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Updated: Jun 10, 2026
A Generalized Method for Determining Free Soluble Phenolic Acid Composition and Antioxidant Capacity of Cereals and Legumes
Published on: June 10, 2022
Release of phenolic acids from defatted rice bran by subcritical water treatment
Cynthia Fabian1, Ngoc Yen Tran-Thi, Novy S Kasim
1National Taiwan University of Science and Technology, Taipei, Taiwan.
Background:
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.
Results:
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.
Conclusion:
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.
