Hydrogen peroxide modification affects the structure and physicochemical properties of dietary fibers from white turnip (Brassica Rapa L.)

Qi Gao,Jia-Le Wu,You-Lin Xue,Han Lin,Rui Ma,Xue-Jie Zhou,Xue Peng,Masaru Tanokura

doi:10.1038/s41598-020-80410-1

Qi Gao, Jia-Le Wu + Show 6 more

Open Access

https://doi.org/10.1038/s41598-020-80410-1

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Abstract

Turnip (Brassica rapa L.) is widely consumed as a vegetable and traditional Chinese medicine with high dietary fiber content. Soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) were obtained from white turnips, and the IDF was modified with alkaline hydrogen peroxide to obtain modified IDF (MIDF) and modified SDF (MSDF). The compositional, structural, and functional properties of the four samples were investigated. After modification, the modified dietary fibers (MDFs) showed smaller particle sizes and lower contents of pectin and polyphenol than those of unmodified dietary fibers (DFs) The results of scanning electron microscopy (SEM), Fourier transformed infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that compared to the DFs, the MDFs were smaller and had more exposed hydroxyl groups. Analysis of the microrheological behaviors showed that the MDFs had higher viscosity than that of the DFs, with a looser structure for the MSDF and a stable structure for the MIDF. Therefore, due to structural changes, the physical and functional properties of the MDFs were improved compared to those of the unmodified DFs. Pearson correlation analysis showed that the particle size was positively correlated with the pectin content. The water holding capacity (WHC), oil adsorption capacity (OAC) and water swelling capacity (WSC) showed positive correlations with each other. This work indicated that white turnip could be a potential new source of DFs, which presented desirable functional properties after modification.

Highlights

The cultivation of turnip (Brassica Rapa L.) has a long history
The modification treatment resulted in a significant reduction in the pectin content, and the modified IDF (MIDF) had the lowest pectin content
Based on the color measurements, modified dietary fibers (DFs) (MDFs) were obviously whiter than DFs, and modified SDF (MSDF) was the whitest, followed by MIDF, insoluble dietary fiber (IDF) and Soluble dietary fiber (SDF), which was caused by the bleaching effect of hydrogen p eroxide[16]

Summary

Introduction

As one kind of Cruciferae, turnip is adapted to the adverse environments of the Qinghai-Tibetan Plateau and possesses feeding, edible, and pharmaceutical value, which is highly appreciated as vegetable and traditional Chinese medicine[1,2]. It is consumed in enormous quantities in Tibet, China, and throughout the world due to its rich phytochemicals, including glucosinolates, isothiocyanates, polysaccharides, triterpenoids, polyphenols and flavonoids[3,4]. The capacities of water holding, water swelling, oil adsorption, cation exchange and cholesterol absorption of the samples were determined to explore the effects of the modification and the potential commercial value and health benefits

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