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

• Main Authors: Fabian, Cynthia B., Ngoc, Tran-Thi Yen, Kasim, Novy Srihartati, Ju, Yi Hsu
• Format: text
• Published: Animo Repository 2010
• Subjects: Phenolic acids; Rice bran; Thermogravimetry; Water—Purification; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/5108
• Institution: De La Salle University

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.