Effect of steeping period on the physicochemical and pasting properties of sorghum starch

Abstract

The effects of steeping periods on the proximate composition, amylose content, functional and pasting properties of sorghum starch were investigated. Sorghum grains steeped for 6, 12, 18 and 24 h with water were processed into starch and sample from unsteeped sorghum served as control. The starch samples were evaluated for proximate composition, amylose content, functional properties and pasting properties using standard procedures. Moisture content (8.47-13.75%), total ash (0.99-1.29%), crude fat (4.64-8.92%), Crude protein (7.76-15.82%), crude fibre (1.05-1.63%), carbohydrate (76.62-79.31%), amylose content (18.9-23.60%), water absorption capacity (1.71-2.81 g/g), oil absorption capacity (1.31-1.79 g/g), bulk density (0.61-0.75 g/cm3), swelling index (0.71-0.99 g/ml), least gelation (14-20%), foaming capacity (21.90-22.58%), foaming stability (82.00-83.67%), Peak viscosity (111.56-170.30 RVU), trough (83.55-126.85 RVU), breakdown (16.27-46.85 RVU), final viscosity (128.21-248.55 RVU), setback (55.58-125.07 RVU), peak time (4.97-6.26 min) and pasting temperature (83.66 oC-85.95 oC). Steeping of sorghum grains enhances its nutritional attributes, functional and pasting properties of sorghum based foods. The effect of steeping on shelf stability of sorghum starch could be further investigated.

Key words:sorghum, starch, proximate composition, amylose, functional properties and pasting properties