The Volatile Compounds and Aroma Profile of Some Pigmented Rice Brans After Fermentation

Abstract

Pigmented rice is known to have nutritional and bioactive compounds which commonly concentrated in the bran layers. Solid-state fermentation is known to enhance the bioactive compounds of rice bran. The study aims to identify fermented rice bran’s volatile compounds and aroma attributes from some pigmented rice (Inpari 24, Saodah, Cempo Ireng and Jeliteng). The rice brans were sterilized at 121oC for 15 minutes and produced non-fermented rice bran and some of them were fermented for 72 hours at 30ºC using Rhizopus oligosporus. Both non-fermented and fermented rice brans were analysed using solid-phase microextraction-gas chromatography/mass spectrometry (GC/MS) and qualitative descriptive analysis (QDA). The result showed that a total 114 of volatile compounds were identified from fermented and non-fermented rice bran. They consisted of 14 aldehydes, 12 ketones, 14 alcohols, 15 hydrocarbons, 8 acids, 23 esters, 9 benzenes, 5 phenols, 6 furans, 2 lactones, 1 monoterpene, 1 sesquiterpene, 1 thiazole, 1 pyrazine and 1 pyridine. The aroma attributes of fermented rice brans obtained by 10 trained panellists in QDA were sweet, caramel, vanilla, grass, milky, fatty, nutty, smokey, rancid, acid, cereal, pungent, earthy and fermented. The non-fermented rice bran has the same aroma as the corresponding fermented rice bran except fermented aroma. Furthermore, Pearson’s correlation test has resulted in several positive correlations between GC-MS results and QDA. These studies indicated that fermented rice bran might increase the volatile compound of rice bran; thus, it may provide opportunities to develop the production of fermented rice bran as a functional ingredient.