Study On The Preparation Pumpkin Seed Protein And Peptide

Pumpkin seeds are rich in nutrients.The crude protein content is 31.3%,the crude fat content is 42.3%,the crude fiber content is 2.5%,the moisture content is6.0%and the ash content is 4.3%.Pumpkin seed protein has the effects of lowering blood sugar,anti-oxidation and inhibiting tumor microproliferation.As a by-product of pumpkin seed oil extraction,pumpkin seed meal has a huge yield and a protein content of 62.45%.Most of the pumpkin seed meal is added to the feed as a protein supplement,which is a great waste of protein resources.In this paper,the preparation of pumpkin seed protein powder was studied,the conditions of pumpkin seed protein extraction were optimized and the purity of protein was improved by saccharification enzyme treatment.The pumpkin seed protein was moderately hydrolyzed by enzyme to improve the functional properties of the protein.The preparation process of the polypeptide obtains the biologically active polypeptide,the effect of fully utilizing the pumpkin seed protein is improved and the utilization rate of the pumpkin seed protein in the food is improved.The results of this paper are as follows:?1?The pumpkin seed protein powder obtained by supercritical CO₂ extraction method was compared by comparing the pumpkin seed oil obtained by the supercritical CO₂ extraction method,the leaching method and the ultrasonic assisted solvent extraction method.This is because compared with the other two methods,the pumpkin seed oil obtained by supercritical CO₂ extraction method has better peroxide value,acid value and fatty acid composition,but its oxidation stability is poor;pumpkin obtained by supercritical CO₂ extraction method.There is no significant difference in the residual oil and protein content of seed protein powder.The method has low degree of denaturation and no solvent residue,but the whiteness of protein powder is slightly poor.The extraction of pumpkin seed oil by supercritical CO₂ extraction is a method of high input and high income.?2?Pumpkin seed protein powder which obtained by supercritical CO₂ extraction is used as raw material,and pumpkin seed protein was extracted by alkali-soluble acid precipitation method.The liquid-to-liquid ratio was analyzed by single factor experiment.Study on the effects of alkali extraction pH,alkali extraction temperature and alkali extraction time on the extraction rate of pumpkin seed protein.The optimized process conditions were as follows:alkali extraction pH was9.5,alkali extraction temperature was 50°C,alkali extraction time was 120min,liquid to material ratio was 10:1.The verification experiment was carried out under the optimal conditions,and the extraction rate of pumpkin seed protein was75.35%.The pumpkin seed protein was purified by saccharification enzyme and the optimal conditions were as follows:enzymatic hydrolysis temperature was 55°C,enzymatic hydrolysis pH was 4.5,enzymatic hydrolysis time was 90 min,he ratio of material to liquid was 1:8 and the enzyme addition amount was 0.3%.Under this condition,the purity of the pumpkin seed protein was 91.38%.?3?Three different degrees of hydrolysis of pumpkin seed proteins DH3,DH8,DH18 and PSPI were selected to analyze their functional properties.With the increase of hydrolysis degree,the solubility,water holding capacity,emulsifying property and foaming property of pumpkin seed protein are improved,and it is not obviously affected by pH;il holding property is lowered,emulsion stability and foaming stability are stabilized.The tendency to increase first and then decrease,the degree of denaturation of the protein increases and the viscosity of the protein also decreases.The effect of enzymatic hydrolysis on the structure of pumpkin seed protein is the formation of more intermolecular hydrogen bonds,indicating that moderate hydrolysis of pumpkin seed protein can improve protein function,but deep hydrolysis leads to partial function reduced.?4?The alkaline protease and flavor protease were compounded,the hydrolysis conditions,DPPH free radical scavenging ability and ABTS free radical scavenging ability were used as the response values.The process conditions of enzymatic hydrolysis of pumpkin seed protein by complexed protease were optimized by response surface methodology.The optimal hydrolysis conditions were as follows:substrate concentration is 5.0%,hydrolysis pH 8.5,hydrolysis temperature 55.0°C,hydrolysis time 8.0 h,verification of actual DH was22.56%,ABTS free radical scavenging capacity was 75.62%,DPPH was free radical scavenging ability 95.65%.The pumpkin seed polypeptide has a relative molecular weight distribution of 89.46%of the total ratio below 1000 Da.