Thaw rigor in Atlantic salmon (Salmo salar) fillets, as affected by thawing rate and frozen storage time

Summary

The influence of stress, storage time and thawing regimes was investigated with respect to rigor development and other related physical traits, on farmed Atlantic salmon. The fish were sampled from a commercial slaughterhouse production line, filleted, vacuum packaged and quickly frozen, pre-rigor. The investigated parameters were selected to maintain fresh-like quality. No significant (p > 0.600) effects were seen between rigor contraction and stress parameters measured at time of slaughter. Frozen storage time significantly (p = 0,003) affected contraction, while no effect of thawing method (p = 0.824) was detected. The liquid loss of the frozen groups was significantly (p = 0.019) affected by thawing method, while frozen storage time had no significant (p = 0.087) effect. Further, drip loss was not affected by fillet contraction (p = 0.075). Increasing frozen storage time significantly (p = 0.042) decreased the redness and thawing in air rather than water significantly (p = 0.015) decreased the yellowness of the fillets. Fillet stored for 1 month had significantly (p = 0.004) lower F-break force, while no significant (p > 0.227) effect of storage or thawing was seen on hardness. Frozen fillets were comparable to 7 days old vacuum packaged fresh fillets stored on ice for seven days, albeit with some increase in drip loss and some differences in texture, but with comparable color and fillet contraction.