Discover the optimal enzymatic production of rice peptides with high solubility and low viscosity for wide food industry applications.

Abstract

This study focuses on the enzymatic hydrolysis of rice protein to produce rice peptides, comparing the hydrolysis progress curves of alkaline protease, neutral protease, composite protease, and flavorzyme. Alkaline protease exhibited the best hydrolysis effect under optimal conditions: 10% substrate concentration, pH 9.0, 45°C, enzyme to substrate ratio of 48 AU/kg, for 150 minutes. Under these conditions, the yield of rice peptides was 46.8%, with a purity of 71.3%. Rice peptides demonstrated good solubility and low viscosity, making them widely applicable in food products.

Keywords: rice peptide; alkaline protease; technology; characteristics

Introduction

Numerous studies have shown that the absence of certain peptides that regulate physiological functions can lead to changes in human body function. From a nutritional perspective, supplementing certain peptides in the food structure, while meeting the body’s need for essential amino acids, can enhance disease resistance and delay aging. Hence, the research and development of peptides have become a hotspot in the international food industry.

China’s annual rice output accounts for more than one-third of the world’s total production. Despite many grain processing plants, distilleries, condiment factories, and starch sugar factories, resources like early indica rice, broken rice, aged rice, and the residues from condiment and starch sugar production have not been fully utilized. Developing rice protein and peptides from these resources is an effective way to add value, drawing national attention as part of a key scientific and technological project.

Rice protein is a high-quality plant protein, comparable to fish, shrimp, and beef, and importantly, has low allergenicity, making it suitable for infant formula. However, rice protein’s application is limited due to its solubility only in alkaline solutions. Compared to rice protein, rice peptides have better solubility, acid and heat stability, and lower viscosity, in addition to being easily absorbed and having antihypertensive and antioxidant effects. This makes rice peptides a promising functional food ingredient with a wide range of applications in the food industry.

Materials and Methods

The study utilized homemade rice protein and various enzymes from Novo Nordisk. The enzymatic hydrolysis of rice protein was conducted with different proteases under specified conditions. The hydrolysis degree (DH) was determined using the pH-stat method. The best enzymatic preparation conditions for rice peptides were established, and their characteristics, including solubility and viscosity, were analyzed.

Results and Discussion

Alkaline protease was identified as the most effective enzyme for hydrolyzing rice protein, with the best hydrolysis observed at 10% substrate concentration, pH 9.0, 45°C, and an enzyme to substrate ratio of 48 AU/kg for 150 minutes. Under these conditions, the rice peptides yield was 46.8% with a purity of 71.3%.

Rice peptides showed good solubility across a pH range of 2-10 and had lower viscosity compared to rice protein, making them suitable for a wide range of food applications. The enzymatic hydrolysis effectively reduced the molecular weight of rice protein, transforming it into peptides with better functional properties.

Conclusions

The study concluded that alkaline protease is the most suitable enzyme for producing rice peptides from rice protein. The optimal hydrolysis conditions were established, resulting in rice peptides with good solubility and low viscosity. These characteristics make rice peptides a versatile ingredient for the food industry, with potential applications in infant nutrition, convenience foods, instant beverages, and condiments. The development of rice peptides can contribute significantly to the utilization of rice resources, offering a valuable addition to functional foods and nutraceuticals.

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Original research by Chen Jiwang1, Sun Qingjie2, Xia Wenshui1, Wang Zhihua1, Zhang Jiao3
(1. School of Food Science and Engineering, Wuhan Institute of Technology, Wuhan 430023; 2. Hunan Jinjian Rice Industry Co., Ltd., Changde 415001;
3． Southeast Fragrant Rice Industry Development Co., Ltd., Kamata 351111) Article ID: 002-6819 (2006) 06-0178-04