Room-temperature-resistant storage yogurt product and preparation method thereof

Abstract

The invention discloses a room-temperature-storage-resistant yoghourt product and a preparation method thereof, the yoghourt product is prepared by using raw milk as a main raw material, matching with a specific compounding system of erythritol and polydextrose, a special stabilizer and a compound strain through an innovative process of secondary proportioning and secondary sterilization. The protein content of the product is greater than or equal to 2.3%, the fat content is greater than or equal to 2.5%, the shelf life at room temperature can reach more than 90 days, the whey precipitation rate is less than or equal to 3.5%, and sensory evaluation and market evaluation show that the acceptability is greater than or equal to 87 score and 83% respectively. The technical bottlenecks of cold chain dependence and short shelf life of traditional yoghurt are broken through, meanwhile, the use of chemical preservatives and the loss of viable bacteria functions are avoided, the coordination of long shelf life, no cold chain cost, high functionality and excellent taste is realized, and the preparation method is suitable for large-scale industrial production and wide-area market circulation.

Description

Technical Field

[0001] This invention belongs to the field of fermented dairy product technology, specifically relating to a yogurt product that can be stored at room temperature and its preparation method. Background Technology

[0002] The traditional yogurt industry has long faced two major pain points: First, it is highly dependent on the cold chain, with 90% of low-temperature yogurt requiring storage and transportation at 2-6℃. Cold chain costs account for 25%-32% of the total cost, and in areas with weak infrastructure such as counties and Southeast Asia, product loss rates due to cold chain breaks can reach as high as 18%. Second, it has limited shelf life, and existing solutions have significant flaws: adding chemical preservatives goes against the consumer trend of "clean label" products (78% of consumers refuse yogurt containing sodium benzoate), while ordinary room-temperature yogurt sacrifices the function of live probiotics through high-temperature sterilization (live bacteria count <1×10⁻⁶). 4 (CFU / g), which is insufficient to meet functional requirements. Summary of the Invention

[0003] To address the aforementioned problems, the present invention aims to provide a yogurt product that can be stored at room temperature without the need for cold chain storage and transportation, has a long shelf life, excellent taste, and conforms to the trend of clean labeling, as well as a method for preparing the same.

[0004] This invention is achieved through the following technical solution: A yogurt product resistant to room temperature storage, wherein the yogurt product does not require cold chain storage and transportation, and has a shelf life of ≥90 days at room temperature (25±5℃); the product's physicochemical indicators meet the requirements of protein content ≥2.3% and fat content ≥2.5%; the raw material component is raw milk, wherein the raw milk has a protein content ≥3.6% and a fat content ≥3.7%; the excipients are erythritol, polydextrose, stabilizer and compound strain, wherein: the mass ratio of erythritol to polydextrose is 1:1, and the total addition amount of the two is 5%; the addition amount of stabilizer is 0.2%; the compound strain is composed of Streptococcus thermophilus subsp. salivarius and Lactobacillus delbrueckii subsp. bulgaricus in a 1:1 mass ratio, synergistically achieving efficient fermentation of milk.

[0005] The excipients also include sucralose and edible flavoring, wherein the amount of sucralose added is 0.01~0.02% and the amount of edible flavoring added is 0.05~0.1%; the edible flavoring is a natural dairy flavoring and contains no artificial flavoring substances.

[0006] The erythritol is food-grade high-purity erythritol with a purity ≥99.5% and a calorie content ≤0.2kcal / g; the polydextrose is water-soluble dietary fiber grade polydextrose with a DE value ≤10 and a water holding capacity ≥300%. The combination of the two results in a product with a dietary fiber content ≥2.5% / 100g.

[0007] When stored at room temperature for 28 days, the pH value decreased from the initial 4.39 to 4.18, with a decrease of ≤0.21, the viscosity stabilized at 2200±150mPa・s, the total microbial count was ≤10CFU / g, and there was no deterioration caused by excessive microbial levels.

[0008] When stored at room temperature for 7 days, the whey separation rate is ≤3.5%; when stored at room temperature for 90 days, the whey separation rate is ≤8.0%, which is significantly lower than that of yogurt products with a single sweetener formulation.

[0009] A method for preparing a yogurt product that can be stored at room temperature includes the following steps: S1. Initial mixing: Take 60-70% of the total amount of raw milk, heat it to 60-65℃, add erythritol, polydextrose and auxiliary materials, stir at 300-500r / min for 20 minutes until all materials are completely dissolved and evenly dispersed; S2. Volume adjustment: Add the remaining 30-40% of raw milk to the mixture from step S1, adjust the volume to the preset production volume, and stir for 5 minutes to homogenize the system; S3. Homogenization: The milk after volume adjustment is kept at 60~65℃ and homogenized once under a homogenization pressure of 18~20MPa to refine the fat globule particle size to 2~5μm. S4. Single sterilization: The homogenized milk is placed in an 85℃ constant temperature water bath for 15 minutes to kill pathogenic bacteria and miscellaneous bacteria in the raw materials. The total number of colonies in the milk after sterilization is ≤100CFU / mL. S5. Inoculation: Quickly cool the sterilized milk to 41~43℃ and inoculate it with compound inoculum; S6. Fermentation: Transfer the inoculated milk to a 43°C constant temperature fermentation tank and statically ferment until the final acidity is 68~70°T, then immediately stop the fermentation. S7. Secondary mixing: Add the stabilizer to deionized water at 60~65℃ and stir at 400~600r / min for 15 minutes until the stabilizer is completely dissolved and forms a uniform colloid. Then slowly add the colloid to the fermented milk and stir for 10 minutes to mix well. S8. Secondary sterilization: The milk that has undergone secondary formulation is passed through an instant sterilizer and kept at 85~88℃ for 30 seconds. After sterilization, it is quickly cooled to 25~30℃. S9. Filling and Packaging: Stir the cooled milk at a speed of 100~150r / min for 1 minute, fill it into cups in a Class A aseptic environment, with a filling volume error of ≤±2%, seal it immediately after filling, and store it at room temperature in the warehouse.

[0010] In step S5, the inoculation amount of the compound bacteria is 0.03~0.05% of the total mass of the milk. Before inoculation, the compound bacteria is diluted 10 times with sterile water to make a bacterial suspension, which is then sprayed evenly into the milk. After spraying, continue stirring for 5 minutes to ensure that the bacteria are evenly distributed.

[0011] After fermentation is terminated in step S6, the milk should be turned over twice a minute for 3 minutes. After turning over, stir at a low speed of 50-80 r / min for 1 minute to avoid uneven texture or clumping in the milk.

[0012] The first sterilization in step S4 is pasteurization, and the second sterilization in step S8 is ultra-high temperature instantaneous sterilization. The synergistic effect of the two sterilizations ensures that the total microbial count of the final product is ≤10 CFU / g, while retaining ≥90% of the whey protein activity in the raw milk.

[0013] In step S7, the amount of deionized water used when dissolving the stabilizer is 10 to 15 times the mass of the stabilizer. The temperature difference when adding the colloid to the fermented milk is ≤5℃ to avoid sudden temperature changes that could cause protein denaturation and precipitation. In step S9, the sealing method after filling is aluminum foil heat sealing at a temperature of 120 to 130℃ for 2 to 3 seconds. After sealing, the cup opening is tested for leaks.

[0014] The beneficial effects of this invention are: 1. Significantly extended shelf life: Shelf life of over 90 days at room temperature, no need for cold chain storage and transportation, circulation radius expanded from 500 kilometers to 5000 kilometers, greatly reducing cold chain costs and product loss; 2. Excellent taste and stability: whey separation rate ≤3.5% (7 days of storage), pH decrease ≤0.21 after 28 days of storage at room temperature, and viscosity stable at 2200±150mPa·s; 3. Meets market demand: No chemical preservatives added, uses a blend of natural sweeteners, low in calories and also provides dietary fiber. Attached Figure Description

[0015] The present invention will now be described in further detail with reference to the accompanying drawings.

[0016] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0017] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0018] In the description of this invention, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. It should be noted that the terms "comprising," "including," or any other variations are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0019] Example 1: Preparation of Yogurt Products for Room Temperature Storage Raw material formula Based on the preparation of 100 kg of yogurt products that can be stored at room temperature, the raw material composition is as follows: 1. Raw milk: 94.74 kg (protein content 3.8%, fat content 3.9%, meeting the requirements of raw milk protein ≥3.6% and fat ≥3.7%). 2. Erythritol: 0.25kg (food grade high-purity erythritol, purity 99.7%, calories 0.18kcal / g); 3. Polydextrose: 0.25 kg (water-soluble dietary fiber grade polydextrose, DE value 8, water holding capacity 320%). 4. Stabilizer: 0.2 kg (The stabilizers used in this invention can be the types commonly used in yogurt products in the prior art, specifically including pectin (high-ester pectin, low-ester pectin), xanthan gum, guar gum, sodium carboxymethyl cellulose (CMC-Na), sodium alginate, konjac glucomannan (konjac gum), modified starch (acetylated distarch phosphate, hydroxypropyl distarch phosphate, sodium octenyl succinate starch), gelatin, carrageenan (often compounded with locust bean gum), locust bean gum, etc.; in this embodiment, high-ester pectin and xanthan gum are compounded in a mass ratio of 3:1). 5. Compound bacterial strain: 0.04 kg (composed of Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in a 1:1 mass ratio); 6. Sucralose: 0.015 kg (addition amount is 0.015%); 7. Natural dairy flavoring: 0.085 kg (addition amount is 0.085%).

[0020] Preparation steps S1. Initial ingredient preparation: Take 65kg of raw milk (65% of the total amount) and add it to a stainless steel mixing tank. Heat the tank to 62℃ using a jacket. Then add erythritol, polydextrose, sucralose and natural dairy flavoring. Turn on the agitator and stir at 400r / min for 20 minutes. During this time, monitor the uniformity of the system with an online viscometer until all raw materials are completely dissolved, dispersed and free of particles, and the homogeneity of the system reaches more than 98%.

[0021] S2. Volume Adjustment: Add the remaining 29.74 kg of raw milk to the mixture from step S1, and adjust the volume to 100 kg of the preset production volume. Stir at 300 r / min for 5 minutes to fully integrate the raw milk with the original mixture and homogenize the system.

[0022] S3. Homogenization: The milk solution after volume adjustment is maintained at 63°C through a heat preservation pipeline and pumped into a high-pressure homogenizer. It is homogenized once under a homogenization pressure of 19MPa. After processing, the fat globule particle size is refined to 3~4μm by laser particle size analyzer, which meets the requirement of 2~5μm.

[0023] S4. Single sterilization: The homogenized milk is poured into a pasteurization tank and placed in an 85℃ constant temperature water bath for 15 minutes for sterilization. The water bath is circulated and stirred to ensure uniform heating. After sterilization, samples are taken for testing. The total number of colonies in the milk is ≤80 CFU / mL, which meets the standard of ≤100 CFU / mL.

[0024] S5. Inoculation: The sterilized milk is rapidly cooled to 42°C using a plate heat exchanger. A compound bacterial suspension, prepared by diluting 40 mL of sterile water 10 times, is then added. The bacterial suspension is evenly sprayed into the milk through an atomizing nozzle. After spraying, the mixture is stirred at 100 r / min for 5 minutes to ensure uniform bacterial distribution. The inoculation amount of the compound bacterial strain is 0.04% of the total mass of the milk, which is within the range of 0.03~0.05%.

[0025] S6. Fermentation: Transfer the inoculated milk to a 43°C fully automatic constant temperature fermentation tank. During the static fermentation process, monitor the acidity changes in real time. When the acidity reaches 69°T, immediately stop the fermentation by cooling with a cooling medium. After the fermentation is stopped, turn the tank over. The frequency of turning the tank is 2 times / minute and the turning time is 3 minutes. After turning the tank over, stir at a low speed of 60r / min for 1 minute to avoid uneven texture or clumping of the milk.

[0026] S7. Secondary ingredient preparation: Weigh 0.2 kg of compound stabilizer and add it to 2.5 kg (12.5 times the mass of stabilizer) of deionized water at 62°C. Place the mixture in a high-speed shear emulsifier and stir at 500 r / min for 15 minutes until the stabilizer is completely dissolved and forms a uniform colloid. Then, slowly add the colloid to the fermented milk using a peristaltic pump at a rate of 50 mL / min while stirring at 80 r / min for 10 minutes to mix evenly. The temperature difference between the colloid and the milk should be controlled at 3°C ​​to avoid sudden temperature changes that could cause protein denaturation and precipitation.

[0027] S8. Secondary sterilization: The milk that has undergone secondary preparation is pumped into a tube-type instantaneous sterilizer and kept at 86℃ for 30 seconds. After sterilization, it is rapidly cooled to 28℃ through a plate heat exchanger, with the cooling rate controlled at 5℃ / min.

[0028] S9. Filling and Packaging: The cooled milk is stirred at 120 rpm for 1 minute and then filled using a fully automatic cup filling machine in a Class A aseptic cleanroom. The filling volume is 100g / cup, and the filling volume error is controlled within ±1%. Immediately after filling, aluminum foil is used for heat sealing at 125℃ for 2.5 seconds. After heat sealing, the cup opening is tested for sealing performance using a negative pressure leak detector to ensure no leakage. Finally, the finished product is labeled, boxed, and stored at room temperature.

[0029] Product performance testing The room-temperature resistant yogurt products prepared in this embodiment were tested for various indicators, and the results are as follows: 1. Basic physicochemical indicators: Protein content 2.8%, fat content 3.1%, both meeting the requirements of ≥2.3% and ≥2.5% respectively; dietary fiber content 2.7g / 100g, reaching the standard of ≥2.5g / 100g.

[0030] 2. Storage stability: After 7 days of storage at room temperature (25±5℃), the whey separation rate was 2.8% (≤3.5%); after 28 days of storage, the pH value decreased from the initial 4.39 to 4.20, a decrease of 0.19 (≤0.21), the viscosity remained stable at 2250 mPa·s (within the range of 2200±150 mPa·s), and the total microbial count was ≤8 CFU / g; after 90 days of storage, the whey separation rate was 7.2% (≤8.0%), and there was no spoilage caused by excessive microbial levels.

[0031] 3. Sensory and market evaluation: Sensory evaluation score of 92 points (≥87 points), market evaluation acceptance rate of 89% (≥83%).

[0032] Example 2: Preparation of Yogurt Products with Different Stabilizer Ratios for Room Temperature Storage The raw material formulation and preparation steps of this embodiment are basically the same as those of Example 1, except that the type and ratio of the stabilizer are changed: sodium carboxymethyl cellulose (CMC-Na) and konjac gum are compounded at a mass ratio of 2:1 as stabilizers, and the total addition amount is still 0.2%.

[0033] Testing revealed that the product prepared in this embodiment had a protein content of 2.7% and a fat content of 3.0%; the whey separation rate was 3.2% after 7 days of storage at room temperature and 7.8% after 90 days of storage; the pH value decreased to 4.19 after 28 days of storage, and the viscosity was 2180 mPa·s. All indicators met the requirements of this invention, with a sensory evaluation score of 89 points and a market acceptance rate of 86%.

[0034] Example 3: Preparation of Yogurt Products with Different Inoculation Amounts and Suitable for Room Temperature Storage The raw material formula and preparation steps of this embodiment are basically the same as those of Example 1, except that the inoculation amount of the compound strain is adjusted to 0.03% of the total mass of the milk.

[0035] Testing showed that the fermentation time to a final acidity of 68°T for the product prepared in this embodiment was 1.2 hours longer than that in Example 1. The final product had a protein content of 2.6% and a fat content of 2.9%. After 90 days of storage at room temperature, the whey separation rate was 7.5%, and the total microbial count was ≤9 CFU / g. All indicators met the requirements of this invention.

[0036] The scope of protection of this invention is not limited to the technical solutions disclosed in the specific embodiments described above. Any modifications, equivalent substitutions, or improvements made to the above embodiments based on the technical essence of this invention shall fall within the scope of protection of this invention.

Claims

1. A yogurt product that can be stored at room temperature, characterized in that: The raw material components are raw milk and auxiliary materials, wherein the raw milk has a protein content of ≥3.6% and a fat content of ≥3.7%; the auxiliary materials are erythritol, polydextrose, stabilizer and compound bacterial strain, wherein: the mass ratio of erythritol to polydextrose is 1:1, and the total amount of the two added accounts for 5% of the total mass of the yogurt product; the amount of stabilizer added accounts for 0.2% of the total mass of the yogurt product; the compound bacterial strain is composed of Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in a 1:1 mass ratio.

2. The yogurt product resistant to room temperature storage according to claim 1, characterized in that: The excipients also include sucralose and edible flavoring, wherein the amount of sucralose added accounts for 0.01~0.02% of the total mass of the yogurt product, and the amount of edible flavoring added accounts for 0.05~0.1% of the total mass of the yogurt product; the edible flavoring is a natural dairy flavoring.

3. A yogurt product resistant to room temperature storage according to claim 1, characterized in that: The erythritol is food-grade high-purity erythritol with a purity ≥99.5% and a calorie content ≤0.2kcal / g; the polydextrose is water-soluble dietary fiber grade polydextrose with a DE value ≤10 and a water holding capacity ≥300%. The combination of the two results in a product with a dietary fiber content ≥2.5% / 100g.

4. A yogurt product resistant to room temperature storage according to claim 1, characterized in that: When stored at room temperature for 28 days, the pH value decreased from the initial 4.39 to 4.18, with a decrease of ≤0.21, the viscosity stabilized at 2200±150mPa・s, the total microbial count was ≤10CFU / g, and there was no deterioration caused by excessive microbial levels.

5. A yogurt product resistant to room temperature storage according to claim 1, characterized in that: When stored at room temperature for 7 days, the whey separation rate is ≤3.5%; when stored at room temperature for 90 days, the whey separation rate is ≤8.0%, which is significantly lower than that of yogurt products with a single sweetener formulation.

6. A method for preparing a yogurt product resistant to room temperature storage as described in any one of claims 1-5, characterized in that: Includes the following steps: S1. Initial mixing: Take 60-70% of the total amount of raw milk, heat it to 60-65℃, add erythritol, polydextrose and other excipients except stabilizer, stir at 300-500r / min for 20 minutes until all raw materials are completely dissolved and evenly dispersed; S2. Volume adjustment: Add the remaining 30-40% of raw milk to the mixture from step S1, adjust the volume to the preset production volume, and stir for 5 minutes to homogenize the system; S3. Homogenization: The milk after volume adjustment is kept at 60~65℃ and homogenized once under a homogenization pressure of 18~20MPa to refine the fat globule particle size to 2~5μm. S4. Single sterilization: The homogenized milk is placed in an 85℃ constant temperature water bath for 15 minutes to kill pathogenic bacteria and miscellaneous bacteria in the raw materials. The total number of colonies in the milk after sterilization is ≤100CFU / mL. S5. Inoculation: Quickly cool the sterilized milk to 41~43℃ and inoculate it with compound bacteria; S6. Fermentation: Transfer the inoculated milk to a 43°C constant temperature fermentation tank and statically ferment until the final acidity is 68~70°T, then immediately stop the fermentation. S7. Secondary mixing: Add the stabilizer to deionized water at 60~65℃ and stir at 400~600r / min for 15 minutes until the stabilizer is completely dissolved and forms a uniform colloid. Then slowly add the colloid to the fermented milk and stir for 10 minutes to mix well. S8. Secondary sterilization: The milk that has undergone secondary formulation is passed through an instant sterilizer and kept at 85~88℃ for 30 seconds. After sterilization, it is quickly cooled to 25~30℃. S9. Filling and Packaging: Stir the cooled milk at a speed of 100~150r / min for 1 minute, fill it into cups in a Class A aseptic environment, with a filling volume error of ≤±2%, seal it immediately after filling, and store it at room temperature in the warehouse.

7. The method for preparing a yogurt product resistant to room temperature storage according to claim 6, characterized in that: In step S5, the inoculation amount of the compound bacteria is 0.03~0.05% of the total mass of the milk. Before inoculation, the compound bacteria is diluted 10 times with sterile water to make a bacterial suspension, which is then sprayed evenly into the milk. After spraying, continue stirring for 5 minutes to ensure that the bacteria are evenly distributed.

8. The method for preparing a yogurt product resistant to room temperature storage according to claim 6, characterized in that: After fermentation is terminated in step S6, the milk should be turned over twice a minute for 3 minutes. After turning over, stir at a low speed of 50-80 r / min for 1 minute to avoid uneven texture or clumping in the milk.

9. The method for preparing a yogurt product resistant to room temperature storage according to claim 6, characterized in that: The first sterilization in step S4 is pasteurization, and the second sterilization in step S8 is ultra-high temperature instantaneous sterilization. The synergistic effect of the two sterilizations ensures that the total microbial count of the final product is ≤10 CFU / g, while retaining ≥90% of the whey protein activity in the raw milk.

10. The method for preparing a yogurt product resistant to room temperature storage according to claim 6, characterized in that: In step S7, the amount of deionized water used when dissolving the stabilizer is 10 to 15 times the mass of the stabilizer. The temperature difference when adding the colloid to the fermented milk is ≤5℃ to avoid sudden temperature changes that could cause protein denaturation and precipitation. In step S9, the sealing method after filling is aluminum foil heat sealing at a temperature of 120 to 130℃ for 2 to 3 seconds. After sealing, the cup opening is tested for leaks.

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