A sweet bamboo shoot flavored coagulated fermented milk and its preparation method

Abstract

A sweet bamboo shoot flavored coagulated fermented milk and its preparation method are disclosed, relating to the field of fermented dairy product processing technology. The purpose of this invention is to solve the problems of whey separation and curd structure destruction caused by the addition of bamboo shoot ingredients. The fermented milk of this invention is made by fermenting a fermentation base with a lactic acid bacteria starter culture. The fermentation base is obtained by completely replacing the water used in reconstituted milk preparation with sweet bamboo shoot extract, and then mixing it with whole milk powder and sucrose. The amount of sucrose added is 7% of the mass of the fermentation base. The finished fermented milk has a pH of 4.28–4.35, a titratable acidity of 89–96°T, and a viable lactic acid bacteria count ≥6.5 × 10⁻⁶. 8 CFU / mL. This invention uses clarified sweet bamboo shoot juice instead of water in its fermented milk, preventing whey separation, resulting in a smooth, uniform curd and improved texture. The sweet bamboo shoot juice promotes the growth of lactic acid bacteria, stabilizing fermentation. Adjusting the feed-to-water ratio modifies the flavor, blending the aromas of sweet bamboo shoots, milk, and fermentation to meet consumer acceptance. It is compatible with existing production lines, requiring no new equipment, and is easily promoted through raw material substitution.

Description

Technical Field

[0001] This invention belongs to the field of fermented dairy product processing technology, specifically relating to a coagulated fermented milk prepared by replacing water with sweet bamboo shoot juice and its preparation method. Background Technology

[0002] Set-type yogurt is the mainstream fermented dairy product on the market. It relies on lactic acid bacteria to metabolize lactose in milk to produce acid curd, which has both nutritional and flavor value. As consumers' demand for product differentiation and health is increasing, fruit and vegetable compound fermented milk has become an innovative direction. However, existing technologies often directly add fruit and vegetable particles or cloudy juice, which will destroy the three-dimensional gel network of the milk matrix. This will lead to a large amount of whey separation after fermentation, a decrease in curd strength, and an uneven texture, which will seriously affect the product's sensory properties and shelf stability.

[0003] Sweet bamboo shoots are rich in natural reducing sugars, vitamins, minerals, and dietary fiber, and have a naturally sweet and fragrant flavor. Currently, they are mainly used in fresh consumption, pickling, and canning, with very little application in fermented dairy products. Existing attempts to introduce bamboo shoots into yogurt generally involve directly adding bamboo shoot particles. However, this approach has several drawbacks: firstly, solid particles disrupt the milk gel structure, causing a significant decrease in hardness, viscosity, and cohesiveness, resulting in severe whey separation and an inability to form a suitable coagulated structure; secondly, the proportion of bamboo shoots added is difficult to control, and excessively high concentrations can cause a sudden increase in osmotic pressure, inhibiting the growth and metabolism of lactic acid bacteria and leading to fermentation failure. Furthermore, an overpowering bamboo shoot aroma can mask the milky and fermented aromas, resulting in poor flavor harmony.

[0004] Therefore, developing a preparation method that can preserve the nutritional and flavor characteristics of sweet bamboo shoots while ensuring the good texture, fermentation activity, and flavor harmony of coagulated yogurt is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention provides a sweet bamboo shoot flavored coagulated fermented milk and its preparation method. By completely replacing water with clarified sweet bamboo shoot juice to prepare reconstituted milk, the invention solves the problems of whey separation and curd structure damage caused by the addition of bamboo shoot raw materials. At the same time, by optimizing the sweet bamboo shoot juice-to-water ratio, the invention achieves a balance between fermentation activity, physicochemical quality and flavor harmony.

[0006] This invention discloses a bamboo shoot-flavored coagulated fermented milk, which is made by fermenting a fermentation base with a lactic acid bacteria starter culture. The fermentation base is prepared by completely replacing the water used in reconstituted milk preparation with bamboo shoot extract, and then mixing it with whole milk powder and sucrose. The bamboo shoot extract is obtained by constant-temperature extraction and filtration of fresh bamboo shoots and water at a mass ratio of 1:(3-10), followed by sludge removal. The amount of sucrose added is 7% of the mass of the fermentation base. The finished fermented milk has a pH of 4.28-4.35, a titratable acidity of 89-96°T, and a viable lactic acid bacteria count ≥6.5×10⁻⁶.8 CFU / mL.

[0007] Furthermore, the mass ratio of the sweet bamboo shoots to water is 1:(5-7).

[0008] Furthermore, the lactic acid bacteria starter is a compound starter of Streptococcus thermophilus and Lactobacillus bulgaricus, and the total inoculum amount is 2% of the fermentation substrate volume.

[0009] The method for preparing the sweet bamboo shoot flavored coagulated fermented milk of the present invention is as follows:

[0010] (1) Preparation of sweet bamboo shoot extract: Select fresh sweet bamboo shoots, wash, peel and cut them, add water at a mass ratio of sweet bamboo shoots to water of 1:(3~10) and extract at a constant temperature. Filter to remove residue to obtain clear sweet bamboo shoot extract.

[0011] (2) Preparation of fermentation base: Add whole milk powder and sucrose to the sweet bamboo shoot extract, dissolve and mix thoroughly to obtain the fermentation base;

[0012] (3) Sterilization and cooling: Sterilize the fermentation substrate under high pressure steam, and then cool it to the inoculation temperature;

[0013] (4) Inoculation and fermentation: Add 2% by volume of compound lactic acid bacteria starter to the cooled fermentation substrate, mix well, and then let it stand at a constant temperature of 30~35℃ for fermentation until the pH and titratable acidity of the system reach the standard, which is the end point of fermentation.

[0014] (5) Cold refrigeration and ripening: After fermentation, the product is refrigerated at 4℃ to obtain the finished product.

[0015] Furthermore, in step (1), filtration is performed using gauze or filter paper.

[0016] Furthermore, the mass ratio of the sweet bamboo shoots to water in step (1) is 1:(5-7).

[0017] Furthermore, the criteria for determining the fermentation endpoint in step (4) are: titration acidity of the system ≥ 89°T, pH value ≤ 4.35.

[0018] The present invention has the following beneficial effects

[0019] Significantly optimized texture: By completely replacing water with clarified sweet bamboo shoot juice, the solid particles are avoided from cutting and damaging the latex gel network. No whey is separated in the finished product, and the curd is uniform and smooth. The texture indicators such as hardness, viscosity, and cohesiveness are significantly better than those of the direct addition of sweet bamboo shoot particles, which greatly improves the texture defects of fruit and vegetable type coagulated yogurt.

[0020] Excellent and stable fermentation activity: The natural reducing sugars, vitamins and minerals contained in the appropriate concentration of sweet bamboo shoot juice can serve as nutrients for lactic acid bacteria, promoting bacterial growth and reproduction.

[0021] Highly controllable and harmonious flavor: The flavor profile of the product can be precisely adjusted by regulating the ratio of sweet bamboo shoot juice to water: the aroma of sweet bamboo shoots, milky aroma and fermented aroma are balanced and blended, resulting in a mellow and harmonious flavor that not only has the product's distinctive features but also meets consumers' acceptance of the flavor of traditional yogurt.

[0022] High process compatibility: This invention is highly compatible with existing industrial production lines for coagulated yogurt. No new special equipment is required. Product innovation can be achieved simply by replacing raw materials, making it easy to scale up and promote. Attached Figure Description

[0023] Figure 1 The photos show the finished fermented milk products. The top row is a top-down view, and the bottom row is a test photo. From left to right, the photos show the blank control group, the sweet bamboo shoot granule group, and the sweet bamboo shoot juice reconstituted group. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the spirit of the contents disclosed in the present invention will be described in detail below. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0025] The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0026] Example 1: Sweet bamboo shoot flavored fermented milk with a sweet bamboo shoot feed-to-water ratio of 1:3

[0027] The preparation steps are as follows:

[0028] 1. Preparation of sweet bamboo shoot juice: Fresh sweet bamboo shoots are selected, washed, peeled and cut. Water is added at a mass ratio of sweet bamboo shoots to water of 1:3. After constant temperature extraction, the juice is filtered through four layers of gauze to obtain clear sweet bamboo shoot juice.

[0029] 2. Base material preparation: Replace all the water with the above-mentioned sweet bamboo shoot juice, add whole milk powder and 7% sucrose, dissolve and mix thoroughly to prepare the fermentation base material;

[0030] 3. Sterilization and cooling: Sterilize with high-pressure steam at 115℃ for 15 minutes, and then cool to 33℃ after sterilization;

[0031] 4. Inoculation and fermentation: Inoculate with 2% (v / v) of compound fermentation agent, mix well, dispense into containers, and incubate at a constant temperature of 33°C until the titratable acidity reaches approximately 96°T.

[0032] 5. Post-cold ripening: After refrigeration at 4℃ for 12 hours, the finished product is obtained.

[0033] The product test results in this embodiment are as follows: pH value 4.35, titratable acidity 96.00°T, and viable lactic acid bacteria count 8.7 × 10⁻⁶. 8 CFU / mL; The characteristic aroma of sweet bamboo shoots is prominent, accompanied by fermented sour and milky aromas, with a relatively strong bamboo shoot fragrance.

[0034] The flavored fermented milk process of this embodiment was examined:

[0035] 2.1 Determination of Basic Fermentation Process for Yogurt

[0036] Basic formula for reconstituted milk: Reconstituted milk is prepared using whole milk powder per 100 mL of system, with 7% sucrose added as a fermentation carbon source to provide sufficient fermentable sugar for lactic acid bacteria and ensure normal growth and metabolism of bacteria; sweet bamboo shoot juice is used to completely replace water for preparation, and the amount of other raw materials is controlled to be consistent to ensure a single variable in the experiment.

[0037] Preparation of sweet bamboo shoot juice: Fresh sweet bamboo shoots are selected, cleaned, peeled, and cut. They are then soaked in water at five ratios: sweet bamboo shoot: water = 1:1, 1:3, 1:5, 1:7, and 1:10. The soaking temperature and time are controlled. After constant temperature soaking, the mixture is filtered through gauze or filter paper to remove residue and obtain clear sweet bamboo shoot juice for later use. This ensures that the difference in concentration of each group of sweet bamboo shoot juice is determined only by the ratio.

[0038] Sterilization process: A high-pressure steam sterilizer is used, and the temperature is set at 115 ℃ for 15 minutes to effectively kill the bacteria in the system. At the same time, it avoids excessive damage to the flavor and nutrients of the sweet bamboo shoot juice caused by long-term high-temperature treatment, and provides a safe and stable environment for subsequent fermentation.

[0039] Microbial strains and inoculum size: Commercial compound starter culture (Streptococcus thermophilus + Lactobacillus bulgaricus) was used, with a total inoculum size of 2%. The two strains worked synergistically to ensure normal curdling, acid production and flavor formation of the yogurt. A uniform inoculum size was used to eliminate the influence of microbial strains on the experimental results.

[0040] Fermentation conditions: constant temperature fermentation at 33 ℃, with the fermentation endpoint defined as the system pH and titratable acidity reaching the standard for yogurt; after fermentation, the system is refrigerated at 4 ℃ for post-fermentation maturation.

[0041] 2.2 Experimental group setup

[0042] This experiment consisted of 5 experimental groups, with the single variable being the ratio of bamboo shoots to water: bamboo shoots to water of 1:1, 1:3, 1:5, 1:7, and 1:10. Each group had 3 batches, with 3 parallel samples per batch to minimize systematic and random errors.

[0043] 2.3 Completed Experimental Content

[0044] 2.3.1. Raw material pretreatment: Complete the selection, cleaning, cutting, soaking and filtering of sweet bamboo shoots to prepare five groups of sweet bamboo shoot juices with different concentrations; complete the weighing of raw materials such as milk powder and sucrose and the preparation of reconstituted milk.

[0045] 2.3.2. Sterilization and fermentation: All samples were sterilized, cooled, inoculated, fermented at constant temperature, and then refrigerated for post-ripening in strict accordance with the established process, and the experimental conditions were kept consistent throughout the process.

[0046] 2.3.3. Index determination: pH value, titratable acidity, and viable lactic acid bacteria count (pour plate method) were measured for all experimental group samples; volatile flavor fingerprint detection was performed using the PEN3 electronic nose.

[0047] 3. Data Processing and Result Analysis

[0048] 3.1 Data Preparation

[0049] This experiment consisted of 5 groups of samples, with 3 parallel samples in each group. The average value was taken as the final analysis data. The results of pH value, titration acidity and viable lactic acid bacteria count for each group are shown in Table 1 below.

[0050] Table 1. Effects of different proportions of sweet bamboo shoots on yogurt fermentation

[0051]

[0052] 3.2 Data Analysis

[0053] 3.2.1 pH value index analysis

[0054] The pH values ​​of the five groups of samples differed significantly. The pH value of the group with a ratio of 1:1 (bamboo shoot:water) reached 5.76, which was much higher than the other four groups. The pH values ​​of the four groups with ratios of 1:3, 1:5, 1:7, and 1:10 (bamboo shoot:water) were concentrated between 4.28 and 4.35, with little fluctuation between the groups.

[0055] At a 1:1 ratio of sweet bamboo shoot to water, the concentrations of solids and soluble substances from the sweet bamboo shoot were highest, leading to a sharp increase in the system's osmotic pressure. Simultaneously, the high dietary fiber content altered the milk matrix structure, significantly stressing the lactic acid bacteria, resulting in a substantial decrease in bacterial metabolic activity, insufficient lactic acid production, and a final product with a high pH, ​​failing to meet the standards for qualified yogurt. Increasing the sweet bamboo shoot dilution ratio (1:3-1:10) reduced the system's osmotic pressure to the optimal range for lactic acid bacteria growth, allowing for normal bacterial reproduction and acid production. The pH of each group stabilized within the normal range for fermented milk, indicating a good fermentation process.

[0056] 3.2.2 Analysis of Titration Acidity Index

[0057] Titration acidity and pH value showed a typical negative correlation. The group with beetroot:water = 1:1 had the lowest acidity, at only 64.00 °T; the group with beetroot:water = 1:3 had the highest acidity, at 96.00 °T; as the dilution ratio of beetroot continued to increase (1:5→1:7→1:10), the titration acidity showed a slow decreasing trend.

[0058] The natural reducing sugars in the sweet bamboo shoot juice can serve as a supplementary carbon source for lactic acid bacteria. Within a suitable concentration range, the higher the proportion of sweet bamboo shoots, the more abundant the carbon source supply, and the stronger the acid production capacity of the bacteria. Therefore, the acid production reaches its peak in the 1:3 group. When the ratio of sweet bamboo shoots to 1:1, the high osmotic pressure inhibits the growth of lactic acid bacteria, the acid production capacity decreases significantly, and the acidity is at its lowest. In the 1:5, 1:7, and 1:10 groups, the sweet bamboo shoot content gradually decreases, the exogenous carbon source decreases, and the lactic acid bacteria mainly utilize lactose in the milk for metabolism, resulting in a gradual decrease in acid production, and the overall fermentation state remains stable.

[0059] 3.2.3 Analysis of viable lactic acid bacteria count

[0060] The trend of viable bacterial count was positively correlated with titratable acidity and negatively correlated with pH value. The group with a beetroot:water ratio of 1:1 had the lowest viable bacterial count, at only 1.2 × 10⁻⁶. 8 CFU / mL; the highest viable bacterial count was observed in the group with a ratio of beetroot:water = 1:3, reaching 8.7 × 10⁻³. 8 CFU / mL; The viable bacterial count in the 1:5, 1:7, and 1:10 groups showed a slow decreasing trend as the proportion of sweet bamboo shoots decreased, which was completely consistent with the acid production pattern.

[0061] The natural reducing sugars, vitamins, and minerals in bamboo shoot juice can serve as supplementary nutrients for lactic acid bacteria. Within a suitable concentration range (1:3~1:10), the higher the concentration of bamboo shoot juice, the better the nutritional conditions for bacterial growth and reproduction, resulting in a higher viable bacteria count. When the concentration of bamboo shoot juice is too high (1:1), the high osmotic pressure and dietary fiber stress the bacteria, inhibiting their growth and significantly reducing the viable bacteria count. The viable bacteria count in the 1:5~1:10 groups remained at 6.5×10⁻⁶. 8 The CFU / mL level is above 1, which meets the national standard requirements for the number of live bacteria in fermented milk.

[0062] 3.2.4 Electronic nose flavor detection and analysis

[0063] This experiment used a PEN3 electronic nose to perform three parallel tests on five groups of yogurt samples. The obtained radar spectral data showed good consistency and significant flavor profile differentiation. The specific analysis is as follows:

[0064] 3.2.4.1. Sensor Response Characteristics

[0065] Three sets of parallel spectra show that sn_1, sn_5, sn_6, sn_14, and sn_18 are the main response sensors, corresponding to alcohols, aldehydes, ketones, terpenes, and oxygen-containing compounds. These substances are the core components constituting the complex flavor of yogurt. The response values ​​of samples with different proportions differed significantly on these sensors, indicating that the proportion of sweet bamboo shoot juice added has a decisive influence on the composition of volatile substances in yogurt.

[0066] 3.2.4.2. Flavor differences among samples with different formulation ratios

[0067] - Sweet bamboo shoot:water = 1:3 group: The concentration of sweet bamboo shoot is relatively high, and the sensor response value is second only to the 1:1 group. The characteristic aroma of sweet bamboo shoot is still relatively prominent, but the sour aroma and milky aroma produced by fermentation begin to appear. The flavor profile presents the dual characteristics of "bamboo shoot aroma + milky aroma", and the sense of layering is better than the 1:1 group.

[0068] - Sweet bamboo shoots:water = 1:5 group: The sensor response value is moderate, and the response values ​​of sn_1, sn_5, sn_14, and sn_18 are balanced. The aroma of sweet bamboo shoots, milky aroma and fermentation aroma are integrated with each other. The flavor profile is round and harmonious, without any single aroma being too strong or too weak. The overall flavor is highly acceptable.

[0069] - Sweet bamboo shoot: water = 1:7 group: The sensor response value is slightly lower than that of the 1:5 group. The proportion of response values ​​of the milk aroma and fermentation aroma corresponding to sn_5 and sn_6 is increased. The sweet bamboo shoot aroma exists as an auxiliary aroma. The flavor is "milky aroma as the main flavor and bamboo shoot aroma as the auxiliary flavor". The coordination is close to that of the 1:5 group, and the overall flavor is closer to the traditional yogurt flavor.

[0070] - Sweet bamboo shoot:water = 1:10 group: The concentration of sweet bamboo shoot is the lowest, the radar curve shrinks inward as a whole, the sensor response values ​​of sn_1, sn_14, and sn_18 are significantly reduced, the aroma of milk and fermentation become the dominant flavor, with only a faint sweet bamboo shoot fragrance. The flavor profile is highly similar to that of plain yogurt, and the distinctiveness is weak.

[0071] 3.2.4.3. Repeatability analysis of parallel samples

[0072] The radar spectrum curves of the three parallel detections showed high overlap, and the sensor response values ​​of the same sample ratio fluctuated little, indicating that the electronic nose detection results had good repeatability and the data were reliable. The flavor profile differences of the samples with different ratios remained consistent in all three experiments, further confirming that the proportion of sweet bamboo shoot juice added is a key factor in regulating the flavor of the compound yogurt.

[0073] 3.3 Preliminary Conclusions

[0074] 3.3.1. The 1:1 ratio of sweet bamboo shoots to water is too high, resulting in a high content of sweet bamboo shoot solids and a high osmotic pressure, which severely inhibits the growth and metabolism of lactic acid bacteria. This formulation has a high pH, ​​insufficient titratable acidity, and a low number of viable lactic acid bacteria. Furthermore, the grassy aroma of sweet bamboo shoots is too strong and poorly coordinated with the milky and fermented aromas of yogurt, making it impossible to form yogurt with satisfactory texture and flavor. Therefore, this ratio is not suitable for the production of compound yogurt.

[0075] 3.3.2. The ratio of sweet bamboo shoots to water (1:3) showed the most vigorous lactic acid bacteria metabolism, with both the number of live bacteria and the amount of acid produced reaching their peak, indicating the deepest fermentation process. However, the aroma of sweet bamboo shoots in this group was still too prominent, which to some extent masked the flavor of the yogurt itself, resulting in a relatively simple overall flavor and a lack of richness in texture.

[0076] 3.3.3. The ratios of sweet bamboo shoot to water (1:5, 1:7, and 1:10) showed stable fermentation, with physicochemical indicators and viable cell counts meeting the national standard requirements for fermented milk. Among them, the 1:5 and 1:7 ratios had sufficient viable cell counts and excellent physicochemical indicators, with a harmonious blend of sweet bamboo shoot aroma, milky aroma, and fermented aroma, resulting in the highest flavor acceptance and representing the optimal ratio for overall quality. The 1:10 ratio met the physicochemical and microbiological indicators and had a flavor closest to traditional original flavor yogurt, but the distinctive characteristics of sweet bamboo shoot were weaker, resulting in insufficient product recognition.

[0077] 4. Considering the fermentation characteristics, physicochemical quality, viable cell count, and electronic nose flavor performance of each group, the samples in the range of 1:5 to 1:7 of sweet bamboo shoot:water showed the best performance in terms of fermentation stability, quality, and flavor harmony. This range can be identified as the core ratio range for subsequent optimization experiments, providing a clear direction for further refining the gradient and optimizing the formula.

[0078] Comparative Example 1: Blank Control Group (Pure Fermented Milk)

[0079] Pure milk coagulated fermented milk was prepared by replacing the sweet bamboo shoot juice with purified water, while keeping the rest of the formula and process the same as in Example 1.

[0080] Comparative Example 2: Sweet Bamboo Shoot Granules

[0081] Sweet bamboo shoot particles were added directly to pure cow's milk reconstituted milk, and the rest of the process was the same as in Example 1.

[0082] Comparative Example 3: Fermented milk with a sweet bamboo shoot feed-to-water ratio of 1:1

[0083] The preparation method is the same as in Example 1, except that the mass ratio of sweet bamboo shoots to water is adjusted to 1:1.

[0084] Table 2 Sensory Evaluation

[0085]

[0086] Table 3. Determination of hardness, viscosity, chewiness, cohesiveness, and stickiness.

[0087]

[0088] As shown in Tables 2 and 3, Comparative Example 1 has a rich frankincense aroma, a smooth and delicate texture, a sensory score of 82.25±2.63, a hardness of 37.03±0.43g, and a viscosity of 694.04±26.37g·s.

[0089] Comparative Example 2: The finished product had severe whey separation, an uneven and non-uniform structure, a sensory score of 73.67±3.86, a hardness of 26.16±4.73g, and a viscosity of 572.75±16.32g·s, indicating that the curd structure was significantly damaged.

[0090] Comparative Example 3: Finished product test results: pH value 5.76, titratable acidity 64.00°T, viable lactic acid bacteria count 1.2 × 10⁻⁶. 8 The concentration of CFU / mL indicates insufficient fermentation, failing to meet the standards for qualified yogurt; furthermore, the aroma of sweet bamboo shoots and grass is too strong, masking the milky aroma and resulting in poor flavor harmony.

[0091] The addition of cantaloupe particles reduces the firmness, viscosity, chewiness, cohesiveness, and stickiness of yogurt. For example, it makes it difficult to form a good set-type yogurt. Reconstituted milk made with cantaloupe juice can significantly mitigate the effects of the added cantaloupe particles. However, to achieve indistinguishability from cow's milk, the dry matter content needs to be increased.

[0092] Compared to the sweet bamboo shoot granule group, the sweet bamboo shoot juice reconstituted group had better texture, no whey separation, better acceptability, and a distinct aroma.

[0093] like Figure 1 As shown, Figure 1 From left to right are the blank control group, the sweet bamboo shoot granule group, and the sweet bamboo shoot juice reconstituted group, respectively.

[0094] The blank control group and the sweet bamboo shoot juice reconstituted group showed no difference when viewed from the side, exhibiting a smooth and uniform appearance; the sweet bamboo shoot granule group showed severe whey separation, with an uneven and non-uniform structure.

[0095] Top view: The blank control group was smooth and delicate, while the sweet bamboo shoot granule group showed obvious whey separation and unevenness. Although the sweet bamboo shoot juice reconstituted group showed no whey separation, its surface was uneven.

Claims

1. A sweet bamboo shoot flavored coagulated fermented milk, characterized in that, The sweet bamboo shoot flavored coagulated fermented milk is made by fermenting a fermentation base with lactic acid bacteria starter culture. The fermentation base is prepared by completely replacing the water used in reconstituted milk preparation with sweet bamboo shoot extract, and then mixing it with whole milk powder and sucrose. The sweet bamboo shoot extract is obtained by constant-temperature extraction and filtration of fresh sweet bamboo shoots and water at a mass ratio of 1:(3-10). The amount of sucrose added is 7% of the mass of the fermentation base. The finished fermented milk has a pH of 4.28-4.35, a titratable acidity of 89-96°T, and a live lactic acid bacteria count ≥6.5×10⁻⁶. 8 CFU / mL.

2. The sweet bamboo shoot flavored coagulated fermented milk according to claim 1, characterized in that, The mass ratio of the sweet bamboo shoots to water is 1:(5-7).

3. The sweet bamboo shoot flavored coagulated fermented milk according to claim 1, characterized in that, The lactic acid bacteria starter is a compound starter of Streptococcus thermophilus and Lactobacillus bulgaricus, and the total inoculum amount is 2% of the fermentation substrate volume.

4. A method for preparing the sweet bamboo shoot flavored coagulated fermented milk according to any one of claims 1 to 3, characterized in that, The method is as follows: (1) Preparation of sweet bamboo shoot extract: Select fresh sweet bamboo shoots, wash, peel and cut them, add water at a mass ratio of sweet bamboo shoots to water of 1:(3~10) and extract at a constant temperature. Filter to remove residue to obtain clear sweet bamboo shoot extract. (2) Preparation of fermentation base: Add whole milk powder and sucrose to the sweet bamboo shoot extract, dissolve and mix thoroughly to obtain the fermentation base; (3) Sterilization and cooling: Sterilize the fermentation substrate under high pressure steam, and then cool it to the inoculation temperature; (4) Inoculation and fermentation: Add 2% by volume of compound lactic acid bacteria starter to the cooled fermentation substrate, mix well, and then let it stand at a constant temperature of 30~35℃ for fermentation until the pH and titratable acidity of the system reach the standard, which is the end point of fermentation. (5) Cold refrigeration and ripening: After fermentation, the product is refrigerated at 4℃ to obtain the finished product.

5. The preparation method according to claim 1, characterized in that, In step (1), filtration is performed using gauze or filter paper.

6. The preparation method according to claim 1, characterized in that, The mass ratio of sweet bamboo shoots to water in step (1) is 1:(5-7).

7. The preparation method according to claim 1, characterized in that, The criteria for determining the fermentation endpoint in step (4) are: titration acidity of the system ≥ 89°T, pH value ≤ 4.35.

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