Studies On The Preparation Of Peptides From Enzymatic Hydrolysis Of Swimming Crab Waste

The swimming crab wastes were litters from the processing of the swimming crab, consisting of crab claws, crab tergum, viscera and so on which are rich in proteins of 30%-40%. The extraction of antioxidant peptides and antibacterial peptides from swimming crab which nearly makes full use of their proteins can not only increase its value-added, but also reduce environmental pollution. So it has sound economic and social benefits.This research was aimed to study on preparation of peptides-antioxidant peptides and antibacterial peptides from enzymatic hydrolysis of swimming crab. The suitable condition of enzymatic hydrolysis for making antioxidant peptides from crab was studied; Methods for purification of antioxidant peptides with Sephadex chromatography and physical and chemical properties of purified antioxidant peptides such as molecular weight distribution were determined; The suitable condition of enzymatic hydrolysis for making antibacterial peptides from crab was studied. The results were as following:(1) The suitable condition of enzymatic hydrolysis for making antioxidant peptides from crab was studied. The results showed that neutral protease was suitable for the hydrolysis of swimming crab waste; The optimal hydrolysis condition was 1:6 of material-liquid ratio,1.5h of water-bath heating time, temperature 50℃, pH 7.5,3000u/g of enzyme amount,4h of hydrolysis time. The content of polypeptides in hydrolysates was 65.66%. Yield of crud antioxidant peptides of crab was 43.3%.(2)The antioxidant peptide made by enzyme hydrolyzing swimming crab was separated by Sephadex G-50 and Sephadex G-25. The result showed that the peptide collected in the third elution peak has better antioxidant activity; it was purified basically by HPLC analysis; its molecular weight was about 1096.5;it was composed of llkinds of amino acid,rich in Tyr, Cys and His which have antioxidant activity. Ingredient 3 has good dissolving capacity and dissolution stability, and has strong oil absorption, which can be better used in food industry. Yield of antioxidant peptides of crab was 13.3%.(3) The suitable condition of enzymatic hydrolysis for making antibacterial peptides from crab was studied. The results showed that neutral protease was suitable for making antibacterial peptides; the optimal hydrolysis condition was 1:5.9 of material-liquid ratio,1.5h of water-bath heating time;temperature 45℃, pH 6,3616.2u/g of enzyme amount,4.5h of hydrolysis time.The highest inhibition zone diameter of Aureus was 19.0mm in hydrolysates obtained under the optimal hydrolysis condition and the content of polypeptides in hydrolysates was 58.46%. Yield of crud antibacterial peptides of crab was 38.3%.