Varietal Discrimination of Purple, Red, and White Rice Bran Oils Based on Physicochemical Properties, Bioactive Compounds, and Lipidomic Profiles

TL;DR

This study compares purple, red, and white rice bran oils to determine their differences in nutrients and health benefits.

Contribution

The study identifies unique lipid signatures and bioactive profiles in colored rice bran oils for quality evaluation and targeted use.

Findings

Purple rice bran oil (PRBO) has higher unsaturated fatty acids and bioactive compounds compared to red and white rice bran oils.

Untargeted lipidomics revealed distinct lipid signatures, such as ceramide phosphate in PRBO and sitosteryl esters in RRBO.

PRBO showed the highest antioxidant activity and oxidative stability, making it suitable for health-oriented applications.

Abstract

Rice bran oil (RBO) is increasingly valued for its bioactive constituents and associated health benefits. This study presents a comprehensive comparative analysis of RBOs derived from purple (PRBO), red (RRBO), and white (WRBO) rice bran, focusing on their physicochemical properties, fatty-acid profiles, bioactive components, antioxidant activity, oxidative stability, and lipidomics. Our results demonstrate that PRBO consistently exhibited a more favorable fatty-acid composition, characterized by a higher proportion of unsaturated fatty acids and significantly greater concentrations of bioactive compounds (including tocopherols/tocotrienols, γ-oryzanol, phytosterols, and squalene). Accordingly, PRBO showed the highest radical-scavenging activity and storage oxidative stability, followed by RRBO and WRBO. Additionally, untargeted lipidomics using UPLC–MS–MS identified 2908 lipid species spanning 57 subclasses and revealed distinct variety-specific lipid signatures. PRBO was uniquely enriched in lipid species such as ceramide phosphate (CerP) and monogalactosyldiacylglycerol (MGDG). RRBO was characterized by a distinct abundance of sitosteryl esters (SiE), phosphatidic acid (PA), and cardiolipin (CL), while WRBO was distinguished by phosphatidylethanol (PEt), lysodimethylphosphatidylethanolamine (LdMePE), and sphingomyelin (SM). Overall, PRBO possessed not only a broader repertoire of lipid species but also higher relative abundances of nutritionally significant lipids. These results enable quality evaluation and varietal authentication of colored RBOs and guide their targeted use in health-oriented foods and nutritional interventions.

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