Preparation method of pea whey protein yoghourt with high antioxidant activity and high digestibility

Abstract

The invention discloses a preparation method of pea whey protein yoghourt with high antioxidant activity and high digestibility, and belongs to the technical field of processing and utilization of agricultural and sideline products. The method comprises the following steps: by taking pea whey wastewater as a raw material, carrying out electrodialysis desalination treatment, and adding polysaccharide solid powder and pea whey protein to carry out complex coacervation so as to recover the pea whey protein; the preparation method comprises the following steps: performing freeze-drying pretreatment on a pea whey protein-polysaccharide compound to obtain a yoghourt base material capable of being quickly fermented, and then screening and optimizing a compound fermentation strain to prepare the pea whey protein yoghourt with high antioxidant activity and high digestibility. According to the invention, effective recovery of pea whey protein is realized, and environmental pollution and protein resource waste are reduced; the economic added value of pea byproduct processing can be improved, and technical guidance is provided for high-valued application of pea whey protein resources in food.

Description

Technical Field

[0001] The invention relates to a method for preparing pea whey protein yogurt with high antioxidant activity and high digestibility by utilizing protein resources of pea whey wastewater, and belongs to the technical field of processing and utilization of agricultural and sideline products. Background Art

[0002] As a byproduct of pea protein isolate, pea whey protein mainly exists in pea whey. It has a large total amount and certain physiological activity. It is a superior protein resource. The effective recovery and utilization of pea whey protein can not only avoid environmental pollution, but also increase the added value of pea processing. Plant yogurt can increase the beneficial ingredients of yogurt and reduce anti-nutritional factors and allergic components. Plant-based yogurt contains a large amount of high-quality plant protein and is rich in dietary fiber. In addition to the advantages of ordinary yogurt, it also has unique plant nutrients, such as isoflavones, γ-aminobutyric acid and phenolic substances. It adapts to more special consumers in terms of nutrition, and brings good news to people who are allergic to milk protein, have high cholesterol, and are concerned about animal welfare and environmental protection. According to relevant standards, the protein content of plant-based fermented milk products is generally not less than 2.0%; however, the protein content in pea whey wastewater is very low (~0.3-0.5%), so direct fermentation cannot meet the requirements of plant-based yogurt products; if whey concentration treatment is performed, while the protein content increases, a large amount of salt ions in pea whey are also concentrated exponentially, which will lead to slow fermentation and the problem of not being able to reach the end of fermentation. In order to solve the above technical problems, the present application recovers pea whey protein through polysaccharide complex coagulation, and uses it as a fermentation base for lactic acid bacteria fermentation, which not only meets the protein content requirements, but also does not cause an increase in salt concentration, and has the technical advantage of fast fermentation speed. In addition, the introduced polysaccharide component can further improve the texture of yogurt and enhance the taste and stability of yogurt.

[0003] At present, there are few reports on the preparation of plant-based yogurt using pea alone, and no reports on the preparation of yogurt using pea whey protein have been found. Guo Jiaxi used pea and whole milk powder as raw materials to optimize the raw material ratio, enzymatic hydrolysis conditions and fermentation conditions; Li Ying et al. used pea protein powder and milk as the main raw materials, acidity and sensory evaluation as indicators, and studied the effects of protein powder addition, starter inoculation amount and fermentation time on the quality of coagulated pea yogurt; Denkova et al. reported on the preparation of yogurt and acidophilic beverages by probiotic fermentation of pea milk and skim milk mixtures in different proportions; Yousseef et al. prepared yogurt products by fermenting a mixture of pea protein and milk or milk powder; Denkova et al.'s research showed that saccharomyces sacchariformis 25-G can grow and metabolize in a substrate containing skim milk and pea milk, and the resulting product has a high number of viable bacteria and medium titratable acidity. From current reports, almost all pea yogurts are fermented by mixing pea protein with other raw materials. Therefore, there is a lack of pure plant-based yogurt that is suitable for more special consumers and is environmentally friendly and made solely from pea-derived protein. In addition, since plant seeds, including peas and soybeans, often contain a variety of anti-nutritional factors, which affect the digestion and absorption of nutrients such as protein, the digestion and absorption characteristics of their fermented products are difficult to compare with traditional milk yogurt. Therefore, how to improve the digestion and absorption characteristics of plant-based yogurt is an important technical challenge. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the present invention provides a method for preparing pea whey protein yogurt with high antioxidant activity and high digestibility by utilizing protein resources of pea whey wastewater. The purpose is to utilize pea whey wastewater raw materials, recover whey protein by adding polysaccharide solid powder, freeze-dry the pea whey protein-polysaccharide complex to obtain a yogurt base that can be rapidly fermented, and then optimize the fermentation strain and fermentation process conditions to prepare a pure plant-based yogurt with high antioxidant activity and high digestibility, thereby realizing high added value application of pea whey protein.

[0005] The first technical solution provided by the present invention is as follows:

[0006] A method for preparing pea whey protein yogurt with high antioxidant activity and high digestibility comprises the following steps:

[0007] (1) Recovery of pea whey protein: first, desalt the pea whey wastewater, add polysaccharide powder, mix well, adjust the pH of the mixture to 3.4-4.2, stir and centrifuge, collect the precipitate, and obtain the recovered pea whey protein-polysaccharide complex;

[0008] (2) Pretreatment of the fermentation base: dispersing the pea whey protein-polysaccharide complex of step (1) in water, adjusting the pH to 7.0-7.5, stirring until completely dissolved, and then freeze-drying to obtain a freeze-dried powder of the complex, which is the pretreated fermentation base;

[0009] (3) Preparation of the fermentation liquid: Add a certain amount of deionized water to the pretreated fermentation base obtained in step (2) to prepare a solution with a protein concentration of 2.0% to 3.0%, add a carbon source, add vegetable oil after stirring, sterilize after high-speed shearing, and cool to room temperature to obtain the fermentation liquid;

[0010] (4) Preparation of pea whey protein yogurt: adding a composite starter to the fermented liquid obtained in step (3), fermenting at 40-43° C. for 4-10 h, cooling to room temperature and storing in a refrigerator at 2-6° C. for 8-12 h to obtain pea whey protein yogurt.

[0011] In one embodiment, in step (1), the electrodialysis desalination treatment is performed for 1-2 hours, and the final conductivity is controlled at 1.0-1.5 mS / cm.

[0012] In one embodiment, in step (1), the polysaccharide powder added at a certain mass concentration includes carrageenan, sodium alginate, and pectin, preferably carrageenan or sodium alginate, and the added amount is 0.05%-0.25%.

[0013] In one embodiment, in step (1), high-speed shearing is used for uniform mixing, the rotation speed of the high-speed shearing is 8000-10000 rpm, and the time of the high-speed shearing is 3-5 min.

[0014] In one embodiment, in step (1), the stirring time is 15-30 min.

[0015] In one embodiment, in step (1), the centrifugal speed is 4000-8000 rpm, and the centrifugal time is 15-30 min.

[0016] In one embodiment, in step (2), the pea whey protein-polysaccharide complex is dispersed in water according to a certain mass volume ratio so that the solid concentration is 3.0%-8.0%.

[0017] In one embodiment, in step (3), the carbon sources are sucrose and glucose, wherein the amount of sucrose added is 5%-8% of the fermented liquid, and the amount of glucose added is 1.5%-2.0% of the fermented liquid.

[0018] In one embodiment, in step (3), the vegetable oil includes sunflower oil, linseed oil, corn oil, palm oil, etc.; the added amount is 0.5%-2.0% by mass of the fermentation liquid.

[0019] In one embodiment, in step (3), the rotation speed of the high-speed shearing is 8000-10000 rpm, and the time of the high-speed shearing is 1-2 min.

[0020] In one embodiment, in step (3), the stirring time is 30 minutes.

[0021] In one embodiment, in step (3), the sterilization parameters are as follows: sterilization at 95° C. for 30-40 min.

[0022] In one embodiment, it is characterized in that, in step (4), the composite starter culture comprises thermophilic streptococcus, bulgaricus lactobacillus and lactococcus lactis, wherein the mass fraction of thermophilic streptococcus and bulgaricus lactobacillus accounts for 75-80% of the composite starter culture; the inoculation amount of the composite starter culture is (1.0-2.5)×10 6 CFU / g fermentation broth.

[0023] The second technical solution provided by the present invention is a pea whey protein yogurt prepared by the method described in the first technical solution.

[0024] The third technical solution provided by the present invention is the use of the method described in the first technical solution or the pea whey protein yogurt described in the second technical solution in the preparation of health products with antioxidant function.

[0025] The technical effects of the present invention are as follows:

[0026] The pea whey protein yogurt prepared by the present invention is fermented by using protein resources recovered from pea whey wastewater, which not only avoids environmental pollution but also increases the added value of pea processing; the pea whey protein yogurt prepared by the present invention has high antioxidant activity (scavenging ABTS free radical IC 50 The lowest value is 8.51mg / ml, scavenging hydroxyl free radical IC 50 value is 19.70mg / ml), high digestibility (protein digestibility and fat digestibility can reach more than 70%); the preparation process of the invention is simple and the cost is low; the invention does not add any animal ingredients, which brings good news to people who are allergic to milk protein, have high cholesterol, and care about animal welfare and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a flow chart of the preparation process of pea whey protein yogurt.

[0028] Figure 2This is the pH curve of the pea whey protein yogurt fermentation of Examples 1-3. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0030] Test method:

[0031] 1. In vitro digestibility:

[0032] Stomach digestion: Take 10g of sample and preheat it at 37℃ for 5min. Preheat SGF at 37℃ for 5min, then take 10mL and add it to the above sample, quickly adjust the pH of the mixed system to 2.5 with 1mol / L HCl solution, and digest it at 37℃ constant temperature water bath shaker (100rpm) for 2h.

[0033] Intestinal digestion: Use 2 mol / L NaOH solution to quickly adjust the pH of the mixed system after the above process to 7.0. Preheat SIF at 37°C for 5 min, add SIF (1 mL), bile salt solution (2.33 mL), lipase solution (1.66 mL) and pancreatin solution (1.66 mL) to the sample after gastric digestion in sequence, and stir and digest in a 37°C water bath for 2 h. During this period, use 0.1 mol / L NaOH solution to titrate the mixed system to maintain the pH of 7.0.

[0034] Gastric juice was prepared as follows:

[0035]

[0036] The intestinal fluid was prepared as follows:

[0037]

[0038] (1) Fat digestibility

[0039] The in vitro digestibility of fat was calculated based on the amount of NaOH used during small intestinal digestion.

[0040] Fatty acid release rate / % = (V×c×M) / 2m×100%

[0041] Where V refers to the volume of NaOH solution used when the digestion time is t (mL);

[0042] c refers to the concentration of the NaOH solution used in the titration (mol / L);

[0043] M refers to the average molecular mass of fat (g / mol);

[0044] m refers to the mass of fat (mg).

[0045] (2) Protein digestibility

[0046] After digestion, the sample was placed in a 95°C water bath to inactivate the enzyme for 15 minutes and cooled to room temperature. 10 g of the sample after in vitro simulated gastrointestinal digestion was taken, and an equal volume of 10% trichloroacetic acid was added to precipitate the protein. After stirring for 15 minutes and standing for one hour, the mixture was centrifuged at 8000 rpm and 4°C for 15 minutes, and the supernatant was taken to determine the protein content in the supernatant.

[0047] Protein digestibility = (protein content in supernatant - protein content in blank sample) / total protein content before digestion.

[0048] The blank yogurt sample was replaced with water, and the other conditions remained unchanged.

[0049] 2. Antioxidant activity:

[0050] Take 8 g of sample, add 5 mL of 80% (v / v) methanol solution and extract by ultrasonic at 60°C for 1 h, centrifuge (10000×g, 20 min, 4°C), then add 3 mL of 80% (v / v) methanol solution and extract by ultrasonic at 60°C for 1 h, take the supernatant and set aside.

[0051] (1) ABTS free radical scavenging rate

[0052] Mix equal volumes of 2.45mmol / L potassium persulfate solution and 7mmol / L ABTS solution, and react at room temperature in the dark for 12-16h to prepare ABTS free radical solution. Dilute the ABTS free radical solution with anhydrous ethanol to a certain multiple before use, ensuring that the absorbance of the dilution is 0.70±0.02 at 734nm.

[0053] Add 50uL sample solution and 150uL ABTS free radical solution to a 96-well ELISA plate, mix well, react at room temperature in the dark for 30 minutes, and measure the absorbance of the reaction mixture at 734nm. In order to deduct the influence of the sample itself on the test results, replace the ABTS free radical solution with an equal volume of deionized water as the sample control group, and replace the sample solution with an equal volume of deionized water as the negative group. Use VC as the positive control. Calculate the ABTS free radical scavenging rate according to the following formula:

[0054] ABTS free radical scavenging rate (%) = (A1-(B1-B2)) / A1×100

[0055] In the formula, A1 is the absorbance of the negative group;

[0056] B1 is the absorbance of the sample group;

[0057] B2 is the absorbance of the sample control group.

[0058] (2) Hydroxyl radical scavenging rate

[0059] First, add 50 μL of sample to the ELISA plate, then add 50 μL FeSO4 solution (3 mmol / L) and an equal volume of salicylic acid-ethanol solution (3 mmol / L), and finally add 50 μL H2O2 solution (6 mmol / L). React in the dark for 30 minutes, and measure the absorbance at 510 nm after the reaction. Use an equal volume of deionized water as the sample control group and negative group, and VC as the positive control. Calculate the scavenging rate of hydroxyl radicals and cation radicals according to the following formula:

[0060] Hydroxyl radical scavenging rate (%) = (A1-(B1-B2)) / A1×100

[0061] In the formula, A1 is the absorbance of the negative group;

[0062] B1 is the absorbance of the sample group;

[0063] B2 is the absorbance of the sample control group.

[0064] The raw materials used in the examples are:

[0065] From Zhengzhou Hehe Bioengineering Technology Co., Ltd., the strain numbers are as follows:

[0066] 1. Lactobacillus acidophilus: HH-LA26;

[0067] 2. Streptococcus thermophilus: HH-ST08;

[0068] 3. Lactobacillus bulgaricus: HH-LB57;

[0069] 4. Lactobacillus rhamnosus: PB-LR76;

[0070] 5. Lactobacillus casei: PB-LC39;

[0071] 6. Lactobacillus paracasei: HH-LP58;

[0072] 7. Lactobacillus plantarum: HH-LP56;

[0073] 8. Lactobacillus fermentum: HH-LF39;

[0074] 9. Lactococcus lactis: HH-LLL39.

[0075] Example 1

[0076] refer to Figure 1 , the specific steps are as follows:

[0077] (1) Recovery of pea whey protein: First, the pea whey wastewater was subjected to electrodialysis desalination treatment at a voltage of 24 V for 1 h, and the final conductivity was about 1.5 mS / cm. After desalination, sodium alginate powder with a mass concentration of 0.125% was added to the desalted pea whey, and high-speed shearing was performed at 10,000 rpm for 3 min. The mixture was fully mixed, and the pH of the mixed solution was adjusted to 4.0. The mixture was stirred for 30 min, and centrifuged at 9,000 rpm for 10 min. The precipitate was collected to obtain the recovered pea whey protein-sodium alginate complex.

[0078] (2) Pretreatment of fermentation base: The pea whey protein-sodium alginate complex prepared in step (1) is dispersed in water at a certain mass volume ratio so that the solid concentration is 7.0%, the pH is adjusted to 7.0, and the mixture is stirred until completely dissolved and then freeze-dried to obtain a freeze-dried powder of the complex, which is the pretreated fermentation base.

[0079] (3) Preparation of the fermented liquid: Add a certain mass of deionized water to the pretreated fermentation base obtained in step (2) to prepare a solution with a protein concentration of 2.5%, add 7% sucrose and 2.0% glucose based on the mass of the above fermentation base, stir for 30 minutes, add 0.5% palm stearate, high-speed shear at 9000 rpm for 2 minutes, sterilize at 95°C for 40 minutes, and cool to room temperature to obtain the fermented liquid.

[0080] (4) Preparation of pea whey protein yogurt: Add a composite starter (Streptococcus thermophilus, Lactobacillus bulgaricus and Lactococcus lactis, in a ratio of 5:3:2) to the fermented liquid obtained in step (3), with an inoculum size of 1.0×10 6 CFU / g fermentation liquid, fermented at 42℃ for 4h to end point pH 4.5, fermentation pH curve as shown Figure 2 , cooled to room temperature and then stored in a refrigerator at 4°C for 12 hours to obtain pea whey protein yogurt.

[0081] The protein digestibility of the above pea whey protein yogurt was determined to be 74.77%, the fat digestibility was 79.86%, and the antioxidant activity: scavenging ABTS hydroxyl radical IC 50 The value is 8.51mg / ml, scavenging hydroxyl free radical IC 50 The value is 19.70 mg / ml (see Table 1).

[0082] Example 2

[0083] The specific steps are as follows:

[0084] (1) Recovery of pea whey protein: First, the pea whey wastewater was subjected to electrodialysis desalination treatment at a voltage of 24 V for 1 h, and the final conductivity was about 1.5 mS / cm. After desalination, carrageenan powder with a mass concentration of 0.1% was added to the desalted pea whey, and high-speed shearing was performed at 10,000 rpm for 3 min. The mixture was fully mixed, and the pH of the mixed solution was adjusted to 3.6. The mixture was stirred for 30 min, and centrifuged at 8,000 rpm for 15 min. The precipitate was collected to obtain the recovered pea whey protein-carrageenan complex.

[0085] (2) Pretreatment of the fermentation base: The pea whey protein-carrageenan complex prepared in step (1) is dispersed in water at a certain mass volume ratio so that the solid concentration is 5.0%, the pH is adjusted to 7.0, and the mixture is stirred until completely dissolved and then freeze-dried to obtain a freeze-dried powder of the complex, which is the pretreated fermentation base.

[0086] (3) Preparation of the fermented liquid: Add a certain mass of deionized water to the pretreated fermentation base obtained in step (2) to prepare a solution with a protein concentration of 2.0%, add 8% sucrose and 1.5% glucose based on the mass of the fermentation base, stir for 30 minutes, add 0.5% sunflower oil, high-speed shear at 8000 rpm for 2 minutes, sterilize at 95° C. for 40 minutes, and cool to room temperature to obtain the fermented liquid.

[0087] (4) Preparation of pea whey protein yogurt: Add a composite starter (Streptococcus thermophilus, Lactobacillus bulgaricus and Lactococcus lactis, in a ratio of 5:3:2) to the fermented liquid obtained in step (3), with an inoculum size of 1.0×10 6 CFU / g fermentation liquid, fermented at 42℃ for 6h to the end point pH 4.5, the fermentation pH curve is as follows Figure 2 , cooled to room temperature and then stored in a refrigerator at 4°C for 12 hours to obtain pea whey protein yogurt.

[0088] Example 3

[0089] The specific steps are as follows:

[0090] (1) Recovery of pea whey protein: First, the pea whey wastewater was subjected to electrodialysis desalination treatment at a voltage of 24 V for 1 h, and the final conductivity was about 1.5 mS / cm. After desalination, pectin powder with a mass concentration of 0.1% was added to the desalted pea whey, and high-speed shearing was performed at 10,000 rpm for 3 min. The mixture was fully mixed, and the pH of the mixture was adjusted to 3.4. The mixture was stirred for 30 min, and centrifuged at 8,000 rpm for 15 min. The precipitate was collected to obtain the recovered pea whey protein-pectin complex.

[0091] (2) Pretreatment of the fermentation base: The pea whey protein-pectin complex prepared in step (1) is dispersed in water at a certain mass volume ratio so that the solid concentration is 8.0%, the pH is adjusted to 7.0, and the mixture is stirred until completely dissolved and then freeze-dried to obtain a freeze-dried powder of the complex, which is the pretreated fermentation base.

[0092] (3) Preparation of the fermented liquid: Add a certain mass of deionized water to the pretreated fermentation base obtained in step (2) to prepare a solution with a protein concentration of 2.8%, add 8% sucrose and 2.0% glucose based on the mass of the above fermentation base, stir for 30 minutes, add 0.5% corn oil, high-speed shear at 9000 rpm for 2 minutes, sterilize at 95°C for 40 minutes, and cool to room temperature to obtain the fermented liquid.

[0093] (4) Preparation of pea whey protein yogurt: Add a composite starter (Streptococcus thermophilus, Lactobacillus bulgaricus and Lactococcus lactis, in a ratio of 3:5:2) to the fermented liquid obtained in step (3), with an inoculum size of 1.0×10 6 CFU / g fermentation liquid, fermented at 42℃ for 8h until the end point pH 4.5, the fermentation pH curve is as follows Figure 2 , cooled to room temperature and then stored in a refrigerator at 4°C for 12 hours to obtain pea whey protein yogurt.

[0094] Comparative Example 1:

[0095] Specific implementation method Referring to Example 1, the difference is that in step (2), after stirring until completely dissolved, freeze drying is not performed, and the remaining steps remain unchanged. The pH value is measured at 4h, 6h and 12h of fermentation to detect whether the sample reaches the fermentation end point pH 4.5.

[0096] After measurement, the pH of the sample in comparative example 1 was 5.17 when fermented for 4 hours, 5.02 when fermented for 6 hours, and 4.82 when fermented for 12 hours. The above data show that the fermentation base material that has not been freeze-dried cannot reach the fermentation end point within 12 hours and cannot form pea whey protein yogurt; while the fermentation end point time of example 1 is only 4 hours.

[0097] Comparative Example 2:

[0098] Specific implementation method Referring to Example 1, the difference is that after the fermentation liquid is prepared, no fermentation is performed, that is, step 4 is omitted, and the other steps remain unchanged. The in vitro digestibility and antioxidant activity are determined, and the IC value of antioxidant activity is obtained by SPSS analysis. 50 value.

[0099] After measurement, as shown in Table 1, the in vitro digestibility and antioxidant activity of the unfermented sample of Comparative Example 2 were significantly lower than those of Example 1, indicating that pea whey protein yogurt has high in vitro digestibility and high antioxidant activity.

[0100] Table 1. Comparison table of comparative example 2 and embodiment

[0101]

[0102] Comparative Example 3:

[0103] Specific implementation method Referring to Example 1, the difference is that in step (4), 9 types of bacteria are used for single-strain fermentation, and the inoculation amount remains unchanged. The in vitro digestibility and antioxidant activity of the samples are measured, and the IC values ​​of antioxidant activity are obtained by SPSS analysis. 50 value.

[0104] After measurement, as shown in Table 2, the in vitro digestibility and antioxidant activity of the pea whey protein yogurt fermented with 9 single strains in Comparative Example 3 were significantly lower than those in Example 1 (Table 1), indicating that the optimized composite fermentation strains of this invention significantly enhanced the protein digestion and absorption rate and antioxidant activity of pea whey protein yogurt.

[0105] Table 2. In vitro digestibility and antioxidant activity of comparative example 3

[0106]

[0107]

[0108] Comparative Example 4:

[0109] Specific implementation method Referring to Example 1, the difference is that the 0.5% palm stearate in step 1 is adjusted to 3.0%, and the other steps remain unchanged. The in vitro digestibility and antioxidant activity were determined, and the IC value of antioxidant activity was obtained by SPSS analysis. 50 value.

[0110] The protein digestibility of the above pea whey protein yogurt was determined to be 65.78%, the fat digestibility was 42.35%, and the antioxidant activity: scavenging ABTS free radical IC 50 The value is 13.56mg / ml, scavenging hydroxyl free radical IC 50 The value is 27.37mg / ml.

[0111] The in vitro digestibility and antioxidant activity of the yogurt sample obtained in Comparative Example 4 were significantly lower than those in Example 1, indicating that the pea whey protein yogurt prepared by the present invention has a high in vitro digestibility and high antioxidant activity.

[0112] Comparative Example 5:

[0113] Specific implementation method Referring to Example 1, the difference is that the carrageenan in step 1 is replaced with xanthan gum, and the other steps remain unchanged. The pH value is measured at 6h, 12h and 18h ​​of fermentation to detect whether the sample reaches the fermentation end point pH 4.5.

[0114] After determination, the pH of the sample in comparative example 5 was 5.20 when fermented for 6 hours, 4.98 when fermented for 12 hours, and 4.71 when fermented for 18 hours. The above data show that after replacing carrageenan with xanthan gum, the fermentation speed is slow, and the fermentation end point of 4.5 cannot be reached in 18 hours, and pea whey protein yogurt cannot be prepared.

[0115] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing pea whey protein yogurt, characterized in that: The following steps are involved: (1) Recovery of pea whey protein: After desalting the pea whey wastewater, add polysaccharide powder, mix well, adjust the pH of the mixture to 3.4-4.2, stir and centrifuge, collect the precipitate, and obtain the recovered pea whey protein-polysaccharide complex; (2) Pretreatment of the fermentation base: dispersing the pea whey protein-polysaccharide complex of step (1) in water, adjusting the pH to 7.0-7.5, stirring until completely dissolved, and then freeze-drying to obtain a freeze-dried powder of the complex, which is the pretreated fermentation base; (3) Preparation of the fermentation liquid: the pretreated fermentation base material in step (2) is prepared into an aqueous solution with a protein concentration of 2.0% to 3.0%, a carbon source is added, and vegetable oil is added after stirring, sterilized after high-speed shearing, and cooled to room temperature to obtain the fermentation liquid; (4) Preparation of pea whey protein yogurt: adding a composite starter to the fermented liquid of step (3), fermenting at 40-43° C. for 4-10 h, cooling to room temperature and storing in a refrigerator at 2-6° C. for 8-12 h to obtain pea whey protein yogurt.

2. The method according to claim 1, characterized in that In step (1), the electrodialysis desalination treatment is carried out for 1-2 hours, and the final conductivity is controlled at 1.0-1.5 mS / cm.

3. The method according to claim 1, characterized in that In step (1), the amount of polysaccharide powder added is 0.05%-0.25% of the desalted pea whey wastewater, and the polysaccharide includes carrageenan, sodium alginate, and pectin; optionally, the polysaccharide is carrageenan or sodium alginate.

4. The method according to claim 1, characterized in that In step (1), the mixture is mixed uniformly by high-speed shearing, wherein the rotation speed of the high-speed shearing is 8000-10000 rpm and the time of the high-speed shearing is 3-5 min.

5. The method according to claim 1, characterized in that In step (2), the pea whey protein-polysaccharide complex is dispersed in water according to a certain mass volume ratio so that the solid concentration is 3.0%-8.0%.

6. The method according to claim 1, characterized in that In step (3), the carbon sources are sucrose and glucose, wherein the amount of sucrose added is 5%-8% of the fermented liquid, and the amount of glucose added is 1.5%-2.0% of the fermented liquid; The vegetable oil includes sunflower oil, linseed oil, corn oil, palm oil and the like; the added amount is 0.5%-2.0% by mass of the liquid to be fermented.

7. The method according to claim 1, characterized in that In step (3), the rotation speed of the high-speed shearing is 8000-10000 rpm, and the time of the high-speed shearing is 1-2 min.

8. The method according to claim 1, characterized in that In step (4), the composite fermentation agent comprises thermophilic streptococcus, bulgaricus lactobacillus and lactococcus lactis, wherein the mass fraction of thermophilic streptococcus and bulgaricus lactobacillus accounts for 75-80% of the composite fermentation agent; the inoculation amount of the composite fermentation agent is (1.0-2.5)×10 6 CFU / g fermentation broth.

9. Pea whey protein yogurt prepared by the method according to any one of claims 1 to 8.

10. Use of the method according to claims 1 to 8 or the pea whey protein yogurt according to claim 9 in preparing a health product with antioxidant function.

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