| Summary: | 碩士 === 國立海洋大學 === 食品科學系 === 91 === To improve the properties of fish muscle protein as new material source of protein, commercial bromelain and papain were used to degrade tilapia muscle protein to the product which was rich in larger molecular weight peptide mixture. The quality of enzymic modified protein was monitored by SDS-PAGE, viscosity, emulsification ability, gel-strength, whiteness and organoleptic evaluation.
The viscosity and breaking force of gel made from enzymic modified tilapia muscle protein with 2% NaCl declined sharply at the initial hydrolysis stage. The viscosity decreased with the extending hydrolysis time. The whiteness of gel from hydrolysates prepared with 1‰ bromelain was higher than that of 1.5‰ papain, but the salt intensity of the former was lower than that of the latter. The emulsification ability of the hydrolysates prepared with proteases increased with hydrolysis time.
The viscosity and breaking force of homogenate gel became lower after freeze drying. The addition of 3.5% sucrose and 0.15% polyphosphates as cryoprotectants of freeze drying could improve the viscosity and breaking force of gel from the homogenate rehydrated with 2% NaCl. The cryoprotectants also improve the emulsifying stability of the homogenate and hydrolysates prepared with 1.5‰ papain. Freeze drying showed no significant effect on emulsifying properties of rehydrated tilapia meat hydrolysates prepared with 1‰ bromelain.
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