Preparation And Properties Of Selenium-enriched Oyster Mushroom Peptide

Selenium is an essential trace element for human life activities.It participates in the synthesis of various selenium-containing enzymes and selenoproteins in the human body,and has the functions of enhancing the body's immunity and anti-aging.Pleurotus ostreatus is rich in varieties,and has been proven to have strong selenium-rich and selenium-tolerant ability during the growth process.Studies have pointed out that selenium-enriched Pleurotus ostreatus is rich in selenoprotein content and reasonable in amino acid composition,has high nutritional value and medicinal value,and is a new type of high-quality plant protein.Studying the preparation technology and properties of selenium-enriched oyster mushroom peptide has practical significance for the development and utilization of selenium-enriched oyster mushroom and broadening the selenium-enriched food industry chain.In this study,Enshi selenium-enriched oyster mushroom was used as raw material,single-enzyme hydrolysis,superfine pulverization assisted enzymatic hydrolysis,and protein dissolution rate and degree of hydrolysis were used as evaluation indicators.The peptides and polysaccharides were separated by filtration,and the selenium-enriched oyster mushroom peptide was optimized by the response surface test and the nanofiltration desalting process,and then concentrated and freeze-dried to obtain the selenium-enriched oyster mushroom peptide.The antioxidant activity of the selenium-enriched oyster mushroom peptide was analyzed;The amino acid composition of Enshi selenium-enriched oyster mushroom peptide and the type and content of organic selenium.The main research contents and conclusions are as follows:1.To study the effect of ordinary crushing and superfine crushing on the function and structural characteristics of selenium-enriched oyster mushroom.After the selenium-enriched oyster mushroom is superfinely pulverized,the water retention,oil retention,water swelling,water solubility,and cation exchange capacity of the powder are increased;the particle size of the powder is significantly reduced,the particle distribution is more uniform,and the heat The stability has been slightly improved.Therefore,proper ultra-fine pulverization treatment can improve the function and structural performance of oyster mushroom powder to a certain extent,the intensive processing of selenium-enriched oyster mushroom,the extraction and preparation of selenium-enriched oyster mushroom's biologically active ingredients(selenoprotein,selenium polysaccharide,etc.)It is of great significance.2.The enzymatic hydrolysis of Se-enriched Pleurotus ostreatus under two different raw material processing methods was studied,and the optimal preparation process parameters of Se-enriched Pleurotus ostreatus peptide were screened through single factor and orthogonal experiments.(1)Using selenium-enriched oyster mushroom coarse powder as raw material,on the basis of single factor test,hydrolysis is the main evaluation index,and the process of hydrolyzing selenium-enriched oyster mushroom protein by alkaline protease is optimized through orthogonal test.The best hydrolysis conditions are:the ratio of material to liquid is 1:30,the temperature is 55?,the amount of enzyme added is 4200U/g,and the p H is 10.5.Under these conditions for 4 hours,the hydrolysis degree of selenium-enriched oyster mushroom protein was 28.46%,and the protein dissolution rate was 82.85%.(2)Using ultra-finely crushed oyster mushroom powder as raw material,orthogonal test was carried out on the basis of single factor test,and the best test conditions obtained were:material-to-liquid ratio 1:50,temperature55°C,and enzyme amount 3500U/g,p H10.5.Under these conditions for 2h,the hydrolysis degree of selenium-enriched oyster mushroom protein was 33.72%,and the protein dissolution rate was 88.25%.(3)Comparing the two processes,it can be seen that when the amount of substrate is constant,the hydrolysis time of the ultra-fine pulverization process is reduced by two hours,the amount of enzyme used is reduced by 700U/g,and the degree of hydrolysis and protein dissolution rate are significantly improved.In summary,the ultrafine pulverization treatment can increase the degree of hydrolysis of selenium-enriched oyster mushroom protein and the rate of protein dissolution,and finally determine the best process conditions for selenium-enriched oyster mushroom protein hydrolysis:first use a ball mill at700r/min for oyster mushroom powder Treat for 30 min,then carry out enzymolysis under the conditions of material-liquid ratio 1:50,temperature 55 ?,alkaline protease plus enzyme amount 3500U/g,p H10.5,enzymolysis time 2h.3.Using the selenium-enriched oyster mushroom enzymatic hydrolysate as the raw material,after microfiltration and ultrafiltration,the nanofiltration equipment with a molecular weight cut-off of 200?300Da is used for desalination.On the basis of the single factor test,the desalination rate is used as an evaluation index to study the influence of the feed temperature,pressure,and feed concentration on the desalination rate.Through the response surface optimization of the nanofiltration desalination process,the optimal conditions for the nanofiltration desalination process of the selenium-enriched oyster mushroom enzymatic hydrolysate were finally determined as the feed temperature of 36?,the pressure of 0.55 MPa,and the feed concentration of 10%.Under these conditions for 4 times of nanofiltration,the desalination rate was 72.55%,the peptide recovery rate was 86.72%,and the total selenium content of the obtained selenium-enriched oyster mushroom peptide was237.20?g/g.4.By measuring the scavenging rate of selenium-enriched oyster mushroom peptide and protein on free radicals,the results show that the antioxidant activity of selenium-enriched pleurotus ostreatus peptide is better than that of selenium-enriched oyster mushroom protein,but not as good as Vc.Selenium-enriched Pleurotus ostreatus contains 17 amino acids(excluding tryptophan),of which essential amino acids account for 31.37% of the total amino acid content,and semi-essential amino acids and essential amino acids account for37.89% of the total amino acid content.The content of methylselenocysteine in the selenium-enriched pleurotusin was 16.6?g/g,the content of selenocystine was0.633?g/g,and the content of selenomethionine was 1.05?g/g.