Changes in the odorants of boiled carp fillet (Cyprinus carpio L.) as affected by increasing methionine levels in feed

Sixty common carp in groups of five in four tanks per treatment were given three diets containing different increasing amounts of methionine. The arom a extract dilution analysis (AEDA) of the boiled carp fillets resulted in 3 2 odorants, of which 26 were identified. Ten compounds were quantified usin g an internal standard (IS), and the very low concentrations of 2-acetyl-1- pyrroline, (Z)-1,5-octadien-3-one, and methional were calculated by the nas ally determined detection limit. The concentration of methional seemed to i ncrease with increasing methionine in the diet. Because the unstable methio nal could be converted by beta-elimination into methanethiol, the impact re sulting in an off-flavor was investigated by headspace analysis. The invest igation revealed no difference in the methanethiol contents between the tre atments with the lowest and highest methionine supplies.