1990 Volume 37 Issue 6 Pages 413-420
Amino acids of water soluble fraction (W-S) and n-butanol soluble fraction (Bu-S) from non-salted and several kinds of soybean miso were detertmined in order to investigate bitterness in non-salted soybean miso. (1) W-S of several kinds of soybean miso, contained a lot of free and bound types of hydrophilic amino acids such as glutamic and as partic acid, in contrast to a small quantity of free and low level of bound types of hydrophobic amino acids such as leucine, isoleucine, phenylalanine and valine. (2) In Bu-S a large quantity of hydrophobic amino acids were detected in the order of leucine> phenylalanine>isoleucine>valine, however the ratio of bound type hydrophobic amino acids was low. (3) In Bu-S of several kinds of soybean miso was detected 1-14m mol/100g of free type tryptophan which was concentrated 5-10 times in W-S. (4) In Bu-S, the free type of hydrophobic amino acids (mol%) was concentrated to about 3 times, those bound type to about 4 times in W-S. (5) From these results, it was estimated that strong bitterness of non-salted soybean miso and weak bitterness of soybean miso were attributable to a large quantity of free type and low ratio of bound type of hydrophobic amino acids such as leucine, isoleucine, phenylalanine and valine and in addition, free type of tryptophan.
