Rice Bran Stabilisation and Oil Extraction Using the Microwave-Assisted Method and Its Effects on GABA and Gamma-Oryzanol Compounds

Abstract

Rice bran oil (RBO) is a valuable ingredient extracted from rice bran (RB), a side stream of polishing rice grain in the milling process. RBO is rich in bioactive ingredients with potential health benefits, such as gamma-oryzanol (GO) and gamma-aminobutyric acid (GABA). Despite its benefits, the quality of RBO depends on the degree of stabilisation of the RB, which is easily affected by lipase enzymes, and thus needs an effective treatment prior to RBO production. To assess the potential of the microwave-assisted method for RB stabilisation and RBO extraction, three Carolino rice varieties (Ariete, Teti, Luna) were tested. The effect of RB stabilisation was evaluated via acid value, water absorption, and GO and GABA levels. The RBO yield was optimised by solvent, temperature, and solvent-to-sample ratio, and the GO and fatty acid levels were determined. The RB stabilisation for the Luna variety did not affect the GO and GABA; for the Ariete and Teti varieties, the GO decreased by 34.4% and 24.2%, and the GABA increased by 26.5% and 47.0%, respectively. The GO levels in RBO samples were not affected by RB stabilisation. The RBO nutritional value was confirmed by the suitable ratio (>2) between polyunsaturated (PUFA) and saturated fatty acids (SFA), with the Teti variety presenting the highest ratio.

Optimization of Oil Recovery from Japonica Luna Rice Bran by Supercritical Carbon Dioxide Applying Design of Experiments: Characterization of the Oil and Mass Transfer Modeling

“…The main fatty acids identified in all the samples analyzed were palmitic (C16:0), linoleic (C18:2), and oleic (C18:1) acids, with the compositions of the latter two being commensurable in the bran rice oil. The composition values determined by us have some deviations from those of other authors [2,[32][33][34], but they are insignificant. In addition, the results demonstrate that the extraction operational parameters do not appreciably affect the fatty acids profile of the rice bran oils, an observation in complete accordance with that reported in a previous work [33] and valid for oils obtained from other biomasses [18,35].…”

Kinetic parameter for scale-up and γ-oryzanol content of rice bran oil as antioxidant: Comparison of maceration, ultrasonication, pneumatic press extraction

“…According to Ref. [ 19 ], (i) Cell Wall Disruption: The rice bran's cell walls are physically damaged by the extraction techniques used, which makes it easier for oil to escape. For instance, ultrasonication produces imploding cavitation bubbles that send shock waves into the cell walls, breaking them [ 20 ].…”

“…In extraction processes, it presents the maximum amount of solute (e.g., oil, γ-oryzanol) that can be extract in the solvent; (ii) Differences between Extraction Methods: The extraction method significantly influences the Cs value, because it affects the efficiency and mechanism of solute release the matrix into the solvent. Factors include the method's ability to discrupt cell walls, solute –solvent interaction, and mass transfer efficiency [ 19 , 20 ], and [ 21 ]. Maceration: involves soaking the solid matrix in solvent, relying passive diffusion to extract the solute.…”

Composition, Microbiota, Mechanisms, and Anti-Obesity Properties of Rice Bran

“…RB oil (RBO) composition varies depending on the extraction methods [ 7 ]. RBO contains nutritionally beneficial compounds like sterols, tocopherols, tocotrienols, γ-oryzanol, range of fats and other bioactive compounds [ 8 ]. γ-oryzanol has a beneficial effect on lipid metabolism [ 9 ], glucose metabolism [ 10 ], and the cardiovascular system [ 11 ].…”

“…γ-oryzanol has a beneficial effect on lipid metabolism [ 9 ], glucose metabolism [ 10 ], and the cardiovascular system [ 11 ]. RB also contains gamma-aminobutyric acid (GABA), a known neurotransmitter [ 8 ].…”