Change in volatiles, soluble sugars and fatty acids of glutinous rice, japonica rice and indica rice during storage

Rice flavor is one of the most important rice qualities, consisting of aroma and taste. In this paper, aroma- and sweetness-related compounds were investigated and compared in glutinous, japonica, and indica rice. More volatile compounds were found in glutinous rice, as compared with japonica and indica rice. Hexanal, nonanal, octanal, trans-2-octenal, trans-2-nonenal, heptanal, decanal, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, 2-pentylfuran, 2-n-butylfuran, 1-octen-3-ol, 2-ethylhexyl acrylate, 2-decanone, and 2-nonen-4-one were important contributors to the aromatic profile, according to their relative odor activity values. Sucrose was found to be the main contributor to sweetness, while other soluble sugars had little sweetness contribution. During storage, the contents of fatty acids and soluble sugars decreased, except for fructose. The decrease in soluble sugar content had an adverse effect on the sweetness of cooked rice and the Maillard reaction during cooking, resulting in lower quality rice flavor. In addition, the content of volatiles, such as aldehydes, ketones, and furans, increased during rice storage and negatively impacted rice aroma.

Automated summary

Rice flavor is determined by its aroma and taste, with glutinous rice containing more volatile compounds compared to japonica and indica rice. Aromatic profile analysis revealed several key contributors to rice aroma, including hexanal, nonanal, octanal, trans-2-octenal, trans-2-nonenal, heptanal, decanal, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, 2-pentylfuran, 2-n-butylfuran, 1-octen-3-ol, 2-ethylhexyl acrylate, 2-decanone, and 2-nonen-4-one. Sucrose was found to be the main contributor to sweetness, while other soluble sugars had little impact. Storage resulted in a decrease in fatty acids and soluble sugars, except for fructose, leading to a decline in sweetness and quality of rice flavor. Additionally, volatile compounds such as aldehydes, ketones, and furans increased during storage and negatively affected rice aroma.