Myofibrillar protein hydrolysates

Antioxidative Peptides in Porcine Myofibrillar Protein Hydrolysates by Protease Treatment... 

In present study, we investigated antioxidant activity of porcine myofibrillar protein hydrolysates obtained enzymatic treatment in the peroxidation system of linolenic aqueous induced by Fe. Furthermore, antioxidant peptides are isolated from its hydrolysate. 

Figure 2. Separation of myofibrillar protein hydrolysate by ion-exchange column chromatography...

Modification of fish proteins by proteolytic enzymes to increase their solubilities illustrates a variety of techniques and approaches. Basically, three general enzymic methods have been used to prepare fish proteins or hydrolysates with altered solubilities and other functionalities. These methods include (a) the enzymic solubilization of fish protein concentrate prepared by hot solvent extraction of fish, (b) the enzymic modification of myofibrillar proteins extracted from fish with 0.6M NaCl, and (c) the proteolysis of whole fish to prepare biological fish protein concentrate (FPC). 

Spinelli et al. (14) determined the emulsion stability and emulsion capacity of polypeptides recovered from hydrolysates of fish myofibrillar protein using hexametaphosphate. In general the emulsion capacity and emulsion stability increased through 30 min of proteolysis but then declined. Even the unhydrolyzed protein-phosphate complex yielded better emulsion stability and capacity values compared with sodium caseinate. The effect of the residual hexametaphosphate in the hydrolysate conceivably could have a beneficial effect on emulsifying characteristics of the modified fish myofibrillar proteins. 

Proteins. Protein hydrolysates have already been mentioned as new marine-derived ingredients, but of a type that must be considered an additive for a specific use and not as an integral part of the food. The proteins present in fish muscle are usually divided into three fractions the sarcoplasmic proteins, the myofibrillar proteins and the connective tissue proteins. 

A proteolytic hydrolysate of porcine myofibrillar proteins was hydrolyzed in 6 N HCl at 110 C for 24h. Amino acid composition of peptides in the hydrolysate was analyzed with an amino acid analyzer (Shimazu Co, Kyoto Japan). 

Antioxidative activities of the hydrolysates from porcine myofibrillar protein were measured in a linolenic acid oxidation system The hydrolysates at the concentration of 0.02, 0.2 and 2% exhibited antioxidative activities. All hydrolysates exhibited stronger antioxidative activity, as the concentration was higher in the production of hydroperoxides. On the other hand, the addition of 0.2% hydrolysate suppressed the production of TEARS most strongly, and the antioxidative activity in the addition of 2% hydrolysate was lower than that of 0.2% in the method of TEARS. It is well known that 2-thiobarbituric acid (TEA) reacts with aldehyde compounds including malondialdehyde (MDA) formed by Upid peroxidation. Two percent hydrolysates contained a lot of amino confounds including free amino acids and peptides. Therefore, the production of aldehyde compounds seems to be accelerated by amino-carbonyl reaction between hydrolysate and lipid in lipid peroxidation system including 2% hydrolysate. This might be the reason why the antioxidative activity of 2% hydrolysate was lower than that of 0.2 % hydrolysate in the method of TEARS. 

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