Effect of salt-aided control on quality attributes of roasted grass carp (Ctenopharyngodon idella) fillets

To investigate the effect of salt amount and salting time on the quality attributes of roasted fillets from Ctenopharyngodon idella, the scales, head, tail, and internal organs of fresh C. idella were removed and cut into fillets, then salted respectively using a dry salting method salt amount (5%, 6%, 7%) for 4 h, or salting time (2, 4, 6 h) with 6% of salt and roasted at 200 °C for 15 min. The salt content, weight loss rate, and physicochemical properties of myofibrillar protein secondary structure, surface hydrophobicity index (H₀), and total sulfhydryl and disulfide bond contents of the salted fillets from C. idella, as well as the shear force, color, sensory score, and moisture, ash, and protein contents of roasted fillets from C. idella were evaluated. The results showed that as salt amount increased and salting time prolonged, the contents of salt and disulfide bond and H₀ of the salted fillets from C. idella gradually increased, the total sulfhydryl content underwent an opposite trend. α-helix and β-sheet of myofibrillar protein were turned into β-turn and random coil. Compared to the control (unsalted), the L^* and a^* values, shear force, and moisture and protein contents of the roasted fillets from C. idella with salting dropped sharply, while the ash content significantly increased. Furthermore, as the salt amount increased or salting time prolonged, the moisture content increased and ash content decreased, while the sensory score firstly increased, followed by decreasing. These results suggested that salt amount added and salting time significantly affected the secondary structure of the myofibrillar protein from salted C. idella fillets, and enhanced their denaturation, leading to the changes in quality attributes of the roasted fillets from C. idella. Compared to other salting conditions, the roasted fillets from C. idella had higher moisture and protein contents and lower ash content, as well as the better color and tenderness and the higher sensory score when fillets were salted for 4 h at 6% of salt.