Heat-induced changes in the physicochemical properties and in vitro digestibility of rice protein fractions

Abstract

The effects of heat treatment on protein interaction, surface hydrophobicity, protein profile, amino acid composition, and in vitro digestibility of individual rice protein fractions were investigated. Heat treatment at 100 °C for 20 min had no negative effect on essential amino acids in rice protein. Surface hydrophobicity increased significantly with the increased heat treatment temperature. Moreover, free-thiol content decreased significantly with increased temperature and time extension. Hydrophobic interactions contributed to the heat-induced interaction of glutelin and prolamin. Intramolecular disulfide linkages participated in the heat-induced interaction of all rice-protein fractions. Heat treatment had no effects on the in vitro digestibility of glutelin, globulin, and albumin. Thus, the heat-induced interactions of glutelin, globulin, and albumin were not related to their digestibility. By contrast, the formation of intramolecular disulfide bonds and hydrophobic interactions in prolamin may reduce its digestibility by strengthening protein bodies-Is.

Heat-Moisture Treatment Further Reduces In Vitro Digestibility and Enhances Resistant Starch Content of a High-Resistant Starch and Low-Glutelin Rice

“…In the HMT flour samples, all the bands on the gel became weaker along with the reduction in the flour mass fraction. The fact that all the bands on the protein gel became weaker following HMT suggests a reduction in free proteins, which might be owing to the increased interactions between proteins and between starch and proteins, which reduced the solubility and digestibility of proteins during the HMT process as reported by previous studies [31,39,48,49].…”

A Narrative Review on Rice Proteins: Current Scenario and Food Industrial Application

“…The lower aqueous solubility of intact rice protein is mainly due to the presence of glutelin, the major protein fraction in rice protein. Substantial aggregation, hydrophobic interactions, and crosslinking through disulfide bonds are the cause of the low water solubility of glutelin [ 49 ]. Increased dissociation of glutelin aggregates will promote solubility in acidic or alkaline pH.…”

Dry-heat processing at different conditions impact the nutritional composition andin vitrostarch and protein digestibility of immature rice-based products

“…Food & Function phobic interactions or S-S bonds in roasted samples. [77][78][79] However, the gain in protein solubility with solvent S2 was higher in samples roasted at lower temperatures suggesting that hydrophobic interactions were more critical in those samples. The protein solubility further increased in solvent S3…”

“…24 The protein solubility in PBS (solvent S1) was significantly higher in raw rice and pepeta than roasted products and decreased with roasting temperature. Technically, the protein fractions soluble in the PBS buffer should be the albumin and globulin fractions, suggests that part of the albumin and globulin becomes insoluble after heat treatment, 77 whereas the mechanical pounding immediately after roasting during pepeta preparation could influence the solubility of albumin and globulin fractions. The sharpest increase in protein solubility was observed at 80°C (55-58%) compared to raw rice (36%) sample in solvent S2, indicating aggregations of proteins by hydrophobic interactions.…”