Physico-chemical and functional properties of flours from Indian kidney bean (Phaseolus vulgaris L.) cultivars

Flours of four kidney bean (Phaseolus vulgaris L.) cultivars (French Yellow, Contendor, Master Bean and Local Red) were studied. The moisture, ash, protein, fat and crude fibre contents of kidney bean flours varied from 99–104, 30–35, 223–267, 16–20 and 14–21 g/kg, respectively. Synaeresis of flour gels increased from 141 g/kg after 24 h to 194 g/kg after 120 h of storage at 4 °C. Scanning electron microscopy of flours revealed starch granules of varied shapes associated with protein and non-protein components. Peak, breakdown and setback viscosity varied significantly (p ≤ 0.05) from 591.0–1030.3 cP, 21.3–93.3 cP and 383.7–750.0 cP, respectively. Kidney bean flours displayed two endothermic transitions corresponding to starch gelatinization (60.9–75.2 °C) and disruption of the amylose–lipid complex (103.6–129.6 °C). Hardness and adhesiveness of flour gels varied significantly from 14.9–19.5 g and 31.5–81.3 g, respectively. Foaming capacity and foaming stability at different pH showed significant differences. Emulsion activity index at different pH varied from 6.03 to 25.21 m2/g while emulsion stability index was in the range of 15.51–76.21 min. Protein solubility of 8.1–97.8% was observed in the pH range of 2–10.