Physico-chemical, structural, pasting and thermal properties of starches of fourteen Himalayan rice cultivars.

Starch of fourteen rice cultivars grown in Himalayan region were evaluated for physico-chemical, structural, pasting and thermal properties. The rice cultivars selected showed a wide variation in apparent amylose content (AAC), ranging between 10.76%-26.87%, highest in CH-1039 and lowest in SKAU-292 starch. There were ten low, three intermediate and one high AAC rice. Resistant starch content varied significantly among the rice cultivars, ranging from 6.00% to 19.60%. Generally, high ACC starches presented high contents of resistant starch. Water absorption capacity (80.10-130.32%), swelling (5.73-9.61g/g) and solubility (0.037-0.090g/g) indices varied significantly among the rice cultivars. The rice starch granule morphology showed polyhedral or irregular shapes and granular sizes in the range of 1.8-6.7μm in different rice starches. Pasting profile of starch varied significantly among the rice cultivars, probably due to variations in their AAC. Thermal properties of the starches ranged considerably among different rice cultivars: onset temperature of gelatinization, T (58.25-72.49°C), peak temperature of gelatinization, T (69.93-93.26°C), conclusion temperature of gelatinization, T (97.28±8.28-112.16°C) and gelatinization enthalpy ΔH (14.29-29.63J/g). The ATR-FTIR spectroscopy of rice starches identified most of the α-1→4 glucosidic linkages within the absorption bands of 1149-1023cm.