Preparation process and application of microencapsulated probiotic corn whole grain flour

Abstract

The invention provides a preparation technology and application of microencapsulated probiotic corn whole grain flour, and belongs to the technical field of food processing. The preparation process comprises the following steps: preparation and pretreatment of raw materials: cleaning, crushing and pre-gelatinizing original corn kernels; enzymolysis: performing continuous enzymolysis treatment of cellulase and protease on the corn pulp; fermenting: performing compound fermentation on the milk-based raw materials to obtain fermented yogurt; mixing and refining: mixing the fermented yoghurt with the corn slurry after enzymolysis, and refining particles; microencapsulation: mixing a microencapsulated wall material aqueous solution with the refined mixed solution, and performing spray drying to obtain microencapsulated corn flour; and mixing: mixing the microencapsulated corn flour with the bacillus coagulans powder to obtain the microencapsulated probiotic corn whole grain flour. The microencapsulated probiotic corn whole grain flour prepared by the method is free of gluten, low in GI value, multiple in probiotic variety, high in activity, more comprehensive in nutrition, fine and smooth in taste and high in product safety.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a preparation process and application of microencapsulated probiotic corn whole grain flour. Background Art

[0002] As people's health awareness improves, the demand for functional foods is growing. As an important component of functional foods, probiotics have received widespread attention due to their role in promoting intestinal health, enhancing immunity, and preventing diseases. The application of probiotics in cereal flour is also gradually increasing, especially in whole corn grain flour, which is favored for its rich nutrients and good taste. However, the existing probiotic cereal flour preparation technology has many shortcomings, which limits its wide application in the market.

[0003] 1. Low survival rate of probiotics: Traditional methods of preparing probiotic cereal powders usually use high-temperature drying technologies, such as spray drying and hot air drying. Although these methods can effectively remove moisture, high-temperature treatment will seriously damage the survival rate of probiotics. Studies have shown that the survival rate of probiotics drops sharply in an environment above 60°C, and almost all of them are inactivated above 80°C. Therefore, how to protect probiotics during the drying process and improve their survival rate has become an urgent problem to be solved.

[0004] 2. Loss of nutrients: Whole grain corn flour is rich in nutrients such as vitamins, minerals, dietary fiber, and functional oils. However, traditional high-temperature treatment and long processing time will lead to a large loss of these nutrients. For example, high-temperature treatment will destroy heat-sensitive vitamins such as vitamin C and vitamin E, and long enzymatic hydrolysis will decompose some dietary fiber, thereby reducing the nutritional value of the product. Therefore, how to maximize the retention of nutrients in corn during processing is the key to improving product quality.

[0005] 3. Poor taste: Unoptimized processing technology may result in a rough taste of the final product, affecting consumer acceptance. For example, traditional spray drying technology may result in overly large or uneven particles, affecting the solubility and taste of the product. In addition, high temperature treatment will also volatilize the natural flavor substances in corn, resulting in a single flavor of the product. Therefore, how to improve the taste and flavor of the product by improving the processing technology is an important factor in improving market competitiveness.

[0006] 4. Food safety issues: The traditional fermentation process may produce harmful substances such as fumonisin and aflatoxin produced by Pseudomonas cerebroventris, which pose a threat to consumer health. Pseudomonas cerebroventris is a common food contamination bacterium. The fumonisin produced by it is highly toxic and can cause food poisoning. Aflatoxin is a strong carcinogen, and long-term intake will have serious effects on human health. Therefore, it is crucial to strictly control the growth of microorganisms during the fermentation process to ensure the safety of the product.

[0007] 5. Poor stability: Probiotics are easily inactivated during storage and transportation, resulting in a short shelf life of the product, which limits its market promotion. The survival rate of probiotics is affected by factors such as temperature, humidity, and oxygen. Especially in high temperature and high humidity environments, the survival rate of probiotics will drop significantly. Therefore, how to extend the shelf life of the product by improving packaging and storage conditions is the key to improving market competitiveness.

[0008] 6. Low utilization rate of functional ingredients: Existing probiotic grain powder preparation technology often cannot fully utilize the functional ingredients in corn, such as polyphenols, flavonoids and other antioxidant substances. These functional ingredients have multiple biological activities such as antioxidant, anti-inflammatory, and anti-cancer, but they are easily destroyed or lost during traditional processing. Therefore, how to improve the utilization rate of functional ingredients by improving processing technology is an important way to increase product added value.

[0009] In summary, the existing probiotic cereal powder preparation technology has many shortcomings, which limits its wide application in the market. An innovative food processing technology is urgently needed to solve the above problems and prepare microencapsulated probiotic corn whole grain powder with high probiotic survival rate, good taste and nutritional value to meet market demand and improve market competitiveness. Summary of the invention

[0010] The purpose of the present invention is to provide a preparation process of microencapsulated probiotic corn whole grain flour, which significantly improves the survival rate of probiotics, reduces the GI value, and improves the comprehensive performance of the product through integrated innovative food processing technology.

[0011] In order to achieve the above object, the present invention provides the following technical solutions:

[0012] A preparation process of microencapsulated probiotic corn whole grain powder comprises the following steps:

[0013] (1) Raw material preparation and pretreatment: The corn kernels are cleaned, crushed after adding water to obtain corn slurry, the pH value of the corn slurry is adjusted to 6.0-7.0, the corn slurry is appropriately pre-gelatinized, and cooled to room temperature after the treatment is completed;

[0014] (2) Enzymatic hydrolysis: transferring the cooled corn slurry to an enzymatic hydrolysis tank, adding cellulase and protease respectively for continuous enzymatic hydrolysis to obtain enzymatically hydrolyzed corn slurry for later use;

[0015] (3) fermentation: inoculating a composite lactic acid bacteria fermentation agent into a milk-based raw material, wherein the composite lactic acid bacteria fermentation agent includes Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium longum subspecies longum and Bifidobacterium animalis subspecies lactis, heating to 36-38° C., maintaining a constant temperature, and fermenting for 12-24 hours to obtain fermented yogurt;

[0016] (4) Mixing and refining: mixing the fermented yogurt obtained in step (3) with the corn slurry obtained in step (2), and processing the mixed solution through a colloid mill or a homogenizer to further refine the particles;

[0017] (5) Microencapsulation: preparing an aqueous solution of a microencapsulation wall material, mixing the aqueous solution of the microencapsulation wall material with the mixed solution refined in step (4), heating to 40 to 50° C., stirring, and spray drying the mixture at a spray drying temperature of 50 to 60° C. for 30 to 60 minutes to obtain microencapsulated corn flour;

[0018] (6) Mixing: mixing the microencapsulated corn flour with the Bacillus coagulans powder to obtain the microencapsulated probiotic corn whole grain flour.

[0019] Furthermore, in step (1), the mass ratio of the original corn kernels to water is 1:(3-5); the temperature of the moderate pre-gelatinization treatment is 60-70°C, and the time is 10-20 minutes; and the cooling is performed by flowing water cooling or cooler cooling.

[0020] Furthermore, the continuous enzymatic hydrolysis treatment in step (2) is specifically as follows:

[0021] (i) adding 2000-3000 u / mL of corn slurry cellulase, heating to 45-50° C., maintaining constant temperature, performing cellulase enzymolysis for 1-2 hours, stirring continuously during the enzymolysis process, and after the enzymolysis is completed, heating to 90-95° C., maintaining for 5-10 minutes, performing inactivation treatment, and cooling the inactivated corn slurry to room temperature;

[0022] (ii) adding 3000-4000 u / mL of protease in corn slurry, heating to 45-50° C., maintaining constant temperature, and performing protease enzymolysis for 1-2 hours, stirring continuously during the enzymolysis process. After the enzymolysis is completed, heating to 90-95° C., maintaining for 5-10 minutes, and performing inactivation treatment, and cooling the inactivated corn slurry to room temperature.

[0023] Furthermore, the cellulase is endoglucanase and exoglucanase, and the protease is alkaline protease or neutral protease.

[0024] The present invention uses cellulase and protease for continuous enzymatic hydrolysis, which firstly improves the solubility and bioavailability of nutrients: cellulase can decompose cellulose in corn and convert it into soluble fiber, which helps to improve intestinal health and improves the solubility and digestibility of cellulose; protease can decompose the macromolecular protein in corn slurry into small molecular peptides and amino acids, which are more easily absorbed and utilized by the human body, thereby improving the bioavailability of protein. Secondly, continuous enzymatic hydrolysis can also improve the efficiency of subsequent treatment: by pre-decomposing macromolecular substances, more favorable conditions are provided for subsequent fermentation and microencapsulation treatment, thereby improving the efficiency and effect of these steps.

[0025] Furthermore, the milk-based raw material in step (3) is milk or vegetable milk.

[0026] Furthermore, the amount of Lactobacillus bulgaricus added in step (3) is 10 6 -10 7 CFU / mL milk-based raw material, the amount of thermophilic Streptococcus added is 10 9 -10 10 CFU / mL milk-based raw materials, the addition amount of Bifidobacterium longum subsp. longum is 10 8 -10 9 CFU / mL milk-based raw materials, the addition amount of Bifidobacterium animalis subsp. lactis is 10 6 -10 7 CFU / mL milk-based raw material.

[0027] The present invention adopts a composite lactic acid bacteria fermentation agent compounded with Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium longum subspecies longum and Bifidobacterium animalis lactis subspecies for fermentation. First, the survival rate of probiotics is improved: the metabolites produced by the composite lactic acid bacteria fermentation agent can adjust the pH value of the environment, inhibit the growth of harmful microorganisms, and provide a more suitable living environment for probiotics. Secondly, the taste and flavor of the product can be improved: the various metabolites produced during the composite fermentation process, such as lactic acid, acetic acid, propionic acid, etc., can give the product a unique flavor and improve the taste of the product; the metabolites produced during the fermentation process can also improve the texture of the product, making it more delicate and smooth. In addition, the GI value of the base powder can also be reduced: the composite lactic acid bacteria fermentation process can further degrade starch, reduce its digestion rate, and thus reduce the GI value of the product; the metabolites produced during the fermentation process can also further degrade cellulose, improve its solubility, and help control blood sugar levels. In addition, the complex fermentation process can also improve the bioavailability of nutrients: the fermentation process can further degrade proteins, generate small molecule peptides and amino acids, and improve the bioavailability of proteins; vitamins (such as B vitamins) can also be synthesized during the fermentation process to increase the nutritional value of the product.

[0028] Furthermore, in step (4), the mass ratio of the fermented yogurt to the corn slurry is 1:2-4.

[0029] Furthermore, in step (4), the microencapsulation wall material is gum arabic, sodium alginate, chitosan and maltodextrin, and the mass ratio is (2-3): (1-2): (0.5-1.5): (1.5-2.5), the mass concentration of the microencapsulation wall material aqueous solution is 5%-10%, and the mass ratio of the microencapsulation wall material aqueous solution to the refined mixed solution is 1: (2-3).

[0030] The present invention microencapsulates corn flour to form a protective layer that can effectively resist adverse factors such as high temperature, humidity, oxygen and acidic environment, ensuring the survival rate of probiotics during drying, storage and transportation. The microencapsulation wall material can form a protective barrier in gastric juice and intestinal juice to prevent probiotics from being destroyed by gastric acid and digestive enzymes, ensuring that the probiotics can smoothly reach the intestine and exert their functions. The microencapsulation technology can also slowly release probiotics in the intestine, prolong their action time in the intestine, and improve the bioavailability of probiotics.

[0031] Furthermore, in step (5), the mass ratio of the microencapsulated corn flour to the Bacillus coagulans powder is (20-30):1.

[0032] Microencapsulated corn flour has formed a stable protective layer through the wall material. After further mixing with Bacillus coagulans powder, Bacillus coagulans itself has strong tolerance, which can further enhance the survival rate of probiotics. After mixing Bacillus coagulans powder with microencapsulated corn flour, a more stable physical structure can be formed, which reduces the aggregation and agglomeration between particles and improves the fluidity of the product. Bacillus coagulans and other probiotics (such as Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium longum subsp. longum and Bifidobacterium animalis subsp. lactis) work together to provide multiple probiotic functions, such as improving intestinal health, enhancing immunity, preventing diseases, etc., further enhancing the functionality of the product.

[0033] The invention also provides application of the preparation process in preparing whole-grain corn flour.

[0034] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0035] 1. Improve the survival rate of probiotics: Through the protection of microencapsulation wall materials, the survival rate of probiotics during drying, storage and transportation is significantly improved. The use of compound lactic acid bacteria fermentation agents produces a variety of metabolites, which further enhances the stability and protection effect of microencapsulation wall materials and improves the survival rate of probiotics.

[0036] 2. Retain nutrients: Low temperature treatment is used throughout the preparation process to avoid the destruction of nutrients such as vitamins, minerals, dietary fiber and functional oils by high temperature, and to retain the nutrients in corn to the maximum extent. Through continuous enzymatic treatment with cellulase and protease, macromolecular substances are effectively decomposed, and the bioavailability of nutrients is improved.

[0037] 3. Improve taste and flavor: Through colloid mill or homogenizer processing, the mixed liquid is refined into uniform small particles, which improves the solubility and taste of the product. Low temperature treatment and microencapsulation technology effectively protect the natural flavor substances in corn, avoid the loss of flavor caused by high temperature treatment, and make the product have better flavor.

[0038] 4. Improve product safety: Through strict fermentation condition control and screening of high-quality probiotic strains, the growth of harmful microorganisms is prevented, and the production of harmful substances such as fumonisin and aflatoxins by Pseudomonas cocovenenans is avoided, ensuring the safety of the product.

[0039] 5. Reduce the GI value of base flour: Through enzymatic hydrolysis of cellulase and protease, and fermentation of compound lactic acid bacteria, the GI value of corn whole grain flour is effectively reduced, making it more suitable for people who need to control blood sugar. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The enzymes and bacteria used in the present invention are all commercially available products, and the specific details are as follows:

[0042] Neutral protease, purchased from Shanghai Yuanye Biotechnology Co., Ltd., enzyme activity 100u / mg;

[0043] Endoglucanase, purchased from Nanning Dongheng Huadao Biotechnology Co., Ltd., with an enzyme activity of 40,000 u / mg;

[0044] Papain, purchased from Shanghai Yuanye Biotechnology Co., Ltd., enzyme activity 800u / mg;

[0045] β-glucanase, purchased from Shanghai Yuanye Biotechnology Co., Ltd., enzyme activity 40u / mg;

[0046] Lactobacillus bulgaricus was purchased from China Center for Type Culture Collection, No.: CCTCC CB 20082294;

[0047] Streptococcus thermophilus was purchased from China Center for Type Culture Collection, No.: CCTCCAB 2010206;

[0048] Bifidobacterium longum subsp. longum was purchased from Shanghai Collection of Microorganisms, No.: SHMCC D80218;

[0049] Bifidobacterium animalis subsp. lactis was purchased from Shanghai Collection of Microorganisms, No.: SHMCC D18563;

[0050] Bacillus coagulans was purchased from Shanghai Collection of Microorganisms, number: SHBCC D50597;

[0051] Lactobacillus brevis was purchased from Shanghai Collection of Microorganisms, number: SHBCC D14346;

[0052] Lactobacillus plantarum was purchased from China Center for Type Culture Collection, No.: CCTCC AB2010210;

[0053] Lactobacillus casei, purchased from Shanghai Collection of Microorganisms, number: SHBCC D24737;

[0054] Lactobacillus paracasei was purchased from Shanghai Collection of Microorganisms, number: SHBCC D51555;

[0055] Bacillus subtilis was purchased from China Industrial Microbiological Culture Collection Center, No.: CICC 10732.

[0056] Example 1

[0057] This embodiment provides a preparation process of microencapsulated probiotic corn whole grain flour, comprising the following steps:

[0058] (1) Raw material preparation and pretreatment: The corn kernels were cleaned, crushed after adding water to obtain corn slurry, the mass ratio of corn kernels to water was 1:4, the pH value of the corn slurry was adjusted to 7.0, and the corn slurry was pre-gelatinized at 60° C. for 15 minutes. After the treatment, it was cooled to room temperature with running water;

[0059] (2) Enzymolysis: The cooled corn slurry was transferred to an enzymolysis tank, the pH value was adjusted to 4.5, 3000 u / mL corn slurry endoglucanase was added, and the mixture was heated to 46° C. and kept at a constant temperature for 1.5 hours for cellulase enzymolysis. The mixture was stirred continuously during the enzymolysis process. After the enzymolysis was completed, the mixture was heated to 90° C. and kept at this temperature for 8 minutes for inactivation treatment. The inactivated corn slurry was cooled to room temperature.

[0060] The pH value was adjusted to 7.0, 4000u / mL of neutral protease in corn slurry was added, and the mixture was heated to 48°C and kept at a constant temperature for 1.5 hours for protease enzymolysis. The mixture was stirred continuously during the enzymolysis. After the enzymolysis was completed, the mixture was heated to 90°C and kept for 8 minutes for enzyme inactivation. The inactivated corn slurry was cooled to room temperature to obtain corn slurry after enzymolysis for standby use.

[0061] (3) Fermentation: The composite lactic acid bacteria fermentation agent is inoculated into the milk-based raw material milk. The addition amount of the composite lactic acid bacteria fermentation agent is as follows: the addition amount of Lactobacillus bulgaricus is 10 7 CFU / mL milk-based raw material, the amount of thermophilic Streptococcus added is 10 9 CFU / mL milk-based raw materials, Bifidobacterium longum subspecies longum added at a dosage of 10 8 CFU / mL milk-based raw materials, the addition amount of Bifidobacterium animalis subsp. lactis is 10 6 CFU / mL milk-based raw material, heated to 37°C, maintained at a constant temperature, and fermented for 20 hours to obtain fermented yogurt;

[0062] (4) Mixing and refining: mixing the fermented yogurt obtained in step (3) and the corn slurry obtained in step (2) at a mass ratio of 1:3, and subjecting the mixture to a colloid mill to further refine the particles;

[0063] (5) Microencapsulation: Gum arabic, sodium alginate, chitosan and maltodextrin in a mass ratio of 2.5:1.5:1.0:2.0 were weighed and dissolved in deionized water to obtain a microencapsulation wall material aqueous solution with a total mass concentration of 8%, and the microencapsulation wall material aqueous solution was mixed with the mixed solution after refinement in step (4) in a mass ratio of 1:2.5, heated to 45° C., stirred, and the mixture was spray-dried at a spray drying temperature of 55° C. for 40 minutes to obtain microencapsulated corn flour;

[0064] (6) Mixing: mixing the microencapsulated corn flour and the Bacillus coagulans powder in a mass ratio of 25:1 to obtain the microencapsulated probiotic corn whole grain flour.

[0065] Example 2

[0066] This embodiment provides a preparation process of microencapsulated probiotic corn whole grain flour, comprising the following steps:

[0067] (1) Raw material preparation and pretreatment: The corn kernels were cleaned, crushed after adding water to obtain corn slurry, the mass ratio of corn kernels to water was 1:4, the pH value of the corn slurry was adjusted to 7.0, and the corn slurry was moderately pre-gelatinized at 70° C. for 12 minutes. After the treatment, it was cooled to room temperature with running water;

[0068] (2) Enzymolysis: The cooled corn slurry was transferred to an enzymolysis tank, the pH value was adjusted to 4.5, 2000 u / mL corn slurry endoglucanase was added, and the mixture was heated to 46° C. and kept at a constant temperature for 1.5 hours for cellulase enzymolysis. The mixture was stirred continuously during the enzymolysis process. After the enzymolysis was completed, the mixture was heated to 90° C. and kept at this temperature for 8 minutes for inactivation treatment. The inactivated corn slurry was cooled to room temperature.

[0069] The pH value was adjusted to 7.0, 3000u / mL of neutral protease in corn slurry was added, and the mixture was heated to 48°C and kept at a constant temperature for protease enzymolysis for 1.5 hours. The mixture was stirred continuously during the enzymolysis process. After the enzymolysis was completed, the mixture was heated to 90°C and kept for 8 minutes for inactivation. The inactivated corn slurry was cooled to room temperature to obtain corn slurry after enzymolysis for standby use.

[0070] (3) Fermentation: The composite lactic acid bacteria fermentation agent is inoculated into the milk-based raw material milk. The addition amount of the composite lactic acid bacteria fermentation agent is as follows: the addition amount of Lactobacillus bulgaricus is 10 6 CFU / mL milk-based raw material, the amount of thermophilic Streptococcus added is 10 10 CFU / mL milk-based raw materials, Bifidobacterium longum subspecies longum added at a dosage of 10 9 CFU / mL milk-based raw materials, the addition amount of Bifidobacterium animalis subsp. lactis is 10 7 CFU / mL milk-based raw material, heated to 37°C, maintained at a constant temperature, and fermented for 20 hours to obtain fermented yogurt;

[0071] (4) Mixing and refining: mixing the fermented yogurt obtained in step (3) and the corn slurry obtained in step (2) at a mass ratio of 1:3, and subjecting the mixture to a colloid mill to further refine the particles;

[0072] (5) Microencapsulation: Gum arabic, sodium alginate, chitosan and maltodextrin in a mass ratio of 2.0:2.0:1.0:1.5 were weighed and dissolved in deionized water to obtain a microencapsulation wall material aqueous solution with a mass concentration of 10%, and the microencapsulation wall material aqueous solution was mixed with the mixed solution after refinement in step (4) in a mass ratio of 1:3, heated to 45° C., stirred, and the mixture was spray-dried at a spray drying temperature of 55° C. for 40 minutes to obtain microencapsulated corn flour;

[0073] (6) Mixing: mixing the microencapsulated corn flour and the Bacillus coagulans powder in a mass ratio of 20:1 to obtain the microencapsulated probiotic corn whole grain flour.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is that the neutral protease is replaced by papain, and the endoglucanase is replaced by β-glucanase.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that the milk-based raw material milk is subjected to gradient fermentation, specifically, Lactobacillus bulgaricus (10 7 CFU / mL milk-based raw material), anaerobic fermentation was carried out at 37°C for 5 hours, and thermophilic Streptococcus (10 9 CFU / mL milk-based raw material), anaerobic fermentation was carried out at 37°C for 5 hours, and Bifidobacterium longum subsp. longum (10 8 CFU / mL milk-based raw material), anaerobic fermentation was carried out at 37°C for 5 hours, and Bifidobacterium animalis subsp. lactis (10 6 CFU / mL milk-based raw material), and anaerobically fermented at 37°C for 5 hours to obtain fermented yogurt.

[0078] Comparative Example 3

[0079] The difference between this comparative example and Example 1 is that Lactobacillus bulgaricus is replaced by Lactobacillus brevis, Streptococcus thermophilus is replaced by Lactobacillus plantarum, Bifidobacterium longum subsp. longum is replaced by Lactobacillus casei, and Bifidobacterium animalis subsp. lactis is replaced by Lactobacillus paracasei.

[0080] Comparative Example 4

[0081] The difference between this comparative example and Example 1 is that gum arabic and maltodextrin are replaced by sodium carboxymethyl cellulose and corn starch respectively.

[0082] Comparative Example 5

[0083] The difference between this comparative example and Example 1 is that Bacillus coagulans is replaced by Bacillus subtilis.

[0084] Performance test 1 GI value determination

[0085] The GI values ​​of the corn whole grain flours prepared in Examples 1-2 and Comparative Examples 1-5 were tested according to the method specified in ISO 26642:2010 "Determination of Glycemic Index (GI) of Foods and Recommendations for Food Classification". The results are shown in Table 1:

[0086] Table 1 GI value test results

[0087]

[0088] The above results show that the corn whole grain flour prepared by the present invention has a lower GI value and is suitable for people who need to control blood sugar. In comparative example 1, neutral protease is replaced by papain, and endoglucanase is replaced by beta-glucanase. The mechanism of action and efficiency of these enzymes are different, which may cause the macromolecular substances in the corn slurry to be decomposed incompletely. The incompletely decomposed protein and cellulose will increase the digestion rate of starch during the digestion process, resulting in an increase in the GI value. In addition, incomplete enzymolysis will affect the subsequent fermentation effect, and the metabolites (such as lactic acid) produced during the fermentation process may be reduced, and the GI value cannot be effectively reduced. In comparative example 2, gradient fermentation was adopted, that is, a strain was added each time to ferment for 5 hours. This fermentation method may not be as good as the fermentation effect of adding all strains at one time. Gradient fermentation may cause the metabolites of some strains to be insufficient to completely change the properties of corn slurry, thereby affecting the GI value. In comparative example 3, Lactobacillus bulgaricus was replaced by Lactobacillus brevis, Streptococcus thermophilus was replaced by Lactobacillus plantarum, Bifidobacterium longum subspecies long was replaced by Lactobacillus casei, and Bifidobacterium animalis subspecies lactis was replaced by Lactobacillus paracasei. These strains have different metabolic characteristics and cannot produce enough metabolites to reduce the GI value. In Comparative Example 4, gum arabic and maltodextrin were replaced by sodium carboxymethyl cellulose and corn starch, respectively. The physicochemical properties of these alternative materials are different, which may affect the effect of microencapsulation, resulting in insufficient protection of probiotics and slightly affecting the GI value. In Comparative Example 5, Bacillus coagulans was replaced by Bacillus subtilis. The metabolic characteristics of these two strains are different, which slightly affects the GI value of the product.

[0089] Performance Test 2 Probiotic Activity Detection

[0090] The probiotic survival rates of the corn whole grain flour prepared in Examples 1-2 and Comparative Examples 1-5 were tested after being placed for 12 months and in artificial gastric juice and artificial intestinal juice.

[0091] Test method:

[0092] (1) Determination of initial viable count:

[0093] Take 1g of sample from freshly prepared cereal powder and add it to 9mL of sterile saline to make a diluent. Take 0.1mL of the diluent and spread it evenly on MRS medium and culture it at 37℃ for 48 hours. Count the number of colonies on the plate and calculate the number of colonies per gram of sample (CFU / g).

[0094] (2) Determination of viable bacterial count after 12 months:

[0095] After the corn whole grain flour prepared in Examples 1-2 and Comparative Examples 1-5 was placed at room temperature for 12 months, the colony count was determined according to the method in (1).

[0096] (3) Probiotic survival test in artificial gastric juice and artificial intestinal juice:

[0097] Preparation of artificial gastric juice: 0.2 g pepsin was dissolved in 1000 mL of hydrochloric acid solution with pH 2.0 at 37°C with shaking.

[0098] Preparation of artificial intestinal fluid: 0.1 g trypsin was dissolved in 1000 mL of pH 7.0 phosphate buffer at 37°C with shaking.

[0099] Take 1g of sample from cereal powder that has been stored at room temperature for 12 months, add it to 9mL of sterile saline to make a diluent. Add the diluent to artificial gastric juice and shake it at 37°C for 2 hours. Add the sample treated with artificial gastric juice to artificial intestinal juice and shake it at 37°C for 2 hours. Take 0.1mL of the treated solution, spread it evenly on MRS culture medium, and culture it at 37°C for 48 hours. Count the number of colonies on the plate and calculate the number of colonies per gram of sample (CFU / g).

[0100] The results are shown in Table 2:

[0101] Table 2 Probiotic activity test results

[0102]

[0103]

[0104] The above results show that the corn whole grain flour prepared by the present invention has the characteristics of high activity and high stability after long-term storage and treatment with gastric juice and intestinal juice. Comparative Example 1 replaces the neutral protease with papain, and replaces the endoglucanase with β-glucanase. The different mechanisms of action and efficiencies of these enzymes result in incomplete decomposition of macromolecular substances in the corn slurry, affecting the formation and structural stability of the microencapsulation wall material, thereby reducing the protective effect of the probiotics; the enzymatic hydrolysis products of papain and β-glucanase are not as conducive to the formation of a stable microcapsule structure as the enzymatic hydrolysis products of neutral protease and endoglucanase, resulting in insufficient protection of probiotics in gastric juice and intestinal juice, and are easily destroyed by digestive enzymes and acidic environments. Gradient fermentation was used in Comparative Example 2, which may cause the metabolites of some strains to be insufficient to completely change the properties of corn slurry, thereby affecting the formation and structural stability of microencapsulation wall materials and reducing the protective effect of probiotics; Gradient fermentation also causes uneven distribution of probiotics in corn slurry, and probiotics in some areas are not fully protected; In addition, the shorter time of each fermentation is not enough to fully degrade starch and other macromolecular substances, resulting in the microcapsule structure being not stable enough, and probiotics are easily destroyed in gastric juice and intestinal juice. In Comparative Example 3, Lactobacillus bulgaricus was replaced with Lactobacillus brevis, Streptococcus thermophilus was replaced with Lactobacillus plantarum, Bifidobacterium longum subspecies long was replaced with Lactobacillus casei, and Bifidobacterium animalis subspecies lactis was replaced with Lactobacillus paracasei. These strains have different metabolic characteristics and cannot produce enough metabolites to form a stable microcapsule structure, thus affecting the protective effect of probiotics; in addition, the synergistic effect between different strains is not as effective as the original combination, resulting in reduced stability of the microcapsule structure; in addition, the acid resistance and bile resistance of these strains may not be as good as the original strains, resulting in reduced survival rate in gastric juice and intestinal juice. In Comparative Example 4, gum arabic and maltodextrin were replaced with sodium carboxymethyl cellulose and corn starch, respectively. The microcapsule structure formed by the microencapsulation wall material after replacement is not as stable as the structure of Examples 1 and 2; different wall materials have different protective effects on probiotics. The microcapsules formed in Comparative Example 4 have poor stability in gastric juice and intestinal juice, resulting in the probiotics being easily destroyed by digestive enzymes and acidic environments. In Comparative Example 5, Bacillus coagulans was replaced with Bacillus subtilis. The metabolites of Bacillus subtilis are not as conducive to the formation of stable microcapsule structure as those of Bacillus coagulans, which affects the protective effect of probiotics; the acid and bile resistance of Bacillus subtilis are not as good as those of Bacillus coagulans, resulting in a lower survival rate in gastric juice and intestinal juice.

[0105] The above is 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 principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A process for preparing microencapsulated probiotic corn whole grain flour, comprising the following steps: (1) Raw material preparation and pretreatment: The corn kernels are cleaned, crushed after adding water to obtain corn slurry, the pH value of the corn slurry is adjusted to 6.0-7.0, the corn slurry is appropriately pre-gelatinized, and cooled to room temperature after the treatment is completed; (2) Enzymatic hydrolysis: transferring the cooled corn slurry to an enzymatic hydrolysis tank, adding cellulase and protease respectively for continuous enzymatic hydrolysis to obtain enzymatically hydrolyzed corn slurry for later use; (3) fermentation: inoculating a composite lactic acid bacteria fermentation agent into a milk-based raw material, wherein the composite lactic acid bacteria fermentation agent includes Lactobacillus bulgaricus, Streptococcus thermophilus, Bifidobacterium longum subspecies longum and Bifidobacterium animalis subspecies lactis, heating to 36-38° C., maintaining a constant temperature, and fermenting for 12-24 hours to obtain fermented yogurt; (4) Mixing and refining: mixing the fermented yogurt obtained in step (3) with the corn slurry obtained in step (2), and processing the mixture through a colloid mill or a homogenizer to further refine the particles; (5) Microencapsulation: preparing an aqueous solution of a microencapsulation wall material, mixing the aqueous solution of the microencapsulation wall material with the mixed solution refined in step (4), heating to 40 to 50° C., stirring, and spray drying the mixture at a spray drying temperature of 50 to 60° C. for 30 to 60 minutes to obtain microencapsulated corn flour; (6) Mixing: mixing the microencapsulated corn flour with the Bacillus coagulans powder to obtain the microencapsulated probiotic corn whole grain flour.

2. The preparation process according to claim 1, characterized in that: In step (1), the mass ratio of the original corn kernels to water is 1:(3-5); the temperature of the moderate pre-gelatinization treatment is 60-70° C., and the time is 10-20 minutes; and the cooling is performed by flowing water cooling or cooler cooling.

3. The preparation process according to claim 1, characterized in that: The continuous enzymatic hydrolysis treatment in step (2) is specifically as follows: (i) adding 2000-3000 u / mL of corn slurry cellulase, heating to 45-50° C., maintaining constant temperature, performing cellulase enzymolysis for 1-2 hours, stirring continuously during the enzymolysis process, and after the enzymolysis is completed, heating to 90-95° C., maintaining for 5-10 minutes, performing inactivation treatment, and cooling the inactivated corn slurry to room temperature; (ii) adding 3000-4000 u / mL of protease in corn slurry, heating to 45-50° C., maintaining constant temperature, and performing protease enzymolysis for 1-2 hours, stirring continuously during the enzymolysis process. After the enzymolysis is completed, heating to 90-95° C., maintaining for 5-10 minutes, and performing inactivation treatment, and cooling the inactivated corn slurry to room temperature.

4. The preparation process according to claim 3, characterized in that: The cellulase is endoglucanase and exoglucanase, and the protease is alkaline protease or neutral protease.

5. The preparation process according to claim 1, characterized in that: The milk-based raw material in step (3) is milk or vegetable milk.

6. The preparation process according to claim 1, characterized in that: The amount of Lactobacillus bulgaricus added in step (3) is 10 6 -10 7 CFU / mL milk-based raw material, the amount of thermophilic Streptococcus added is 10 9 -10 10 CFU / mL milk-based raw materials, the addition amount of Bifidobacterium longum subsp. longum is 10 8 -10 9 CFU / mL milk-based raw materials, the addition amount of Bifidobacterium animalis subsp. lactis is 10 6 -10 7 CFU / mL milk-based raw material.

7. The preparation process according to claim 1, characterized in that: The mass ratio of the fermented yogurt to the corn slurry in step (4) is 1:(2-4).

8. The preparation process according to claim 1, characterized in that: The microencapsulation wall material in step (4) is gum arabic, sodium alginate, chitosan and maltodextrin, and the mass ratio is (2-3): (1-2): (0.5-1.5): (1.5-2.5). The mass concentration of the microencapsulation wall material aqueous solution is 5%-10%, and the mass ratio of the microencapsulation wall material aqueous solution to the refined mixed solution is 1: (2-3).

9. The preparation process according to claim 1, characterized in that: The mass ratio of the microencapsulated corn flour to the Bacillus coagulans powder in step (5) is 20-30:

1.

10. Use of the preparation process according to any one of claims 1 to 9 in the preparation of whole-grain corn flour.

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