A method for preparing a pea whey protein yogurt with high antioxidant activity and high digestibility

Abstract

The application discloses a preparation method of pea whey protein yogurt 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: taking pea whey wastewater as raw material, desalting treatment is carried out through electrodialysis, polysaccharide solid powder is added, and pea whey protein is recovered through complex coagulation of the pea whey protein; the pea whey protein-polysaccharide compound is pretreated through freeze-drying to obtain yogurt base material which can be quickly fermented, then through screening and optimization of compound fermentation strains, the pea whey protein yogurt with high antioxidant activity and high digestibility is prepared. The application not only realizes effective recovery of pea whey protein, reduces environmental pollution and protein resource waste, but also can improve the economic added value of pea byproduct processing, and provides technical guidance for high-value application of pea whey protein resources in food.

Description

Technical Field

[0001] This invention relates to a method for preparing pea whey protein yogurt with high antioxidant activity and high digestibility using protein resources from pea whey wastewater, belonging to the field of agricultural and sideline product processing and utilization technology. Background Technology

[0002] Pea whey protein, a byproduct of pea protein isolate, is mainly found in pea whey. It is abundant, possesses certain physiological activity, and is a superior protein resource. Effective recycling and utilization of pea whey protein can not only avoid environmental pollution but also increase the added value of pea processing. Plant-based yogurt can increase the beneficial components of yogurt while reducing anti-nutritional factors and allergenic 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 regular yogurt, it also possesses unique plant nutrients such as isoflavones, gamma-aminobutyric acid (GABA), and phenolic substances, making it nutritionally suitable for more consumers with specific needs. This is beneficial for those with milk protein allergies, high cholesterol, or those concerned about animal welfare and environmental protection. According to relevant standards, the protein content of plant-based fermented milk products should generally not be 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 for plant-based yogurt products. If whey concentration is performed, while the protein content increases, the large amount of salt ions in the pea whey are also concentrated many times over, leading to slow fermentation and failure to reach the fermentation endpoint. To solve the above technical problems, this application recovers pea whey protein through polysaccharide coagulation and uses it as a fermentation base for lactic acid bacteria fermentation. This not only meets the protein content requirements but also does not cause an increase in salt concentration, offering the technical advantage of rapid fermentation. In addition, the introduced polysaccharide components can further improve the texture of yogurt, enhancing its taste and stability.

[0003] Currently, there are few reports on the preparation of plant-based yogurt using peas alone, and no reports have been found on the preparation of yogurt using pea whey protein. Guo Jiaxi optimized the raw material ratio, enzymatic hydrolysis conditions, and fermentation conditions using peas and whole milk powder as raw materials; Li Ying et al. used pea protein powder and milk as the main raw materials, and studied the effects of the amount of protein powder added, the amount of starter culture inoculated, and the fermentation time on the quality of set-type pea yogurt using acidity and sensory evaluation as indicators; Denkova et al. reported on the preparation of yogurt and acid-loving beverages by fermenting different proportions of pea milk and skim milk mixtures with probiotics; Yousseef et al. prepared yogurt products by fermenting a mixture of pea protein and milk or milk powder; the research of Denkova et al. showed that saccharified yeast 25-G can grow and metabolize in a substrate containing skim milk and pea milk, and the resulting product has a high viable count and moderate titratable acidity. Current reports indicate that almost all pea yogurts are made by fermenting pea protein with other ingredients. Therefore, there is a lack of purely plant-based yogurts made solely from pea protein that cater to a wider range of specific consumer needs and are environmentally friendly. Furthermore, plant seeds, including peas and soybeans, often contain various anti-nutritional factors that affect the digestibility and absorption of nutrients such as protein, making the digestibility and absorption characteristics of their fermented products difficult to match those of traditional milk yogurts. Therefore, providing plant-based yogurt with the same digestibility and absorption characteristics presents a significant technological challenge. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a method for preparing pea whey protein yogurt with high antioxidant activity and high digestibility using protein resources from pea whey wastewater. The purpose is to utilize pea whey wastewater as raw material, recover whey protein by adding polysaccharide solid powder, freeze-dry the pea whey protein-polysaccharide complex to obtain a yogurt base material that can be fermented quickly, and then optimize the fermentation strains and fermentation process conditions to prepare pure plant-based yogurt with high antioxidant activity and high digestibility, thereby realizing a high-value-added application of pea whey protein.

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

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

[0007] (1) Recovery of pea whey protein: First, the pea whey wastewater is desalinated, then polysaccharide powder is added, mixed evenly, the pH of the mixture is adjusted to 3.4-4.2, stirred and centrifuged, and the precipitate is collected to obtain the recovered pea whey protein-polysaccharide complex.

[0008] (2) Pretreatment of fermentation substrate: Disperse the pea whey protein-polysaccharide complex from step (1) in water, adjust the pH to 7.0-7.5, stir until completely dissolved, and then freeze dry to obtain the freeze-dried complex powder, which is the pretreated fermentation substrate.

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

[0010] (4) Preparation of pea whey protein yogurt: Add compound starter culture to the fermentation liquid obtained in step (3), ferment at 40-43℃ for 4-10 h, cool to room temperature and store in a refrigerator at 2-6℃ for 8-12 h to obtain pea whey protein yogurt.

[0011] In one embodiment, 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.

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

[0013] In one embodiment, in step (1), the mixture is homogenized by high-speed shearing, wherein the high-speed shearing speed is 8000-10000 rpm and the high-speed shearing time is 3-5 min.

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

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

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

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

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

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

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

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

[0022] In one embodiment, the compound fermentation agent, in step (4), comprises *Streptococcus thermophilus*, *Lactobacillus bulgaricus*, and *Lactococcus lactis*, wherein the mass fraction of *Streptococcus thermophilus* and *Lactobacillus bulgaricus* accounts for 75-80% of the compound fermentation agent; the inoculum size of the compound fermentation agent is (1.0~2.5)×10⁻⁶. 6 CFU / g fermentation broth

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

[0024] The third technical solution provided by the present invention is the application 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 functions.

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

[0026] The pea whey protein yogurt prepared by this invention is fermented 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 this invention has high antioxidant activity (scavenging ABTS free radicals IC50). 50 The lowest value was 8.51 mg / ml, and the IC50 value for scavenging hydroxyl radicals was [missing value]. 50 It has a value of 19.70 mg / ml and high digestibility (both protein and fat digestibility can reach over 70%). The preparation process of this invention is simple and low-cost. This invention does not add any animal ingredients, which is good news for people with milk protein allergies, high cholesterol, and those who are concerned about animal welfare and environmental protection. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation process of pea whey protein yogurt.

[0028] Figure 2 The pH curves for fermentation of pea whey protein yogurt in Examples 1-3 are shown. Detailed Implementation

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

[0030] Test method:

[0031] 1. In vitro digestibility:

[0032] Gastric digestion: 10g of sample was preheated at 37℃ for 5 min. SGF was preheated at 37℃ for 5 min, and then 10 mL was added to the above sample. The pH of the mixture was quickly adjusted to 2.5 with 1 mol / L HCl solution, and digested in a constant temperature water bath shaker (100 rpm) at 37℃ for 2 h.

[0033] Enteric digestion: The pH of the mixture after the above process was rapidly adjusted to 7.0 using 2 mol / L NaOH solution. SIF was preheated at 37°C for 5 min. SIF (1 mL), bile salt solution (2.33 mL), lipase solution (1.66 mL), and pancreatic enzyme solution (1.66 mL) were added sequentially to the gastric-digested sample. The mixture was then digested in a 37°C water bath with stirring for 2 h. During this time, the pH of the mixture was maintained at 7.0 by titration with 0.1 mol / L NaOH solution.

[0034] Gastric juice is prepared as follows:

[0035]

[0036] The intestinal fluid is prepared as follows:

[0037]

[0038] (1) Fat digestibility

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

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

[0041] In the formula, V refers to the volume (mL) of NaOH solution used when the digestion time is t.

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

[0043] M refers to the average molecular weight 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℃ water bath for 15 minutes to inactivate the enzyme, and then cooled to room temperature. 10g 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. The mixture was stirred for 15 minutes and allowed to stand for one hour. Then, it was centrifuged at 8000 rpm and 4℃ for 15 minutes. The supernatant was collected, and the protein content in the supernatant was determined.

[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, while all other conditions remained unchanged.

[0049] 2. Antioxidant activity:

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

[0051] (1) ABTS free radical scavenging rate

[0052] An equal volume of 2.45 mmol / L potassium persulfate solution and 7 mmol / L ABTS solution were mixed and reacted at room temperature in the dark for 12–16 h to prepare an ABTS radical solution. Before use, the ABTS radical solution was diluted with anhydrous ethanol to a certain factor to ensure that the absorbance of the diluted solution was 0.70 ± 0.02 at 734 nm.

[0053] Add 50 μL of sample solution and 150 μL of ABTS radical solution to a 96-well microplate, mix thoroughly, and react at room temperature in the dark for 30 min. Measure the absorbance of the reaction mixture at 734 nm. To eliminate the influence of the sample itself on the experimental results, an equal volume of deionized water was used instead of ABTS radical solution as the sample control group, and an equal volume of deionized water was used instead of the sample solution as the negative control group. Vitamin C was used as the positive control. Calculate the ABTS radical scavenging rate using the following formula:

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

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

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

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

[0058] (2) Hydroxyl radical scavenging rate

[0059] First, add 50 μL of sample to the ELISA plate, followed by 50 μL of FFeSO4 solution (3 mmol / L) and an equal volume of salicylic acid-ethanol solution (3 mmol / L). Finally, add 50 μL of H2O2 solution (6 mmol / L). Incubate in the dark for 30 min, and measure the absorbance at 510 nm after the reaction. Use equal volumes of deionized water as the sample control and negative control, and VC as the positive control. Calculate the hydroxyl radical cation radical scavenging rate using the following formula:

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

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

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

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

[0064] Raw materials used in the examples:

[0065] The strain is from Zhengzhou Hehe Biotechnology Co., Ltd., and its strain number is 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 desalted by electrodialysis at 24 V for 1 h, and the final conductivity was about 1.5 mS / cm. After desalting, sodium alginate powder with a mass concentration of 0.125% was added to the desalted pea whey, and the mixture was sheared at 10000 rpm for 3 min to mix thoroughly. The pH of the mixture was adjusted to 4.0, stirred for 30 min, and centrifuged at 9000 rpm for 10 min. The precipitate was collected to obtain the recovered pea whey protein-sodium alginate complex.

[0078] (2) Pretreatment of fermentation substrate: 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 after stirring until completely dissolved, it is freeze-dried to obtain the freeze-dried complex powder, which is the pretreated fermentation substrate.

[0079] (3) Preparation of fermentation broth: Add a certain amount of deionized water to the pretreated fermentation substrate obtained in step (2) to prepare a solution with a protein concentration of 2.5%. Based on the mass of the above fermentation substrate, add 7% sucrose and 2.0% glucose. After stirring for 30 min, add 0.5% palmitate. After high-speed shearing at 9000 rpm for 2 min, sterilize at 95℃ for 40 min and cool to room temperature to obtain the fermentation broth.

[0080] (4) Preparation of pea whey protein yogurt: Add a compound starter culture (Streptococcus thermophilus, Lactobacillus bulgaricus and Lactococcus lactis in a ratio of 5:3:2) to the fermentation liquid obtained in step (3), with an inoculum size of 1.0 × 10⁻⁶. 6 The fermentation broth was in CFU / g concentration and fermented at 42℃ for 4 hours until the final pH reached 4.5. The fermentation pH curve is shown below. Figure 2 After cooling to room temperature, it was stored in a refrigerator at 4°C for 12 hours to obtain pea whey protein yogurt.

[0081] The above-mentioned pea whey protein yogurt was tested and found to have a protein digestibility of 74.77% and a fat digestibility of 79.86%. Its antioxidant activity included scavenging ABTS hydroxyl radicals (IC50). 50 The value was 8.51 mg / ml, and the IC50 value for scavenging hydroxyl radicals was 50 The value was 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 desalted by electrodialysis at 24 V for 1 h, and the final conductivity was about 1.5 mS / cm. After desalting, 0.1% carrageenan powder was added to the desalted pea whey, and the mixture was sheared at 10,000 rpm for 3 min. The mixture was thoroughly mixed, the pH of the mixture was adjusted to 3.6, 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 fermentation substrate: 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 after stirring until completely dissolved, it is freeze-dried to obtain the freeze-dried complex powder, which is the pretreated fermentation substrate.

[0086] (3) Preparation of fermentation liquid: Add a certain mass of deionized water to the pretreated fermentation substrate obtained in step (2) to prepare a solution with a protein concentration of 2.0%. Based on the mass of the above fermentation substrate, add 8% sucrose and 1.5% glucose. After stirring for 30 min, add 0.5% sunflower seed oil. After high-speed shearing at 8000 rpm for 2 min, sterilize at 95℃ for 40 min and cool to room temperature to obtain the fermentation liquid.

[0087] (4) Preparation of pea whey protein yogurt: Add a compound starter culture (Streptococcus thermophilus, Lactobacillus bulgaricus and Lactococcus lactis in a ratio of 5:3:2) to the fermentation liquid obtained in step (3), with an inoculum size of 1.0 × 10⁻⁶. 6 The fermentation broth was in CFU / g concentration and fermented at 42℃ for 6 hours until the final pH reached 4.5. The fermentation pH curve is shown below. Figure 2 After cooling to room temperature, it was 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 desalted by electrodialysis at 24 V for 1 h, and the final conductivity was about 1.5 mS / cm. After desalting, 0.1% pectin powder was added to the desalted pea whey, and the mixture was sheared at 10000 rpm for 3 min. The mixture was thoroughly mixed, the pH of the mixture was adjusted to 3.4, stirred for 30 min, and centrifuged at 8000 rpm for 15 min. The precipitate was collected to obtain the recovered pea whey protein-pectin complex.

[0091] (2) Pretreatment of fermentation substrate: 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 after stirring until completely dissolved, it is freeze-dried to obtain the freeze-dried complex powder, which is the pretreated fermentation substrate.

[0092] (3) Preparation of fermentation liquid: Add a certain mass of deionized water to the pretreated fermentation substrate obtained in step (2) to prepare a solution with a protein concentration of 2.8%. Based on the mass of the above fermentation substrate, add 8% sucrose and 2.0% glucose. After stirring for 30 min, add 0.5% corn oil. After high-speed shearing at 9000 rpm for 2 min, sterilize at 95℃ for 40 min. Cool to room temperature to obtain the fermentation liquid.

[0093] (4) Preparation of pea whey protein yogurt: Add a compound starter culture (Streptococcus thermophilus, Lactobacillus bulgaricus and Lactococcus lactis in a ratio of 3:5:2) to the fermentation liquid obtained in step (3), with an inoculum size of 1.0 × 10⁻⁶. 6 The fermentation broth was in CFU / g state and fermented at 42℃ for 8 hours until the final pH reached 4.5. The fermentation pH curve is shown below. Figure 2 After cooling to room temperature, it was stored in a refrigerator at 4°C for 12 hours to obtain pea whey protein yogurt.

[0094] Comparative Example 1:

[0095] For specific implementation details, refer to Example 1. The difference is that in step (2), after stirring until completely dissolved, no freeze-drying is performed, while the other steps remain unchanged. The pH value was measured at 4h, 6h, and 12h of fermentation to determine whether the sample had reached the fermentation endpoint of pH 4.5.

[0096] Measurements showed that the pH of Comparative Example 1 sample was 5.17 after 4 hours of fermentation, 5.02 after 6 hours, and 4.82 after 12 hours. These data indicate that the fermentation substrate without freeze-drying treatment could not reach the fermentation endpoint within 12 hours and therefore could not form pea whey protein yogurt; while Example 1 reached the fermentation endpoint in just 4 hours.

[0097] Comparative Example 2:

[0098] The specific implementation method is the same as in Example 1, except that fermentation is not performed after the fermentation broth is prepared, i.e., step 4 is omitted, while the remaining steps remain unchanged. In vitro digestibility and antioxidant activity were measured, and the IC50 of the antioxidant activity was obtained by SPSS analysis. 50 value.

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

[0100] Table 1. Comparison of Comparative Example 2 and the Example 2

[0101]

[0102] Comparative Example 3:

[0103] The specific implementation method is the same as in Example 1, except that in step (4), nine different types of bacterial strains are used for single-strain fermentation, while the inoculum size remains unchanged. The in vitro digestibility and antioxidant activity of the samples are measured, and the IC50 of the antioxidant activity is obtained by SPSS analysis. 50 value.

[0104] As shown in Table 2, the in vitro digestibility and antioxidant activity of the pea whey protein yogurt fermented by the nine single strains in Comparative Example 3 were significantly lower than those in Example 1 (Table 1), indicating that the optimized compound fermentation strains of this invention significantly enhanced the protein digestibility and antioxidant activity of pea whey protein yogurt.

[0105] Table 2. In vitro digestibility and antioxidant activity of Comparative Example 3

[0106]

[0107] Comparative Example 4:

[0108] The specific implementation method is the same as in Example 1, except that the 0.5% palmitate in step 3 is adjusted to 3.0%, while the other steps remain unchanged. In vitro digestibility and antioxidant activity were measured, and the IC50 of the antioxidant activity was obtained by SPSS analysis. 50 value.

[0109] The above-mentioned pea whey protein yogurt was tested and found to have a protein digestibility of 65.78%, a fat digestibility of 42.35%, and antioxidant activity: scavenging ABTS free radicals (IC). 50 The value was 13.56 mg / ml, and the IC50 value for scavenging hydroxyl radicals was [value missing]. 50 The value was 27.37 mg / ml.

[0110] 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 high in vitro digestibility and high antioxidant activity.

[0111] Comparative Example 5:

[0112] For the specific implementation method, refer to Example 2, except that carrageenan in step 1 is replaced with xanthan gum, while the other steps remain unchanged. The pH value was measured at 6h, 12h, and 18h ​​of fermentation to determine whether the sample had reached the fermentation endpoint of pH 4.5.

[0113] The pH values ​​of Comparative Example 5 were measured to be 5.20 after 6 hours of fermentation, 4.98 after 12 hours, and 4.71 after 18 hours. These data indicate that replacing carrageenan with xanthan gum slows down the fermentation process, and the pH of 4.5 cannot be reached even after 18 hours, making it impossible to produce pea whey protein yogurt.

[0114] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing pea whey protein yogurt, characterized in that, Includes the following steps: (1) Recovery of pea whey protein: After desalting the pea whey wastewater, polysaccharide powder is added, mixed evenly, and the pH of the mixture is adjusted to 3.4-4.

2. After stirring, the mixture is centrifuged and the precipitate is collected to obtain the recovered pea whey protein-polysaccharide complex. The amount of polysaccharide powder added is 0.05%-0.25% of the mass concentration of the desalted pea whey wastewater. The polysaccharides include carrageenan, sodium alginate, and pectin. (2) Pretreatment of fermentation substrate: Disperse the pea whey protein-polysaccharide complex from step (1) in water, adjust the pH to 7.0-7.5, stir until completely dissolved, and then freeze dry to obtain the freeze-dried complex powder, which is the pretreated fermentation substrate. (3) Preparation of fermentation liquid: The pretreated fermentation substrate in step (2) is prepared into an aqueous solution with a protein concentration of 2.0%-3.0%, carbon source is added, and after stirring, vegetable oil is added. After high-speed shearing, it is sterilized and cooled to room temperature to obtain the fermentation liquid. (4) Preparation of pea whey protein yogurt: Add a compound starter culture to the fermentation liquid in step (3), ferment at 40-43℃ for 4-10 h, cool to room temperature, and store in a refrigerator at 2-6℃ for 8-12 h to obtain pea whey protein yogurt; the compound starter culture includes Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactococcus lactis, wherein Streptococcus thermophilus and Lactobacillus bulgaricus account for 75-80% of the compound starter culture; the inoculum amount of the compound starter culture is (1.0~2.5)×10 6 CFU / g fermentation broth 2. The method according to claim 1, characterized in that, In step (1), the mixture is homogenized by high-speed shearing. The high-speed shearing speed is 8000-10000 rpm and the high-speed shearing time is 3-5 min.

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

4. 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 high-speed shearing time is 1-2 min.

5. Pea whey protein yogurt prepared by the method according to any one of claims 1 to 4.

6. The application of the method according to any one of claims 1 to 4 or the pea whey protein yogurt according to claim 5 in the preparation of health products with antioxidant functions.

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