Abstract
This study investigated the effects of frying duration on the physicochemical properties, nutritional composition, and sensory quality of Hilsa (Tenualosa ilisha) fried in mustard oil at 170°C-180°C for 0-12 min. Frying resulted in significant moisture loss (68.50%-41.35%) accompanied by increased fat content (12.32%-27.25%) due to oil absorption. Although protein content increased on a wet basis (18.52%-21.26%), dry-basis protein declined markedly (58.79%-35.55%), indicating thermal degradation. Prolonged frying caused substantial reductions in essential amino acids, particularly lysine and histidine, and significant losses of polyunsaturated fatty acids including a 59% decrease in eicosapentaenoic acid (C20:5n-3, EPA). Conversely, saturated fatty acids increased from 42.64% to 49.17%, along with a rise in trans fatty acids. Lipid oxidation intensified with frying time, as evidenced by increases in peroxide value (5.11-6.84 meq O(2)/kg) and acid value (3.95-6.85 mg KOH/g), alongside a decline in iodine value (57.34-38.68 g I(2)/100 g). Color analysis showed significant darkening (L* decreased from 65.22 to 41.24) and increased redness (a* from 2.56 to 5.32), whereas textural properties indicated increased hardness (12.50-36.52 N) and chewiness, with reduced springiness and cohesiveness. Mineral contents increased due to moisture loss and concentration effects. Sensory evaluation identified 3-6 min as the optimal frying duration, yielding the highest scores for flavor, texture, and overall acceptability.