ABSTRACT
Rice bran protein has been found to be of high quality and of importance for food and pharmaceutical applications. It is a plant protein that can be derived from rice bran, an abundant and cheap agricultural byproduct. The protein content in rice bran is about 10-15% and it consists of 37% water-soluble, 31% salt-soluble, 2% alcohol-soluble, and 27% alkali-soluble storage proteins. Its unique property as being hypoallergenic and having anti-cancer activity makes it a superior cereal protein that may find a wide range of applications. There were already reports on the extraction of rice bran protein several decades ago. However, as of now, commercial rice bran protein is still unavailable in the market. This review is aimed at providing valuable discussions on rice bran protein, that is, storage protein, its various properties, and extraction methods for the development of an effective processing scheme. Also, an update on the current processing methods is also included.
Subject(s)
Dietary Proteins/isolation & purification , Oryza/chemistry , Plant Proteins/chemistry , Albumins/analysis , Anticarcinogenic Agents , Chemical Phenomena , Dietary Supplements/analysis , Emulsifying Agents/analysis , Energy Intake , Food Handling/methods , Globulins/analysis , Glutens/analysis , Humans , Nitrogen/metabolism , Prolamins/analysisABSTRACT
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.
