Example 8

[0077] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 30kg of trehalose, 20kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0078] The preparation method is the same as in Example 1.

[0079] Example 9

[0080] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 30kg of trehalose, 10kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0081] The preparation method is the same as in Example 1.

[0082] Example 10

[0083] This embodiment provides a lactic acid bacteria beverage, which, based on 1000kg of frozen lactic acid bacteria beverage, includes 40kg of skim milk powder, 50kg of white sugar, 5kg of edible glucose, 30kg of trehalose, 5kg of tremella polysaccharide, 20kg of polydextrose, 3kg of citrus fiber, 25g of Lactobacillus casei, and the remainder of water.

[0084] The preparation method is the same as in Example 1.

[0085] Comparative Example 1

[0086] This comparative example provides a lactic acid bacteria beverage. Compared with Example 1, the trehalose and tremella polysaccharide in the raw materials are replaced with white sugar in equal amounts, while the amount of other components added remains the same as in Example 1.

[0087] The preparation method is the same as in Example 1.

[0088] Comparative Example 2

[0089] This comparative example provides a lactic acid bacteria beverage. Compared with Example 1, the trehalose in the raw materials is replaced with an equal amount of white sugar, and the amount of other components added is the same as in Example 1.

[0090] The preparation method is the same as in Example 1.

[0091] Comparative Example 3

[0092] This comparative example provides a lactic acid bacteria beverage. Compared with Example 1, the amount of tremella polysaccharide in the raw materials is replaced with white sugar in equal amounts, while the amount of other components added remains the same as in Example 1.

[0093] The preparation method is the same as in Example 1.

[0094] Comparative Example 4

[0095] This comparative example provides a lactic acid bacteria beverage. Compared with Example 1, the trehalose in the raw materials is replaced with polydextrose in an equal amount, and the amount of other components added is the same as in Example 1.

[0096] The preparation method is the same as in Example 1.

[0097] Comparative Example 5

[0098] This comparative example provides a lactic acid bacteria beverage. Compared with Example 1, the tremella polysaccharide in the raw materials is replaced with polydextrose in equal amounts, while the amount of other components added remains the same as in Example 1.

[0099] The preparation method is the same as in Example 1.

[0100] The refrigeration stability of the lactic acid bacteria beverages obtained in Examples 1-10 and Comparative Examples 1-5 was tested, and the results are shown in Table 1.

[0101] Table 1

[0102]

[0103]

[0104]

[0105] As shown in Table 1, the lactic acid bacteria beverages obtained in Examples 1-10 and Comparative Examples 1-5 exhibit good stability under refrigeration conditions, with no water separation or stratification.

[0106] The viable bacteria count of the lactic acid bacteria beverages obtained in Examples 1-10 and Comparative Examples 1-5 was tested under refrigeration conditions (4°C). The test method was as specified in the National Food Safety Standard for Microbiological Examination of Food (GB 4789.35-2010). The test results are shown in Table 2.

[0107] Table 2

[0108]

[0109]

[0110] As shown in Table 2, the initial viable counts of the lactic acid bacteria beverages obtained in Examples 1-10 and Comparative Examples 1-5 were all relatively high, and the viable counts of the lactic acid bacteria beverages in each group showed a gradual decreasing trend with the extension of refrigeration time.

[0111] As shown in Tables 1 and 2, the lactic acid bacteria beverages obtained in Examples 1-10 and Comparative Examples 1-5 exhibit good stability and quality. The lactic acid bacteria beverages obtained in Examples 1-10 and Comparative Examples 1-5 were then bottled into 150g stand-up pouches and frozen in a deep freezer (freezing temperature < -60℃) for 1-2 hours to obtain active lactic acid bacteria beverage ice. The obtained active lactic acid bacteria beverage ice was subjected to repeated freeze-thaw tests. The test method is as follows (at least three samples were taken each time; at least one pouch was used to confirm the thawing effect, at least one pouch was used for repeated freeze-thaw cycles, and at least one pouch was used for viable bacteria counting):

[0112] After placing the frozen lactic acid bacteria beverage at room temperature (25℃) for 15 minutes, squeeze the surface of the product by hand every 5-10 minutes and record the waiting time required for the product to be taken out of the refrigerator and for the sample in the middle and bottom of the stand-up pouch to be deformed by squeezing.

[0113] Repeat the freeze-thaw cycle: After confirming that the sample has been completely thawed, shake it well and put it back into the cryogenic freezer for rapid freezing. After 1 hour, transfer the cryogenic sample to a -18℃ freezer for storage, then place the sample at 25℃ room temperature for storage. Record the thawing time, and then put it back into the cryogenic freezer for freezing.

[0114] The melting time of the ice in the active lactic acid bacteria beverage is shown in Table 3:

[0115] Table 3

[0116]

[0117] As shown in Table 3, compared with Comparative Example 1, the frozen lactic acid bacteria beverage with added trehalose and tremella polysaccharide melts relatively slowly. Comparing the examples with Comparative Examples 2-5, it can be seen that the melting speed of the frozen lactic acid bacteria beverage with added trehalose or tremella polysaccharide alone does not change significantly. The data from the examples show that when the amount of trehalose added is constant, the greater the amount of tremella polysaccharide added, the slower the melting speed of the frozen lactic acid bacteria beverage; similarly, when the amount of tremella polysaccharide added is constant, the greater the amount of trehalose added, the slower the melting speed of the frozen lactic acid bacteria beverage. Furthermore, the data in the table above shows that the melting speed of the frozen lactic acid bacteria beverage increases with the number of freeze-thaw cycles.

[0118] The results of the live bacteria count test of the active lactic acid bacteria beverage ice with different freezing and thawing times and freezing time are shown in Table 4 (wherein, a single freeze-thaw cycle refers to the number of live lactic acid bacteria measured after the first freezing and subsequent thawing; the same applies to double and triple freeze-thaw cycles):

[0119] Table 4

[0120]

[0121] As shown in Table 4, compared with Comparative Example 1, the combination of trehalose and tremella polysaccharide in the examples can maintain a viable count of more than 4 × 10⁻⁶ in the frozen lactic acid bacteria beverage after three freeze-thaw cycles. 4 After being stored at -18°C for 14 days, the number of viable bacteria (CFU / mL) was greater than 4 × 10⁻⁶. 5 Comparing the examples with Comparative Examples 2-5, it can be seen that trehalose or tremella polysaccharide alone has limited protective effect on live bacteria in frozen lactic acid bacteria beverages. Furthermore, it can be observed that the number of live bacteria in frozen lactic acid bacteria beverages tends to decrease with increasing freeze-thaw cycles or prolonged freezing time.

[0122] The lactic acid bacteria beverages obtained in Examples 1-10 and Comparative Examples 1-5 were made into lactic acid bacteria beverage ice. After being stored at room temperature (25°C) for 20 minutes, the samples were directly squeezed and tasted (six internally qualified tasters tested the samples). The results are shown in Table 5.

[0123] Table 5

[0124]

[0125]

[0126] As shown in Table 5, when the amount of tremella polysaccharide added is 30 kg / t, the amount of trehalose added must be ≥20 kg / t to ensure the smooth texture of the product shaved ice; when the amount of trehalose added is 30 kg / t, the amount of tremella polysaccharide added must be ≥5 kg / t to ensure the smooth texture of the product shaved ice.

[0127] In conclusion, lactic acid bacteria drinks containing trehalose and tremella polysaccharides can maintain a live bacteria count >1×10⁻⁶ after being refrigerated at 2-10℃ for 28 days. 8 The product maintained a CFU / mL level without unacceptable stratification or precipitation, and produced no noticeable off-odors. After freezing, the product, when stored at -18°C for 14 days, maintained a viable bacterial count of ≥4×10⁻⁶. 5 CFU / mL. After three freeze-thaw cycles, the viable count remained ≥4×10⁻⁶. 4 CFU / mL.

[0128] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A protective agent composition for extending the shelf life of cold chain products under refrigeration, freezing, or repeated freeze-thaw conditions, characterized in that, Composed of trehalose and tremella polysaccharide; The mass ratio of trehalose to tremella polysaccharide is (1~6):(0.5~4); The composition is used to add to cold chain products so that the viable bacterial count of the cold chain products is ≥4×10⁻⁶ after freezing at -18°C for 14 days. 5 CFU / mL, viable bacterial count ≥4×10⁻⁶ after three freeze-thaw cycles at -18℃ to 25℃. 4 CFU / mL.

2. A cold chain product, characterized in that, Includes the protective agent composition according to claim 1.

3. The cold chain product according to claim 2, characterized in that, The cold chain product is a lactic acid bacteria beverage; The lactic acid bacteria beverages include white lactic acid bacteria beverages or brown lactic acid bacteria beverages.

4. The cold chain product according to claim 3, characterized in that, The lactic acid bacteria beverage comprises, by weight: 30-60 parts milk, 0-0.25 parts stabilizer, 4-9 parts sweetener, 1.5-10 parts protective agent composition, 2-7 parts dietary fiber, and 0.001-0.1 parts fermenting agent.

5. The cold chain product according to claim 4, characterized in that, The milk includes any one or more of whole milk, low-fat milk, or skim milk; The sweeteners include white sugar and / or glucose; The fermenting agent includes any one or more of Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus bulgaricus, or Streptococcus thermophilus.

6. The cold chain product according to claim 4, characterized in that, The dietary fiber includes polydextrose and citrus fiber; The mass ratio of the polydextrose to citrus fiber is (1.5~4):(0.5~3).

7. The cold chain product according to claim 4, characterized in that, The stabilizer includes thickeners and emulsifiers.

8. The cold chain product according to claim 7, characterized in that, The thickener includes any one or more of gellan gum, sodium carboxymethyl cellulose, propylene glycol alginate, locust bean gum, gelatin, agar, gum arabic, guar gum, xanthan gum, carrageenan, pectin, or hydroxypropyl starch oxidized. The emulsifier includes any one or more of glyceryl monostearate, glyceryl distearate, polyglycerol ester, sucrose ester, sodium stearoyl lactylate, glyceryl monocitrate, glyceryl monotartrate, glyceryl monosuccinate, glyceryl monoacetate, or sodium caseinate.

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