Protein Quality Evaluation of Cooked Monkfish (Lophiomus setigerus) Meats

To investigate the effect of cooking methods on protein quality of domestic fresh monkfish meat (FMM) and imported frozen monkfish meat (IMM), in vitro protein qualities were determined by amino acid anlysis, trypsin indigestible substrate (TIS) formation, and protein digestibility using the four-enzyme method. Crude protein contents of the boiled FMM and IMM were $90\%$ of the dry base, which were higher than fresh FMM $(82\%)$ and IMM $(84\%)$. Profiles of total amino acid in FMM and IMM were not changed by cooking methods. Total free amino acid contents decreased to $ 29.0-33.6\%$ for boiled $(l00^{\circ}C,\;10 min)\;and\;24\%$ for steamed $(100^{\circ}C,\;10\;min)$ samples. In vitro protein digestibilities of boiled and steamed FMM incnased $86.6-86.8\%$, compared to raw IMM $(82.9\%)$, boiled and steamed IMM $85.1-85.5\%$ and raw IMM $(83.6\%)$. TIS of FMM (23.6 mg/g solid) and IMM (15.9 mg/g solid) showed no significant (p<0.05) difference in cooking methods. The C-PERs (computed protein efficiency ratio) of boiled FMM (2.63) and IMM (2.50) were significantly higher (<0.05) than raw (1.97) and steamed FMM(1.97) and IMM(1.94). These results demonstrate that boiling of FMM and IMM improves protein digestibility and C-PER when compared to steamed FMM and IMM. Therefore, boiling could be an excellent means to maintain high-protein quality of monkfish meat. Also, the cooking method may be applicable to the preparation of monkfish stew without any loss of free amino acids.