| In order to realize the comprehensive utilization of golden melon seed,the golden melon seed oil was extracted by ultrasonic assisted water enzymatic method,and the quality of the golden melon seed oil was analyzed.The golden melon seed meal was used to enzymolysis into the anti-oxidation peptide.The structure of the target antioxidant were identified after he anti-oxidation peptides were separated and purified.The antioxidative stability of the anti-oxidative peptides of golden melon seed during the simulated processing and storage process and simulated gastrointestinal digestion was investigated.The main results of the study are as follows:(1)Golden melon seeds contain 40.58% crude fat and 29.94% crude protein.Gourd seeds contained 17 kinds of fatty acids and total up to 76147.74 mg/kg,among which the monounsaturated fatty acid(MUFA)accounted to 36.65%,the polyunsaturated fatty acids(PUFA)21.24%.The SFA:MUFA:PUFA was 1.15:1.00 : 0.58.The atherosclerosis index(AI)and thrombosis index(TI)were 0.69 and 1.31,respectively.(2)The best process conditions of ultrasonic-assisted aqueous enzymatic extraction of gold melon seed oil was: the ratio of gold melon seed powder of 80 mesh to water was 1:7,and 2% of complex protease was added after ultrasonic for 30 min at 25 kHz.the enzymolysis was carried out at pH 7.4 under 56 ? for 2.2 h.The extraction rate of the gold melon seed oil was 66.19%.(3)The main kinds of volatile substances of the gold melon seed oil prepared by hot pressing method and cold pressing method are similar,and they are mainly terpenes,esters,aldehydes and ketones.But the contents of volatile substances is very different.The main kinds of volatile enzymatic of the gold melon seed oil preparaed by aqueous enzymatic is terpenes,alcohols and esters,and the contents were 49.23%,17.34% and 13.75%,respectively.The acid value and peroxide value of aqueous enzymatic preparation of gold melon seed oil were lower than those were made by hot pressing method and cold pressing method.(4)There is 40.94% protein in gold melon seed meal,and the amount of 16 kinds amino acid of protein in gold melon seed meal total up to 38.21 g/100 g.The proportion of essential amino acids to total amino acids is 30.21%.The amino acid ratio coefficient(RCAA)and amino acid ratio coefficient score(SRCAA)values of the goldseed meal protein were 68.97 and 67.33,respectively.The first limiting amino acid was the sulfur-containing amino acid(Met+Cys).(5)The optimum conditions for the preparation of antioxidant peptides from gold melon seed meal were as follows: 3% alkaline protease was added to the gold melon seed meal of6% concentrationat pH 8.50 under 55 ? and enzymatic hydrolysis for 90 min.The hydroxyl radical scavenging rate of the enzymolysis product was 58.19%,the DPPH radical scavenging rate was 61.12%,and the reducing power was 0.523.(6)The hydrolysates gold melon seed mealpeptides which have strong antioxidant activity were isolated and identified using reversed-phase high performance liquid chromatography-electrospray ionization mass spectrometry on the basis of ultrafiltration and gel chromatography.The amino acid sequence of 6 segments of peptides were obtained by comparison with the peptide library.(7)The thermal stability of anti-oxidant activity of gold melon seed peptides is good under 20 ? to 60 ?.It is sensitive to light,and the activity remained good in the environment with the pH from 6 to 8.The in vitro gastrointestinal digestion experiments showed that: gold melon seed antioxidative peptides are mainly degraded in the intestine.The amino acids in the final product of anti-oxidative peptides such as molecular weight less than3 kDa,3 to 5 kDa and greater than 5 kDa after digested in the digestive tract were 41.72%,36.94%,and 33.93%,respectively.The others were mainly peptides with a relative molecular weight of less than 500 Da.The antioxidant activity with different molecular weights of antioxidant is stronger than that of before gastrointestinal digestion. |
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