Stability of astaxanthin and canthaxanthin in raw and smoked atlantic salmon (Salmo salar) during frozen storage

The objective of the present study was to establish the effect of frozen storage and smoking on the stability of astaxanthin and canthaxanthin in farm raised salmon. Salmon samples were obtained from two sea farms where they had been maintained on commercial feeds containing either astaxanthin or canthaxanthin. The results showed that there was no significant change in visual colour score or carotenoid content of astaxanthin-fed fish during frozen storage for up to 12 weeks. However, smoking fish from this group after frozen storage for 6 and 12 weeks significantly decreased pigment content from an initial level of 9.39 ± 0.23 to 7.99 ± 0.08 and 7.26 ± 0.07 mg kg−1, respectively. Furthermore, Hunter L and a∗ values of raw fish were affected at 6 weeks but not at 12 weeks of storage. Significant changes were measured in canthaxanthin-fed fish stored for up to 12 weeks at −20 °C. Visual colour scores decreased and carotenoid content of the flesh decreased from 10.6 ± 0.27 to 4.36 ± 0.2 mg kg−1. Hunter L values increased, while a∗ values decreased. Smoking canthaxanthin-pigmented fish had no significant effect on the carotenoid content.