Effects of Cooking Conditions on Protein Quality of Chub Mackerel (Scomber japonicus)

Abstract

Effects of cooking methods (grilling, frying, steaming and microwaving) on proximate composition and protein quality of chub mackerel (Scomber japonicus) treated with 2, 6 and 10% sodium chloride (NaCl) brine were investigated. Moisture content decreased in all cooked samples from 60.22% in the raw sample to 48.7% in the fried samples. The 10% NaCl brine treatments of all samples recorded the highest moisture loss than the 2 and 6% treatments. All cooked samples showed a decrease in their fat contents except the fried sample. Protein content increased in all cooked samples, from 47.21% in the raw sample to 63.87% in the grilled sample. The 10% NaCl brine treatment of all samples recorded the highest degree of fat oxidation (TBA value and TBARS), which was highest in the fried sample and lowest in the microwaved sample. The level of trypsin inhibitor (TI) was highest in the microwaved sample and lowest in the fried sample. In all samples, the 6% salt treatments recorded the lowest level of trypsin inhibitor and highest rates of in vitro protein digestibility. In vitro digestibility increased from 79.4% in the raw sample to 86.43% in the fried sample. The total essential amino acids of all cooked samples increased. Results from the study indicated that grilling and steaming had beneficial effects on the protein quality of chub mackerel.