Protein Quality Evaluation of Cooked Hagfish (Eptatretus burgeri) Meats

Abstract

The effect of cooking methods on in vitro and in vivo indices of the protein quality of hagfish meat were investigated. In vitro protein digestibilities of cooked meats (81.3～83.5%) were not significant different (p＜0.05) from those of raw meat (82.9%), with the exception of steamed (110℃, 15 min) meat (86.3%). Convection oven cooking (220℃, 15 min) resulted in a higher trypsin indigestible substrate (TIS, 49.2 mg/g solid) compared with that of raw meat (38.9 mg/g solid). Free amino acid content of raw meat was decreased after boiling (100℃, 10 min). Both convection oven and microwave cooking (2,450 MHz, 3 min) decreased available lysine from 4.9 g /16 g N to 3.8～4.1 g/16 g N. In vivo apparent protein digestibilites (AD) of hagfish meat were similar for raw (92.4%) and cooked meats, but were somewhat lower than ANRC (Animal Nutrition Research Council) casein (94.3%). The PERs (3.7～4.1) and NPRs (3.7～4.9) of cooked meats were significantly higher (p＜0.05) than those of raw meat (PER 3.3, NPR 3.6) and ANRC casein (PER 2.5, NPR 2.6), despite their lower in vivo protein digestibilities. These results demonstrate that cooking at optimal conditions resulted in remarkably positive effects on in vitro and in vivo protein qualities of hagfish meats. Therefore, steamed hagfish meat is an excellent source of high quality protein from seafood products.