Changes of High-Purity Insoluble Fiber from Soybean Dregs (Okara) after Being Fermented by Colonic Flora and Its Adsorption Capacity.

Bo Lyu,Lianzhou Jiang,Yuxi Chen,Xin Zhang,Hansong Yu,Yi Wang,Tong Liu,Jianyu Hao,Hongling Fu,Yang Li

doi:10.3390/foods10102485

Abstract

In order to explore the changes and properties of high-purity insoluble dietary fiber from okara (HPIDF) after entering the colon and be fermented by colonic flora, fermented high-purity insoluble dietary fiber (F-HPIDF) was obtained by simulated fermentation in vitro by HPIDF and colonic flora from C57BL/6 mice. For exploring the differences of HPIDF and F-HPIDF, the changes of structure (SEM. FTIR, XRD, particle size, specific surface area, monosaccharide composition) and adsorption properties (water, oil, heavy metal irons, harmful substances) of HPIDF/F-HPIDF were explored. The results showed that F-HPIDF had a higher water-holding capacity (19.17 g/g), water-swelling capacity (24.83 mL/g), heavy metals-adsorption capacity (Cd2+: 1.82 μmol/g; Pb2+: 1.91 μmol/g; Zn2+: 1.30 μmol/g; Cu2+: 0.68 μmol/g), and harmful substances-adsorption capacity (GAC: 0.23 g/g; CAC: 14.80 mg/g; SCAC: 0.49 g/g) than HPIDF due to the changes of structure caused by fermentation. In addition, with the fermentation of HPIDF, some beneficial substances were produced, which might be potential intestinal prebiotics. The study of F-HPIDF strengthens the speculation that HPIDF may have potential bioactivities after entering the colon, which proved that okara-HPIDF may have potential functionality.

Highlights

The functionality of insoluble dietary fiber (IDF) has been gradually accepted by consumers [1,2,3]
The results suggested that after being fermented by colonic microorganisms, the structure and properties of okara-high-purity insoluble dietary fiber from okara (HPIDF) changed greatly
These findings provide a more accurate analysis of HPIDF after entering the digestive system

Summary

Introduction

The functionality of insoluble dietary fiber (IDF) has been gradually accepted by consumers [1,2,3]. Recent studies have shown that some kinds of IDF are not necessarily beneficial to intestinal health [7,8,9], which may be due to the complex fermentation mode of IDF after entering the colon. It had been proved that roughly ten subtypes of dietary fibers described to date, categorized as soluble or insoluble, with varying chemical structures, and large differences in their fermentation profiles [10]. This means that the changes of gut microbiota and colonic environment are complex. The changes of different kinds of IDF in the colon become worthy to study

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