Non-invasive and non-destructive percutaneous analysis of farmed salmon flesh by near infra-red spectroscopy

Near infra-red (NIR) reflectance spectroscopy (700-1100 nm wavelength range) has been applied to the percutaneous measurement of oil and moisture in farmed salmon carcasses. Spectra were recorded through the skin and scales by means of a fibre-optic probe. Six selected sites were used on the dorsal and ventral surfaces of each fish side; 294 sample sites were utilized. Reference chemical values for oil and moisture were determined on these sites after excision. Calibrations were developed and evaluated separately for dorsal and ventral sites. The best dorsal calibration produced a standard error of prediction (SEP) for oil and moisture of 2.0 and 1.45%, respectively; corresponding figures for the best ventral calibration were 2.4 and 1.9%, respectively.