The Volatile Compounds and Aroma Description in Various Rhizopus oligosporus Solid-State Fermented and Nonfermented Rice Bran

Abstract

Rice bran is known to have beneficial nutrients. Current studies suggest that solid-state fermentation affects the rice bran’s volatile profile. The aim of this study is to identify the volatile compounds and aroma description of fermented and nonfermented rice bran (FRB and NFRB) of Ciherang, Inpari30, IR64 and Inpari42. The fermentation was conducted using Rhizopus oligosporus solid-state fermentation. Headspace-solid phase microextraction coupled with GC/MS was performed, and the aroma was translated by 10 trained panelists through quantitative descriptive analysis (QDA). The result showed that 72 and 68 compounds were identified in FRB and NFRB, respectively. They are aldehydes, ketones, alcohols, acids, esters, fatty acid, phenol, benzenes, furan, thiazole, pyrazines, pyridine, lactones, terpenes, and hydrocarbons. The PCA showed that FRB was dominated by alcohols, whereas NFRB was dominated by aldehydes. The QDA described nine aromas, i.e., rancid, smoky, musty, grassy, green, earthy, cereal, and sweet in NFRB. The fermentation process added fermented attributes to the aroma description to FRB and enhanced the rancid, smoky, and musty aromas. 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.

Effect of post-milling process on the oxidation of the rice bran

“…According to Stevenson and Chen (1996), lipid oxidation typically produces straight aldehydes with six or more carbon atoms. Slightly different from aldehydes, ketones are generally derived from the amino acid degradation and betaoxidation of saturated fatty acids (Astuti et al, 2022). The majority of ketone volatiles found in this study gradually decreased during storage, implying utility as markers of degradation.…”

“…Regarding the key aroma volatiles in the stabilised rice bran, most of the volatiles unique to grain or cereal are produced via the Maillard reaction and Strecker degradation, which is triggered by lipid oxidation and high-temperature (Nada et al, 2021). Carbohydrates and proteins are the major precursors of these two processes (Astuti et al, 2022) In bran stored in sealed containers, the most signi cant pathway of lipid oxidation is the autoxidation process. Sealing the bran during storage was expected to slow the autooxidation of the lipid in the stabilised rice bran by limiting exposure to oxygen.…”

Production of a Cheese-Like Aroma via Fermentation of Plant Proteins and Coconut Oil with the Basidiomycetes Cyclocybe aegerita and Trametes versicolor

“…A similar odor perception has already been reported at the production of other fermented soybased products (e.g., tempeh) with molds and lactic acid bacteria. 23,24 The increase in pungency and putridity is caused by the progress of hydrolysis of the proteins and metabolization of the lipids. With increasing fermentation time, proteolysis and lipolysis lead to the formation of high concentrations of free amino acids and fatty acids, which can be further degraded by enzymatic reactions and transformed into unpleasant aromaactive compounds.…”

Role of Microbial Fermentation in the Bio-Production of Food Aroma Compounds from Vegetable Waste

“…[31], (ii) apple and orange pomace by Brettanomyces bruxellensis CCT 3469 [32], and (iii) rice bran with a strain of Rhizopus oligosporous sp. [33].…”