A Comparison of the Chemical Composition, In Vitro Bioaccessibility and Antioxidant Activity of Phenolic Compounds from Rice Bran and Its Dietary Fibres

Guanghe Zhao,Mingwei Zhang,Fei Huang,Lihong Dong,Ruifen Zhang,Yongxuan Ma,Yuanyuan Deng,Yan Zhang,Juan Xiao,Lei Liu,Zhencheng Wei

doi:10.3390/molecules23010202

Abstract

The composition, in vitro bioaccessibility and antioxidant activities of the phenolic compounds in defatted rice bran (DRB) and its soluble and insoluble dietary fibres were systematically evaluated in this study. The total phenolic content of insoluble dietary fibre from DRB (IDFDRB) was much higher than that of the soluble dietary fibre from DRB (SDFDRB) but was 10% lower than that of DRB. Bound phenolics accounted for more than 90% of the total phenolics in IDFDRB, whereas they accounted for 34.2% and 40.5% of the total phenolics in DRB and SDFDRB, respectively. Additionally, the phenolic profiles and antioxidant activities were significantly different in DRB, SDFDRB and IDFDRB. The phenolic compounds in IDFDRB were much less bioaccessibility than those in DRB and SDFDRB due to the higher proportion of bound phenolics in IDFDRB. Considering that bound phenolics could be released from food matrices by bacterial enzymes in the large intestine and go on to exert significant beneficial health effects in vivo, further studies on IDFDRB are needed to investigate the release of the phenolics from IDFDRB via gut microbiota and the related health benefits.

Highlights

Many studies in humans and experimental models have demonstrated the numerous health benefits associated with an increased intake of dietary fibre
Recent reports have shown that bound phenolics, which are those phenolics that are mainly bound to the fibre, may give dietary fibre a range of physiological functions
The ORAC values of the free fractions contributed more than 60% of the total ORAC value of defatted rice bran (DRB), but less than 40% and 10% to soluble dietary fibre from DRB (SDFDRB) and insoluble dietary fibre from DRB (IDFDRB), respectively

Summary

Introduction

Many studies in humans and experimental models have demonstrated the numerous health benefits associated with an increased intake of dietary fibre These benefits include regulating body weight and insulin sensitivity, reducing the risk of coronary heart disease, alleviating metabolic syndrome, improving large bowel function, and preventing some cancers [1,2,3]. These health benefits may be closely related to the bioactive components bound to the dietary fibre, especially the active small molecule components such as phenolic compounds [4,5,6].

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Methods

Results