Free Amino Acids in Potato (Solanum tuberosum) May Cause Egumi-Taste in Food Products

Abstract

Potatoes sometimes have an unpleasantly harsh, somewhat bitter, and astringent taste that is called egumi-taste and which results in the deterioration of the quality of potato products. Egumi-taste tends not to be favoured by Japanese consumers. The aim of this study was to clarify the causal agents of egumi-taste in potatoes. Of the four cultivars used here, two were shown in a sensory evaluation of steamed potatoes to have an egumi-taste. The content of the glycoalkaloids that cause a bitter taste had no correlation with egumi-taste. On the other hand, the free amino acids, especially the bitter-tasting amino acids, were higher in the cultivars evaluated as egumi-tasting than in other cultivars. Additionally, the tyrosine content in the tubers of egumi-tasting cultivars was also higher than that in other cultivars. A metabolite of tyrosine, homogentisic acid, is known to be responsible for the egumi-taste of bamboo shoots, and thus, the high tyrosine content might be the cause of the egumi-taste of some potatoes.