Multifunctional Chinese yam composite peptide composition, preparation method and application in heart strengthening

Abstract

The invention belongs to the technical field of functional food, and discloses a multifunctional Chinese yam composite peptide composition, a preparation method and application in the aspect of strengthening the heart, the preparation method of the multifunctional Chinese yam composite peptide composition comprises the following steps: preparing pea protein powder; preparing pea peptide powder A; and preparing the multifunctional Chinese yam composite peptide composition. The high-activity pea peptide powder and the Chinese yam powder are subjected to wet graft copolymerization, polysaccharide in the Chinese yam can effectively neutralize the bitter taste of pea peptide, the hydrolysis rate of the pea peptide is increased to 94.32% under the condition that the pH is 2.0-3.0, meanwhile, the oxidation resistance and the gastric mucosa protection capacity of the pea peptide are remarkably improved, the hygroscopicity is improved, and the water content is 8.79%.

Description

Technical Field

[0001] The present invention belongs to the technical fields of polypeptides and functional foods, and in particular relates to a multifunctional Chinese yam composite peptide composition, a preparation method thereof, and an application thereof in strengthening the heart. Background Art

[0002] The spleen is in charge of transportation and transformation, which is the central link of the energy metabolism of the whole body tissues. Its physiological structure is the hub of the transportation and transformation of essence and dampness, and is responsible for the metabolism of the whole diet of the body; its anatomical structure is the largest digestive organ, the liver, in modern medicine; the material exchange system is responsible for the digestive system of digestion, absorption, and excretion and metabolism. Spleen deficiency and damp turbidity often cause and effect each other and coexist. Spleen deficiency, qi deficiency, and heavy dampness are all common constitutions or health problems in traditional Chinese medicine.

[0003] Chinese yam tastes sweet and is neutral in nature, and enters the three meridians of the spleen, lung, and kidney. It has the effects of replenishing qi and nourishing yin, tonifying the spleen, lung, and kidney, and astringing essence and arresting leucorrhea. It can be used for spleen deficiency syndromes. Chinese yam tonifies qi and yin evenly, and is also astringent in nature. Therefore, it can be used for those with poor appetite due to spleen deficiency, fatigue and loose stools, leucorrhea in women, and indigestion in children. Clinically, it is often used for symptoms such as poor appetite due to spleen deficiency, chronic diarrhea, cough due to lung deficiency, spermatorrhea due to kidney deficiency, leucorrhea, frequent urination, consumptive thirst with fever, and neurasthenia.

[0004] Pea peptide is a protein hydrolysate obtained by the action of protease on pea protein and then through special treatment. As a more high-quality and new deep-processed pea product and nutritional product, it has shown an attractive development and application prospect in the fields of food, medicine, daily chemical industry, etc.

[0005] Since the abundant cellulose in Chinese yam is difficult to be completely digested and absorbed in a short time, for people with weak digestive system function or those with a tendency to constipation, excessive consumption of Chinese yam may cause abdominal distension or aggravate constipation. Pea peptide is a small molecule peptide extracted from pea protein through enzymatic hydrolysis technology. It is not only easy to digest and absorb, but also has a higher bioavailability, enters the blood faster, and quickly provides nutrition for the body, especially suitable for post-exercise recovery. It also has additional health benefits such as antioxidant, anti-inflammatory, and regulation of intestinal flora. Compared with traditional proteins, pea peptide has a lighter burden on the digestive system during the absorption process and is suitable for people with weak gastrointestinal function. Therefore, it is considered to graft pea peptide and Chinese yam by wet method to obtain a polymer to improve the digestion and absorption problems that occur when patients with spleen deficiency take Chinese yam. At the same time, its antioxidant property and the ability to protect the gastric mucosa are significantly improved. However, after this treatment, the hygroscopicity of the polymer increases and the problem of allergic reaction caused by "acetylcholine" in Chinese yam still exists.

[0006] The neurotransmitter "acetylcholine" in Chinese yam is the cause of allergic reactions, which can cause symptoms of autonomic nerve disorder and vasodilation, such as itching all over the body, decreased heart rate, decreased blood pressure, palpitations, flushing, sweating, nausea, vomiting, abdominal pain, diarrhea, bronchoconstriction, bronchial asthma, etc. Existing studies have shown that Lactobacillus johnsonii can prevent allergic reactions, regulate allergic constitution, and reduce the infection of bacteria or viruses. In addition, Lactobacillus johnsonii can also stabilize the intestinal flora and stimulate the mucosa to strengthen the immune response, and can also play a good role in adjusting acute diarrhea, abdominal distension, enteropathy, etc. Therefore, innovatively using Lactobacillus johnsonii IOB 801 for the graft copolymerization of Chinese yam and pea peptide and the biological fermentation of the product can reduce the risk of patients being allergic to Chinese yam, and explore the effects of the fermented Chinese yam composite peptide composition on the five internal organs of patients with spleen deficiency. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a multifunctional Chinese yam composite peptide composition, a preparation method and its application in strengthening the heart.

[0008] The technical solution adopted by the present invention to solve its technical problems is:

[0009] A preparation method of a multifunctional Chinese yam composite peptide composition includes the following steps:

[0010] Preparation of pea protein powder;

[0011] Preparation of pea peptide powder A;

[0012] Preparation of the multifunctional Chinese yam composite peptide composition:

[0013] Add pea peptide powder A and Chinese yam powder in a mass ratio of 3:5 to an appropriate amount of 3 mol / L phosphate buffer solution, mix well completely, and use an edible sodium hydroxide solution or hydrochloric acid solution with a mass concentration of 20% to adjust the pH of the mixed solution to 7.0 ± 0.2;

[0014] Place the mixed solution in a water bath at 87 ± 2 °C to react, and at the same time carry out magnetic stirring at a rotation speed of 35 ± 5 r / min, and the reaction time is 3 ± 0.5 h;

[0015] After the reaction is complete, quickly place it in ice water to cool down to stop the reaction. In the cooled mixed solution, inoculate the seed solution of Lactobacillus johnsonii IOB 801 at an inoculation amount of 1%, at 37 °C, keep the pH at 6.0 - 6.5, and the rotation speed at 45 ± 5 r / min, and culture for 8 ± 2 h; after the fermentation broth is concentrated, it is spray-dried to obtain the multifunctional Chinese yam composite peptide composition.

[0016] Furthermore, the preparation method of the pea protein powder is specifically:

[0017] Pretreatment of peas: Wash, screen and peel fresh peas, soak the peas in water for 12 h with a material-liquid ratio of g:mL of 1:30, and after soaking, crush and grind them into a homogeneous slurry;

[0018] Primary separation: Sieve the homogeneous slurry, separate the pulp and residue, and reserve the slurry for use;

[0019] Alkaline extraction: Add an edible sodium hydroxide solution with a mass concentration of 20% to the slurry, adjust the pH to 8.0, the extraction temperature is 35 °C, the extraction time is 40 min, after the extraction is completed, centrifuge at 4000 r / min for 30 min, and take the supernatant;

[0020] Acid precipitation separation: Concentrate the supernatant, add a hydrochloric acid solution with a mass concentration of 20% after cooling, adjust the pH of the concentrated solution to 4.0, precipitate for 30 min, centrifuge at 4000 r / min for 30 min to obtain pea protein precipitate;

[0021] Spray drying: Add an edible sodium hydroxide solution with a mass concentration of 20%, adjust the pH to 7.0, neutralize the pea protein precipitate, and carry out spray drying to obtain pea protein powder.

[0022] Furthermore, the preparation method of pea peptide powder A is specifically as follows:

[0023] Prepare pea protein liquid: Add pea protein powder to pure water according to a mass ratio of pea protein powder: pure water of 1:10, stir for 30 min to obtain pea protein liquid;

[0024] Prepare compound protease: Compound neutral protease, alkaline protease and flavor protease according to a mass ratio of 1.0:0.2:0.8 to obtain compound protease system A;

[0025] Hydrolysis of compound protease system A: Using pea protein liquid as the substrate, add compound protease system A with a final mass concentration of 1.0% - 1.5% and stir, carry out enzymatic hydrolysis at 52 °C for 5 - 6 h, after the enzymatic hydrolysis is completed, inactivate the enzyme at 90 °C to obtain pea peptide hydrolysate;

[0026] Membrane filtration: Centrifuge the obtained pea peptide hydrolysate at 6000 r / min for 8 min, collect the supernatant, and filter through the membrane by suction to obtain pea peptide collection solution;

[0027] Freeze drying: After pre-freezing the pea peptide collection solution, carry out vacuum freeze drying to obtain pea peptide powder A.

[0028] Furthermore, the Lactobacillus johnsonii IOB 801 is a strain of Lactobacillus johnsonii screened from fermented pickles.

[0029] Furthermore, the Lactobacillus johnsonii IOB 801 has the following information: Name: Lactobacillus johnsonii IOB 801, Classification Name: Lactobacillus johnsonii, Deposit Number: CGMCC No. 16824, Deposit Date: November 26, 2018, Depositary Institution: General Microbiology Center, China National Culture Collection Center, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0030] Furthermore, the preparation method of the Lactobacillus johnsonii IOB 801 seed liquid is as follows:

[0031] Strain activation: Activate the cryopreserved Lactobacillus johnsonii IOB 801 on an MRS agar plate three times. Pick a single colony and inoculate it into an MRS liquid medium. After culturing at 37°C for 10 ± 2 h, transfer it to an MRS liquid medium with an inoculation amount of 1%, and use it as the seed liquid after culturing at 37°C for 10 ± 2 h.

[0032] The multifunctional Chinese yam composite peptide composition prepared by the preparation method as described above.

[0033] Application of the multifunctional Chinese yam composite peptide composition as described above in the preparation of cardiac tonics.

[0034] Application of the multifunctional Chinese yam composite peptide composition as described above in the preparation of drugs for restoring cardiac function in the spleen deficiency and dampness excess type.

[0035] Furthermore, the multifunctional Chinese yam composite peptide composition can significantly improve the weight loss of rats with spleen deficiency and dampness excess, that is, the recovery rate is increased by 60%, loose stools, that is, the fecal humidity is reduced from 65.54% to 37.40%, and abnormal organ index, that is, the spleen index is restored from 3.23 to 2.64.

[0036] The advantages and positive effects achieved by the present invention are as follows:

[0037] 1. By compounding neutral protease, alkaline protease and flavor protease, the present invention develops an efficient enzymatic hydrolysis system. The three enzymes act synergistically to significantly improve the enzymatic hydrolysis efficiency of pea protein, making the peptide content ≥ 81.72%, while reducing the generation of bitter peptides, overcoming the defects of low peptide yield and poor taste in the traditional single-enzyme process.

[0038] 2. The present invention carries out wet graft copolymerization of high-activity pea peptide powder and Chinese yam powder. The polysaccharides in Chinese yam can effectively neutralize the bitterness of pea peptides, and increase the hydrolysis rate at pH 2.0 - 3.0 to 94.32%. At the same time, its antioxidant capacity and gastric mucosa protection ability are significantly improved, but the hygroscopicity increases, and the water content is 8.79%.

[0039] 3. Experiments of the present invention show that Lactobacillus johnsonii IOB 801 is used to ferment the grafted Chinese yam composite peptide to obtain a Chinese yam composite peptide composition, which significantly reduces the allergenicity of Chinese yam, and at the same time the water content is reduced to 5.31%, reducing the hygroscopicity; components such as saponins and allantoin synergistically act with the small molecule active peptides of pea peptides to target and regulate the metabolic disorders, inflammatory reactions and multi-organ functions related to spleen deficiency, achieving the comprehensive curative effect of "tonifying the spleen and removing dampness, strengthening the five internal organs", among which the strengthening effect on heart function is the best.

[0040] The Chinese yam composite peptide composition can significantly improve the weight loss (the recovery rate is increased by 60%), loose stools (the stool humidity is reduced from 65.54% to 37.40%) and abnormal organ indices (the spleen index is restored from 3.23 to 2.64) of rats with excessive spleen deficiency and dampness, prevent and relieve cardiovascular and cerebrovascular diseases, etc., and verify its multi-system synergistic intervention mechanism by regulating serum inflammatory factors and endocrine metabolism indexes. It fills the blank in the combination of functional peptide compounding and traditional Chinese medicine theory in the prior art, and provides a new strategy for the nutritional intervention of spleen deficiency-related diseases.

[0041] 4. The present invention uses different ratios of multiple proteases to compound-hydrolyze pea protein, significantly increasing the peptide content of pea peptides; then through the wet graft copolymerization of pea peptides and Chinese yam powder, the taste of pea peptides is improved, the digestion problem of Chinese yam powder is solved, and at the same time the antioxidant property and the ability to protect the gastric mucosa are improved.

[0042] Using Lactobacillus johnsonii IOB 801 to ferment the polymer of pea peptides and Chinese yam powder, the obtained Chinese yam composite peptide composition significantly reduces the allergenicity and hygroscopicity of Chinese yam powder; finally, through animal experiments, it is verified that the Chinese yam composite peptide composition obtained by fermentation with Lactobacillus johnsonii IOB 801 can unexpectedly significantly restore the heart function of rats with excessive spleen deficiency and dampness, thereby promoting the health of other organs and improving symptoms such as listlessness, body inflammation, endocrine disorders, and reduced functions of various organs caused by spleen deficiency in mice. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a graph showing the change of the body weight of rats in the present invention;

[0044] Figure 2 It is a graph showing the nitric oxide level in the blood of rats in the present invention;

[0045] Figure 3 It is a graph showing the level of endothelin-1 (ET-1) in the blood of rats in the present invention;

[0046] Figure 4 It is a graph showing the level of triiodothyronine (T3) in the blood of rats in the present invention;

[0047] Figure 5It is the graph of the level of thyroxine (T4) in the blood of rats in the present invention;

[0048] Figure 6 It is the graph of the level of motilin (MTL) in the rats in the present invention;

[0049] Figure 7 It is the graph of the level of gastrin (GAS) in the rats in the present invention;

[0050] Figure 8 It is the graph of the level of the inflammatory factor interleukin-6 (IL-6) in the serum of rats in the present invention;

[0051] Figure 9 It is the graph of the level of the inflammatory factor tumor necrosis gene α (TNF-α) in the serum of rats in the present invention;

[0052] Figure 10 It is the graph of the level of the inflammatory factor transforming growth factor β (TGF-β) in the serum of rats in the present invention;

[0053] Figure 11 It is the graph of the level of aldosterone (ALD) in the serum of rats in the present invention;

[0054] Figure 12 It is the graph of the level of atrial natriuretic peptide (ANP) in the serum of rats in the present invention;

[0055] Figure 13 It is the comparative graph of periodic acid-Schiff (PAS) staining of the cardiac tissue of rats in the present invention;

[0056] Figure 14 It is the comparative graph of the scavenging rate of 1,1-diphenyl-2-picrylhydrazyl (DPPH) in Example 4 of the present invention;

[0057] Figure 15 It is the comparative graph of the scavenging rate of superoxide anion radicals in Example 4 of the present invention;

[0058] Figure 16 It is the HE staining graph of the gastric mucosa tissue sections of each group of mice in Example 5 of the present invention.

[0059] A strain of Lactobacillus johnsonii IOB 801 screened from fermented pickles, named: Lactobacillus johnsonii IOB 801, classified name: Lactobacillus johnsonii, deposit number: CGMCC No. 16824, deposit date: November 26, 2018, deposit unit: China General Microbiological Culture Collection Center, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. Detailed implementation mode

[0060] The present invention will be further described below in conjunction with embodiments. The following embodiments are narrative and not restrictive, and the protection scope of the present invention cannot be limited by the following embodiments.

[0061] For various experimental operations involved in the specific embodiments, they are all conventional techniques in the art. For parts not specifically annotated in this article, those of ordinary skill in the art can refer to various commonly used reference books, scientific and technological literatures, or relevant specifications, manuals, etc. before the application date of the present invention for implementation.

[0062] A preparation method of a multifunctional Chinese yam composite peptide composition includes the following steps:

[0063] Preparation of pea protein powder;

[0064] Preparation of pea peptide powder A;

[0065] Preparation of the multifunctional Chinese yam composite peptide composition:

[0066] Add pea peptide powder A and Chinese yam powder in a mass ratio of 3:5 to an appropriate amount of 3 mol / L phosphate buffer solution, mix thoroughly, and use an edible sodium hydroxide solution or hydrochloric acid solution with a mass concentration of 20% to adjust the pH of the mixed solution to 7.0 ± 0.2;

[0067] Place the mixed solution in a water bath at 87 ± 2 °C for reaction, and at the same time perform magnetic stirring at a rotation speed of 35 ± 5 r / min, and the reaction time is 3 ± 0.5 h;

[0068] After complete reaction, quickly place it in ice water to cool down to stop the reaction. In the cooled mixed solution, inoculate the seed solution of Lactobacillus johnsonii IOB 801 at an inoculation amount of 1%, at 37 °C, keep the pH at 6.0 - 6.5, and the rotation speed at 45 ± 5 r / min, and culture for 8 ± 2 h; after the fermentation broth is concentrated, spray drying is used to prepare the multifunctional Chinese yam composite peptide composition.

[0069] Preferably, the preparation method of pea protein powder is specifically as follows:

[0070] Pea pretreatment: Wash, screen, and peel fresh peas, soak the peas in water for 12 h, with the material-liquid ratio of g:mL being 1:30, and after soaking, crush and grind them into a homogeneous slurry;

[0071] Preliminary separation: Perform sieving treatment on the homogeneous slurry, separate the slurry and residue, and reserve the slurry for use;

[0072] Alkaline extraction: Add an edible sodium hydroxide solution with a mass concentration of 20% to the slurry, adjust the pH to 8.0, the extraction temperature is 35 °C, the extraction time is 40 min, after the extraction is completed, centrifuge at a rotation speed of 4000 r / min for 30 min, and take the supernatant;

[0073] Acid precipitation separation: Concentrate the supernatant, cool it, add hydrochloric acid solution with a mass concentration of 20%, adjust the pH of the concentrated solution to 4.0, precipitate for 30 min, and centrifuge at 4000 r / min for 30 min to obtain pea protein precipitate;

[0074] Spray drying: Add edible sodium hydroxide solution with a mass concentration of 20%, adjust the pH to 7.0, neutralize the pea protein precipitate, and spray dry to obtain pea protein powder.

[0075] Preferably, the preparation method of pea peptide powder A is as follows:

[0076] Prepare pea protein liquid: Add pea protein powder to pure water according to the mass ratio of pea protein powder: pure water of 1:10, stir for 30 min to obtain pea protein liquid;

[0077] Prepare compound protease: Compound neutral protease, alkaline protease and flavor protease according to the mass ratio of 1.0:0.2:0.8 to obtain compound protease system A;

[0078] Hydrolysis of compound protease system A: Using pea protein liquid as the substrate, add compound protease system A with a final mass concentration of 1.0% - 1.5% and stir, carry out enzymatic hydrolysis at 52 °C for 5 - 6 h, after the enzymatic hydrolysis is completed, inactivate the enzyme at 90 °C to obtain pea peptide hydrolysate;

[0079] Membrane filtration: Centrifuge the obtained pea peptide hydrolysate at 6000 r / min for 8 min, collect the supernatant, and filter through the membrane by suction to obtain pea peptide collection liquid;

[0080] Freeze drying: Pre-freeze the pea peptide collection liquid and then carry out vacuum freeze drying to obtain pea peptide powder A.

[0081] Preferably, the Lactobacillus johnsonii IOB 801 is a strain of Lactobacillus johnsonii screened from fermented pickles.

[0082] Preferably, the Lactobacillus johnsonii IOB 801 has the name: Lactobacillus johnsonii IOB 801, the classification name: Lactobacillus johnsonii, the preservation number: CGMCC No. 16824, the preservation date: November 26, 2018, and the preservation unit: China General Microbiological Culture Collection Center, No. 3, Building 1, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0083] Preferably, the preparation method of the Lactobacillus johnsonii IOB 801 seed liquid is as follows:

[0084] Activation of strain: Lactobacillus johnsonii IOB 801 stored frozen was activated three times on MRS agar plates. Single colonies were picked and inoculated into MRS liquid medium. After culturing at 37 °C for 10 ± 2 h, it was transferred to MRS liquid medium with an inoculation amount of 1%, and after culturing at 37 °C for 10 ± 2 h, it was used as the seed liquid.

[0085] The multifunctional Chinese yam composite peptide composition prepared by the preparation method as described above.

[0086] Application of the multifunctional Chinese yam composite peptide composition as described above in the preparation of cardiac tonics.

[0087] Application of the multifunctional Chinese yam composite peptide composition as described above in the preparation of drugs for restoring cardiac function in the syndrome of spleen deficiency with dampness stagnation.

[0088] Preferably, the multifunctional Chinese yam composite peptide composition can significantly improve the weight loss of rats with spleen deficiency and dampness stagnation, that is, the recovery rate is increased by 60%, loose stools, that is, the fecal humidity is reduced from 65.54% to 37.40%, and abnormal organ index, that is, the spleen index is restored from 3.23 to 2.64.

[0089] Specifically, the relevant preparation and detection are as follows:

[0090] Example 1

[0091] This example is a preparation method of pea protein powder, including the following steps:

[0092] S1. Pea pretreatment: Fresh peas were washed, screened, and peeled, soaked in water for 12 h with a material-liquid ratio of g:mL of 1:30, and after soaking, they were crushed and ground into a homogeneous slurry.

[0093] S2. Preliminary separation: The homogeneous slurry was sieved, the slurry and residue were separated, and the slurry was reserved for use.

[0094] S3. Alkaline extraction: An edible sodium hydroxide solution with a mass concentration of 20% was added to the slurry, the pH was adjusted to 8.0, the extraction temperature was 35 °C, the extraction time was 40 min, and after the extraction was completed, centrifugation was carried out at 4000 r / min for 30 min, and the supernatant was taken.

[0095] S4. Acid precipitation separation: The supernatant was concentrated, and after cooling, a hydrochloric acid solution with a mass concentration of 20% was added, the pH of the concentrated solution was adjusted to 4.0, precipitated for 30 min, and centrifuged at 4000 r / min for 30 min to obtain pea protein precipitate.

[0096] S5. Spray drying: An edible sodium hydroxide solution with a mass concentration of 20% was added, the pH was adjusted to 7.0 to neutralize the pea protein precipitate, and spray drying was carried out to obtain pea protein powder (the measured protein content was 81.37%).

[0097] Example 2

[0098] This example is a preparation method of a compound protease, which includes the following steps:

[0099] S1. Prepare pea protein liquid: Add the pea protein powder prepared in Example 1 to pure water according to the mass ratio of pea protein powder to pure water of 1:10, and stir for 30 min to obtain pea protein liquid.

[0100] S2. Prepare compound protease:

[0101] Compound neutral protease, alkaline protease and flavor protease according to the mass ratio of 1.0:0.2:0.8 to prepare compound protease system A.

[0102] S3. Hydrolysis of compound protease system A

[0103] Using the pea protein liquid as the substrate, add compound protease system A with a final mass concentration of 1.0% - 1.5% and stir. Carry out enzymatic hydrolysis at 52 °C for 5 - 6 h. After the enzymatic hydrolysis is completed, inactivate the enzyme at 90 °C to obtain pea peptide hydrolysate.

[0104] S4. Membrane filtration

[0105] Centrifuge the obtained pea peptide hydrolysate at 6000 r / min for 8 min, collect the supernatant, and filter it through a membrane by suction to obtain pea peptide collection solution.

[0106] S5. Freeze-drying

[0107] Pre-freeze the pea peptide collection solution and then carry out vacuum freeze-drying to obtain pea peptide powder A. The recovery rate of the pea peptide product obtained by enzymatic hydrolysis with compound protease system A is 72.14%, the protein content (dry basis) is 87.56%, and the peptide content is 81.72%.

[0108] Example 3

[0109] This example is a preparation method of freeze-dried powder of Chinese yam compound peptide polymer, which includes the following steps:

[0110] S1. Add the pea peptide powder A prepared in Example 2 and Chinese yam powder to an appropriate amount of 3 mol / L phosphate buffer solution according to the mass ratio of 3:5, mix well completely, and use 20% edible sodium hydroxide solution or hydrochloric acid solution to adjust the pH of the mixed solution to 7.0 ± 0.2.

[0111] S2. Place the mixed solution in a water bath at 87 ± 2 °C to react, and at the same time carry out magnetic stirring at a rotation speed of 35 ± 5 r / min. The reaction time is 3 ± 0.5 h.

[0112] S3. After complete reaction, quickly place it in ice water to cool down and stop the reaction. After the cooled mixture is vacuum filtered, place the filtrate in a freeze dryer for freeze drying.

[0113] S4. After freeze drying, obtain the freeze-dried powder of the Dioscorea opposita Thunb. compound peptide polymer. At this time, the Dioscorea opposita Thunb. compound peptide polymer obtained after graft copolymerization can neutralize the bitterness in the pea peptide, with excellent taste and flavor. And under the condition of pH 2.0 - 3.0, the hydrolysis rate reaches 94.32%, but the hygroscopicity increases, and the water content is 8.79%.

[0114] Example 4

[0115] Determination of the in vitro antioxidant capacity of the Dioscorea opposita Thunb. compound peptide polymer includes the following steps:

[0116] S1. Preparation of the Dioscorea opposita Thunb. compound peptide powder for the control group: Mix the multifunctional peptide, namely pea peptide powder A, and Dioscorea opposita Thunb. powder in a mass ratio of 3:5 to obtain the Dioscorea opposita Thunb. compound peptide powder.

[0117] S2. Using vitamin C as the positive control, detect whether the antioxidant capacity of the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3 is improved compared with the Dioscorea opposita Thunb. compound peptide powder prepared in S1. Respectively detect the scavenging rates of the two on two key antioxidant indicators, diphenylpicrylhydrazyl (DPPH) and superoxide anion. The results are as Figure 14 and Figure 15 shown.

[0118] As Figure 14 and Figure 15 shown, with the increase of the concentrations of the Dioscorea opposita Thunb. compound peptide powder and the Dioscorea opposita Thunb. compound peptide polymer, the scavenging abilities on DPPH free radicals and superoxide anions also increase; when the concentration of the Dioscorea opposita Thunb. compound peptide powder is 8 mg / mL, the DPPH scavenging rate is 46.23%, while when the concentration of the Dioscorea opposita Thunb. compound peptide polymer is 8 mg / mL, the DPPH scavenging rate has tended to 100%; when the concentration of the Dioscorea opposita Thunb. compound peptide powder is 16 mg / mL, the superoxide anion scavenging rate is 39.30%, while when the concentration of the Dioscorea opposita Thunb. compound peptide polymer is 16 mg / mL, the superoxide anion scavenging rate is 71.71%; it shows that the scavenging abilities of the polymer on DPPH free radicals and superoxide anions are significantly stronger than those of the Dioscorea opposita Thunb. compound peptide powder.

[0119] Example 5

[0120] Determination of the ability of the Dioscorea opposita Thunb. compound peptide polymer to protect gastric mucosa includes the following steps:

[0121] S1. Randomly divide 32 healthy male Kunming mice into a blank group, a model group, a Dioscorea opposita Thunb. compound peptide powder group, and a Dioscorea opposita Thunb. compound peptide polymer group, with 8 mice in each group.

[0122] S2. The blank group and the model group were intragastrically administered normal saline (10 ml / kg) every day, and the Dioscorea opposita Thunb. compound peptide powder group and the Dioscorea opposita Thunb. compound peptide polymer group were intragastrically administered the same dose (20 mg / kg) of Dioscorea opposita Thunb. compound peptide powder and Dioscorea opposita Thunb. compound peptide polymer every day. After continuous intragastric administration for 14 days, 30 minutes after the last administration on the 14th day, except for the blank group, the mice in other groups were simultaneously intragastrically administered a 50% ethanol solution (10 ml / kg) by volume concentration, once every 12 hours, for a total of 6 times.

[0123] S3. After the last intragastric administration, the mice were fasted and water-deprived for 12 hours, then all the mice were sacrificed, and the gastric tissues were taken for HE section staining to observe the gastric mucosal injury of the mice. The results were as Figure 16 shown.

[0124] It can be seen from Figure 16 that Dioscorea opposita Thunb. compound peptide powder and Dioscorea opposita Thunb. compound peptide polymer have obvious protective effects on the gastric mucosal injury of mice caused by alcohol; and the protective effect of the polymer on the gastric mucosa of mice is significantly stronger than that of Dioscorea opposita Thunb. compound peptide powder.

[0125] Example 6

[0126] This example is a preparation method of a Dioscorea opposita Thunb. compound peptide composition, which includes the following steps:

[0127] S1. Strain activation: The cryopreserved Lactobacillus johnsonii IOB 801 was activated three times on an MRS agar plate, and a single colony was picked and inoculated into an MRS liquid medium. After culturing at 37°C for 10 ± 2 h, it was transferred to an MRS liquid medium at an inoculation amount of 1%, and after culturing at 37°C for 10 ± 2 h, it was used as the seed liquid.

[0128] S2. The strain was inoculated into the cooled mixed solution prepared in steps S3 of Example 3 at an inoculation amount of 1%, cultured at 37°C, with the pH maintained at 6.0 - 6.5 and the rotation speed of 45 ± 5 r / min for 8 ± 2 h.

[0129] S3. After the fermentation broth was concentrated, it was spray-dried to obtain the Dioscorea opposita Thunb. compound peptide composition. After being detected by an allergy test, the Dioscorea opposita Thunb. compound peptide composition prepared by this method significantly reduced the allergenicity, and at the same time the water content was reduced to 5.31%, reducing the hygroscopicity.

[0130] Among them, the Lactobacillus johnsonii IOB 801 is a strain of Lactobacillus johnsonii IOB 801 screened from fermented kimchi, its name is: Lactobacillus johnsonii IOB 801, its classification name is: Lactobacillus johnsonii, its preservation number is: CGMCC No.16824, its preservation date is: November 26, 2018, and its preservation unit is: General Microbiology Center of China National Culture Collection Administration, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0131] The screening method of the Lactobacillus johnsonii IOB801 comprises the following specific steps:

[0132] Take 1 mL of kimchi water from a resident's home in Tianjin and put it into a test tube containing 9 mL of sterile saline (mass concentration of 0.9%). After fully mixing, take 1 mL of water and put it into a test tube containing 9 mL of saline. Then, dilute it to 10% by gradient. -5 . 100 μL of the sample solution was respectively applied to MRS agar medium and cultured at 37°C for 48 hours. Two parallels were made for each gradient. Colonies with different shapes, sizes and colors were selected from the plate, and after repeated streaking and purification, they were placed in a 37°C constant temperature incubator for continuous culture for 48 hours. The above operation was repeated until pure colonies appeared. Finally, the obtained strains were sequenced for 16SrDNA gene, and then numbered and preserved.

[0133] Example 7

[0134] This example is a study on the effect of the composite peptide composition of Dioscorea opposita on improving spleen qi deficiency in rats, including:

[0135] 1.1 Experimental Materials

[0136] 1.1.1 Experimental animals

[0137] Specific pathogen-free (SPF) grade healthy male SD rats were purchased from Sbefor (Beijing, China) with license number SCXK (Beijing) 2024-0001. They were 6-7 weeks old and weighed (180±20) g. Rats had free access to water during the experiment. The temperature in the breeding room was 20-26°C, the relative humidity was 40%-70%, and the lighting cycle was 12 h, 7:00-19:00 lights, 19:00-7:00 dark. All experimental procedures were carried out in accordance with the Guide for the Care and Use of Laboratory Animals.

[0138] 1.2 Experimental methods

[0139] 1.2.1 Experimental Grouping

[0140] After 7 days of adaptive feeding, healthy rats were randomly divided into 7 groups (8 rats in each group): blank control group, model group, positive control group, protection group 1, protection group 2, treatment group 1, and treatment group 2.

[0141] 1.2.2 Establishment and intervention plan of hyperlipidemia rat model with spleen deficiency and dampness excess

[0142] The protection groups were given intragastric administration of the test samples for 30 days. The intragastric administration dose of protection group 1 (the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3) was 1.89 g / kg (body weight), and the intragastric administration dose of protection group 2 (the Dioscorea opposita Thunb. compound peptide composition prepared in Example 6 of the present invention) was 1.89 g / kg (body weight). The test samples were all dissolved in 0.9% physiological saline with a mass concentration of 1 mL / kg (body weight), and then intragastric administration was carried out. The remaining rats were normally fed (ordinary feed, normal eating, cultured at 22 °C).

[0143] After the above feeding for 30 days, model establishment was started. Reserpine was diluted with distilled water and acetic acid to prepare a reserpine solution of 0.2 mg / mL. Except for the blank group, the rats in the other groups were given intramuscular injection of the drug at a dose of 0.2 mg / kg per day. The blank group was subcutaneously injected with the same dose of 0.85% physiological saline. The model establishment period was 7 - 10 days. Scoring was carried out according to Table 2. When the scores of all symptoms were 3 points, the model establishment was successful. After the model establishment was completed, intervention was carried out, and the intervention period was 2 weeks. The specific intervention methods are as follows in the table:

[0144] Table 1 Operation table of intervention treatment for each group

[0145]

[0146] Note: Treatment group 1 was given intragastric administration of the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3, and treatment group 2 was given intragastric administration of the Dioscorea opposita Thunb. compound peptide composition prepared in Example 6. The test samples were dissolved in 0.9% physiological saline with a mass concentration of 1 mL / kg (body weight), and then intragastric administration was carried out.

[0147] Table 2 General condition scoring table of rats

[0148]

[0149] 1.3 Index observation

[0150] 1.3.1 Body weight index

[0151] From the start of adaptive feeding for 7 days until the end of the experiment, the body weight values of the rats in each group were recorded every 7 days, and the body weight changes were recorded.

[0152] 1.3.2 Defecation situation

[0153] After completing all operations according to Section 1.2.2 of Example 7, the last feeding ended, and the rats were fasted but allowed to drink water for 12 h. Record the wet mass and dry mass of the feces of each group of rats within 12 h, and calculate the fecal humidity.

[0154] Fecal humidity (%) = [wet fecal mass (g) - dry fecal mass (g)] / wet fecal mass (g) × 100%

[0155] 1.3.3 Behavioral experiments

[0156] 1.3.3.1 Open field test

[0157] After completing the operation in 1.3.2, conduct the open field test. Place the animal at the center of the bottom surface of the open field box in a quiet environment, and set up a camera 2 m directly above the 1 m × 1 m square area on the bottom surface for simultaneous video recording and timing. Observe the activities of the rats in the field, and record and analyze the percentage of time the rats in each group stay in the central area, the number of grids walked in the open field, the number of standing times, the activity distance, etc.

[0158] 1.3.3.2 Forced swimming test

[0159] After completing the open field test in 1.3.3.1, conduct the forced swimming test. Fill a transparent container with about 30 cm high of clear water at room temperature. 24 h before the formal experiment, each rat undergoes a 10-min adaptive swimming training. During the formal experiment, each rat undergoes a 6-min swimming test with the whole process recorded. Use Etho Vision software to digitally analyze the video and calculate the cumulative immobility time of the rats from 2 - 6 min (the judgment criterion is that the four limbs are immobile or only the hind limbs move slightly).

[0160] 1.3.4 Effects on hemorheology and vascular endothelial cell function

[0161] After completing the behavioral experiments in 1.3.3, take blood from the eyes of all rats, and then sacrifice all rats. Strictly operate according to the kit instructions to measure the contents of bioactive molecules nitric oxide (NO) and endothelin-1 (ET-1) in the rat serum.

[0162] 1.3.5 Detection of endocrine system-related indicators

[0163] Let the whole blood samples obtained in step 1.3.4 stand at room temperature for 2 h or overnight at 4℃, then centrifuge at 3000 r / min for 15 min, take the supernatant, and detect the contents of tetraiodothyronine (T4) and triiodothyronine (T3) according to the kit instructions.

[0164] 1.3.6 Detection of the recovery of gastrointestinal motility in rats

[0165] The rat serum obtained in step 1.3.4 was used to detect the contents of motilin (MTL) and gastrin (GAS) according to the steps in the enzyme-linked immunosorbent assay kit instructions.

[0166] 1.3.7 Determination of serum inflammatory factors

[0167] The rat serum obtained in step 1.3.4 was used to detect the changes in the levels of the pro-inflammatory factors interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and the anti-inflammatory factor transforming growth factor-β (TGF-β) according to the steps in the enzyme-linked immunosorbent assay kit instructions.

[0168] 1.3.8 Determination of renal function indicators

[0169] The rat serum obtained in step 1.3.4 was used to detect the contents of aldosterone (ALD) and atrial natriuretic peptide (ANP) according to the steps in the enzyme-linked immunosorbent assay kit instructions.

[0170] 1.3.9 Organ index

[0171] In step 1.3.4, after sacrificing the rats in each group, the five internal organs (heart, liver, spleen, lung, and kidney) were taken out and the organ indices of the heart, liver, spleen, lung, and kidney were calculated. Taking the spleen as an example, the calculation formulas for the other organ indices were the same.

[0172] Spleen Index = [rat spleen weight (mg) / rat body weight (g)]

[0173] 1.3.10 Histological observation of the heart

[0174] After weighing all the organs of all the rats in 1.3.9, the heart was immersed and fixed in the prepared Bouin's fluid for 2 d, and then fixed and stored in 70% ethanol solution (in a 4°C refrigerator) for later use. The heart tissue blocks were fixed with Bouin's fluid, dehydrated with ethanol and n-butanol, embedded in methacrylate resin, and a 20-μm-thick section was cut from the embedded block. Finally, it was stained with periodic acid-Schiff reagent (PAS) and hematoxylin. Finally, the changes in the heart tissue were observed.

[0175] 1.4 Data statistical processing method

[0176] All data were expressed in the form of mean ± standard deviation, and GraphPad Prism 8 and Origin 2021 software were used for drawing.

[0177] 1.5 Experimental results

[0178] 1.5.1 Body weight changes of rats

[0179] Starting from 7 days after adaptive feeding until the end of the experiment, the body weight values of rats in each group were recorded every 7 days, and the body weight changes were recorded. The results are as Figure 1 shown. During the modeling period, except for the blank group, the body weights of rats in other groups decreased. After 14 days of intervention with normal saline in the two protection groups, the body weights of rats significantly recovered; however, after 14 days of intervention with normal saline in the model group, the body weights of rats did not show significant recovery; after 14 days of intervention in the positive control group, the body weights of rats significantly recovered; after 14 days of intervention with Dioscorea opposita compound peptide in the two treatment groups, the decrease in the body weights of rats was also significantly improved; indicating that the two Dioscorea opposita compound peptides can prevent and treat the decrease in the body weights of rats caused by spleen deficiency and dampness accumulation to a certain extent.

[0180] 1.5.2 Defecation situation

[0181] After 2 weeks of intervention, the wet mass and dry mass of feces of rats in each group within 12 h were recorded, and the fecal humidity was calculated. The results are shown in Table 5. Compared with the blank group (fecal humidity 34.09%), the fecal humidity of rats in the model group (65.54%) increased significantly; compared with the model group, the fecal humidity of rats in the protection groups (fecal humidity of protection group 1 was 37.21% and that of protection group 2 was 19.32%) and treatment groups (fecal humidity of treatment group 1 was 53.45% and that of treatment group 2 was 37.40%) decreased significantly and returned to the normal level, indicating that the Dioscorea opposita compound peptide composition prepared by the present invention can effectively improve the symptom of loose stools in rats with spleen deficiency and dampness accumulation, and the effect is significantly better than the Dioscorea opposita compound peptide polymer prepared in Example 3.

[0182] Table 5 Statistical table of rat fecal quality and humidity

[0183]

[0184] 1.5.3 Behavioral experiments

[0185] 1.5.3.1 Open field experiment

[0186] During the open field experiment, the activity time of rats in the model group in the central area within 10 min was reduced compared with the normal group, indicating that spleen deficiency and dampness accumulation can cause a decrease in the exploratory and autonomous activity ability of rats; the preventive and therapeutic effects of protection group 2 and treatment group 2 on depression and anxiety caused by spleen deficiency and dampness accumulation in rats are stronger than those of protection group 1 and treatment group 1, and the improvement of rat activity and exploration is more significant. As shown in Table 3.

[0187] Table 3 Statistical table of rat central area activity time

[0188]

[0189] 1.5.3.2 Forced swimming experiment

[0190] In the forced swimming test of rats, compared with the normal group, the immobile time of the model group on the water surface increased significantly, indicating that spleen deficiency and dampness accumulation can cause depressive-like behaviors such as fatigue and reduced activity ability in rats; compared with the model group, the immobile time of rats in the protection group 2 and the treatment group 2 in water decreased significantly, which can significantly prevent and relieve negative behaviors such as fatigue and reduced activity ability caused by spleen deficiency and dampness accumulation in rats, and improve the rats' will to survive and self-initiative, and the effect is significantly stronger than that of the protection group 1 and the treatment group 1. As shown in Table 4.

[0191] Table 4 Statistical table of the immobile time of rats swimming

[0192]

[0193] 1.5.4 Effects on hemorheology and vascular endothelial cell function

[0194] Endothelin-1 (ET-1) is the most potent vasoconstrictor factor, while nitric oxide (NO) is a vasodilator factor. The balance of this pair of vasoactive substances is of great significance for maintaining normal vascular tone and blood flow dynamics. It can be Figures 2 - 3 seen that compared with the blank group, the level of NO in the model group decreased significantly, and the level of ET-1 increased significantly, indicating that the NO / ET-1 imbalance in the model group of rats is related to the occurrence of cardiovascular and cerebrovascular diseases; compared with the model group, the level of NO in the protection group 2 and the treatment group 2 increased significantly, and the level of ET-1 decreased significantly, indicating that the Dioscorea opposita Thunb. compound peptide composition prepared by the present invention can significantly prevent and restore the NO / ET-1 imbalance caused by spleen deficiency and dampness accumulation in rats, and can prevent and treat the occurrence of diseases such as cardiovascular and cerebrovascular diseases, and the effect is significantly better than that of the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3.

[0195] 1.5.5 Detection of related indicators of the endocrine system

[0196] The thyroid gland is the largest endocrine gland in the human body, and the main active substances secreted are triiodothyronine (T3) and tetraiodothyronine (T4). It can be Figures 4 - 5 seen that compared with the blank control group, the levels of T3 and T4 in the model group decreased significantly, indicating that the metabolic level of the model group of rats decreased; compared with the model group, the levels of T3 and T4 in the protection group 2 and the treatment group 2 increased significantly, indicating that the Dioscorea opposita Thunb. compound peptide composition prepared by the present invention can prevent and restore the endocrine and metabolic level of rats caused by spleen deficiency and dampness accumulation, and improve the basal metabolic rate, and the effect is significantly better than that of the Dioscorea opposita Thunb. compound peptide powder prepared in Example 3.

[0197] 1.5.6 Detection of the recovery of gastrointestinal motility in rats

[0198] Motilin (MTL) and gastrin (GAS) are hormones normally secreted by the gastrointestinal tract, and they play an important regulatory role in gastrointestinal motility function. AsFigures 6 - 7 As shown, compared with the blank group, the levels of MLT and GAS in the model group were significantly decreased, indicating that the gastrointestinal motility of rats with spleen deficiency and dampness excess was significantly reduced; compared with the model group, the levels of MLT and GAS in the protection group 2 and the treatment group 2 showed varying degrees of increase, indicating that the Dioscorea opposita Thunb. compound peptide composition prepared by the present invention can restore the gastrointestinal motility of rats with spleen deficiency and dampness excess, and the effect is significantly better than that of the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3.

[0199] 1.5.7 Determination of serum inflammatory factors

[0200] The occurrence and development of spleen deficiency syndromes are closely related to inflammatory factors. As Figures 8 - 10 shown, compared with the blank group, the levels of pro-inflammatory factors IL-6 and TNF-α in the serum of rats in the model group were significantly increased, and the level of anti-inflammatory factor TGF-β was significantly decreased, indicating that spleen deficiency and dampness excess can trigger inflammatory reactions in rats; compared with the model group, the levels of pro-inflammatory factors IL-6 and TNF-α in the serum of rats in the protection group 2 and the treatment group 2 were significantly decreased, and the level of anti-inflammatory factor TGF-β was significantly increased, indicating that the Dioscorea opposita Thunb. compound peptide composition prepared by the present invention can prevent and alleviate the inflammatory conditions in rats with spleen deficiency and dampness excess, and the effect is significantly better than that of the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3.

[0201] 1.5.8 Determination of renal function indexes

[0202] ALD is an important mineralocorticoid secreted by the zona glomerulosa of the adrenal cortex, which has the physiological function of regulating sodium and potassium metabolism and extracellular fluid volume; the main function of ANP is to promote sodium and water excretion by the kidneys. Figures 11 - 12 As shown, compared with the blank group, the content of ALD in the serum of rats in the model group was significantly increased, and the content of ANP was significantly decreased, indicating that the renal metabolism of this group of rats was blocked; compared with the model group, the content of ALD in the serum of rats in the protection group 2 and the treatment group 2 was significantly decreased, and the content of ANP was significantly increased, indicating that the Dioscorea opposita Thunb. compound peptide composition prepared by the present invention can effectively regulate renal metabolism, and the effect is significantly better than that of the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3.

[0203] 1.5.9 Organ index

[0204] The five internal organs (heart, liver, spleen, lung, and kidney) of rats in each group were weighed, and the organ index was calculated. The results are shown in Table 6. Compared with the blank group, the organ indexes of rats in the model group were all increased, indicating that the organs of this group of rats showed symptoms such as congestion, edema, or hyperplasia and hypertrophy; compared with the model group, the organ indexes of rats in the protection group 2 and the treatment group 2 returned to the same level as the blank group, indicating that the Dioscorea opposita Thunb. compound peptide composition prepared by the present invention can effectively restore the health of the five internal organs of rats with spleen deficiency and dampness excess, and the effect is significantly better than that of the Dioscorea opposita Thunb. compound peptide polymer prepared in Example 3. As shown in Table 6.

[0205] Table 6 Statistical Table of Organ Index of Rats

[0206]

[0207] 1.5.10 Histological Observation of Heart

[0208] As Figure 13 shown, compared with the blank group, there was obvious glycogen deposition in the heart tissue of rats in the model group, indicating that the heart tissue of rats in this group was damaged. Compared with the model group, the heart color of rats in the protection group 2 and the treatment group 2 returned to be basically the same as that of the blank group, indicating that the Dioscorea opposita Thunb. composite peptide composition prepared by the present invention can effectively promote glycogen metabolism in the heart tissue of rats with spleen deficiency and dampness excess, restore heart health, and the effect is significantly better than that of the Dioscorea opposita Thunb. composite peptide polymer prepared in Example 3. Combined with Table 6, it jointly shows that the Dioscorea opposita Thunb. composite peptide composition can promote the recovery of other organs by restoring and strengthening heart health.

[0209] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that: without departing from the spirit and scope of the present invention and the appended claims, various substitutions, changes and modifications are possible. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments.

Claims

1. A method for preparing a multifunctional yam composite peptide composition, characterized in that: The steps include: Preparation of pea protein powder; Preparation of pea peptide powder A; Preparation of multifunctional yam composite peptide composition: Add pea peptide powder A and Chinese yam powder at a mass ratio of 3:5 to an appropriate amount of 3 mol / L phosphate buffer solution, mix thoroughly, and adjust the pH of the mixture to 7.0±0.2 using edible sodium hydroxide solution or hydrochloric acid solution with a mass concentration of 20%; The mixed solution was placed in a hot water bath at 87±2°C to react, and magnetic stirring was performed at a speed of 35±5r / min. The reaction time was 3±0.5h; After the reaction is complete, the mixture is quickly placed in ice water to cool down to stop the reaction. The cooled mixture is inoculated with 1% inoculation amount of Lactobacillus johnsonii IOB 801 seed liquid, 37°C, pH maintained at 6.0-6.5, rotation speed 45±5r / min, and cultured for 8±2h; after the fermentation liquid is concentrated, it is spray-dried to obtain a multifunctional yam composite peptide composition.

2. The method for preparing the multifunctional yam composite peptide composition according to claim 1, characterized in that: The preparation method of pea protein powder is specifically as follows: Pea pretreatment: Wash, screen and peel the fresh peas, soak them in water for 12 hours, with a solid-liquid ratio of g:mL of 1:30, and grind them into a homogenate after soaking; Initial separation: sieve the homogenized slurry, separate the slurry residue, and keep the slurry for later use; Alkaline extraction: add edible sodium hydroxide solution with a mass concentration of 20% to the slurry, adjust the pH to 8.0, the extraction temperature is 35°C, the extraction time is 40 minutes, after the extraction is completed, centrifuge at a speed of 4000r / min for 30 minutes, and take the supernatant; Acid precipitation separation: The supernatant was concentrated, cooled, and then a 20% hydrochloric acid solution was added to adjust the pH of the concentrate to 4.0, precipitated for 30 minutes, and centrifuged at 4000 r / min for 30 minutes to obtain pea protein precipitate; Spray drying: add edible sodium hydroxide solution with a mass concentration of 20%, adjust the pH to 7.0, neutralize the pea protein precipitate, and spray dry to obtain pea protein powder.

3. The method for preparing the multifunctional yam composite peptide composition according to claim 1, characterized in that: The preparation method of pea peptide powder A is specifically as follows: Prepare pea protein liquid: add pea protein powder to pure water at a mass ratio of pea protein powder to pure water of 1:10, and stir for 30 minutes to obtain pea protein liquid; Preparation of compound protease: neutral protease, alkaline protease and flavor protease were compounded in a mass ratio of 1.0:0.2:0.8 to prepare compound protease system A; Hydrolysis of compound protease system A: using pea protein liquid as substrate, adding compound protease system A with a final mass concentration of 1.0% to 1.5% and stirring, performing enzymolysis at 52°C for 5-6h, and after the enzymolysis is completed, inactivating the enzyme at 90°C to obtain pea peptide enzymolysis liquid; Membrane filtration: The obtained pea peptide hydrolysate was centrifuged at 6000r / min for 8min, the supernatant was collected, and the pea peptide collection solution was obtained by membrane filtration; Freeze drying: After pre-freezing the pea peptide collection liquid, vacuum freeze drying is performed to obtain pea peptide powder A.

4. The method for preparing the multifunctional yam composite peptide composition according to claim 1, characterized in that: The Lactobacillus johnsonii IOB 801 is a strain of Lactobacillus johnsonii screened from fermented kimchi.

5. The method for preparing the multifunctional yam composite peptide composition according to claim 1, characterized in that: The Lactobacillus johnsonii IOB 801 is named: Lactobacillus johnsonii IOB 801, the classification name is: Lactobacillus johnsonii, the preservation number is: CGMCC No.16824, the preservation date is: November 26, 2018, and the preservation unit is: General Microbiology Center of China National Culture Collection Administration, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

6. The method for preparing the multifunctional yam composite peptide composition according to any one of claims 1 to 5, characterized in that: The preparation method of the Lactobacillus johnsonii IOB 801 seed liquid is: Strain activation: Activate the frozen Lactobacillus johnsonii IOB 801 on MRS agar plates three times, pick a single colony and inoculate it into MRS liquid culture medium, culture it at 37°C for 10±2h, transfer it to MRS liquid culture medium with 1% inoculation amount, culture it at 37°C for 10±2h and use it as seed liquid.

7. The multifunctional Dioscorea opposita composite peptide composition prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the multifunctional Dioscorea opposita composite peptide composition as claimed in claim 7 in the preparation of cardiotonic drugs.

9. Use of the multifunctional Dioscorea opposita composite peptide composition as claimed in claim 7 in preparing a drug for restoring cardiac function of spleen deficiency and dampness excess type.

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