Abstract
The reason why bitterness of the autolytic extract is enhanced by shaking during autolysis was investigated from the viewpoint of improving the taste of the extract from fish wastes. Two kinds of extract were prepared from the head-viscera mixture of frigate mackerel after autolysis with (S1) and without shaking (S2). A comparison of the two extracts showed significant differences in their organoleptic and chemical properties. More brown in color, S1 tasted much more bitter than S2, while S1 gave lower contents of free amino acids, higher thiobarbiturate (TBA) values and a smaller ratio of polyunsaturated fatty acids to the total ones. This indicates that lipid oxidation occurred more vigorously in S1 than in S2. Furthermore, it was found that the increase in the bitterness and in the loss of free amino acids was correlated with the increase in TBA values of the extract. In conclusion, lipid oxidation accelerated by shaking during autolysis contributed to the enhanced bitterness and brown discoloration and to the loss of free amino acids of the autolytic extract from fish wastes.
