Instrumental colour analysis of farmed and wild Atlantic salmon when raw, baked and smoked

Abstract

Flesh colour of eight canthaxanthin-pigmented farmed and eight astaxanthin-pig-mented with Atlantic salmon ( Salmo salar L.) was measured by instrumental analysis. The colour of raw, baked and cold smoked flesh from cultured and wild salmon was compared using reflectance spectra transformed into CIE (1976) L ∗a ∗b ∗ values. In this system L ∗ represents lightness of salmon flesh colour, a ∗ redness and b ∗ yellowness. CIE (1976) L ∗a ∗b ∗ values obtained with a portable instrument (Minolta Chroma Meter) showed that intensity of redness ( a ∗ ) of raw, baked and smoked salmon increased with increasing carotenoid concentration of the raw flesh, while lightness ( L ∗ ) decreased. Intensity of yellowness ( b ∗ ) was not significantly influenced by carotenoid concentration. Baking and smoking caused a ∗ to decrease, while L ∗ increased. Values obtained by the portable instrument were in good accordance with corresponding values obtained with a HunterLab LabScan II sphere spectrocolorimeter. The reflectance ratio R 650 R 510 of raw, baked and smoked salmon flesh was significantly correlated to carotenoid concentration, but to a lesser extent than CIE (1976) a ∗ values. The present analyses did not reveal colour differences between farmed and wild salmon except for those caused by differences in carotenoid concentration.