Study On Hydrolysis Viscera Of Channel Catfish

Studies on hydrolysis viscera of channel catfish are described. Viscera were hydrolyzed by endogenous enzymes alone or in combination with commercial protease or in a semi-dry method with base-catalyst and microwave radiation or in a semi-dry method with sulfuric catalyst and microwave radiation. Hydrolysates were characterized with respect to degree of hydrolysis, turbidity, concentration ofα-amino groups and peptide molecular weight distribution.Hydrolysis with commercial protease showed that the product was more favorable than the other methods with less turbidity. Acid protease gave the lowest molecular than alcalase, trypin, and neutral protease.The technology for enzymatic hydrolysis by using acid protease for proteins in channel catfish was studied. The optimized results showed that the maximum degree of hydrolysis (DH) was obtained as high as 18.013% at the condition of the hydrolysis temperature of 45.23℃, hydrolysis pH of 4.04, the hydrolysis time of 6.62 h and substrate concentration of 5.58%. In the above-mentioned optimal conditions, amino acid analytical results of enzymatic hydrolysis liquid showed that it contained lots of attractant amino acid we needed.The relative molecular mass distribution, NSI, viscosity, moisture absorption and moisture retention ability of channel catfish viscera enzyme-hydrolysate by acid protease were studied. These targets could be used to evaluate its nutritional value as feed attractant for further study. The results showed that crude protein reached as high as 78.07%. The results of relative molecular mass distribution determined by gel HPLC showed that the Mr distribution of enzyme-hydrolyzed peptide wasn't continuous, of which large peptides with Mr exceeding 1400 were 4.83%; medium-peptides with Mr 385~625 were 85.57%; and small-peptides and free amino acids with Mr less than 385 were 9.6% .The enzyme-hydrolysate could dissolve well in different pH values and NSI could achieve higher than 80%. However, the viscosity was low in solution. Moisture absorption and moisture retention ability results indicated that the enzyme-hydrolysate could absorb water quickly but moisture retention ability was low relatively.Content of heavy metal such as Pb and Cd was 1.292 mg/kg and 0.23 mg/kg respectively, according with national standard (below 5mg/kg) .Thus it's safe to add it to feed.The product was steady in aqueous solution and was a natural health feed additive with good color, flavor and odor and could be regarded as feed attractant or nutrient supplement.