抄録
In order to elucidate why the bitterness of the autolytic extract was formed, two kinds of extracts were prepared from the head-viscera mixture of frigate mackerel Auxis rochei after autolysis at 15°C for 24h with(S1) and without(S2) shaking. Samples were analyzed for extractive nitrogen content, amino acid composition, and TBA value.
A comparison of the two extracts showed significant differences in their organoleptic and chemical properties. With more brown color, S1 tasted much bitterer than S2. Meanwhile, S1 gave less contents of free amino acids, higher TBA values and a smaller ratio of polyunsaturated fatty acids to the total ones. Moreover, the increase in bitterness and the decrease in free amino acids were correlated with the increase in TBA values of the extract. These results demonstrated that lipid oxidation accelerated by shaking during autolysis contributes to the enhancement of bitterness and the loss of free amino acids of the extract. The bitter substances were also separated by using n-butanol extraction and gel filtration chromatography.
