Release of phenolic acids from defatted rice bran by subcritical water treatment

College

Gokongwei College of Engineering

Department/Unit

Chemical Engineering

Document Type

Article

Source Title

Journal of the Science of Food and Agriculture

Volume

90

Issue

15

First Page

2576

Last Page

2581

Publication Date

2010

Abstract

Oil production from rice bran, an undervalued by-product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV-B-protecting and anti-tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200 °C. Analysis of total phenolics using Folin-Ciocalteu reagent showed about 2-20 g gallic acid equivalent kg(-1) bran in the extracts. High-performance liquid chromatography analysis showed low contents of phenolic acids (about 0.4-2 g kg(-1) bran). Ferulic, p-coumaric, gallic and caffeic acids were the major phenolic acids identified in the extracts. Thermal analysis of the phenolic acids was also done. The thermogravimetric curves showed that p-coumaric, caffeic and ferulic acids started to decompose at about 170 °C, while gallic acid did not start to decompose until about 200 °C. Subcritical water can be used to hydrolyse rice bran and release phenolic compounds, but the high temperatures used in the extraction can also cause the decomposition of phenolic acids.

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Digitial Object Identifier (DOI)

https://doi.org/10.1002/jsfa.4123

Disciplines

Chemical Engineering

Keywords

Phenolic acids; Rice bran; Thermogravimetry; Water—Purification

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