Selenium-enriched walnut compound fruit-flavored probiotic solid beverage and preparation method thereof

Abstract

The application discloses a kind of selenium-rich walnut compound fruit-flavored probiotic solid beverage and preparation method thereof, belong to food processing technical field.The preparation method of the application includes the following steps: (1) pretreatment of raw materials;(2) grinding and homogenizing;(3) enzymolysis;(4) inoculation fermentation;(5) quick freezing, vacuum freeze-drying, low-temperature crushing or not, packaging finished product;The application is configured by stabilizer, integrated innovation combination cold sterilization technology, baking pretreatment technology, low-temperature grinding and homogenizing technology, mixed fermentation technology and vacuum freeze-drying technology, avoids the high loss rate of product biological active substance, the layering of infusion, the group of infusion, the poor flavor, the heavy oxidation taste, the poor live bacteria retention, the difficulty of microbial safety control etc., finally obtains fruit-flavored probiotic solid beverage high live bacteria retention, product biological activity is high, flavor is good, taste is moderate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food processing, and particularly relates to a selenium-rich walnut compound fruit-flavored probiotic solid beverage and a preparation method thereof. BACKGROUND

[0002] China is rich in walnut resources, with the largest planting area and total output in the world, and is also the country with the highest walnut consumption in the world. Walnut is a woody oil tree species with high nutritional and economic values, and has a long history of cultivation in China, with a wide distribution, especially in Xinjiang, Yunnan, Sichuan and other regions. Walnut kernel is a nutritious tonic with kidney-nourishing, stomach-tonifying, lung-moistening and brain-nourishing effects, and is known as one of the world's "four major nuts" together with almond, cashew and hazelnut. It contains various nutrients and bioactive components, and has various health benefits.

[0003] Plant-based yogurt has attracted much attention from consumers in recent years due to its advantages such as no cholesterol, suitable for lactose-intolerant patients and vegetarian consumers. The development of lactic acid bacteria fermented drinks using plant-based slurry instead of milk has become a research hotspot. Currently, the raw materials used in plant-based yogurt on the market are mainly soybeans, coconuts and nuts. China is rich in walnut resources, and walnuts have high nutritional value. Therefore, it is expected to realize the dual advantages of walnut nutrition and lactic acid bacteria fermentation by fermenting walnut milk with lactic acid bacteria.

[0004] The product uses selenium-rich walnut kernels from Hotan, Xinjiang as raw materials, and integrates cold sterilization technology, baking pretreatment technology, low-temperature grinding and homogenization technology, mixed fermentation technology and vacuum freeze-drying technology. Not only does it solve the technical problems such as high loss rate of bioactive substances, poor flavor, heavy oxidation, poor retention of live bacteria, and difficulty in microbial safety control, but also gives the product different dosage forms (powder or block), which can be dissolved or eaten directly, laying a good foundation for further large-scale industrial production. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a selenium-rich walnut compound fruit-flavored probiotic solid beverage and a preparation method thereof. By configuring a stabilizer and integrating innovative combination of cold sterilization technology, baking pretreatment technology, low-temperature grinding and homogenization technology, mixed fermentation technology and vacuum freeze-drying technology, the product avoids high loss rate of bioactive substances, poor flavor, heavy oxidation, poor retention of live bacteria, and difficulty in microbial safety control, and the fruit-flavored probiotic solid beverage has high retention of live bacteria, high bioactivity of the product, good flavor and moderate taste.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect of the present application, a preparation method of a selenium-rich walnut compound fruit-flavored probiotic solid beverage is provided, comprising the following steps:

[0008] (1) Pretreatment of raw materials: the selected selenium-rich walnut kernels and auxiliary materials are cold sterilized, and then the walnut kernels are baked; the cold sterilization treatment of the raw and auxiliary materials can not only completely kill the microorganisms carried by the raw and auxiliary materials, but also better preserve the bioactive substances in the raw and auxiliary materials. Meanwhile, baking the walnut kernels can impart a special roasted flavor to them.

[0009] (2) Grinding and homogenization: the baked walnut kernels, auxiliary materials and stabilizers are mixed, ground and subjected to low-temperature homogenization to obtain a mixed emulsion.

[0010] The stabilizer comprises the following raw materials in parts by weight: 5-10 parts of sodium octenyl succinate starch, 4-8 parts of succinic acid monoglyceride, 6-12 parts of konjac powder, 3-5 parts of β-cyclodextrin, 3-10 parts of malt dextrin, 5-8 parts of sucrose fatty acid ester and 1-2 parts of sodium carboxymethyl cellulose;

[0011] (3) Enzymolysis: the mixed emulsion is inoculated with protease and amylase for enzymolysis to obtain an enzymolysis solution. Proper protease enzymolysis treatment can increase the content of free amino acids and small peptides in the walnut milk; proper amylase hydrolysis can reduce the molecular weight of starch and produce an appropriate amount of fermentable sugars; this can not only provide an effective carbon source for lactic acid bacteria fermentation, but also improve the product's stickiness caused by starch in the walnut; at the same time, proper protease and starch hydrolysis can not only avoid the need for additional exogenous carbon and nitrogen sources, but also effectively increase the lactic acid bacteria acid production rate and shorten the fermentation time, thereby increasing the acidity of the walnut fermented milk in a short time.

[0012] (4) Inoculation and fermentation: lactic acid starter is inoculated into the enzymolysis solution for primary fermentation, and then acid-tolerant Saccharomyces cerevisiae 71B is inoculated for secondary fermentation, and the fermented walnut milk is obtained after the secondary fermentation; the post-fermentation of the acid-tolerant Saccharomyces cerevisiae 71B can not only consume excess fermentable sugars, but also effectively improve the product flavor complexity; the high acidity and fermentable depletion produced by lactic acid bacteria fermentation can effectively improve the biological safety of the product. At the same time, the vacuum freeze-drying under phased temperature control can effectively reduce the energy consumption.

[0013] (5) The fermented walnut milk is injected into a mold, quickly frozen, vacuum freeze-dried, and subjected to low-temperature crushing or not, and then packaged into a finished product. This avoids the loss of heat-sensitive substances caused by thermal effects, and the vacuum freeze-drying also imparts different dosage forms (powder or block) to the product, i.e., the product can be either reconstituted or eaten directly.

[0014] Preferably, the auxiliary materials comprise one or more of apricot, jujube or sea buckthorn.

[0015] Preferably, in step (1), the cold sterilization condition is: the concentration of chlorine dioxide is 60-100 mg / L, and the soaking time is 5-8 min.

[0016] Preferably, in step (2), the roasting condition is: the temperature of the tunnel far-infrared radiation furnace is set to 120-150 ℃, and the sample residence time is 5-8 min by adjusting the conveying belt speed. The far-infrared roasting greatly shortens the roasting time, reduces the loss rate of heat-sensitive substances, and also imparts a special roasted flavor to the product.

[0017] Preferably, in step (2), the weight ratio of walnut kernels, auxiliary materials and stabilizers is 1:(0.5-1):(0.01-0.05).

[0018] Preferably, in step (2), the low-temperature homogenization condition is: 2-5 ℃, 100-150 Mpa, and 3-10 min.

[0019] Preferably, in step (3), the protease is compounded by low-temperature neutral protease and low-temperature flavor enzyme at a weight ratio of 1:(0.5-1), and the amylase is compounded by low-temperature a-amylase and low-temperature glucose amylase at a weight ratio of (0.5-1):1; the enzyme hydrolysis condition is: the protease dosage is 0.05-0.3% of the mass of the mixed emulsion, the amylase dosage is 0.05-0.2% of the mass of the mixed emulsion, the temperature is 45-50 ℃, and the time is 2-4 h.

[0020] Preferably, in step (4), the lactic acid bacteria starter is compounded by Lactobacillus bulgaricus and Streptococcus thermophilus at a weight ratio of 1:(1-1.5); the primary fermentation condition is: the inoculation amount of the lactic acid bacteria starter is 1-4% of the volume of the enzyme hydrolysis liquid, the temperature is 37-45 ℃, and the time is 5-8 h; the secondary fermentation condition is: the inoculation ratio of acid-tolerant Saccharomyces cerevisiae 71B is 2-4% of the volume of the enzyme hydrolysis liquid, the temperature is 28 ℃, and the time is 4 h.

[0021] Preferably, in step (5), the vacuum freeze-drying condition is: the material loading thickness is 1-2.5 cm, the cold trap temperature is -35 to -45 ℃, the hot plate temperature is 85-90 ℃, the vacuum degree is 15-100 Pa, the time is 3-4 h, the hot plate temperature is 65-70 ℃, the vacuum degree is 15-100 Pa, the time is 6-8 h, the hot plate temperature is 45-50 ℃, the vacuum degree is 15-100 Pa, and the time is 9-12 h.

[0022] In the second aspect of the present application, a selenium-rich walnut compound fruit-flavored probiotic solid beverage prepared by the above method is provided.

[0023] The present application has the following beneficial effects:

[0024] (1) The stabilizer used in the selenium-enriched walnut compound fruit-flavored probiotic solid beverage provided by the present application can avoid the problems of oil layering and brewing into a lump during the homogenization and grinding process of the product; the use of enzymatic technology can effectively solve the problem of tooth sticking; the innovative combination of high-tech food processing greatly reduces the loss of biological activity of the product and improves the biological safety of the product. The final selenium-enriched walnut compound fruit-flavored probiotic solid beverage has high live bacteria retention, high biological activity of the product, good flavor, and moderate taste. In addition, the sodium octenyl succinate starch, konjac powder, and succinic acid monoglyceride in the stabilizer have a synergistic effect on the live bacteria retention of the product; cold sterilization, infrared baking, low-temperature homogenization, and controlled-temperature mixed bacteria fermentation technology also have a synergistic effect on reducing the loss of biological activity of the product, improving the high biological safety and sensory quality of the product.

[0025] (2) The selenium-enriched walnut compound fruit-flavored probiotic solid beverage provided by the present application uses selenium-enriched walnuts from Hotan, Xinjiang as raw materials, adopts baking pretreatment to give it a special roasted flavor, optimizes the best formula process of auxiliary materials such as jujube and apricot through response surface experiment, and then performs vacuum freeze-drying after grinding homogenization and mixed bacteria stage probiotic fermentation. The development and preparation of walnut compound fruit-flavored solid beverage not only further extends the walnut deep processing industry chain, but also improves its production added value. It enriches the types of walnut solid beverage, meets the market's diversified demand, provides a new way for the full utilization of walnut resources, ensures the healthy development of walnut economic forests, conforms to the national agricultural industrialization policy and development goals, and is suitable for large-scale industrial production. The product can further realize the comprehensive value of walnut products, thereby improving the utilization rate of walnut resources. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0027] As mentioned earlier, due to the high content of protein and fat in walnuts, problems such as layering, brewing into a lump, severe oxidation, high loss of nutritional components, and unobvious flavor may occur during the preparation of walnut lactic acid bacteria selenium-enriched walnut compound fruit-flavored probiotic solid beverage. The final product has high live bacteria retention, high biological activity of the product, good flavor, and moderate taste.

[0028] Therefore, the application provides a selenium-rich walnut compound fruit-flavored probiotic solid beverage and a preparation method thereof. The application uses sodium starch octenyl succinate, succinic acid monoglyceride, konjac powder, beta-cyclodextrin, malt dextrin, sucrose fatty acid ester and sodium carboxymethyl cellulose as stabilizers. Among them, beta-cyclodextrin, malt dextrin, sucrose fatty acid ester and sodium carboxymethyl cellulose as stabilizers are emulsifiers commonly used in the preparation of fermented milk; sodium starch octenyl succinate is mainly used for preparing emulsified essence and beverage turbidity agent, konjac powder is a hydrophilic macromolecular emulsifier, and succinic acid monoglyceride is an oleophilic small molecule emulsifier, all of which can avoid the stratification of oil and water.

[0029] When configuring the stabilizer, the inventors found through reference that sodium starch octenyl succinate is an excellent stabilizer for a high oil system, so on the basis of the basic components and sodium starch octenyl succinate, distillated monoglyceride, konjac powder, triacylglycerol monostearate, pectin and propylene glycol fatty acid ester are selected as emulsifier components. After multiple tests, it is found that sodium starch octenyl succinate, succinic acid monoglyceride and konjac powder can play a synergistic role in maintaining the number of live bacteria in the product.

[0030] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0031] The test materials used in the embodiments of the application are all conventional test materials in the art and can be purchased through commercial channels. The experimental methods without detailed conditions are carried out according to the conventional test methods or according to the operation instructions recommended by the suppliers.

[0032] In the following examples and comparative examples, the low-temperature neutral protease, low-temperature flavor enzyme and amylase are all purchased from Shanghai Yuan Ye Biotechnology Co., Ltd.; Streptococcus thermophilus is purchased from China Typical Culture Collection Center, with identifier CCTCC AB 2010206; Lactobacillus bulgaricus is purchased from China Typical Culture Collection Center, with identifier CCTCC CB 20082294; acid-tolerant Saccharomyces cerevisiae 71B is from Shanghai Jerabbit Trading Co., Ltd.

[0033] Example 1: Selenium-rich walnut compound fruit-flavored probiotic solid beverage.

[0034] (1) Raw material pretreatment: the selected selenium-rich walnut kernels and auxiliary materials are immersed in 60 mg / L chlorine dioxide solution for 8 min;

[0035] (2) Grinding and homogenization: the walnut kernels are treated in a tunnel type far infrared radiation furnace at 120℃ for 8 minutes, then the roasted walnut kernels are mixed with apricots and stabilizers in a proportion of 1:0.5:0.01 by weight to carry out grinding and homogenization, and a mixed emulsion is obtained; the homogenization conditions are 2℃, 100Mpa, and 5min;

[0036] The stabilizer comprises the following raw materials in parts by weight: 5 parts of sodium octenyl succinate starch, 4 parts of succinic acid monoglyceride, 6 parts of konjac powder, 3 parts of β-cyclodextrin, 3 parts of malt dextrin, 5 parts of sucrose fatty acid ester, and 1 part of sodium carboxymethyl cellulose;

[0037] (3) Enzymatic hydrolysis: the protease is compounded from low-temperature neutral protease and low-temperature flavor enzyme in a proportion of 1:0.5-1 by weight, and the amylase is compounded from low-temperature a-amylase and low-temperature glucose starch in a proportion of 0.5:1 by weight; the enzymatic hydrolysis conditions are as follows: the amount of protease is 0.05% of the mass of the mixed emulsion, the amount of amylase is 0.05% of the mass of the mixed emulsion, the temperature is 45℃, and the time is 4h.

[0038] (4) Inoculation and fermentation: the lactic acid bacteria fermentation agent is compounded from Lactobacillus bulgaricus and Streptococcus thermophilus in a proportion of 1:1 by weight; the fermentation conditions are as follows: the inoculation amount of the lactic acid bacteria fermentation agent is 3% of the volume of the enzymatic hydrolysis liquid, the temperature is 40℃, and the time is 6h; then the acid-tolerant yeast 71B is inoculated in a proportion of 2% of the volume of the enzymatic hydrolysis liquid, the temperature is 28℃, and the time is 4h.

[0039] (5) The vacuum freeze-drying conditions are as follows: the material loading thickness is 1.5cm, the cold trap temperature is -35℃, the hot plate temperature is 85℃, the vacuum degree is 40Pa, the time is 4h, the hot plate temperature is 65℃, the vacuum degree is 40Pa, the time is 8h, the hot plate temperature is 45℃, the vacuum degree is 40Pa, and the time is 12h.

[0040] Example 2: Selenium-rich walnut compound fruit-flavored probiotic solid beverage.

[0041] (1) Raw material pretreatment: the selected selenium-rich walnut kernels and one or more of the auxiliary materials including apricots, dates, or sea buckthorn are immersed in 80mg / L chlorine dioxide solution for 6min;

[0042] (2) Grinding and homogenization: the walnut kernels are treated in a tunnel type far infrared radiation furnace at 135℃ for 7min, then the roasted walnut kernels are mixed with apricots and stabilizers in a proportion of 1:1:0.02 by weight to carry out grinding and homogenization, and a mixed emulsion is obtained; the homogenization conditions are 2℃, 300Mpa, and 3min;

[0043] The stabilizer comprises the following raw materials in parts by weight: 10 parts of sodium octenyl succinate starch, 8 parts of succinic acid monoglyceride, 12 parts of konjac powder, 5 parts of beta-cyclodextrin, 10 parts of malt dextrin, 8 parts of sucrose fatty acid ester and 2 parts of sodium carboxymethyl cellulose;

[0044] (3) Enzymatic hydrolysis; the protease is compounded by low-temperature neutral protease and low-temperature flavor enzyme at a weight ratio of 1:0.8, and the amylase is compounded by low-temperature a-amylase and low-temperature glucose starch at a weight ratio of 0.8:1; the conditions of the enzymatic hydrolysis are as follows: the dosage of the protease is 0.05% of the mass of the mixed emulsion, the dosage of the amylase is 0.1% of the mass of the mixed emulsion, the temperature is 50℃, and the time is 3h.

[0045] (4) Inoculation and fermentation: the lactic acid bacteria fermenting agent is compounded by Lactobacillus bulgaricus and Streptococcus thermophilus at a weight ratio of 1:1.2; the conditions of the fermentation are as follows: the inoculation amount of the lactic acid bacteria fermenting agent is 3.5% of the volume of the enzymatic hydrolysis liquid, the temperature is 38℃, and the time is 7h; then, the acid-tolerant yeast 71B is inoculated at a ratio of 3% of the volume of the enzymatic hydrolysis liquid, the temperature is 28℃, and the time is 3h.

[0046] (5) The conditions of the vacuum freeze-drying are as follows: the material loading thickness is 2.0cm, the cold trap temperature is -40℃, the heating plate temperature is 88℃, the vacuum degree is 50Pa, the time is 3h, the heating plate temperature is 68℃, the vacuum degree is 50Pa, the time is 7h, the heating plate temperature is 48℃, the vacuum degree is 50Pa, and the time is 9h.

[0047] Example 3: Selenium-rich walnut compound fruit-flavored probiotic solid beverage.

[0048] (1) Raw material pretreatment: the selected selenium-rich walnut kernels and the auxiliary materials including one or more of apricots, dates or sea buckthorn are immersed in a 100mg / L chlorine dioxide solution for 5min;

[0049] (2) Grinding and homogenization: the tunnel type far infrared radiation furnace is used to treat the walnut kernels at 150℃ for 5min, then the baked walnut kernels, apricots and a stabilizer are mixed at a weight ratio of 1:1:0.05, and grinding and homogenization are performed to obtain a mixed emulsion; the conditions of the homogenization are as follows: 3℃, 150Mpa and 3min.

[0050] The stabilizer comprises the following raw materials in parts by weight: 8 parts of sodium octenyl succinate starch, 6 parts of succinic acid monoglyceride, 10 parts of konjac powder, 4 parts of beta-cyclodextrin, 6 parts of malt dextrin, 7 parts of sucrose fatty acid ester and 1.5 parts of sodium carboxymethyl cellulose;

[0051] (3) Enzymatic hydrolysis; the protease is a mixture of low-temperature neutral protease and low-temperature flavor enzyme at a weight ratio of 1:1, and the amylase is a mixture of low-temperature a-amylase and low-temperature glucose starch at a weight ratio of 1:1; the conditions for the enzymatic hydrolysis are as follows: the amount of the protease is 0.3% of the mass of the mixed emulsion, the amount of the amylase is 0.2% of the mass of the mixed emulsion, the temperature is 45°C, and the time is 2h.

[0052] (4) Inoculation and fermentation: the lactic acid bacteria fermenting agent is a mixture of Lactobacillus bulgaricus and Streptococcus thermophilus at a weight ratio of 1:1; the conditions for the fermentation are as follows: the inoculation amount of the lactic acid bacteria fermenting agent is 3% of the volume of the enzymatic hydrolysate, the temperature is 42°C, and the time is 5h; then, the acid-tolerant yeast 71B is inoculated at a ratio of 4% of the volume of the enzymatic hydrolysate, the temperature is 28°C, and the time is 2h.

[0053] (5) The conditions for the vacuum freeze-drying are as follows: the material loading thickness is 2.5cm, the cold trap temperature is -45°C, the hot plate temperature is 90°C, the vacuum degree is 60Pa, the time is 3h, the hot plate temperature is 70°C, the vacuum degree is 60Pa, the time is 6h, the hot plate temperature is 50°C, the vacuum degree is 60Pa, and the time is 9h.

[0054] Comparative Example 1:

[0055] The selenium-enriched walnut compound fruit-flavored probiotic solid beverage product is prepared according to the method of Example 1, except that the stabilizer in the present comparative example does not contain sodium stearoyl-2-lactylate and succinylated monoglycerides.

[0056] Comparative Example 2:

[0057] The selenium-enriched walnut compound fruit-flavored probiotic solid beverage is prepared according to the method of Example 1, except that the stabilizer in the present comparative example does not contain sodium stearoyl-2-lactylate and konjac flour.

[0058] Comparative Example 3:

[0059] The selenium-enriched walnut compound fruit-flavored probiotic solid beverage is prepared according to the method of Example 1, except that the stabilizer in the present comparative example does not contain konjac flour and succinylated monoglycerides.

[0060] Comparative Example 4:

[0061] The selenium-enriched walnut compound fruit-flavored probiotic solid beverage is prepared according to the method of Example 1, except that the stabilizer in the present comparative example does not contain konjac flour, succinylated monoglycerides, and sodium stearoyl-2-lactylate.

[0062] Comparative Example 5:

[0063] The selenium-enriched walnut compound fruit-flavored probiotic solid beverage is prepared according to the method of Example 1, except that the present comparative example does not perform the cold sterilization in step (1).

[0064] Comparative Example 6:

[0065] Selenium-enriched walnut compound fruit-flavored probiotic solid beverage was prepared according to the method of Example 1, except that in the present comparative example, step (2) was homogenized at room temperature.

[0066] Comparative Example 7:

[0067] Selenium-enriched walnut compound fruit-flavored probiotic solid beverage was prepared according to the method of Example 1, except that in the present comparative example, step (3) was not hydrolyzed by protease.

[0068] Comparative Example 8:

[0069] Selenium-enriched walnut compound fruit-flavored probiotic solid beverage was prepared according to the method of Example 1, except that in the present comparative example, step (3) was not hydrolyzed by amylase.

[0070] Comparative Example 9:

[0071] Selenium-enriched walnut compound fruit-flavored probiotic solid beverage was prepared according to the method of Example 1, except that in the present comparative example, step (4) was not fermented by acid-resistant yeast 71B.

[0072] Comparative Example 10:

[0073] Selenium-enriched walnut compound fruit-flavored probiotic solid beverage was prepared according to the method of Example 1, except that in the present comparative example, step (5) was spray dried.

[0074] Test Example: Detection of various indexes of selenium-enriched walnut compound fruit-flavored probiotic solid beverage.

[0075] According to T / CNFIA 131-2021 Probiotic Food T / WSJD 12-2020 Plant Protein Beverage Plant Yogurt, the protein content of plant yogurt product is not less than 1%, pH≤4.5, acidity≥30.0°T. Among them, acidity is an important factor affecting the production cycle, production efficiency and final flavor of yogurt. The live bacteria number of T / CNFIA 131-2021 Probiotic Food product shall not be less than 1.0×10 7 .

[0076] (1) Test method:

[0077] The pH value of the product was determined using a PHS-3TC high-precision acidimeter, the acidity determination method referred to the method specified in GB 5009.239-2016 "National Food Safety Standard Determination of Acidity in Foods", and 0.1 mol / L NaOH standard solution was used for titration; the method for determining the number of viable bacteria referred to the test method specified in GB 4789.35-2016 "National Food Safety Standard Food Microbiological Examination Lactic Acid Bacteria Examination". The performance test of the stabilizer was determined by centrifugation at 3000 rpm for 30 min to observe whether it was layered; the total phenol was determined by Folin-Ciocalteu method; the Vc was determined according to the method specified in GB 14754-2010 "National Food Safety Standard Food Additive Vitamin C (Ascorbic Acid)"; the determination of E. coli used the scheme specified in GB 4789.3 "National Food Safety Standard Food Microbiological Examination E. coli Count"; the mold and yeast count used the method specified in GB 4789.15 "National Food Safety Standard Food Microbiological Examination Mold and Yeast Count"; the sensory evaluation used RHB 104-2020 "Fermented Milk Sensory Evaluation Rules", and the test results are shown in Tables 1 and 2.

[0078] (2) Test results:

[0079] Table 1 Microbial indicators of selenium-rich walnut compound fruit-flavored probiotic solid beverage product

[0080]

[0081] Table 2: Indicators of selenium-rich walnut compound fruit-flavored probiotic solid beverage product

[0082]

[0083]

[0084] First, analyze the data in Table 1. The mold count of products in Comparative Examples 5 and 6 is higher than 50, and the viable bacteria count of the product in Comparative Example 10 is lower than 10 6 , so the final product is unqualified, and therefore the final product in Table 2 is not evaluated. Comparing the data of Examples 1-3 and Comparative Examples 7-9, it can be shown that the combination of raw material cold sterilization and low-temperature homogenization can improve the stability of the product; the combination of freeze-drying and related technologies can improve the retention rate of viable bacteria; protease and amylase enzymolysis is an essential step, and the combination of various high-tech organic technologies can improve the quality of the product.

[0085] It can be known from analyzing the data in Table 2 that the pH value and acidity of the walnut fermented milk products prepared by each component meet the national standards, which indicates that the walnut fermented milk products prepared in the example have good flavor. After centrifugation for 30 min, stratification occurs in Comparative Examples 1-4, but stratification does not occur in Example 1-3, which indicates that the stabilizer of the application can effectively prevent oil-water stratification of the emulsion and improve the stability of the walnut kernel emulsion. At the same time, by comparing the viable cell count and stability test data of Example 1 and Comparative Examples 1-4, it can be found that succinic acid monoglyceride, konjac powder and sodium octenyl succinate starch in the stabilizer used in the application have a synergistic effect on maintaining the viable cell count.

[0086] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art based on the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a selenium-enriched walnut compound fruit-flavored probiotic solid beverage, characterized by, The method comprises the following steps: (1) Pretreatment of raw materials: cold sterilization of selenium-rich walnut kernels and auxiliary materials, and then baking the walnut kernels; (2) Grinding and homogenizing: mixing the baked walnut kernels, auxiliary materials and stabilizers, and then grinding and low-temperature homogenizing to obtain a mixed emulsion; wherein the weight ratio of the walnut kernels, auxiliary materials and stabilizers is 1:(0.5-1):(0.01-0.05); the stabilizers comprise the following raw materials in the following proportions by weight: 5-10 parts of sodium octenyl succinate starch, 4-8 parts of succinic acid monoglyceride, 6-12 parts of konjac powder, 3-5 parts of beta-cyclodextrin, 3-10 parts of malt dextrin, 5-8 parts of sucrose fatty acid ester and 1-2 parts of sodium carboxymethyl cellulose; (3) Enzymatic hydrolysis: inoculating protease and amylase into the mixed emulsion to obtain an enzymatic hydrolysate; wherein the protease is compounded from low-temperature neutral protease and low-temperature flavor enzyme at a weight ratio of 1:(0.5-1), and the amylase is compounded from low-temperature a-amylase and low-temperature glucoamylase at a weight ratio of (0.5-1):1; the conditions for the enzymatic hydrolysis are as follows: the amount of protease is 0.05-0.3% of the mass of the mixed emulsion, the amount of amylase is 0.05-0.2% of the mass of the mixed emulsion, the temperature is 45-50 DEG C, and the time is 2-4 h; (4) Inoculation and fermentation: inoculating lactic acid starter into the enzymatic hydrolysate for primary fermentation, and then inoculating acid-tolerant Saccharomyces cerevisiae 71B for secondary fermentation, and obtaining fermented walnut milk after the secondary fermentation; the lactic acid starter is compounded from Lactobacillus bulgaricus and Streptococcus thermophilus at a weight ratio of 1:(1-1.5); the conditions for the primary fermentation are as follows: the inoculation amount of the lactic acid starter is 1-4% of the volume of the enzymatic hydrolysate, the temperature is 37-45 DEG C, and the time is 5-8 h; the conditions for the secondary fermentation are as follows: the inoculation amount of the acid-tolerant Saccharomyces cerevisiae 71B is 2-4% of the volume of the enzymatic hydrolysate, the temperature is 28 DEG C, and the time is 4 h; (5) Injecting the fermented walnut milk into a mold, quick-freezing, vacuum freeze-drying, low-temperature crushing or not, and packaging to obtain the finished product.

2. The process for the preparation of selenium enriched walnut complex fruit flavored probiotic solid beverage as claimed in claim 1, wherein, The auxiliary materials comprise one or more of apricot, jujube or sea buckthorn.

3. The process for the preparation of selenium enriched walnut complex fruit flavored probiotic solid beverage as claimed in claim 1, wherein, In step (1), the cold sterilization conditions are as follows: soaking the selenium-rich walnuts and auxiliary materials in a chlorine dioxide solution, wherein the concentration of the chlorine dioxide solution is 60-100 mg / L, and the soaking time is 5-8 min.

4. The process for the preparation of selenium enriched walnut complex fruit flavored probiotic solid beverage as claimed in claim 1, wherein, In step (1), the baking conditions are as follows: a tunnel-type far infrared radiation furnace, the temperature is set to 120-150 DEG C, and the sample residence time is 5-8 min by adjusting the speed of the conveying belt.

5. The process for the preparation of selenium enriched walnut complex fruit flavored probiotic solid beverage as claimed in claim 1, wherein, In step (2), the low-temperature homogenizing conditions are as follows: 2-5 DEG C, 100-150 Mpa, and 3-10 min.

6. The process for the preparation of selenium enriched walnut complex fruit flavored probiotic solid beverage as claimed in claim 1, wherein, In step (5), the vacuum freeze-drying conditions are as follows: the material loading thickness is 1-2.5 cm, the cold trap temperature is -35 to -45 DEG C, the heating plate temperature is 85-90 DEG C, the vacuum degree is 15-100 Pa, the time is 3-4 h, the heating plate temperature is 65-70 DEG C, the vacuum degree is 15-100 Pa, the time is 6-8 h, the heating plate temperature is 45-50 DEG C, the vacuum degree is 15-100 Pa, and the time is 9-12 h.

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