The effect of stabilization heat treatment on rice bran quality parameters, including total phenolic content, gamma oryzanol content, antioxidant potential, oxidative stability and extraction yield during storage

Abstract

The impact of rice bran stabilization thermal treatments on oxidative stability, extractability, and antioxidant potential was investigated. Freshly milled rice bran samples of the variety “Ld 368 –red” were subjected to four heat treatments: steaming, hot air drying, microwave treatment, and a combination of microwave and steaming. Solvent extraction was used to obtain rice bran oil (RBO). The Phenolic, γ-oryzanol contents and antioxidant potential of RBO were analyzed. Oil yield, free fatty acid content (FFA), and peroxide value (PV) were measured during 50-days storage at room temperature, with data collected at an interval of 10 days. The highest extraction yield was in coupled treatment (22.26 %). The coupled treatment and microwave were the most effective for the stabilization of rice bran in terms of oxidative stability, which provided the lowest FFA value (2.950 % & 2.993 %) and PV (0.518 & 0.620 mEqv/kg oil) (p ≤ 0.05). The lowest increment of FFA (2.945 %) and PV (4.23 mEqv/kg) was detected in RB stabilized by coupled treatment in 50 days of storage time. The microwaved sample exhibited the highest total phenolic content (4.147±0.190 mg GAE/g of extract), γ-oryzanol content (1.536±0.0173 %), and the highest antioxidant activity/ lowest IC50 value among the stabilized sample.