The effect of hydrolyzing time on cooked Tuna fish (Skipjack tuna) wastes by alcalase on protein recovery and the hydrolysate molecular weight

The best approach to create value added materials from fish processing wastes is protein hydrolyzing by enzymes. In the current research, hydrolysis was carried out using Alcalase at 55°C, PH= 8.5 with 35 Au/kg protein enzyme activity in three times, 10, 20 and 30 min (s), each with three stages using a completely randomized design and three replications. After hydrolysis process enzyme inactivation happened at 90°C for 15min. Soluble proteins separated from the insoluble by 5min. centrifuge at 3000×g. The freeze dried supernatant was used for degree of hydrolysis, protein recovery, peptide chain length and molecular weight determinations. The results showed that in the first stage of hydrolysis for 30min(s). Sample, the highest degree of hydrolysis (8.12%) and the highest protein recovery (27.71 %) was obtained (p<0.05). In the third stage of 10 min. sample, the length of peptide chain reached to its maximum value (48.23%). Molecular weights of the hydrolysates in all samples were under 12.5 KDA.