Nuclear Magnetic Resonance technique for quality control of cold-pressed rice bran oil
Jirada Singkhonrat ^1* Chutima Ponchurdchai ¹ and Wipharat Chuachuad Chaiyasit ^2
1 Department of Chemistry, Faculty of Science and technology, Thammasat University.
² Department of Chemistry, Faculty of Science, Naresuan University.

Abstract

A Nuclear Magnetic Resonance (NMR) method is developed and applied for fingerprint characterization of rice bran oil from Thai domestic production and quantitative determination of fatty acid compositions. Freshness evaluation was investigated by analysis of diacylglycerol or monoacylglycerol level in cold-pressed rice bran oil. The investigation using -carbon intensity of triacylglycerol as reference peak and internal standard demonstrated that the method presented variance (Analysis of variance, p 0.05) with high Level of Confidence (95%). This method allows rapid identification of rice bran oil in the market, claimed as cold-pressed rice bran oil from domestic production in Thailand. Applying NMR technique, Thai export industry of rice bran oils can meet satisfied specification by international importers without many wet, dirty and error prone chemical methods in Quality Control laboratory. Qualitative analysis of diacylglycerol or monoacylglycerol showed no signal in freshly samples, but revealed with slightly stronger peaks after one year storage, represent by proportion of 1,2-diacylglycerol and 1-monoacylglycerol in triacylglycerol which changed over time. Results obtained in this study will serve as quality control and useful reference for supplement development and pharmaceutical industry.