QUALITY EVALUATION OF SHORTBREAD BISCUITS PRODUCED FROM WATER YAM-WHEAT FLOUR BLENDS

Abstract

Water yam is a tuber crop that is valued for its nutrient composition amongst other yam cultivars. This study investigated the quality of shortbread biscuits produced from water yam and wheat flour blends. Shortbread biscuits were produced from seven formulations of composite flours made from wheat and two varieties of water yam (purple and white) at 30%, 50% and 60% ratios. Shortbread biscuits produced from 100% wheat flour served as control. The functional properties of the composite flours as well as the proximate composition, physical and sensory properties of the shortbread biscuits produced were determined. The functional properties of the flour blends such as oil absorption capacity, water absorption capacity, foam stability, gelatinization temperature and gelatinization time significantly (p˂0.05) increased with increase in the incorporation of water yam flours. Foam capacity, emulsion capacity and wettability recorded highest for the control sample. Bulk density showed no significant difference (p˃0.05) among all the flour blends. Shortbread biscuits differed significantly (p˂0.05) in the proximate composition with the moisture content, crude protein, ash, carbohydrate and energy with the incorporation of water yam flours. The control recorded the highest values for crude fat (14.03%) and crude fiber (1.25%). The physical properties of the shortbread biscuits varied significantly (p˂0.05) in terms of weight, thickness, height and breaking strength. The result of the sensory properties revealed a high general acceptability for all the shortbread biscuit samples. The result of this study deduced that up to 30% water yam substitution can be used for baked food products.