A room-temperature yogurt that is heat-resistant and can be heat-filled, and its preparation method.

Abstract

This invention belongs to the field of dairy processing technology, specifically relating to a room-temperature yogurt that is heat-resistant, sterilizable, and hot-fillable, and its preparation method. The room-temperature yogurt comprises the following raw material components by weight percentage: 80%-85% raw milk, 7%-8% white sugar, 0.4%-0.7% sodium carboxymethyl cellulose, 0.05%-0.15% gellan gum, 1%-1.5% hydroxypropyl distarch phosphate, 0.33%-2.1% bacterial cellulose nanosol, and 0.005%-0.02% starter culture. This invention solves many technical problems in the preparation of UHT-sterilized room-temperature yogurt by controlling the amount of bacterial cellulose nanosol added. Under the conditions of terminal UHT high-temperature sterilization and hot-filling processes, it ensures the good taste and texture stability of the room-temperature yogurt, while also reducing equipment investment and production operation costs.

Description

Technical Field

[0001] This invention belongs to the field of dairy processing technology, specifically relating to a room-temperature yogurt that is heat-resistant and sterilizable and can be hot-filled, and its preparation method. Background Technology

[0002] Traditional room-temperature yogurt often employs a two-stage sterilization process, currently using three main methods: high-temperature short-time heat treatment (75℃ / 25s), which requires aseptic filling and involves high equipment investment; high-temperature long-time heat treatment (80℃ / 30min), which allows for non-aseptic filling, but prolonged high temperatures can cause flavor deterioration and a rough texture, necessitating the addition of flavorings, fragrances, and flavor enhancers to optimize the taste, failing to meet current consumer preferences for clean label products; and ultra-high temperature (UHT) sterilization (115℃ / 15s), which allows for non-aseptic filling, but generally faces challenges such as a sharp drop in viscosity and whey separation due to the high temperature of UHT, making it difficult to maintain a stable system.

[0003] To simplify processes and reduce costs, recent studies have attempted to achieve single-stage UHT sterilization by combining stabilizers such as sodium carboxymethyl cellulose, gellan gum, and hydroxypropyl distarch phosphate, but the results have been less than ideal. Bacterial cellulose possesses excellent water-holding capacity and heat-resistant gelling ability, and has been reported for improving yogurt texture; however, its application in the preparation of UHT-sterilized room-temperature yogurt still faces numerous technical challenges, such as adapting the stabilizer system. Therefore, there is an urgent need to develop a type of room-temperature yogurt that can withstand terminal UHT high-temperature sterilization and can be hot-filled, eliminating the need for aseptic filling equipment and reducing equipment investment and operating costs. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a room-temperature yogurt that is heat-resistant, sterilizable, and hot-fillable, along with its preparation method. By controlling the addition of bacterial cellulose nanosol to 0.33%-2.1%, this invention solves the technical challenges of dispersibility, post-addition mixing uniformity, and thermal stability of bacterial cellulose in the sodium carboxymethyl cellulose system. Furthermore, by optimizing the preparation process and adding the bacterial cellulose nanosol at low speed after fermentation, this invention further ensures that the fermentation effect and the yogurt gel structure are not damaged. This achieves good taste and texture stability of the room-temperature yogurt under UHT high-temperature sterilization and hot-filling processes, while reducing equipment investment and production operation costs.

[0005] To achieve the objectives of this invention, the following technical solution is adopted: This invention provides a room-temperature yogurt that is heat-resistant and sterilizable and can be hot-filled, comprising the following raw material components by weight percentage: 80%-85% raw milk, 7%-8% white sugar, 0.4%-0.7% sodium carboxymethyl cellulose, 0.05%-0.15% gellan gum, 1%-1.5% hydroxypropyl distarch phosphate, 0.33%-2.1% bacterial cellulose nanosol, 0.005%-0.02% starter culture, and the balance being water.

[0006] When the inventors applied bacterial cellulose to the preparation of UHT-sterilized room-temperature yogurt, they discovered several technical challenges that needed to be addressed. The first challenge was the difficulty in dispersion. In a high-concentration sodium carboxymethyl cellulose system, the dense molecular chains of sodium carboxymethyl cellulose inhibited the uniform dispersion of bacterial cellulose nanofibers, leading to uneven local gelation and the appearance of particles or clumps in the product. The second challenge was insufficient thermal stability. Bacterial cellulose tends to aggregate and precipitate at the high temperature of UHT, making it impossible to effectively maintain the viscosity of the system, and even causing precipitation or stratification.

[0007] During the research process, the inventors discovered that when the amount of bacterial cellulose was too high, the gel clumped and the texture was abnormal; when the amount was too low, the viscosity of the finished product was low and the system stability was insufficient. This invention solves the problem of difficult dispersion of bacterial cellulose in high-concentration sodium carboxymethyl cellulose systems by limiting the specific amount of bacterial cellulose nanosol and avoiding the physical obstruction of bacterial cellulose nanofibers by high-concentration sodium carboxymethyl cellulose molecular chains.

[0008] In addition, bacterial cellulose is added in the form of nano-sol, which introduces it into the system in a pre-dispersed nano-fiber state, resulting in better fluidity and significantly improving its penetration and distribution ability in viscous emulsions. This prevents uneven gelation caused by excessive local aggregation, thus solving the problem of uneven mixing, aggregation, and stratification of bacterial cellulose in yogurt curd when added after fermentation.

[0009] The nanosol morphology of bacterial cellulose enhances the interfacial interaction between bacterial cellulose and raw milk and sodium carboxymethyl cellulose, synergistically establishing a more stable structure. Furthermore, by controlling the amount of bacterial cellulose added, its heat-resistant gel support function can be utilized without causing phase separation or precipitation due to excessive amount, effectively maintaining product viscosity and uniformity, and significantly improving the thermal stability of UHT high-temperature sterilization.

[0010] Preferably, the heat-resistant and heat-fillable room-temperature yogurt comprises the following raw material components by weight percentage: 82% raw milk, 7.5% white sugar, 0.6% sodium carboxymethyl cellulose, 0.1% gellan gum, 1.3% hydroxypropyl distarch phosphate, 1.28% bacterial cellulose nanosol, 0.01% starter culture, and the balance being water.

[0011] Preferably, the fermenting agent includes at least two of the following: Streptococcus salivarius subsp. thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum, Bifidobacterium animalis subsp. lactis, or Lactobacillus delbrueckii subsp. bulgaricus.

[0012] More preferably, the fermenting agent includes *Streptococcus salivarius* subsp. *thermophilus* and *Lactobacillus delbrueckii* subsp. *bulgaricus*.

[0013] More preferably, the fermenting agent includes Lactobacillus acidophilus, Bifidobacterium animalis subsp. lactis, Streptococcus salivarius subsp. thermophilus, and Lactobacillus delbrueckii subsp. bulgaricus.

[0014] More preferably, the fermenting agent comprises 1.0 × 10 10 -1.0×10 12 CFU / g of Streptococcus salivarius subsp. thermophilus and 1.0×10 8 -1.0×10 10 CFU / g Lactobacillus delbrueckii subsp. bulgaricus.

[0015] More preferably, the fermenting agent comprises 1.0 × 10 10 -1.0×10 12 CFU / g Streptococcus salivarius subsp. thermophilus, 1.0×10 8 -1.0×10 10 CFU / g Lactobacillus delbrueckii subsp. bulgaricus, 4.0×10 11 -6.0×10 11 CFU / g Lactobacillus acidophilus and 2.0×10 11 -4.0×10 11 CFU / g Bifidobacterium animalis subsp. lactis.

[0016] Preferably, the preparation method of the bacterial cellulose nanosol includes the following steps: Bacterial cellulose was dispersed in water and homogenized to obtain the bacterial cellulose nanosol.

[0017] More preferably, the amount of water added is 10-20 times the mass of bacterial cellulose.

[0018] More preferably, the temperature of the water is 40-50℃.

[0019] More preferably, the dispersion rotation speed is 8000-10000 rpm.

[0020] More preferably, the dispersion time is 10-15 minutes.

[0021] More preferably, the pressure of the homogenization is 100-150 MPa.

[0022] More preferably, the homogenization is performed 1-3 times.

[0023] For example, there is no need to further limit the homogenization time for each homogenization; it is sufficient to ensure that the total homogenization time is 10-15 minutes.

[0024] More preferably, the bacterial cellulose nanosol has a particle size D90 ≤ 5 μm.

[0025] The present invention also provides a method for preparing the heat-resistant and heat-fillable room-temperature yogurt, comprising the following steps: S1: Weigh each component according to the mass ratio, mix the raw milk, white sugar, sodium carboxymethyl cellulose, gellan gum and hydroxypropyl distarch phosphate evenly, sterilize, then add the starter culture for fermentation, break the emulsion, cool, and obtain yogurt base material; S2: At a stirring speed of 20-30 rpm, the bacterial cellulose nanosol is added to the yogurt base and mixed evenly to obtain a mixed liquid. S3: The mixture is sterilized, filled, cooled, and post-ripened to obtain room-temperature yogurt that is heat-resistant and can be hot-filled.

[0026] The inventors discovered through research that adding bacterial cellulose before fermentation would slow down the fermentation of the entire system, make it difficult to reach the required acidity, and seriously affect the taste and texture of the finished product. If bacterial cellulose powder or coarse dispersion is added after fermentation, a second problem arises: bacterial cellulose is difficult to mix evenly into the formed yogurt curd, which can easily lead to white spots, fiber bundle aggregation, or stratification.

[0027] This invention overcomes the problem of slow fermentation caused by adding bacterial cellulose nanosol before fermentation by adding bacterial cellulose after fermentation. It also solves the problem of the entire system being too viscous and difficult to disperse in the early stage of yogurt fermentation and shaping. This allows the bacterial cellulose nanosol to be better dispersed in the system, reducing the problem of uneven dispersion leading to poor taste and texture stability of the finished yogurt. This invention also limits the stirring speed when adding bacterial cellulose nanosol to further ensure that the nanosol is not damaged and can be mixed evenly as quickly as possible.

[0028] Furthermore, in S1, the mixing is homogeneous, with a homogenization temperature of 55-65℃, a pressure of 15-25MPa, and a time of 5-20min.

[0029] Furthermore, in S1, the sterilization temperature is 90-95℃ and the time is 300-400s.

[0030] Furthermore, in S1, the sterilization process requires cooling to 40-45°C before adding the fermentation agent.

[0031] Furthermore, in S1, the fermentation temperature is 38-42°C.

[0032] Furthermore, in S1, the fermentation endpoint is reached when the acidity reaches 65-70°T.

[0033] Furthermore, in S1, the cooling temperature is 15-20°C.

[0034] Furthermore, in S2, the stirring temperature is 15-20°C.

[0035] Furthermore, in S2, the feeding time of the bacterial cellulose nanosol is 3-8 minutes.

[0036] Furthermore, in S3, the sterilization temperature is 113-117℃ and the time is 13-17s.

[0037] Furthermore, in S3, the filling temperature is 80-88°C.

[0038] Furthermore, in S3, the cooling temperature is 23-27°C.

[0039] Furthermore, in S3, the post-ripening time is 12-24 hours.

[0040] The beneficial effects provided by this invention are: (1) The room temperature yogurt provided by the present invention adopts terminal UHT high temperature sterilization and hot filling process. The viscosity of the yogurt is still stable, and the viscosity of the finished product is ≥1500cP. The finished product has good stability at room temperature storage. There is no whey separation, no layering, and no sedimentation for 6 months. The finished product has a delicate taste, and the nano-level bacterial cellulose sol is evenly dispersed, without particle feel, fiber bundles, or clumping.

[0041] (2) The method for preparing room temperature yogurt that is heat-resistant and sterilizable and can be hot-filled provided by the present invention has low equipment investment, does not require an aseptic filling system, and can be produced by ordinary hot filling equipment, which greatly reduces costs. Detailed Implementation

[0042] The present invention will be further described in detail below through specific embodiments, but this is only for the purpose of helping to understand the present invention and enabling those skilled in the art to implement or use the present invention, and does not constitute any limitation on the present invention.

[0043] In Example 1, the starter culture was *Streptococcus salivarius* subsp. *thermophilus* JMCC0022, accession number CGMCC No. 15822, and *Lactobacillus delbrueckii* subsp. *bulgaricus* JMCC0018, accession number CGMCC No. 14425.

[0044] In Example 2, the starter culture was *Streptococcus salivarius* subsp. *thermophilus* JMCC0022, accession number CGMCC No. 15822, and *Lactobacillus delbrueckii* subsp. *bulgaricus* JMCC0018, accession number CGMCC No. 14425.

[0045] The starter culture in Example 3 includes (1) Streptococcus salivarius subsp. thermophilus JMCC0022, accession number CGMCC No.15822 and Lactobacillus delbrueckii subsp. bulgaricus JMCC0018, accession number CGMCC No.14425 (2) Lactobacillus acidophilus, model La28-1000, accession number CGMCC No.11506 (3) Bifidobacterium animalis subsp. lactis, model BB12, accession number DSM15954.

[0046] Bacterial cellulose was purchased from Foshan Sailuna Technology Co., Ltd., model BCS60NP, in powder form.

[0047] The following description is based on specific embodiments.

[0048] Example 1 This embodiment provides a room-temperature yogurt that is heat-resistant, sterilizable, and can be hot-filled. Its raw material composition is as follows (per ton of final product): 820 kg raw milk, 75 kg white sugar, 6 kg sodium carboxymethyl cellulose, 1 kg gellan gum, 13 kg hydroxypropyl distarch phosphate, 12.8 kg bacterial cellulose nanosol, and 0.1 kg starter culture. The starter culture contains 1.0 × 10⁻⁶... 11 CFU / g of Streptococcus salivarius subsp. thermophilus and 1.0×10 9 CFU / g Lactobacillus delbrueckii subsp. bulgaricus, balance water; The preparation method of bacterial cellulose nanosol includes the following steps: Take 0.8 kg of bacterial cellulose powder, add 12 kg of sterile water at 45℃, disperse it for 12 min at 9000 rpm using a high-shear emulsifier, and then treat it twice with a high-pressure microfluidic homogenizer at 110 MPa for a total homogenization time of 13 min to obtain 12.8 kg of bacterial cellulose nanosol with an average particle size D90 of 3.2 μm. The method for preparing the heat-resistant and heat-fillable room-temperature yogurt includes the following steps: S1: Take the formula amount of raw milk, white sugar, sodium carboxymethyl cellulose, gellan gum, and hydroxypropyl distarch phosphate and mix them. Homogenize them at 60℃ and 20MPa for 15 minutes. Pasteurize them at 95℃ for 300 seconds, cool them to 42℃, inoculate them with starter culture, and ferment them at 40℃ until the acidity reaches 70°T. Demulsify and cool them to 18℃ to obtain the yogurt base. S2: Under stirring at 18℃ and 25 rpm, the bacterial cellulose nanosol is slowly added to the yogurt base over 5 minutes, and then stirred at a low speed of 25 rpm for 12 minutes until completely homogeneous, to obtain a mixed liquid. S3: The obtained mixture is sterilized by UHT at 115℃ for 15s. After sterilization, it is directly cooled to 85℃ for hot filling to obtain a semi-finished product. S4: Quickly cool the semi-finished product to 25°C and let it stand for 18 hours to ripen, and the finished product is obtained.

[0049] Example 2 This embodiment provides a room-temperature yogurt that is heat-resistant, sterilizable, and can be hot-filled. Its raw material composition is as follows (per ton of final product): 800 kg raw milk, 70 kg white sugar, 4 kg sodium carboxymethyl cellulose, 1.5 kg gellan gum, 10 kg hydroxypropyl distarch phosphate, 3.3 kg bacterial cellulose nanosol, and 0.05 kg starter culture. The starter culture contains 1.0 × 10⁻⁶... 12 CFU / g of Streptococcus salivarius subsp. thermophilus and 1.0×10 8 CFU / g Lactobacillus delbrueckii subsp. bulgaricus, balance water; The preparation method of bacterial cellulose nanosol includes the following steps: Take 0.3 kg of bacterial cellulose powder, add 3 kg of sterile water at 40℃, disperse it for 10 min at 8000 rpm using a high-shear emulsifier, and then treat it three times under a pressure of 100 MPa using a high-pressure microfluidic homogenizer for a total homogenization time of 10 min to obtain 3.3 kg of bacterial cellulose nanosol with an average particle size D90 of 3.9 μm.

[0050] The method for preparing the heat-resistant and heat-fillable room-temperature yogurt includes the following steps: S1: Take the formula amount of raw milk, white sugar, sodium carboxymethyl cellulose, gellan gum, and hydroxypropyl distarch phosphate and mix them. Homogenize them at 55℃ and 15MPa for 5 minutes. Pasteurize them at 90℃ for 400 seconds, cool them to 40℃, inoculate them with starter culture, and ferment them at 28℃ until the acidity reaches 65°T. Demulsify and cool them to 15℃ to obtain the yogurt base. S2: Under stirring at 15℃ and 20 rpm, the bacterial cellulose nanosol is slowly added to the yogurt base over 3 minutes, and then stirred at a low speed of 20 rpm for 10 minutes until completely homogeneous, to obtain a mixed liquid. S3: The obtained mixture is sterilized by UHT at 115℃ for 15s. After sterilization, it is directly cooled to 80℃ for hot filling to obtain a semi-finished product. S4: Quickly cool the semi-finished product to 25°C and let it stand for 12 hours to ripen, and the finished product is obtained.

[0051] Example 3 This embodiment provides a room-temperature yogurt that is heat-resistant and sterilizable, and can be hot-filled. Its raw material composition is as follows (per ton of final product): 850 kg raw milk, 80 kg white sugar, 7 kg sodium carboxymethyl cellulose, 0.5 kg gellan gum, 15 kg hydroxypropyl distarch phosphate, 21 kg bacterial cellulose nanosol, and 0.2 kg starter culture. The starter culture contains 1.0 × 10⁻⁶... 10 CFU / g Streptococcus salivarius subsp. thermophilus, 1.0×10 10 CFU / g Lactobacillus delbrueckii subsp. bulgaricus, 5.0×10 11 CFU / g Lactobacillus acidophilus and 3.0×10 11 CFU / g Bifidobacterium animalis subsp. lactis, balance: water; The preparation method of bacterial cellulose nanosol includes the following steps: Take 1.0 kg of bacterial cellulose powder, add 20 kg of sterile water at 50℃, disperse it for 15 min at 10000 rpm using a high-shear emulsifier, and then treat it once with a high-pressure micro-jet homogenizer at 150 MPa for a total homogenization time of 15 min to obtain 21 kg of bacterial cellulose nanosol with an average particle size D90 of 4.3 μm. The method for preparing the heat-resistant and heat-fillable room-temperature yogurt includes the following steps: S1: Take the formula amount of raw milk, white sugar, sodium carboxymethyl cellulose, gellan gum, and hydroxypropyl distarch phosphate and mix them. Homogenize them at 65℃ and 25MPa for 20 minutes. Pasteurize them at 93℃ for 360 seconds, cool them to 45℃, inoculate them with starter culture, and ferment them at 42℃ until the acidity reaches 68°T. Demulsify and cool them to 20℃ to obtain the yogurt base. S2: Under stirring at 20℃ and 30rpm, the bacterial cellulose nanosol is slowly added to the yogurt base over 8 minutes, and then stirred at 30rpm for 15 minutes until completely homogeneous to obtain a mixed liquid. S3: The obtained mixture is sterilized by UHT at 115℃ for 15s. After sterilization, it is directly cooled to 88℃ for hot filling to obtain a semi-finished product. S4: Quickly cool the semi-finished product to 25°C and let it stand for 24 hours to ripen, and the finished product is obtained.

[0052] Comparative Example 1 This comparative example provides a room-temperature yogurt that is heat-resistant and sterilizable and can be hot-filled. The difference from Example 1 is that the amount of bacterial cellulose nanosol is increased. The specific raw material composition is as follows (per ton of final product): 820 kg raw milk, 75 kg white sugar, 6 kg sodium carboxymethyl cellulose, 1 kg gellan gum, 13 kg hydroxypropyl distarch phosphate, 24 kg bacterial cellulose nanosol, and 0.1 kg starter culture. The starter culture contains 1.0 × 10⁻⁶... 11 CFU / g of Streptococcus salivarius subsp. thermophilus and 1.0×10 9 CFU / g Lactobacillus delbrueckii subsp. bulgaricus, balance water; The other components and preparation methods are the same as in Example 1 of this invention. The bacterial cellulose nanosol is prepared by taking 1.5 kg of bacterial cellulose powder, adding 22.5 kg of sterile water, and finally obtaining 24 kg of bacterial cellulose nanosol.

[0053] Comparative Example 2 This comparative example provides a room-temperature yogurt that is heat-resistant and can be hot-filled, which differs from Example 1 in that the amount of bacterial cellulose nanosol is reduced. The specific raw material composition is as follows (per ton of final product): 820 kg raw milk, 75 kg white sugar, 6 kg sodium carboxymethyl cellulose, 1 kg gellan gum, 13 kg hydroxypropyl distarch phosphate, 3.2 kg bacterial cellulose nanosol, and 0.1 kg starter culture. The starter culture contains 1.0 × 10⁻⁶... 11 CFU / g of Streptococcus salivarius subsp. thermophilus and 1.0×10 9 CFU / g Lactobacillus delbrueckii subsp. bulgaricus, balance water; The other components and preparation methods are the same as in Example 1 of this invention. The bacterial cellulose nanosol is prepared by taking 0.2 kg of bacterial cellulose powder, adding 3 kg of sterile water, and finally obtaining 3.2 kg of bacterial cellulose nanosol.

[0054] Comparative Example 3 This comparative example provides a room-temperature yogurt that is heat-resistant and sterilizable and can be hot-filled. The difference from Example 1 is that the bacterial cellulose nanosol is replaced with an equal amount of bacterial cellulose; the bacterial cellulose is added in the form of dry powder. The other components and preparation methods are the same as in Example 1 of this invention.

[0055] Comparative Example 4 This comparative example provides a room-temperature yogurt that is heat-resistant and can be hot-filled, differing from Example 1 in that bacterial cellulose nanosol is added before fermentation: The specific preparation methods include the following: S1: Take the formula amount of raw milk, white sugar, sodium carboxymethyl cellulose, gellan gum, hydroxypropyl distarch phosphate and bacterial cellulose nanosol and mix them. Homogenize them at 60℃ and 20MPa for 15min. Pasteurize them at 95℃ for 300s. Cool them to 42℃, inoculate them with starter culture, and ferment them at 40℃ until the acidity reaches 50°T. Demulsify and cool them to 18℃ to obtain the mixed liquid. S2: The obtained mixture is sterilized by UHT at 115℃ for 15s. After sterilization, it is directly cooled to 85℃ for hot filling to obtain a semi-finished product. S3: Quickly cool the semi-finished product to 25°C, let it stand for 18 hours to ripen, and the finished product is obtained; The other components and preparation methods are the same as in Example 1 of this invention.

[0056] Comparative Example 5 This comparative example provides a room-temperature yogurt that is heat-resistant and sterilizable and can be hot-filled. The difference from Example 1 is that the stirring rate of the bacterial cellulose nanosol in S2 is increased from 25 rpm to 100 rpm. The other components and preparation methods are the same as in Example 1 of this invention.

[0057] Comparative Example 6 This comparative example provides a room-temperature yogurt that is heat-resistant and can be hot-filled. The difference from Example 1 is that in S3, the obtained mixed liquid is sterilized by UHT at 115°C for 15s. After sterilization, it is directly cooled to 25°C and filled under aseptic conditions to obtain a semi-finished product. The other components and preparation methods are the same as in Example 1 of this invention.

[0058] Experimental Example 1 The room-temperature yogurt products prepared in Examples 1-3 and Comparative Examples 1-6 were tested for viscosity, taste, texture stability, and blind taste scores. The specific test methods are as follows: Viscosity test: 21±1℃, Brookfield viscometer, No. 4 rotor, 60rpm, 30s; Blind taste test: 20 randomly selected tasters will conduct a flavor test (also known as a "taste test"). The flavor test will use a scoring method: the scoring method uses numerical scores to evaluate the product or product characteristics, and the final ranking is determined by the average score. The scoring rule starts with 0. 10 points is the interval, 0 2 points is considered a difference, 3 points is considered a difference. 5 points is considered average, 6 points is considered average. 8 points is considered good, 9 points is considered good. A score of 10 is considered excellent. Evaluation criteria include: color, flavor, and texture, as detailed in Table 1.

[0059] Table 1 Evaluation Criteria

[0060] The test results are shown in Table 2.

[0061] Table 2 Test results of room temperature yogurt products

[0062] The room-temperature yogurts prepared in Examples 1-3 have a finished product viscosity ≥1500 cP; the finished product has a delicate taste, while the taste of Example 3 is slightly thicker but still acceptable, and the blind test scores are all greater than 9.0 points; the finished product has good stability when stored at room temperature, with no whey separation, no layering, and no sedimentation after 6 months.

[0063] The bacterial cellulose nanosol used in Comparative Example 1 was used in excessive amounts, which led to deterioration in taste and texture. The gel was too hard, which seriously affected the taste. The texture was rough, the weak gel clumped, cracked in the middle and separated water, the texture was abnormal, and the stability was poor. The blind test score was only 3.2 points.

[0064] The bacterial cellulose nanosol used in Comparative Example 2 was used in too low a quantity, resulting in a low viscosity of only 720 cp in the finished product. The system was not stable enough, and whey separation occurred after 3 months. The product also had a thin texture, weak milk flavor, and a blind test score of only 4.0.

[0065] The bacterial cellulose in Comparative Example 3 was added as dry powder and not made into a nano sol, which led to local clumping. Under the microscope, the fiber bundles and granular texture severely affected the taste and texture stability of the finished product. After one month, uneven dispersion and stratification appeared. The viscosity of the finished product could not be measured due to local clumping, and the blind test score was only 2.5 points.

[0066] Comparative Example 4 involved adding bacterial cellulose before fermentation, which resulted in slow fermentation of the entire system, difficulty in achieving the required acidity, a slight off-odor, no sourness, poor taste, and abnormal fermentation leading to system instability. The system precipitated at the bottom after 0 months, and the viscosity of the finished product could not be measured due to the abnormal fermentation state. The blind test score was only 2.0.

[0067] Comparative Example 5 involved high-speed stirring when bacterial cellulose was added, which disrupted the yogurt gel structure, resulting in a significant decrease in viscosity to only 850 cp. The gel fragmented, the texture became loose, whey separated within 0 months, water separated from the bottom, and the stability was extremely poor. The taste was thin and lacked creaminess, resulting in a blind test score of only 4.2.

[0068] Comparative Example 6 was sterilized with UHT and then aseptically filled at room temperature. The viscosity, taste, texture stability and blind test score of the finished product were similar to those of Example 1, but the equipment cost of Comparative Example 6 was high.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A room-temperature yogurt that is heat-resistant and sterilizable, and can be hot-filled, characterized in that, The raw material components include the following percentages by weight: 80%-85% raw milk, 7%-8% white sugar, 0.4%-0.7% sodium carboxymethyl cellulose, 0.05%-0.15% gellan gum, 1%-1.5% hydroxypropyl distarch phosphate, 0.33%-2.1% bacterial cellulose nanosol, 0.005%-0.02% starter culture, and the balance being water.

2. The room-temperature yogurt that is heat-resistant, sterilizable, and suitable for hot filling as described in claim 1, characterized in that, The heat-resistant and heat-fillable room-temperature yogurt comprises the following raw material components by weight percentage: 82% raw milk, 7.5% white sugar, 0.6% sodium carboxymethyl cellulose, 0.1% gellan gum, 1.3% hydroxypropyl distarch phosphate, 1.28% bacterial cellulose nanosol, 0.01% starter culture, and the balance being water.

3. The room-temperature yogurt that is heat-resistant, sterilizable, and suitable for hot filling as described in claim 1 or 2, characterized in that, The fermenting agent includes at least two of the following: Streptococcus salivarius subsp. thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum, Bifidobacterium animalis subsp. lactis, or Lactobacillus delbrueckii subsp. bulgaricus.

4. The room-temperature yogurt that is heat-resistant, sterilizable, and suitable for hot filling as described in claim 1 or 2, characterized in that, The preparation method of the bacterial cellulose nanosol includes the following steps: Bacterial cellulose was dispersed in water and homogenized to obtain the bacterial cellulose nanosol.

5. The room-temperature yogurt that is heat-resistant, sterilizable, and heat-fillable as described in claim 4, characterized in that, The amount of water added is 10-20 times the mass of the bacterial cellulose; and / or The temperature of the water is 40-50℃; and / or The bacterial cellulose nanosol has a particle size D90 ≤ 5 μm.

6. The room-temperature yogurt that is heat-resistant, sterilizable, and heat-fillable as described in claim 4, characterized in that, The dispersion rotation speed is 8000-10000 rpm; and / or The dispersion time is 10-15 minutes.

7. The room-temperature yogurt that is heat-resistant, sterilizable, and heat-fillable as described in claim 4, characterized in that, The pressure of the homogenizer is 100-150 MPa.

8. A method for preparing a room-temperature yogurt that is heat-resistant, sterilizable, and heat-fillable according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Weigh each component according to the mass ratio, mix the raw milk, white sugar, sodium carboxymethyl cellulose, gellan gum and hydroxypropyl distarch phosphate evenly, sterilize, then add the starter culture for fermentation, break the emulsion, cool, and obtain yogurt base material; S2: At a stirring speed of 20-30 rpm, the bacterial cellulose nanosol is added to the yogurt base and mixed evenly to obtain a mixed liquid. S3: The mixture is sterilized, filled, cooled, and post-ripened to obtain room-temperature yogurt that is heat-resistant and can be hot-filled.

9. The method for preparing room-temperature yogurt that is heat-resistant, sterilizable, and heat-fillable as described in claim 8, characterized in that, In S1, the mixing is homogeneous, with a homogenization temperature of 55-65℃, a pressure of 15-25MPa, and a time of 5-20min; and / or In S1, the sterilization process requires cooling to 40-45°C before adding the fermentation agent.

10. The method for preparing room-temperature yogurt that is heat-resistant, sterilizable, and heat-fillable as described in claim 8, characterized in that, In S2, the stirring temperature is 15-20℃; and / or In S2, the feeding time of the bacterial cellulose nanosol is 3-8 minutes; and / or In S3, the sterilization temperature is 113-117℃, and the time is 13-17s; and / or In S3, the filling temperature is 80-88℃.

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