Rapid compositional analysis of Atlantic salmon (Salmo salar) using visible-near infrared reflectance spectroscopy

Rapid measurement of salmon flesh quality parameters (>400 samplesday(-1)) was demonstrated in the laboratory and remotely at industrial sites. Visible-near infrared spectroscopy (VNIRS) was applied to predict astaxanthin (AX) and fat content in farmed Atlantic salmon. Fish were sampled from thirteen batches (1-6kg whole weight, containing 2.3-16.3% fat and 1.2-12.5 mu gg(-1) AX), and models validated on small (average +/- SD: 1.4 +/- 0.4kg) and large fish (4.2 +/- 0.9kg). Both constituents were well predicted in minced Norwegian Quality Cutlet (NQC) samples (r(2)>= 0.86; standard error of prediction (SEP) <= 0.7% for fat and <= 0.7 mu gg(-1) for AX). Comparable metrics were observed for AX prediction in whole NQCs (r(2)=0.80-0.88; SEP 0.7 mu gg(-1)). Fat was better predicted in small fish than large fish for whole NQCs (r(2)=0.82, SEP 1.0% cf r(2)=0.59, SEP=0.59%) and non-destructive scanning through the skin of whole, gutted fish (r(2)=0.77, SEP=1.2% cf r(2)=0.49, SEP=1.5%). Models were also developed for screening polyunsaturated fatty acid (PUFA) concentrations, e.g. in NQCs for docosahexaenoic acid (r(2)=0.73) and n-3:n-6 PUFA (r(2)=0.89).