Identification of aroma compounds in Thai colored rice varieties

Abstract

Consumers are interested in colored rice because its health benefits and its high fiber and protein content. Normally, the colored rice smell is generally not as strong as the jasmine rice. The first objective of this research was to investigate the proper preheated time and headspace incubation temperature to extract as many volatile compounds as possible from Thai-colored rice using the static headspace GC-MS approach. Secondly, this study aimed to identify the key volatile aroma compounds in Thai native-colored rice varieties. For optimum conditions, Red Hawm Rice (KDML105R-PSL-E-14) was used in this study. The optimal condition was preheated in a hot air oven for 5 hours at 80 °C, followed by a headspace extraction temperature of 120 °C. Afterward, Such conditions were utilized in the second study. Twenty-three rice varieties in four categories: aromatic white, aromatic black, non-aromatic black, and non-aromatic red, were investigated (n = 10 per variety). This study found that the non-aromatic black and red rice containing much lower content of most volatile constituents than the aromatic black and white rice. Focusing on the aromatic black rice, the samples appeared to contain high level of both compound groups of aldehydes (3-methylbutanal, 2-methylbutanal, 2-methylpropanal, pentanal, and hexanal) and alcohols (butane-2,3-diol, pentan-1-ol, and hexan-1-ol).