Effects of freezing and two thawing methods on food quality of Persian sturgeon fillets

In this study، effects of freezing and two thawing methods on food quality of Persian sturgeon fillets (Acipenser persicus) were evaluated. Fresh Persian sturgeon fillets kept frozen at -20ºC up to 4 months، and then thawed by two different thawing methods (in a microwave oven and in a refrigerator at 4ºC). Freezing- thawing increased fat and decreased protein، moisture and ash contents. Thawing in microwave resulted in less decrease in moisture content compared to refrigerator thawing and caused an increase in protein content. Protein solubility decreased after freezing- thawing but it was significant only in few pHs (in both thawing methods). 4 months frozen storage and then defrosting resulted in a decrease in –SH group content. The microbial count increased after freezing and thawing (p<0. 05)، however the increase was less after microwave thawing. Both thawing methods showed higher L* and b* values and smaller a* value compared to control sample (P<0. 05).