Determination of the lipid content of rainbow trout (Oncorhynchus mykiss) filets with the Torry Fish Fat Meter (R)

A Torry Fish Fat Meter(R) was used to estimate the lipid content in the fil ets of rainbow trout Oncorhynchus mykiss weighing from 1.5 to 3 kg. The res ults demonstrate the necessity to carefully wipe the skin of the fish to pr event interferences from the mucus. They also showed the existence of two g radients of lipid deposition in the muscle: anterior-posterior and dorso-ve ntral. A calibration difference of 1.2% was observed when the values were c ompared with reference methods. Lipid content was determined by linear regr ession with a correlation coefficient of 0.58 and a confidence interval of +/- 1.57% (p < 0.05). The evaluation of the mean value of one group of fish es is more accurate than individual measurements but the latter allows the identification of the leanest or most fatty within a group.