Effects of fish protein hydrolysate and freeze–thaw treatment on physicochemical and gel properties of natural actomyosin from Pacific cod

The properties of natural actomyosin (NAM) containing 2% or 8% fish protein hydrolysate (FPH-2, FPH-8) or 8% sucrose–sorbitol blend (SuSo) were compared to control NAM before and after freeze–thaw treatment. Surface hydrophobicity of control and FPH-2 increased after freeze–thaw treatment, while that of FPH-8 did not change, which may be related to greater thermostability of actin and myosin in FPH-8 as observed by differential scanning calorimetry. The cooked gel of freeze–thawed control had 39% expressible moisture after an 8.5% cook loss, whereas gels of freeze–thawed SuSo, FPH-2 and FPH-8 had significantly lower expressible moisture (15–22%) and no cook loss. Gels of freeze–thawed FPH-2 and FPH-8 were similar to unfrozen control gel in hardness, cohesiveness and gumminess. This study demonstrates that FPH effectively stabilised NAM protein structure and function during freeze–thaw treatment.