In vitro digestibilities, predicted glycemic index and sensory evaluation of biscuits produced from composite flours of wheat and processed tiger nut.

This study aimed to evaluate the In vitro digestibilities, predicted glycemic index and sensory evaluation of biscuits produced from composite flours of wheat and processed tiger nut. The tiger nut was sorted and processed by air-drying, blanching, fermentation and dehydration.The processed samples were oven dried at a temperature of 60oC for 17 hours before milling into fine flour to blend with wheat flour (Wf) at the ratio of 20:80. Biscuits were produced from blends of wheat flour and processed tiger nut namely: wheat-tiger nut air dried (W-TNA), wheat- tiger nut blanched (W-TNB), wheat- tiger nut fermented (W-TNF) and wheat- tiger nut dehydrated (W-TND).  The results of In-vitro protein digestibility of the composite biscuit showed W-TNF biscuit to have the highest digestibility (52.53%) and W-TND as the least (39.44%) when compared to wheat flour (48.18%). Highest starch digestibilities were recorded for composite biscuits from Wf (99.45±2.32%) and W- TNF (89.99±1.67%). The highest hydrolysis index (HI) of 138.85%, and 113.79% were observed in W-TNF and W-TND respectively; which also resulted in higher predicted glycemic index (PGI) of 115.93% (W-TNF) and 102.17% (W-TND).The sensory evaluation revealed that the composite biscuits were generally accepted although there were reductions in aroma, texture and taste of the composite biscuits when compared with the control (Wf)