Study On The Key Technology Of Preparation Of Oyster Proteinsmall Molecular Peptide

Oysters have the reputation of “marine milk” and have a long history of eating at home and abroad.They are popular seafood products.As people's awareness of food nutrition continues to increase,the market value of oysters has also increased.However,the deep processing capacity of marine biological resources in China is still very lacking.The comprehensive utilization rate of important resources,such as marine organisms is not enough,resulting in low added value of marine resources products,which seriously restricts the development of China's marine resources to a high level,high level and high utilization rate.Therefore,improving the added value of oyster products and making full use of their nutritional value is a hot topic of research by experts and scholars today.This paper mainly studies the key technologies for the preparation of oyster small molecule peptides.The main conclusions are as follows:1.Crassostrea gigas and brassostrea gigas are two of the most common types of oysters,both of which are high in protein and low in fat.Among them,the crude protein content of crassostrea gigas was 9.36%,which was higher than that of brassostrea gigas.The fat and glycogen content of crassostrea gigas were 2.66% and 2.23% respectively,both of which were lower than those of crassostrea gigas(2.71% and 3.35%).Crassostrea gigas could better reflect the characteristics of high protein and low fat,and had higher nutritional content compared with other shellfish products.The total amino acid content of brachial oysters was 34.16 g/100 g,and that of crassostrea gigas was 47.77 g/100 g.The total contents of essential amino acids were 9.92 g/100 g in brassostrea gigas and 16.86 g/100 g in crassostrea gigas.The first restricted amino acid of the two different types of oysters was methionine(Met)and cystine(Cys),and the score of the first restricted amino acid of brassostrea gigas was 52,slightly lower than that of crassostrea gigas(55).The fatty acid composition of the two kinds of oysters is not different,and the mineral element content is very rich.Therefore,this study will select the local crassostrea gigas in zhoushan as the experimental object.2.Taking the soft part of the local crassostrea gigas in zhoushan as the research object,the soft part of the oyster was hydrolyzed by different kinds of proteases,and it was found that the best protease was flavor protease,and the content of amino nitrogen in the solution was the highest,reaching 6.54 mg /g.After the response surface optimization experiment,the optimal parameters were 1.33% of the enzyme content,6.919 of the pH value and 4.763 h of the enzymatic hydrolysis time.At this time,the theoretical value of amino nitrogen(AAN)content in oyster enzymatic hydrolysate was 5.416 mg/g.Considering the principle of practical production and convenient operation,the optimum technological parameters for enzymatic hydrolysis of oyster meat were determined as follows: enzyme addition amount of 1.3 %,pH value of 7,enzymatic hydrolysis time of 5 h.The content of amino nitrogen(AAN)reached the highest(5.59 ±0.25)mg/g.The results will provide theoretical guidance for oyster proteolysis process.3.Oyster protease hydrolysate is a mixed system with relatively complex components,including protein,amino acids,lipids,nucleic acids,peptides,sugars,inorganic salts and other mixtures.The oyster enzymatic hydrolysate obtained under the optimal technological parameters was used as raw material to extract small molecule protein peptides through a series of separation and purification experiments.The results showed that the crude protein precipitated with ammonium sulfate saturation of 30%~100% had better solubility and DPPH radical scavenging ability.The precipitated and resolubilized protein solution was graded by ultrafiltration membrane with a molecular retention of 3kDa to obtain the molecular weight range of component a(Mw < 3kDa),component b(Mw > 3kDa),and component a as the target protein peptide.The target protein peptide was analyzed by HPLC for the molecular weight composition of component a.The peak time of the four substances was 18.708 min,19.857 min,20.552 min and 23.591 min,respectively.Combined with the standard curve,the molecular weight distribution of the oyster protein small molecule peptide in component a was about 1995.2Da,1258.9 Da,1023.3 Da and 398.1 Da.4.The nutrition evaluation of small molecule polypeptides prepared from oyster mollusk was carried out.The content of essential amino acid(EAA)in the target oyster small molecule peptide was 18.863 %,and the total amino acid content was 43.375 %.Essential amino acid(EAA)accounted for 43.49% of total amino acid(TAA),and the ratio of essential amino acid(NEAA)to non-essential amino acid was 76.95%.The proportion of flavor amino acids was 18.915 %,equivalent to 43.61 % of total amino acids.The results of amino acid evaluation and analysis showed that the chemical score and amino acid score of lysine of oyster small molecule peptide were higher,respectively 95.1 and 122.7.The content of lysine in oyster small molecule polypeptide is relatively rich,which can provide essential nutrients for human body.