The implications of physicochemical, rheological, and thermal properties of seven eminent Indian rice cultivars (PR 114, 121, 122, 123, 124, 126, and 127) on the extrusion behavior and physico-functionalities of the extrudates were investigated. The amylose and amylopectin content of the cultivars ranged between 12.72 to 28.86% and 71.14 to 87.28% in addition with protein and crude fat content that varied from 7.05 to 9.15% and 0.49 to 1.17%, respectively. The onset (r = 0.98), peak (r = 0.95), and conclusion (r = 0.98) temperatures of the cultivars were in positive correlation with amylose. Likewise, pasting temperature (r = 0.979), final viscosity (r = 0.91), set back viscosity (r = 0.89), and stability ratio (r = 0.90) of the cultivars demonstrated a significant positive correlation with the amylose content. However, peak (r = - 0.879) and hold viscosity (r = - 0.89) were negatively correlated. The cultivars were extruded at feed moisture of 15%, screw speed of 500 rpm and barrel temperature of 150°C. The extrudates characteristics viz., expansion ratio-1.82 (PR 123); bulk density-184 g/cc (PR 123); specific mechanical energy-262.35 Wh/kg; water absorption index (WAI)-6.26 (PR 122); water solubility index-48.52% (PR 123); hardness-148.63 N (PR 122); and hydration power-284% (PR 122) were viably hyphenated with the physicochemical and rheological behavior of cultivars. The physico-functional characterization of the extrudates in terms of their starch and protein structural indexes, α-amylase susceptibility; water soluble carbohydrates and proteins revealed the possibility of exploring these cultivars as a functionally viable and diverse ingredient for the production of ready-to-eat extrudates.
Keywords: expansion ratio; extrusion; physico-functional; ready-to-eat; rheological properties; thermal properties.
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