Nutritional Composition, Textural, and in Vitro Digestive Characteristics of Different Indica Brown Rice Varieties

Abstract:

To promote the development of whole-grain foods and low glycemic index (GI) staples, the nutritional composition, textural properties, and in vitro digestion characteristics of eight indica brown rice varieties were systematically compared with those of milled rice. The differences between these varieties and milled rice were discussed, and correlations between indicators were examined. Significant differences (P<0.05) were observed in fat, protein, and dietary fiber contents among different brown rice varieties. All brown rice varieties exhibited significantly higher (P<0.05) γ-aminobutyric acid, total free phenolics, and total free flavonoids than milled rice, accompanied by superior antioxidant capacities. The maximum DPPH and ABTS+ radical scavenging activities observed in the brown rice varieties were approximately four times and three times higher than those in milled rice, respectively. Cooked brown rice demonstrated significantly greater hardness (P<0.05), with the softest brown rice variety still showing a hardness level approximately 1.5 times higher than that of milled rice. The estimated glycemic index (eGI) of brown rice ranged from medium to high levels, with Zhongzao 39 exhibiting the lowest eGI value (61.48), equivalent to 0.8 times that of milled rice. Significant negative correlations (P<0.01) were identified between eGI values and fat, protein, and dietary fiber contents. These findings suggest that brown rice has substantial potential for enhancing nutritional value and developing low-GI functional foods, thus providing theoretical support for processing optimization, formula design, and health function evaluation of brown rice products.