Preparation method of composite probiotic solid beverage

Abstract

The invention provides a compound probiotic solid beverage and a preparation method thereof, and belongs to the field of probiotic beverages. The preparation method of the compound probiotic solid beverage comprises the following steps: S1, independently fermenting probiotic strains, and mixing the fermented probiotic strains with a protective agent to obtain pretreated probiotic feed liquid; s2, uniformly mixing the pretreated probiotic feed liquid with sodium alginate, then spraying the mixture into a CaCl2 solution, and filtering to obtain sodium alginate gel microspheres; s3, mixing the sodium alginate gel microbeads with a chitosan solution, adjusting the pH value, filtering, and freeze-drying to obtain double-coated probiotic microparticles; and S4, uniformly mixing the double-coated probiotic particles, maltodextrin, fructo-oligosaccharide, citric acid and a flavor additive to obtain the composite probiotic solid beverage. According to the method, the gastric juice tolerance is improved through microcapsule embedding (sodium alginate-chitosan double-layer coating), the survival rate of strains is guaranteed to a great extent, the product quality is improved, the viable count of the product is larger than or equal to 10 billion CFU / g, the shelf life is long, and the method is suitable for industrial continuous production.

Description

Technical Field

[0001] The invention relates to the field of probiotic beverages, and in particular to a method for preparing a composite probiotic solid beverage. Background Art

[0002] A wide variety of microorganisms live in the gastrointestinal tract of healthy people. These microorganisms are called intestinal flora. Intestinal flora is composed in a certain proportion, and each bacteria restricts and depends on each other, forming an ecological balance in quality and quantity. Once the internal and external environment of the body changes, it will cause flora imbalance, and its normal physiological combination will be destroyed, and the pathological combination will be produced, causing clinical symptoms, which is called intestinal flora imbalance.

[0003] The number of intestinal probiotics has become one of the standards for testing whether the human body is healthy. Its physiological effects on the human body are as follows: antibacterial, inhibiting putrefactive bacteria by decomposing organic acids in the intestines to reduce intestinal acidity; supplementing human vitamins, probiotics produce various vitamins, and inhibit the decomposition of certain substances to ensure supply; enhancing immune function, stimulating intestinal immune cells and improving immunity. However, in daily life, the deterioration of the environment, unhealthy lifestyles, and increased pressure in life have caused more and more people to experience anxiety, depression and other emotions due to excessive mental stress, leading to dysfunction of the neuroendocrine system. In addition, the long-term and large-scale use of broad-spectrum antibiotics in today's society can inhibit or kill most sensitive bacteria and normal flora, while drug-resistant bacteria can multiply in large numbers due to the selective effect of antibiotics. All of these factors will cause intestinal physiological dysfunction, unbalance the microecological environment in the intestine, and then cause intestinal aging.

[0004] Probiotic products can prevent and treat diseases while increasing nutrition. With the improvement of people's living standards, probiotic products have gradually gained the favor of the public, but liquid products such as probiotic yogurt have limited their sales scope and the public's purchase rate due to high storage and transportation costs and short shelf life. At present, new varieties of probiotic beverages are emerging in an endless stream, and there are many types of compound probiotic solid beverages. Although the appearance, name and taste of various beverages are constantly being renewed, the quality of beverages varies greatly. There is a problem of small number of active probiotics, and even if the initial base number of active bacteria is increased, it will decrease rapidly over time, resulting in a short shelf life. Moreover, after drinking, due to the influence of the probiotics contained in gastric acid and bile salts, a large number of probiotics are inactivated, and only a small part of them can reach the intestines to play a role.

[0005] Therefore, there is an urgent need for a method for preparing a probiotic solid beverage with a large number of live bacteria, a long shelf life and strong tolerance. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a composite probiotic solid beverage. The present invention improves gastric juice tolerance through microcapsule embedding (sodium alginate-chitosan double-layer coating). The preparation method of the present invention can greatly ensure the survival rate of the strain and improve the quality of the product.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a composite probiotic solid beverage, comprising the following steps:

[0009] S1. fermenting the probiotic strains separately and then mixing them with a protective agent to obtain a pretreated probiotic feed solution;

[0010] S2. The pretreated probiotic solution is mixed with sodium alginate and then sprayed into the CaCl2 solution and filtered to obtain sodium alginate gel microbeads;

[0011] S3. mixing the sodium alginate gel microbeads with the chitosan solution, adjusting the pH, filtering and freeze-drying to obtain double-coated probiotic microparticles;

[0012] S4. The double-coated probiotic microparticles, maltodextrin, oligofructose, citric acid and flavor additives are uniformly mixed to obtain a composite probiotic solid beverage.

[0013] Preferably, the probiotic strain in S1 is one or more of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum.

[0014] Preferably, the protective agent in S1 comprises the following components in parts by weight: 15-25 parts of skim milk powder, 5-15 parts of trehalose, 0.5-3 parts of sodium glutamate, 0.1-0.5 parts of ascorbic acid, 0.01-0.03 parts of vitamin E, and 0.01-0.02 parts of β-carotene.

[0015] Preferably, the number of viable bacteria in the S1 pretreated probiotic solution is ≥ 10 billion CFU / g.

[0016] Preferably, the mass ratio of the pretreated probiotic solution to sodium alginate in S2 is 100:(1-6).

[0017] Preferably, the concentration of the CaCl2 solution in S2 is 0.1-0.5 mol / L.

[0018] Preferably, the mass ratio of the sodium alginate gel microbeads to the chitosan solution in S3 is 1:(1-3);

[0019] The concentration of the chitosan solution is 0.5-3wt%;

[0020] The pH was adjusted to 4.5-6.5.

[0021] Preferably, the freeze-drying parameters in S3 are: first equilibrate at 4°C for 1 hour, then pre-freeze at 20°C for 2 hours, and finally deep freeze solidify at 50°C, the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%.

[0022] Preferably, the mass ratio of the double-coated probiotic microparticles, maltodextrin, oligofructose, and color and flavor additives in S4 is 100:(20-50):(10-20):(10-50).

[0023] Preferably, the color and flavor additives include citric acid, food coloring, and flavors.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention improves gastric juice tolerance through microcapsule embedding (sodium alginate-chitosan double-layer coating).

[0026] (2) The preparation method of the present invention can ensure the survival rate of the strain to a great extent and improve the quality of the product.

[0027] (3) This process can achieve a product viable bacterial count of ≥10 billion CFU / g, has a long shelf life, and is suitable for industrial continuous production. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing a composite probiotic solid beverage, comprising the following steps:

[0029] S1. fermenting the probiotic strains separately and then mixing them with a protective agent to obtain a pretreated probiotic feed solution;

[0030] S2. The pretreated probiotic solution is mixed with sodium alginate and then sprayed into the CaCl2 solution and filtered to obtain sodium alginate gel microbeads;

[0031] S3. mixing the sodium alginate gel microbeads with the chitosan solution, adjusting the pH, filtering and freeze-drying to obtain double-coated probiotic microparticles;

[0032] S4. The double-coated probiotic microparticles, maltodextrin, oligofructose, citric acid and flavor additives are uniformly mixed to obtain a composite probiotic solid beverage.

[0033] The invention firstly ferments the probiotic strains independently and then mixes them with a protective agent to obtain a pretreated probiotic feed liquid.

[0034] In the present invention, the probiotic strain in S1 is one or more of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum.

[0035] More preferably, the probiotic strains are composed of Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis and Bifidobacterium longum in a mass ratio of 3:2.5:2.5:2.

[0036] By adopting the above technical solution, Lactobacillus plantarum can decompose complex polysaccharides (such as arabinoxylan) to produce arabinoside, providing substrate for bifidobacteria. Bifidobacteria metabolize to produce acetic acid / propionic acid, inhibiting pathogens. Lactobacillus rhamnosus preferentially utilizes glucose to reduce carbon source competition with bifidobacteria.

[0037] In the present invention, the probiotic strains are respectively subjected to adaptive fermentation until the number of viable bacteria reaches the requirement, and there is no special requirement for the fermentation method.

[0038] In the present invention, the protective agent comprises the following components in parts by weight: 15-25 parts of skim milk powder, 5-15 parts of trehalose, 0.5-3 parts of sodium glutamate, 0.1-0.5 parts of ascorbic acid, 0.01-0.03 parts of vitamin E, and 0.01-0.02 parts of β-carotene; more preferably, the components are 20 parts of skim milk powder, 10 parts of trehalose, 1 part of sodium glutamate, 0.3 parts of ascorbic acid, 0.02 parts of vitamin E, and 0.01 parts of β-carotene.

[0039] In the present invention, the number of viable bacteria in the pretreated probiotic solution is ≥ 10 billion CFU / g.

[0040] Then, the present invention mixes the pretreated probiotic solution and sodium alginate evenly, sprays the mixture into a CaCl2 solution, and filters the mixture to obtain sodium alginate gel microbeads.

[0041] In the present invention, the mass ratio of the pretreated probiotic solution to sodium alginate is 100:(1-6).

[0042] In the present invention, the concentration of the CaCl2 solution is 0.1-0.5 mol / L.

[0043] By adopting the above-mentioned technical means, the present invention forms sodium alginate-wrapped probiotic microbeads by adding sodium alginate to the feed liquid and then spraying the mixed liquid into the CaCl2 solution in the form of a spray, forming an inner layer protection, and the ionic colloid formed by sodium alginate is stable in a low-acid environment, which can enhance the tolerance of the bacteria to gastric acid. In simulated gastric juice, the number of viable probiotics encapsulated in microcapsules does not decrease significantly, while the number of viable probiotics not encapsulated decreases sharply, which shows that sodium alginate microcapsules can improve the survival rate of probiotics in gastric acid environments. Sodium alginate shrinks in an acidic environment and swells and dissociates in an alkaline environment. This characteristic helps to achieve targeted release in a specific environment. In the acidic environment of gastric juice, the contraction of sodium alginate microcapsules can reduce the contact between probiotics and gastric juice, thereby protecting probiotics; and in the alkaline environment of intestinal fluid, the swelling and dissociation of microcapsules are conducive to the release and colonization of probiotics. At the same time, the sodium alginate shell can slow down the oxidation process of the embedded ingredients, prolong their storage stability, and maintain the effectiveness of the active ingredients.

[0044] Then, the present invention obtains double-coated probiotic microparticles by mixing the sodium alginate gel microbeads with the chitosan solution, adjusting the pH, filtering and freeze-drying.

[0045] In the present invention, the mass ratio of the sodium alginate gel microbeads to the chitosan solution is 1:(1-3);

[0046] The concentration of the chitosan solution is 0.5-3wt%;

[0047] The pH was adjusted to 4.5-6.5.

[0048] In the present invention, the freeze-drying parameters are: first equilibrate at 4°C for 1 hour, then pre-freeze at 20°C for 2 hours, and finally deep freeze solidify at 50°C, the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%.

[0049] By adopting the above technical scheme, the present invention uses chitosan, which is a natural cationic polysaccharide with a positive charge, to electrostatically interact with sodium alginate to form a stable multi-electrolyte complex, thereby enhancing the structural strength of the gel and making the microcapsules more effectively resist the mechanical pressure in the gastrointestinal tract; the addition of chitosan can reduce the porosity of the sodium alginate gel and make the gel structure denser, thereby better protecting the probiotics and preventing the invasion of digestive juices such as gastric juice and bile; the sustained-release performance of chitosan can adjust the release rate of the probiotics and ensure the continuous release of the probiotics in the gastrointestinal tract, thereby improving the stability and bioavailability of the probiotics; chitosan has good mucosal adhesion, and the combination of chitosan and sodium alginate can enhance the adhesion ability of the microcapsules in the intestine, making it easier for the probiotics to colonize on the intestinal wall, thereby better exerting their probiotic effects.

[0050] Then, the present invention mixes the double-coated probiotic microparticles, maltodextrin, oligofructose, citric acid and flavor additives uniformly to obtain a composite probiotic solid beverage.

[0051] In the present invention, the mass ratio of the coated probiotic microparticles, maltodextrin, oligofructose, and color and flavor additives is 100:(20-50):(10-20):(10-50).

[0052] By adopting the above technical solution, the addition of maltodextrin as a carrier material is beneficial to improving fluidity and preventing moisture absorption; oligofructose is a prebiotic that is beneficial to the proliferation of beneficial intestinal bacteria.

[0053] In the present invention, the color and flavor additives include citric acid, food coloring, and flavors.

[0054] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0055] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0056] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0057] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0058] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0059] The "room temperature" and "normal temperature" mentioned in the present invention are all calculated as 25±2°C unless otherwise specified.

[0060] The raw materials used in the following examples of the present invention are all commercially available.

[0061] The live bacteria detection of the present invention adopts the detection method specified in the national food safety standard GB 4789.35-2023.

[0062] Example 1

[0063] S1. The probiotic strains are fermented separately and then mixed with a protective agent to obtain a pretreated probiotic solution; the probiotic strains are composed of Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum in a mass ratio of 3:2.5:2.5:2; each strain is cultured to a viable count of ≥3 billion CFU / g; the protective agent includes 20 parts of skim milk powder, 10 parts of trehalose, 1 part of sodium glutamate, 0.3 parts of ascorbic acid, 0.02 parts of vitamin E, and 0.01 parts of β-carotene;

[0064] S2. The pretreated probiotic solution and sodium alginate were mixed uniformly at a mass ratio of 100:3 and then sprayed into a 0.2 mol / L CaCl2 solution and filtered to obtain sodium alginate gel microbeads; the particle size of the sodium alginate gel microbeads was 20 μm;

[0065] S3. The sodium alginate gel microbeads are mixed with 1wt% chitosan solution in a mass ratio of 1:2, the pH is adjusted to 5, and then filtered and freeze-dried to obtain double-coated probiotic microparticles; the freeze-drying parameters are: first equilibrate at 4°C for 1 hour, then pre-freeze at 20°C for 2 hours, and finally deep-cold solidify at 50°C, the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%;

[0066] S4. The double-coated probiotic microparticles, maltodextrin, oligofructose, citric acid, and flavor additives are mixed in a mass ratio of 100:30:15:20 to obtain a composite probiotic solid beverage; the specific mixing steps are: using a V-type mixer, mixing in steps, first premixing the double-coated probiotic microparticles with maltodextrin (speed 15 rpm, 10 minutes), then adding prebiotic oligofructose (speed 20 rpm, 20 minutes), and finally citric acid, food coloring, and flavor (speed 10 rpm, 5 minutes) until the mixing uniformity CV value is ≤5%;

[0067] S5. Granulation and packaging

[0068] Adopt dry granulation technology, roller pressure 30-50kN, flake thickness 0.8-1.2mm, whole granule screen: 20 mesh screen crushing, particle size distribution: 80% in 40-80 mesh, and then adopt multi-layer barrier packaging.

[0069] Example 2

[0070] S1. The probiotic strains are fermented separately and then mixed with a protective agent to obtain a pretreated probiotic solution; the probiotic strains are composed of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum in a mass ratio of 1:1.5:1.5:1:1; each strain is cultured to a viable count of ≥3 billion CFU / g; the protective agent comprises the following components in parts by weight: 15 parts of skim milk powder, 5 parts of trehalose, 0.5 parts of sodium glutamate, 0.1 parts of ascorbic acid, 0.01 parts of vitamin E, and 0.01 parts of β-carotene;

[0071] S2. The pretreated probiotic solution and sodium alginate were mixed uniformly at a mass ratio of 100:1 and then sprayed into a 0.5 mol / L CaCl2 solution and filtered to obtain sodium alginate gel microbeads; the particle size of the sodium alginate gel microbeads was 50 μm;

[0072] S3. The sodium alginate gel microbeads and 3wt% chitosan solution are mixed in a mass ratio of 1:1, the pH is adjusted to 4.5, and then filtered and freeze-dried to obtain double-coated probiotic microparticles; the freeze-drying parameters are: first equilibrate at 4°C for 1 hour, then pre-freeze at 20°C for 2 hours, and finally deep-cold solidify at 50°C, the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%;

[0073] S4. The double-coated probiotic microparticles, maltodextrin, oligofructose, citric acid, and flavor additives are mixed in a mass ratio of 100:20:10:10 to obtain a composite probiotic solid beverage; the specific mixing steps are: using a V-type mixer, mixing in steps, first premixing the double-coated probiotic microparticles with maltodextrin (speed 15 rpm, 10 minutes), then adding prebiotic oligofructose (speed 20 rpm, 20 minutes), and finally citric acid, food coloring, and flavor (speed 10 rpm, 5 minutes) until the mixing uniformity CV value is ≤5%;

[0074] S5. Granulation and packaging

[0075] Adopt dry granulation technology, roller pressure 30-50kN, flake thickness 0.8-1.2mm, whole granule screen: 20 mesh screen crushing, particle size distribution: 80% in 40-80 mesh, and then adopt multi-layer barrier packaging.

[0076] Example 3

[0077] S1. The probiotic strains are fermented separately and then mixed with a protective agent to obtain a pretreated probiotic solution; the probiotic strains are composed of Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum in a mass ratio of 1:2:1:2; each strain is cultured to a viable count of ≥3 billion CFU / g; the protective agent comprises the following components in parts by weight: 25 parts of skim milk powder, 15 parts of trehalose, 3 parts of sodium glutamate, 0.5 parts of ascorbic acid, 0.03 parts of vitamin E, and 0.02 parts of β-carotene;

[0078] S2. The pretreated probiotic solution and sodium alginate were mixed uniformly at a mass ratio of 100:6 and then sprayed into a 0.1 mol / L CaCl2 solution and filtered to obtain sodium alginate gel microbeads; the particle size of the sodium alginate gel microbeads was 10 μm;

[0079] S3. The sodium alginate gel microbeads are mixed with 3wt% chitosan solution in a mass ratio of 1:3, the pH is adjusted to 6.5, and then filtered and freeze-dried to obtain double-coated probiotic microparticles; the freeze-drying parameters are: first equilibrate at 4°C for 1 hour, then pre-freeze at 20°C for 2 hours, and finally deep-cold solidify at 50°C, the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%;

[0080] S4. The double-coated probiotic microparticles, maltodextrin, oligofructose, citric acid, and flavor additives are mixed in a mass ratio of 100:50:20:50 to obtain a composite probiotic solid beverage; the specific mixing steps are: using a V-type mixer, mixing in steps, first premixing the double-coated probiotic microparticles with maltodextrin (speed 15 rpm, 10 minutes), then adding prebiotic oligofructose (speed 20 rpm, 20 minutes), and finally citric acid, food coloring, and flavor (speed 10 rpm, 5 minutes) until the mixing uniformity CV value is ≤5%;

[0081] S5. Granulation and packaging

[0082] Adopt dry granulation technology, roller pressure 30-50kN, flake thickness 0.8-1.2mm, whole granule screen: 20 mesh screen crushing, particle size distribution: 80% in 40-80 mesh, and then adopt multi-layer barrier packaging.

[0083] Comparative Example 1

[0084] S1. The probiotic strains are fermented separately and then mixed with a protective agent to obtain a pretreated probiotic solution; the probiotic strains are composed of Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum in a mass ratio of 3:2.5:2.5:2; each strain is cultured to a viable count of ≥3 billion CFU / g; the protective agent includes 20 parts of skim milk powder, 10 parts of trehalose, 1 part of sodium glutamate, 0.3 parts of ascorbic acid, 0.02 parts of vitamin E, and 0.01 parts of β-carotene;

[0085] S2. The pretreated probiotic liquid is then freeze-dried, and the freeze-drying parameters are: first equilibrate at 4°C for 1 hour, then prefreeze at 20°C for 2 hours, and finally deep freeze solidify at 50°C, and the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%.

[0086] Comparative Example 2

[0087] S1. The probiotic strains are fermented separately and then mixed with a protective agent to obtain a pretreated probiotic solution; the probiotic strains are composed of Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum in a mass ratio of 3:2.5:2.5:2; each strain is cultured to a viable count of ≥3 billion CFU / g; the protective agent includes 20 parts of skim milk powder, 10 parts of trehalose, 1 part of sodium glutamate, 0.3 parts of ascorbic acid, 0.02 parts of vitamin E, and 0.01 parts of β-carotene;

[0088] S2. The pretreated probiotic solution and sodium alginate were mixed uniformly at a mass ratio of 100:3 and then sprayed into a 0.2 mol / L CaCl2 solution and filtered to obtain sodium alginate gel microbeads; the particle size of the sodium alginate gel microbeads was 20 μm;

[0089] S3. The pretreated probiotic liquid is then freeze-dried, and the freeze-drying parameters are: first equilibrate at 4°C for 1 hour, then prefreeze at 20°C for 2 hours, and finally deep freeze solidify at 50°C, and the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%.

[0090] Comparative Example 3

[0091] S1. The probiotic strains are fermented separately to obtain a pretreated probiotic solution; the probiotic strains are composed of Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum in a mass ratio of 3:2.5:2.5:2; each strain is cultured to a viable count of ≥3 billion CFU / g;

[0092] S2. The pretreated probiotic liquid is then freeze-dried, and the freeze-drying parameters are: first equilibrate at 4°C for 1 hour, then prefreeze at 20°C for 2 hours, and finally deep freeze solidify at 50°C, and the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%.

[0093] Comparative Example 4

[0094] The preparation method of this comparative example is the same as that of Example 1, except that no protective agent is used.

[0095] Experimental Example 1

[0096] The viable bacteria counts of the products of each embodiment and comparative example were tested, see Table 1.

[0097] Table 1

[0098]

[0099] As shown in Table 1, it can be known that the present invention can protect the strains through double coating to prevent the freeze-drying process from causing adverse effects on the strains, and the use of protective agents can improve the damage during the coating and freeze-drying process.

[0100] Experimental Example 2

[0101] Shelf life testing

[0102] 10 g of each freeze-dried powder obtained in each example and comparative example was placed in a nitrogen atmosphere (oxygen production rate 1%, 37° C.) for standing, and then the survival rate of the strain was detected, see Table 2.

[0103] Table 2

[0104]

[0105]

[0106] It can be seen from Table 3 that the shelf life of the double-coated product of the present invention is significantly increased.

[0107] Experimental Example 3

[0108] Gastric acid tolerance test

[0109] The probiotic products obtained in Examples 1-3 and Comparative Examples 1-2 of the present invention were resuspended with 1 mL of sterile physiological saline, respectively added into 9 mL of artificial gastric juice with pH = 1.5, placed in a 37°C water bath shaker for shaking culture, and samples were taken at 0 min, 60 min, and 120 min, respectively, and gradient dilutions (10 1 -10 6 ), spread on the plate and count, and measure the viable bacteria rate, see Table 3.

[0110] Table 3

[0111]

[0112] It can be seen from Table 3 that the protection effect of the double-layer coating structure is more obvious than that of the uncoated structure and the single-layer coating structure.

[0113] Experimental Example 4

[0114] Tolerance testing in the intestine

[0115] The probiotic products obtained in Examples 1-3 of the present invention and Comparative Examples 1-2 were added to artificial intestinal fluid for digestion for 45 minutes, and samples were taken every 15 minutes. After dilution, the viable bacteria were counted on MRS solid medium at 37° C. for 48 hours. The viable bacteria rate after treatment with artificial intestinal fluid was calculated, as shown in Table 4.

[0116] Table 4

[0117]

[0118]

[0119] It can be seen from Table 4 that the 45-min effects of single-layer coating and double-layer coating in intestinal fluid are similar, but compared with no coating, there is a significant protective effect. The lower survival rate of single-layer coating at 15-30 minutes may be caused by the excessively fast release rate of the strain.

[0120] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a composite probiotic solid beverage, characterized in that: The following steps are involved: S1. fermenting the probiotic strains separately and then mixing them with a protective agent to obtain a pretreated probiotic feed solution; S2. The pretreated probiotic solution is mixed with sodium alginate and then sprayed into the CaCl2 solution and filtered to obtain sodium alginate gel microbeads; S3. mixing the sodium alginate gel microbeads with the chitosan solution, adjusting the pH, filtering and freeze-drying to obtain double-coated probiotic microparticles; S4. The double-coated probiotic microparticles, maltodextrin, oligofructose, citric acid and flavor additives are uniformly mixed to obtain a composite probiotic solid beverage.

2. The preparation method according to claim 1, characterized in that: The probiotic strains in S1 are one or more of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium lactis, and Bifidobacterium longum.

3. The preparation method according to claim 1, characterized in that: The protective agent in S1 includes the following components in parts by weight: 15-25 parts of skim milk powder, 5-15 parts of trehalose, 0.5-3 parts of sodium glutamate, 0.1-0.5 parts of ascorbic acid, 0.01-0.03 parts of vitamin E, and 0.01-0.02 parts of beta-carotene.

4. The preparation method according to claim 1, characterized in that: The number of viable bacteria in the S1 pretreated probiotic solution is ≥ 10 billion CFU / g.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the pretreated probiotic solution to sodium alginate in S2 is 100:(1-6).

6. The preparation method according to claim 1, characterized in that: The concentration of the CaCl2 solution in the S2 is 0.1-0.5 mol / L.

7. The preparation method according to claim 1, characterized in that: The mass ratio of sodium alginate gel microbeads to chitosan solution in S3 is 1:(1-3); The concentration of the chitosan solution is 0.5-3wt%; The pH was adjusted to 4.5-6.

5.

8. The preparation method according to claim 1, characterized in that: The freeze-drying parameters in S3 are: first equilibrate at 4°C for 1 hour, then pre-freeze at 20°C for 2 hours, and finally deep freeze solidify at 50°C, the cooling rate is ≤1°C / min; then gradually increase the temperature by 20°C, the vacuum degree is 10-30Pa, the duration is 24-36 hours, and then maintain at 25°C for 4 hours, and the final moisture content is ≤3%.

9. The preparation method according to claim 1, characterized in that: The mass ratio of the double-coated probiotic microparticles, maltodextrin, oligofructose, and color and flavor additives in S4 is 100:(20-50):(10-20):(10-50).

10. The preparation method according to claim 9, characterized in that: The color and flavor additives include citric acid, food coloring, and flavors.

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