Effects of High Hydrostatic Pressure Pretreatment on the Functional and Structural Properties of Rice Bran Protein Hydrolysates.

Shirang Wang,Guoping Yu,Lianzhou Jiang,Yingju Cui,Tengyu Wang,Yue Sun

doi:10.3390/foods11010029

Abstract

Rice bran protein (RBP) hydrolysis was conducted after high hydrostatic pressure (HHP) pretreatment. The structural and functional properties of HHP-pretreated rice bran protein hydrolysates (RBPH) were investigated. HHP pretreatments were conducted at 100, 200, and 300 MPa; then, enzymatic hydrolysis at atmospheric pressure was performed using trypsin. An RBPH sample that had not been pretreated by HHP was used as a control. Free sulfhydryl (SH) content, SDS-PAGE profiles, high-performance size exclusion chromatography (HPSEC), Fourier transform infrared (FTIR) spectrum, scanning electron microscopy (SEM), intrinsic fluorescence spectrum, solubility, and emulsifying and foaming properties were evaluated. Changes in particle size and ζ-potential were monitored. Compared with the control, the results of solubility, the emulsifying activity index (EAI) and the emulsifying stability index (ESI) increased significantly (p < 0.05) at 200 MPa. The content of free SH increased significantly (p < 0.05) at 100 MPa. FTIR spectrum and fluorescence analysis confirmed the changes in the secondary and tertiary structures. The experimental results indicated that the structural and functional properties of HHP-pretreated RBPH improved.

Highlights

Rice bran is a low-priced, underutilized major by-product of rice processing [1]
The current work indicated that rice bran protein hydrolysates (RBPH) exhibited significant improvements over the control in terms of the solubility, emulsifying properties, and foaming properties
The findings may indicate that high hydrostatic pressure (HHP) changed the spatial structure of Rice bran protein (RBP), enhancing the efficiency and effect of hydrolysis

Summary

Introduction

Rice bran contains protein (12–16%), fat (15–20%), and fiber (23–28%) [2]. It contains many other nutrients, such as phytosterols, vitamins, and antioxidants [3]. Rice bran protein (RBP), which contains lysine (3–4%), is a high-quality resource of protein for the food processing industry, and the content of lysine in RBP is much higher than that of proteins from many other cereal brans or legumes [4,5]. RBP is used in the modern infant food industry because it is a low-allergy protein [6,7]. Low solubility limits the application of natural RBP owing to the disulfide bonds and hydrophobic interactions in RBP, which control the spatial structure of protein [10,11]. Proper methods of modification are required to obtain suitable functional and structural protein properties

Objectives

Results

Conclusion