Studies on the Characteristics of Scented Rice : IV. Volatile sulfur compounds evolved from cooked rice

Abstract

It is known that scented rice evolves peculiar flavor when it is cooked. As it was thought that scented rice might be useful for improving cooking quality of rice in aspect of flavor, the authors have been engaged in studying on the characteristics of scented rice. In this present paper, the sulfur-containing volatiles evolved from cooking rice of scented varieties (Otsune-bozu, K 10 and Shiroi-kichi, K 11) and ordinary one (Koganenishiki) were analyzed by two different gas chromatographs (FID and FPD). The results are summarized as follows: By a hydrogen flame ionization detector (FID), three sulfur-containing volatiles were identified as following compounds, viz. methyl mercaptan, dimethyl sulfide and dimethyl dlsulfide (Table 3 and 4). While by a flame photometric detector (FPD), five peaks on the chromatogram were recognized (Fig. 1) and identified as hydrogen sulfide (peak 1), methyl mercaptan (peak 2), dimethyl sulfide (peak 3), n-butyl mercaptan (peak 4) and dimethyl disulfide (peak 5) (Table 5). No qualitative differences in sulfur-containing volatile compounds in the head space were found between scented (Shiroi-kichi) and ordinary (Koganenishiki) rice varieties and also between hulled rice and milled one of the two varieties.