Aroma Constituents of Tofu (Soy Bean Curd) Contributing to Its Flavor Character

Abstract

Tofu aroma is faint but is an important factor to its flavor. To isolate the aroma compounds, we adopted the porous polymer adsorption technique. The adsorbed fraction was eluted by ether, followed by being dried and concentrated. The aroma concentrate thus obtained was analyzed by gas chromatography and gas chromatography-mass spectrometry. The amounts of each compounds were calculated from their peak area ratio to that of internal standard. The results were summarized as follows: (1) Three domestic cultivars of soy bean, Enrei, Fukuyutaka and Tachinagaha and one American, Binton 81 were used as materials of Tofu, which were manufactured under the same condition. Fukuyutaka and Tachinagaha showed similar contents of aroma compounds, but higher sensory evaluation of Enrei and Fukuyutaka was thought to be due to their high contents of maltol. (2) The effect of the heating condition during Tofu manufacturing was investigated using Fukuyutaka as starting material. The different temperatures at the maceration stage of soy bean did not effect the formation of Tofu flavor but longer heating of the macerated material (gojiru) to 100°C was evaluated to be more flavorful because of its high contents of hexanol and maltol.