Effects Of Pleurotus Eryngii Polypeptides On The Quality Of Sour Soymilk Fermentation And Synergistic Effects On Antioxidant And Immune

Pleurotus eryngii is rich in a variety of biologically active ingredients,and has anti-aging,anti-cancer,and enhances human immunity.In this study,peptides were extracted from Pleurotus eryngii,separated into different molecular weight components by ultrafiltration,and their antioxidant activity was measured.A functional fermented product was prepared by adding it to sour soymilk to study its antioxidant,immune effects and effects on intestinal flora.The effect of clusters provides a theoretical basis for the development of functional fermented sour soymilk.The findings are as follows:(1)The best process for extracting Pleurotus eryngii protein and optimizing the enzymatic hydrolysis method to prepare the Pleurotus eryngii antioxidant peptides.The optimal enzymatic conditions obtained by single factor and response surface analysis are:enzyme concentration5000 U/g,substrate concentration 4%,enzymolysis time 4 h,at this time DPPH free radical scavenging rate was 60.13%.The antioxidant activity of peptides with different molecular weights was separated and determined by ultrafiltration membrane.Pleurotus eryngii peptides with a molecular weight(27)1k Da have the highest DPPH free radical scavenging rate,with an IC₅₀ value of 0.564 mg/m L;peptides with molecular weights ranging from 1-3 k Da have the highest scavenging hydroxyl radicals,with IC50 of 1.214 mg/m L;The component with the molecular weight ranging from1-3 k Da had the highest total reducing power,and its reducing power reached 0.459 when the concentration was 1.0 mg/m L.Amino acid analysis found that the low-molecular-weight peptide(MW(27)3 k Da)had a hydrophobic amino acid content of 36.465 g/100g and a negatively charged amino acid content of 21.905 g/100g,which was significantly higher than that of crude peptides that were not isolated by ultrafiltration(p(27)0.05).From this analysis,the antioxidant activity of low molecular weight peptides is better.Crude peptides and low molecular weight peptides are added to soybean milk to prepare Pleurotus eryngii peptide sour soymilk.(2)The best process for preparing Pleurotus eryngii peptide sour soymilk by single factor and response surface analysis is fermentation time 5.5h,fermentation temperature 42?,inoculation amount 0.5%,peptide addition amount 0.3%,the sensory score of Pleurotus eryngii peptide sour soymilk is 93.6.The physical and chemical properties of Pleurotus eryngii polypeptide sour soymilk were measured.Compared with the control sour soymilk,the addition of Pleurotus eryngii polypeptide significantly changed the physical and chemical properties of sour milk,the number of lactic acid bacteria,acidity and water holding capacity were significantly increased,and the p H value and protein content were decreased.The effect of low molecular weight peptides on the physical and chemical properties of sour soymilk is more significant.Amino acid analysis found that compared with before fermentation,the amino acid content increased after fermentation,the total amount of amino acids in the control sour soymilk increased by 34.24%,the total amount of low-molecular-weight peptide sour soymilk increased by 9.85%,and the total amount of crude peptide sour soymilk increased by 21.08%.Compared with before fermentation,the content of low molecular weight peptidic sour soymilk proline decreased the most,being 18.81%,followed by tyrosine by 15.34%,lysine by 14.88%,and valine by 12.46%.Crude peptide sour soymilk arginine decreased the most,at 17%,followed by a tyrosine reduction of 1.85%.There was no decrease in the content of various amino acids in the control sour soymilk without added peptides.(3)Effect of Pleurotus eryngii peptide sour soymilk on anti-oxidation and immunity of mice in each group.Compared with the model group,the serum T-AOC,SOD,and CAT activities of the crude peptide and low-molecular-weight peptide acid soybean milk mice were increased to varying degrees,the MDA content was decreased,the thymus index and spleen index were increased,and the serum hemolysin was increased.The number of blood cells was significantly restored,which promoted the proliferation of splenic lymphocytes induced by Con A.Pleurotus eryngii peptide sour soymilk relieves cyclophosphamide-induced oxidative stress injury and immunosuppression in mice,and it is dose-dependent.High-dose low-molecular-weight peptide acid soymilk has the most significant effect on antioxidative and immune effects in mice.The intestinal flora measurement results showed that the low molecular weight peptide acid soybean milk(high-dose)group had the highest diversity of intestinal flora.The Chao index was 1561.42,the Sobs index was 1005.05,and the Shannon index was 7.45,which was significantly higher than the model group(Chao index is 1308.83,Sobs index is 861.45,and the Shannon index is 6.88).The seven groups of samples collectively have 137 OTUs,and the unique OTUs in each group have the most low-molecular-weight peptide soymilk(high-dose)group with the largest number of 875,and the model group with the least number of 748.At the phylum level,the dominant bacterial flora include Bacteroides,Firmicutes,etc.The proportion of Firmicutes in the sour soymilk group was 36.19%,which was significantly higher than the model group(25.8%).Lactobacillus plantarum added to sour soymilk starter belongs to Firmicutes,indicating that Pleurotus eryngii peptide sour soymilk helps to regulate the abundance of Firmicutes in mice.At the genus level,the low-molecular-weight peptide sour soymilk(high-dose)group had the highest proportion of Bacteroides,10.88%,and the model group had the lowest proportion of Bacteroides,7.83%.Lactobacillus also showed differences between the different groups,with the low molecular weight peptidic sour soymilk(high-dose)group accounting for the highest percentage and the model group the lowest.Pleurotus eryngii polypeptide sour soymilk helps to improve the intestinal Lactobacillus of mice and helps to regulate the balance of intestinal flora.In summary,Pleurotus eryngii peptide acid soymilk slows down the oxidative stress and immunity decline caused by cyclophosphamide,improves the diversity of intestinal flora,and regulates the structure of intestinal flora.