The Comparison of Pyrazine Compounds in Non-Salted Fermented Soybean Products.

Abstract

The odor components of six different non-salted fermented soybean products in different parts of the world, Natto (Japan), Thua-nao (Thailand), Pepo (Myanmar), Libi ippa (East Bhutan), Kinema (West Bhutan) and Daddawa (Nigeria) were compared. Especially, the composition of pyrazines contributing to Natto odor was examined in these products. The odor concentrates were prepared by the method using porous polymers and were analyzed by gas chromatography and gas chromatography-mass spectrometry. Pyrazines were considered to contribute to the characteristic odor of the non-salted fermented soybean products because the compounds were detected commonly in all the products except two types of Libi ippa. The total concentration of the pyrazines was lower in Libi ippa, Kinema, and Daddawa and higher in Thua-nao and Pepo when compared with that of Natto. The composition of the pyrazines depended on the products.