Quantitative Studies and Taste Reconstitution Experiments of the Sour and Lingering Mouthful Orosensation in a Debittered Extract of Traditional Japanese Dried and Fermented Skipjack Tuna (Hongarebushi)

Hongarebushi, Japanese dried skipjack tuna and a high quality ingredient of Japanese dashi, was investigated for its taste active composition. The recent investigation focused on a debittered fish fraction, which revealed a strong umami and salt impact accompanied with a pleasant and pronounced sourness. Whereas the umami and salt tastes could be correlated to monosodium glutamate (MSG), ribonucleotides, and mineral salts, the pleasant sourness was not exclusively induced by organic acids. The essential compound imparting the sour orosensation, persistence, and mouthfulness of the debittered skipjack tuna extract was investigated, and omission experiments emphasized the impact of N-acetylglutamic acid (NAG) on the overall taste sensation of the debittered fish extract. This metabolite, which is known to be present as a minor constituent in animal- and plant-derived foods, was quantified in this study for the first time in seafood, soybean products, dried shiitake mushrooms, and dried fish in notable amounts. Furthermore, it was described for the first time as an essential taste contributor to the nonvolatile profile of a foodstuff, in this case of a debittered extract of hongarebushi.