阅读说明：本技术 一种益生菌阿胶低肽复合乳饮料及其制备方法 (Probiotic donkey-hide gelatin low-peptide compound milk beverage and preparation method thereof ) 是由 秦楠 张朔生 缪文玉 王小敏 郭丽丽 于 2020-07-20 设计创作，主要内容包括：本发明公开了一种益生菌阿胶低肽复合乳饮料及其制备方法,复合乳饮料是通过将阿胶低肽粉、双歧杆菌、保加利亚乳杆菌、嗜热链球菌进行混合发酵制备得到的,制备方法包括以下步骤：S1：阿胶低肽粉的制备；S2：复合发酵液的制备；S3：阿胶低肽复合乳饮料的制备；S4：单因素试验；S5：响应面试验；S6：正交优化稳定性试验；S7：对阿胶低肽复合乳饮料稳定性进行评价。本发明通过红枣与黑枸杞汁经过乳酸菌发酵后,游离酚酸、多糖、黄酮类活性成分被充分释放,酯类、酸类及芳香杂环类挥发性风味物质的含量提高,结合阿胶肽粉的高消化吸收率,提供营养价值。(The invention discloses a probiotic donkey-hide gelatin low-peptide composite milk beverage and a preparation method thereof, the composite milk beverage is prepared by mixing and fermenting donkey-hide gelatin low-peptide powder, bifidobacterium, lactobacillus bulgaricus and streptococcus thermophilus, and the preparation method comprises the following steps: s1: preparing donkey-hide gelatin low-peptide powder; s2: preparing composite fermentation liquor; s3: preparing a donkey-hide gelatin low-peptide compound milk beverage; s4: single factor test; s5: testing a response surface; s6: performing orthogonal optimization stability test; s7: and evaluating the stability of the donkey-hide gelatin low-peptide compound milk beverage. According to the invention, after the red dates and the lycium ruthenicum juice are fermented by lactic acid bacteria, free phenolic acid, polysaccharide and flavonoid active ingredients are fully released, the content of esters, acids and aromatic heterocyclic volatile flavor substances is increased, and the high digestibility of the donkey-hide gelatin peptide powder is combined, so that the nutritional value is provided.)

1. The probiotic donkey-hide gelatin low-peptide compound milk beverage is characterized in that: the probiotic donkey-hide gelatin low-peptide composite milk beverage is prepared by mixing and fermenting donkey-hide gelatin low-peptide powder, Bifidobacterium (Bifidobacterium), lactobacillus bulgaricus (lactobacillus bulgaricus) and Streptococcus thermophilus (Streptococcus thermophilus).

2. A preparation method of a probiotic donkey-hide gelatin low-peptide compound milk beverage is characterized by comprising the following steps: the method comprises the following steps:

s1: the preparation method of the donkey-hide gelatin low-peptide powder comprises the following specific steps:

1) the donkey-hide gelatin powder is subjected to enzymolysis by ultrasonic-assisted pepsin and trypsin, and the enzymolysis conditions are as follows: adding pepsin 0.02g, adjusting temperature at 45 deg.C, pH2.0, and time for 2.5h, adding trypsin 0.05g, adjusting temperature at 42 deg.C, pH 8.0, and time for 3.5 h;

2) inactivating enzyme of the enzymolysis liquid at 100 deg.C for 10 min;

3) placing in a rotary evaporator, and concentrating at 55 deg.C to 30% of original volume;

4) freeze drying to obtain colla Corii Asini low peptide powder;

s2: the preparation of the composite fermentation liquor comprises the following specific steps:

1) adding water to 100mL of milk, jujube juice and lycium ruthenicum juice at a volume ratio of 40: 20: 10, and adding donkey-hide gelatin oligopeptide powder according to 5g/100 mL;

2) fermenting the mixed solution by using bifidobacterium and traditional lactic acid bacteria as fermentation strains, wherein the inoculation amount is 3%, the addition amount of sucrose is 2g/100mL, the fermentation temperature is 37 ℃, and the fermentation time is 6 hours;

s3: the preparation method of the donkey-hide gelatin low-peptide compound milk beverage comprises the following specific steps:

1) stirring the composite fermentation liquor by using a high-speed stirrer to demulsify for 10 minutes;

2) adding xylitol, citric acid and compound essence, blending, adding stabilizer, and sterilizing at 85 deg.C for 15 min;

3) cooling to obtain colla Corii Asini low peptide compound milk beverage;

s4: the single factor test comprises the following specific steps:

sensory evaluation is an evaluation index, the influence of the addition amounts of the xylitol, the citric acid, the honey and the compound essence on the sensory quality of the compound milk beverage is respectively considered, and a single-factor test is carried out;

s5: the response surface test comprises the following specific steps:

based on a single-factor test result, selecting three variables of the addition amounts of xylitol, citric acid and composite essence, expressing the three variables by A, B, C, respectively expressing the levels of the variables by +1, 0 and-1, and coding independent variables according to an equation X ═ X-X0)/DeltaX, wherein X expresses the coding value of the variables, X expresses the real value of the variables, X0 expresses the real value of the variables at the central point of the test, DeltaX expresses the step change of the variables, and sensory score Y expresses a response value;

s6: the orthogonal optimization stability test comprises the following specific steps:

according to the single-factor test result, sensory score is used as an evaluation index, the guar gum addition amount, the xanthan gum addition amount and the sucrose ester addition amount are selected as main factors, and the L9 orthogonal test design is adopted to optimize the levels of all factors;

s7: the method for evaluating the stability of the donkey-hide gelatin low-peptide compound milk beverage comprises the following specific steps:

dissolving the stabilizer in hot water, mixing with the composite milk beverage at a certain ratio, standing for 24 hr, observing stability, and evaluating the precipitation, whey precipitation, fat floating, etc. of the composite milk beverage.

3. The preparation method of the probiotic donkey-hide gelatin low-peptide compound milk beverage according to claim 2, characterized by comprising the following steps: the enzyme adding ratio of the bifidobacteria to the traditional lactic acid bacteria in the step S2 is 1: 1.

4. The preparation method of the probiotic donkey-hide gelatin low-peptide compound milk beverage according to claim 2, characterized by comprising the following steps: in the step S4, xylitol is respectively 1g, 2g, 3g, 4g, 5g and 6g, citric acid is respectively 0.05g, 0.1g, 0.15g, 0.20g, 0.25g and 0.30g, honey is respectively 2g, 4g, 6g, 8g, 10g and 12g, and composite essence is respectively 0.02g, 0.04g, 0.06g, 0.08g, 0.10g and 0.12 g.

5. The preparation method of the probiotic donkey-hide gelatin low-peptide compound milk beverage according to claim 2, characterized by comprising the following steps: the regression equation of the sensory score in the step S5 on the addition amount of the independent variable xylitol, the addition amount of the citric acid and the addition amount of the composite essence is as follows:

Y＝93-1.5A-0.25B-2.5C+1.5AB-3.0AC+4.5BC-5.25A2-8.75B2-7.25C2。

Technical Field

The invention relates to the technical field of donkey-hide gelatin peptide powder, in particular to a probiotic donkey-hide gelatin low-peptide compound milk beverage and a preparation method thereof.

Background

The colla Corii Asini is solid block made from fresh or dried skin of Equus asinus of Equidae, and belongs to medicine and food homology. It is rich in various effective components such as gelatin, protein, trace elements, lysine, etc., and has effects of enhancing immunity, relieving fatigue, resisting radiation, resisting tumor, and promoting hematopoiesis.

The red date is rich in sugar, flavonoid substances, protein, calcium, various vitamins and other components, has various health care food therapy functions of soothing nerves, strengthening spleen, tonifying kidney, relieving cough, reducing blood pressure and the like, and is always regarded as an excellent tonic by people. In the prior art, the lactobacillus fermented red date juice is found that the content of free phenolic acid is obviously improved and stronger antioxidant activity is shown.

The Lycium ruthenicum Murr is dry fruit of Lycium ruthenicum Murr of Lycium of Solanaceae, contains abundant anthocyanin, amino acids and microelements, and has effects of improving immunity, resisting oxidation, nourishing liver, improving eyesight, invigorating stomach, nourishing brain, resisting aging and dredging channels. In the prior art, two substances of total flavone and polysaccharide are respectively extracted from lycium ruthenicum, and researches show that the antioxidant activity and the immunological activity are remarkably improved. The research result of fermenting the pickled Chinese wolfberry by utilizing the lactic acid bacteria shows that the lycium barbarum polysaccharide can provide a carbon source for the lactic acid bacteria, and the acid production speed and the acid production capacity are improved.

The compound milk beverage in the prior art is low in digestibility, lacks of utilization and processing technology of donkey-hide gelatin peptide powder, and does not relate to the compound milk beverage combining donkey-hide gelatin, red dates and medlar.

Disclosure of Invention

The invention aims to provide a probiotic donkey-hide gelatin low-peptide compound milk beverage and a preparation method thereof.

In order to achieve the purpose, the invention provides the following technical scheme: the probiotic donkey-hide gelatin low-peptide compound milk beverage is prepared by mixing and fermenting donkey-hide gelatin low-peptide powder, Bifidobacterium (Bifidobacterium), Lactobacillus bulgaricus (Lactobacillus bulgaricus) and Streptococcus thermophilus (Streptococcus thermophilus).

The invention also provides a preparation method of the probiotic donkey-hide gelatin low-peptide compound milk beverage, which comprises the following steps:

s1: the preparation method of the donkey-hide gelatin low-peptide powder comprises the following specific steps:

1) the donkey-hide gelatin powder is subjected to enzymolysis by ultrasonic-assisted pepsin and trypsin, and the enzymolysis conditions are as follows: adding pepsin 0.02g, adjusting temperature at 45 deg.C, pH2.0, and time for 2.5h, adding trypsin 0.05g, adjusting temperature at 42 deg.C, pH 8.0, and time for 3.5 h;

2) inactivating enzyme of the enzymolysis liquid at 100 deg.C for 10 min;

3) placing in a rotary evaporator, and concentrating at 55 deg.C to 30% of original volume;

4) freeze drying to obtain colla Corii Asini low peptide powder;

s2: the preparation of the composite fermentation liquor comprises the following specific steps:

1) adding water to 100mL of milk, jujube juice and lycium ruthenicum juice at a volume ratio of 40: 20: 10, and adding donkey-hide gelatin oligopeptide powder according to 5g/100 mL;

2) fermenting the mixed solution by using bifidobacterium and traditional lactic acid bacteria as fermentation strains, wherein the inoculation amount is 3%, the addition amount of sucrose is 2g/100mL, the fermentation temperature is 37 ℃, and the fermentation time is 6 hours;

s3: the preparation method of the donkey-hide gelatin low-peptide compound milk beverage comprises the following specific steps:

1) stirring the composite fermentation liquor by using a high-speed stirrer to demulsify for 10 minutes;

2) adding xylitol, citric acid and compound essence, blending, adding stabilizer, and sterilizing at 85 deg.C for 15 min;

3) cooling to obtain colla Corii Asini low peptide compound milk beverage;

s4: the single factor test comprises the following specific steps:

sensory evaluation is an evaluation index, the influence of the addition amounts of the xylitol, the citric acid, the honey and the compound essence on the sensory quality of the compound milk beverage is respectively considered, and a single-factor test is carried out;

s5: the response surface test comprises the following specific steps:

based on the result of the single-factor test, selecting three variables of the addition amounts of the xylitol, the citric acid and the compound essence, expressing the three variables as A, B, C, respectively representing the levels of the variables as +1, 0 and-1, and obtaining the formula of (X-X) according to the equation₀) The/Δ X encodes the argument, where X represents the encoded value of the variable, X represents the true value of the variable, and X₀The actual value of the variable at the center of the trial point is indicated, Δ X the step change of the variable, and sensory score Y the response value.

S6: the orthogonal optimization stability test comprises the following specific steps:

according to the result of the single-factor test, sensory score is used as an evaluation index, the addition amount of guar gum, the addition amount of xanthan gum and the addition amount of sucrose ester are selected as main factors, and L is adopted₉Orthogonal test design, optimizing each factor level;

s7: the method for evaluating the stability of the donkey-hide gelatin low-peptide compound milk beverage comprises the following specific steps:

dissolving the stabilizer in hot water, mixing with the composite milk beverage at a certain ratio, standing for 24 hr, observing stability, and evaluating the precipitation, whey precipitation, fat floating, etc. of the composite milk beverage.

Preferably, the ratio of the bifidobacteria to the conventional lactic acid bacteria in step S2 is 1: 1.

Preferably, in step S4, xylitol is 1g, 2g, 3g, 4g, 5g, and 6g, citric acid is 0.05g, 0.1g, 0.15g, 0.20g, 0.25g, and 0.30g, honey is 2g, 4g, 6g, 8g, 10g, and 12g, and compound essence is 0.02g, 0.04g, 0.06g, 0.08g, 0.10g, and 0.12g, respectively.

Preferably, the regression equation of the sensory score in step S5 for the independent variables xylitol addition, citric acid addition and compound essence addition is as follows:

Y＝93-1.5A-0.25B-2.5C+1.5AB-3.0AC+4.5BC-5.25A²-8.75B²-7.25C²。

compared with the prior art, the invention has the beneficial effects that: the invention strictly controls a preparation method of a probiotic donkey-hide gelatin low-peptide compound milk beverage, and determines the optimal formula of the probiotic fermented compound milk beverage through single factor and response surface tests on the basis that the volume ratio of milk, red date juice and black wolfberry liquid is 40: 20: 10(mL) and donkey-hide gelatin low-peptide powder is added by screening probiotics and reasonably matching the probiotics and the donkey-hide gelatin low-peptide powder: 2g/100mL of xylitol, 0.15g/100mL of citric acid, 0.08g/100mL of composite essence and 8g/mL of honey, wherein the stability is one of main factors influencing production, and the phenomena of layering, precipitation and the like can be effectively prevented by adding a compound stabilizer on the basis of optimal raw material ratio. The finished product has unique flavor, proper sour and sweet taste, good taste and good stability.

The product is fermented by lactic acid bacteria, so that the content of free acid phenol and flavonoid in the red dates can be obviously improved, the red dates have strong antioxidant activity, and the black wolfberry polysaccharide is combined with the antioxidant activity and the immunity enhancing activity.

Drawings

FIG. 1 is a graph showing the effect of xylitol addition on sensory quality according to the present invention;

FIG. 2 is a graph showing the effect of citric acid addition on sensory quality according to the present invention;

FIG. 3 is a graph showing the effect of the amount of honey added on sensory quality according to the present invention;

FIG. 4 is a graph showing the effect of the amount of the compound flavor added on sensory quality;

FIG. 5 is a response surface and contour plot of the effect of xylitol and citric acid cross-interaction on sensory score of a composite milk beverage in accordance with the present invention;

FIG. 6 is a response surface and contour plot of the effect of the cross-interaction of xylitol and compound essence on the sensory score of a compound milk beverage;

FIG. 7 is a response surface and contour plot of the impact of the citric acid and complex flavor cross-interaction on the sensory score of a complex milk beverage of the present invention;

fig. 8 is the change of the viable count of the probiotic compound milk beverage during the storage period of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The probiotic donkey-hide gelatin low-peptide compound milk beverage is prepared by mixing and fermenting donkey-hide gelatin low-peptide powder, Bifidobacterium (Bifidobacterium), Lactobacillus bulgaricus (Lactobacillus bulgaricus) and Streptococcus thermophilus (Streptococcus thermophilus).

The invention also provides a preparation method of the probiotic donkey-hide gelatin low-peptide compound milk beverage, which comprises the following steps:

s1: the preparation method of the donkey-hide gelatin low-peptide powder comprises the following specific steps:

1) the donkey-hide gelatin powder is subjected to enzymolysis by ultrasonic-assisted pepsin and trypsin, and the enzymolysis conditions are as follows: adding pepsin 0.02g, adjusting temperature at 45 deg.C, pH2.0, and time for 2.5h, adding trypsin 0.05g, adjusting temperature at 42 deg.C, pH 8.0, and time for 3.5 h;

2) inactivating enzyme of the enzymolysis liquid at 100 deg.C for 10 min;

3) placing in a rotary evaporator, and concentrating at 55 deg.C to 30% of original volume;

4) freeze drying to obtain colla Corii Asini low peptide powder;

s2: the preparation of the composite fermentation liquor comprises the following specific steps:

1) adding water to 100mL of milk, jujube juice and lycium ruthenicum juice at a volume ratio of 40: 20: 10, and adding donkey-hide gelatin oligopeptide powder according to 5g/100 mL;

2) fermenting the mixed solution by using bifidobacterium and traditional lactic acid bacteria as fermentation strains, wherein the inoculation amount is 3%, the addition amount of sucrose is 2g/100mL, the fermentation temperature is 37 ℃, and the fermentation time is 6 hours;

wherein, the enzyme adding ratio of the bifidobacterium to the traditional lactic acid bacteria in the step S2 is 1: 1.

S3: the preparation method of the donkey-hide gelatin low-peptide compound milk beverage comprises the following specific steps:

1) stirring the composite fermentation liquor by using a high-speed stirrer to demulsify for 10 minutes;

2) adding xylitol, citric acid and compound essence, blending, adding stabilizer, and sterilizing at 85 deg.C for 15 min;

3) cooling to obtain colla Corii Asini low peptide compound milk beverage;

s4: the single factor test comprises the following specific steps:

sensory score is an evaluation index, the influence of the addition amounts of the xylitol, the citric acid, the honey and the compound essence on the sensory quality of the compound milk beverage is respectively considered, a single-factor test is carried out, and the gradient conditions of different factors are shown in table 1.

TABLE 1 Single factor horizontal design Table

As shown in figure 1, the sensory score tends to increase first and then decrease with the addition of xylitol, and the beverage is excessively sweet due to the increase of the sweetness of the xylitol, so that the sour-sweet ratio is gradually inconsistent. Therefore, the amount of xylitol to be added is preferably 4g/100 mL.

As shown in FIG. 2, the sensory score increased and then decreased with the increase of the amount of citric acid added, the beverage was gradually sour, and when the amount of citric acid added was more than 0.15g/100mL, the score tended to decrease, and the peracid probably caused the taste disorder, so that the amount of citric acid added was preferably 0.15g/100 mL.

As shown in figure 3, the sensory score gradually increases and then decreases with the addition of honey, and reaches the highest value when the addition is 8g/100mL, under the condition, the milk beverage is sweet and not greasy, and the taste of honey can cover other flavors and shows a moderate degree of over-high after the honey is continuously added. Therefore, the amount of honey to be added is preferably 8g/100 mL.

As shown in fig. 4, the sensory score tends to increase and decrease with the increase of the added amount of the compound essence, and the fragrance gradually becomes more prominent from light to light, but when the added amount exceeds 0.06g/100mL, the essence has a thick taste and a poor mouthfeel, so that the added amount of the compound essence is preferably 0.06g/100 mL.

S5: the response surface test comprises the following specific steps:

based on the single-factor test result, selecting a design scheme of a center combination test Box-Behnken, selecting three variables of the addition amounts of xylitol, citric acid and composite essence, expressing the three variables as A, B, C, respectively expressing the levels of the variables as +1, 0 and-1, and obtaining the value of the equation X (X-X)₀) The/Δ X encodes the argument, where X represents the encoded value of the variable, X represents the true value of the variable, and X₀The true values of the variables at the center of the trial, Δ X the step change of the variables and sensory score Y the response values, see Table 2.

TABLE 2 response surface test factor level coding

Wherein, the sensory evaluation of the composite milk beverage is carried out according to the standard GB/T21732-2008 ' milk beverage containing ' of the people's republic of China, please 20 professional technicians who have received course training of ' food sensory analysis ', and the sensory evaluation is carried out according to the sensory evaluation standard in the table 3, and the specific evaluation standard is shown in the table 3.

TABLE 3 composite milk beverage sensory Scoring criteria

As shown in Table 4, 12 of the 17 test points are factorial points, 5 are null points, and the factorial point is an independent variable value X₁、X₂、X₃The three-dimensional vertices are formed, and the zero point represents the center point of the region, wherein the zero point test is repeated 5 times for estimating the test error.

TABLE 4 Box-Behnken test design and results

The regression equation of the sensory score (Y) of the donkey-hide gelatin low-peptide composite milk beverage to the independent variable xylitol addition (A), the citric acid addition (B) and the composite essence addition (C) is obtained by performing multiple regression fitting on the table 3 test data by using Design-Expert (version8.0.6) software:

Y＝93-1.5A-0.25B-2.5C+1.5AB-3.0AC+4.5BC-5.25A²-8.75B²-7.25C²

TABLE 5 regression model analysis of variance

As can be seen from the ANOVA table 5, the value of the model F is 25.31, P is less than 0.0001, which shows that the model is very significant, the model mismatching term represents the probability that the predicted value and the actual value of the model are not matched, and the model mismatching term P is 0.5645 which is greater than 0.05, which shows that the model is not significant, the matching probability is high, and the error is small when the model is applied to the test. Correlation coefficient R of the model²0.9702 and adjustment of the model determines the coefficient R² _Adj0.9319, the model can be used for 93.19% interpretation of the test results, further demonstrating the good fit of the regression equation.

The magnitude of the F value in table 5 can be used to determine the magnitude of the effect of each factor on the quality of the probiotic fermented milk drink, and the larger the F value, the greater the degree of the effect of the factor on the sensory evaluation. Therefore, according to the table, the influence degrees of the factors on the sensory evaluation of the composite milk beverage are sequentially the composite essence addition amount (C) > the xylitol addition amount (A) > the citric acid addition amount (B).

And drawing a response surface graph according to the regression equation to confirm the influence of 3 factors of the addition amount of the compound essence, the xylitol and the citric acid on the quality of the compound milk beverage, as shown in figures 5 to 7.

As shown in figure 5, the interaction of the addition amount of xylitol and citric acid on the sensory score of the compound milk beverage is not significant. The sensory score is increased and then decreased along with the gradual increase of the addition amount of the two; as shown in figure 6, the interaction of the addition amount of the xylitol and the compound essence on sensory scores is remarkable (p is less than 0.05); as shown in figure 7, the interaction of the addition amount of the citric acid and the compound essence on the sensory score is very obvious (p is less than 0.01), and the gradient of the response surface is steeper through response surface analysis. The sensory score increases with the increase of the citric acid and the compound essence, the growth trend becomes slower when the citric acid reaches 0.16g and the compound essence reaches 0.07g, and the sensory score begins to show a descending trend.

Through Design-Expert 8.0.6 software analysis, the optimal preparation process conditions are that the addition amount of xylitol is 1.96g, the addition amount of citric acid is 0.166g, the addition amount of composite essence is 0.076g, and the sensory evaluation score under the conditions is 93.5. Considering the convenience of actual operation, the optimum parameters are modified as follows: the addition amount of xylitol is 2g, the addition amount of citric acid is 0.15g, the addition amount of the composite essence is 0.08g, in order to verify the accuracy of model prediction, the test is repeated for 3 times, the obtained average value is very close to the theoretical predicted value, the relative error is less than 2%, no significant difference exists (P is more than 0.05), and the repeatability is good.

S6: the orthogonal optimization stability test comprises the following specific steps:

according to the result of the single-factor test, sensory score is used as an evaluation index, the guar gum addition amount (A), the xanthan gum addition amount (B) and the sucrose ester addition amount (C) are selected as main factors, and L is adopted₉(3³) Orthogonal experiment design, optimizing the levels of all factors, wherein the orthogonal experiment factors and levels are shown in table 6.

TABLE 6 orthogonal test factors and levels for stability of composite milk beverages

TABLE 7 optimization of orthogonal test results for compounding of composite milk beverages

TABLE 8 analysis of variance of orthogonal test results

Note: "+" indicates significant difference in results.

As can be seen from Table 7, the main and secondary sequences of the sensory effects of the factors are C > B > A, namely the stability of the composite milk beverage added with the sucrose ester is most affected, the additive amounts of xanthan gum and guar gum are sequentially added, and the optimal combination is A₁B₂C₃Namely, the addition amount of guar gum is 0.04g/100mL, the addition amount of xanthan gum is 0.08g/100mL, and the addition amount of sucrose ester is 0.3g/100 mL. Under this optimal condition, the sensory score of the product was 91. As can be seen from Table 8, factor A, B, C had significantly different effects on stability scores (p < 0.05).

S7: the method for evaluating the stability of the donkey-hide gelatin low-peptide compound milk beverage comprises the following specific steps:

the compound milk beverage belongs to a multi-phase system, has complex components, and the stability is a main factor influencing the product. Dissolving the stabilizer in hot water, mixing with the composite milk beverage at a certain ratio, standing for 24 hr, observing stability, evaluating precipitation, whey precipitation, fat floating, etc. of the composite milk beverage, and scoring into 100 points.

TABLE 9 Scoring criteria for stability of composite milk beverages

In addition, the physical, chemical and microbiological indicators were measured:

measuring the contents of flavone and polysaccharide by spectrophotometry by using rutin and glucose as standard substances; kjeldahl method to determine protein content.

And (3) measuring the viable count: the method comprises the steps of detecting the quantity of the lactic acid bacteria in the probiotic compound milk beverage by adopting a lactic acid bacteria culture Medium (MRS) culture medium method in the national standard GB 4789.35-2016 food safety national standard food microbiology inspection lactic acid bacteria inspection, coating and inoculating a sample into the MRS culture medium, culturing at 37 ℃ for 48 hours, and counting.

Determination of coliform group: the method comprises the steps of detecting the number of escherichia coli in the probiotic compound milk beverage by adopting a plate counting method in national standard GB 4789.3-2016 (food safety national standard food microbiology test coliform group count), pouring and inoculating a sample into a crystal violet neutral red bile salt agar (VRBA) culture medium, culturing at 37 ℃ for 48 hours, and counting.

As can be seen from FIG. 6, the total number of viable bacteria in the probiotic compound milk beverage increases greatly and rapidly in 2-4 days along with the increase of the storage time, and gradually decreases along with the increase of the storage time, which may be related to the inhibition of the acidic environment formed by the accumulation of a large amount of metabolites of the bacteria on the bacteria, or the negative increase of the bacteria in the aging and decay periods.

All test data in the test are processed by Origin and Design-Expert (version8.0.6) statistical software, and the least significant difference method (LSD) is used for carrying out significance difference test.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.