The astaxanthin content in the salmon cutlets was determined by
an HPLC (high-performance liquid chromatography) method.
Cutlet samples pooled by net pen were deskinned, de-boned, and
ground frozen with a meat mincer. Two subsamples of each
pooled sample were accurately weighed (10 ± 0.2 g) and repeatedly
extracted with acetone (40 mL) until colourless. An aliquot
(10 mL) of the pooled, filtered extracts was centrifuged (2397 3 g
for 5 min). The astaxanthin content in the supernatant was determined
using a Hewlett-Packard Series 1050 instrument equipped
with a photodiode array detector (detection wavelength 470 nm).
Analysis was performed on a Vydac 218 BTP 54 reversed-phase
column (i.d. 4.6 mm, length 250 mm; Alltech, USA) with acetonitrile/
methanol (95/5) as a mobile phase (flow 0.8 mL min–1).
The analyses of astaxanthin concentration in the diets were based
on the procedure described by Weber (1988).