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

Abstract

A novel rice germplasm <i>sbeIIb</i>/<i>Lgc1</i> producing grains rich in resistant starch (RS) but low in glutelin has been developed through CRISPR/Cas9-mediated targeted mutagenesis for its potential benefits to patients with diabetes and kidney diseases. In this study, a hydrothermal approach known as heat-moisture treatment (HMT) was identified as a simple and effective method in reinforcing the nutritional benefits of <i>sbeIIb</i>/<i>Lgc1</i> rice. As a result of HMT treatment at 120 °C for 2 h, significant reductions in in vitro digestibility and enhancements in RS content were observed in <i>sbeIIb</i>/<i>Lgc1</i> rice flour when the rice flour mass fraction was 80% and 90%. The low-glutelin feature of <i>sbeIIb</i>/<i>Lgc1</i> rice was not compromised by HMT. The potential impacts of HMT on a range of physicochemical properties of <i>sbeIIb</i>/<i>Lgc1</i> rice flour have also been analyzed. HMT resulted in a darker color of rice flour, alteration in the semi-crystalline structure, an increase in gelatinization temperatures, and reductions in the pasting viscosities as the moisture content increased. This study provides vital data for the food industry to facilitate the application of this dual-functional rice flour as a health food ingredient.