The physico-biochemical and pasting properties of rice and sorghum

Abstract

The physico-biochemical and pasting properties of rice (Indrayani and Local rice) and sorghum (Phule Suchitra and Phule Vasudha) varieties were evaluated to assess their starch composition and processing quality. Rice varieties showed higher total carbohydrate content (76.84 and 79.48 percent) compared to sorghum. Sorghum varieties were nutritionally richer, with higher protein (9.69 and 9.75 percent), fat (2.51 and 2.95 percent), fibre (1.45 and 1.93 percent), and ash (1.22 and 1.41 percent), while rice served primarily as a carbohydrate-dense energy source. Rice varieties contained higher amylopectin (53.61 and 56.94 percent) and total starch (74.63 and 72.08 percent), but lower amylose (17.69 and 20.16 percent) and resistant starch compared to sorghum. Sorghum varieties, particularly Phule Suchitra, showed higher resistant starch (up to 4.49 percent) and a greater amylose/amylopectin ratio (mean value 0.380), reflecting better nutritional quality. The physical properties like water absorption capacity exhibited higher in whole grain flour of rice varieties (3.25 percent) while whole grain sorghum flour showed higher oil absorption capacity (1.43 percent), lowest swelling power (3.8 percent) and solubility (0.156 percent). The pasting properties were evaluated and the whole rice grain flour was recorded significantly higher viscosity (4809.5 cP) and gelatinization maximum (1158 AU), whereas sorghum showed higher beginning of gelatinization (77.4 0C) and gelatinization temperature (88.47 0C). High Am/Ap ratio and resistant starch content of sorghum play crucial role in governing swelling power, gelatinization and pasting characteristics. The results highlight that rice and sorghum possess complementary functional attributes, and their targeted utilization based on starch composition and thermal behaviour can enhance product development in cereal-millet based food systems.