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Optimization and characterization of vinegar produced from rice bran

Abstract

The vinegar is a millenary food, appreciated by consumers worldwide. The rice bran is a rice-processing by-product produced in a large scale, mainly employed in feed. This study describes a method for defatted rice bran (DRB) vinegar production by submerged fermentation, with optimized aeration and stirring conditions, evaluating its physico-chemical properties and acceptance. A 22 Full Factorial Design (FFD) was applied to evaluate the aeration (0.25-1.00 VVM) and stirring (100-500 rpm) effect on the stoichiometric yield (SY), total concentration of ethanol and acetic acid yield (TCY), and acetic acid productivity (AAP). SY ranged from 26.26 to 79.97%, TCY ranged from 78.04 to 100.50%, and AAP varied from 0.056 to 0.473 g L-1 h-1. The stirring had a positive effect in the SY and TCY, while both aeration and stirring had a positive effect in the AAP (p ≤ 0.05). The FFD allowed an acetic acid increase of ≅ 750 times under aeration of 1.00 VVM and stirring of 500 rpm, which made it possible to develop an industrially compatible method for vinegar production using DRB as substrate. Furthermore, DRB presents potential for vinegar production, with functional characteristics - including antioxidant activity - and sensorially accepted.

Keywords:
antioxidant activity; defatted rice bran; fermentation; full factorial design; phytic acid

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