Study On Protein Extraction And Deodorization And Preparation Of Anti-hypertensive Bioactiye Peptide From Mytilus Coruscus Defatted Powder

Mytilus coruscus or thick shell mussel is one of the main mussel species cultured in the shallow sea in large area of China. It is rich in protein, essential amino acids and polyunsaturated fatty acid. Anti-inflammatory function of Mytilus coruscus lipid extract has been proved by studies from our research team and others. Lipids extract of Mytilus coruscus as an anti-inflammatory nutraceutical has become an effective utilization of mussel. A by-product from the thick shell mussel lyophilized powder after extraction of its lipid composition was used as the research material in this study. The protein extraction process, deodorization methods and preparation of anti-hypertensive bioactive peptide of the defatted mussel powder and comparison with a typical vegetable protein, yellow pea (Pisum sativum L) protein which has been proved to be a good source of anti-hypertensive bioactive peptide was investigated and the research results are as follows:1.47.4%high protein content was found in the defatted mussel powder and the isoelectric precipitation of protein extraction process was preliminarily determined by single factor experiment and orthogonal experiment, solid-liquid ration1:20, pH=12, temperature40uC, extraction time50min and the mussel protein isolate contains84.9%protein (dry basis),13.1%ash and0.9%lipid. The ash content was reduced by dialysis and the amino acid composition has no significant change before and after extraction and dialysis.2. A dark brown and unpleasent smell protein isolate was obtained by extraction at pH=12which has a low sensory value. So the protein extraction process was modified and deodorization was performed by extraction with ethanol water solution (v/v,2/1) which can weaken the unpleasent smell of the protein isolate and lead a low loss of protein. So extraction with ethanol water solution (v/v,2/1) can be used as a deodorization treatment before isoelectric precipitation of protein extraction process.3. No significant difference of protein content of the protein isolate extracted in acid (pH=2) and alkaline conditions (pH=12) was found but the acid extraction has a better smell. And the fishy smell of protein isolate was significantly weakened after the deodorization by ethanol water solution (v/v,2/1) and acid isoelectric precipitation method. The deodorization effect of citric acid and CaCl2was studied. Adding citric acid and CaCl2during the extraction of mussel protein can further remove the fishy smell and some unpleasent smell of the protein isolate as well as give a good color and over90%protein content to the mussel protein isolate.4. High degree of hydrolysis (DH) was obtained by the double enzyme digestion and in vitro gastrointestinal digestion of both thick shell mussel protein isolate and yellow pea protein isolate. The DH value of mussel protein isolate in vitro gastrointestinal digestion is the highest, over80%and the flavor protease, alkaline protease and neutral protease showed higher enzymatic properties to thick shell mussel protein isolate than yellow pea protein isolate.5. Inhibition effects of Angitension angiotensin-converting enzyme (ACE) were found from the hydrolysates of both thick shell mussel protein isolate and yellow pea protein isolate. The mussel protein and pea protein hydrolysates from in vitro gastrointestinal digestion showed the highest IC50values,215μg/mL and195μg/mL respectively. In vitro gastrointestinal digestion of thick shell mussel protein can be an effective way to prepare anti-hypertensive bioactive peptide.6. The DH values and inhibition of ACE from citric acid and CaCl2treated and non-treated mussel protein were similar which means the citric acid and CaCl2have no significant effect on the preparation of anti-hypertensive bioactive peptide from thick shell mussel protein but they do weaken the unpleasent smell and increase the protein content of the protein isolate.