PREVENTION OF PROTEIN DENATURATION OF JAC K MACKEREL ACTOMYOSIN (TRACHURUS-MURPHYI) DURING FROZEN STORAGE

Protein denaturation during frozen storage at -18 degrees C for 16 wee ks was studied in jack mackerel (Trachurus murphyi) actomyosin. The cr yoprotective effect of different additives was evaluated at a level of 8% (w/w): sucrose/sorbitol (1:1), maltodextrin 25 DE, milk whey and s odium lactate. The results were compared with a control sample without additives. The decrease in protein solubility and calcium ATPase acti vity confirmed that protein denaturation occurred both during the free zing process and during frozen storage. Higher losses were observed af ter one week at -18 degrees C. Sucrose/sorbitol and maltodextrin 25 DE were the best cryoprotectants. DSC thermograms showed two endothermic transitions with T-max at 46.8 degrees C and 68.9 degrees C assigned to myosin and actin respectively. The best cryoprotective effect was a chieved with sucsrose/sorbitol and maltodextrin 25 DE. These additives showed T-max and Delta H values for myosin and actin significantly hi gher than the control.