Evaluation of Physicochemical Properties and Antioxidant Activity of Wheat-Red Kidney Bean Biscuits

This research was aimed to study the physicochemical properties and antioxidant activity of biscuits fortified with red kidney bean (Phaseolus vulgaris) powder. Proximate compositions, total phenol content, antioxidant activity, and functional properties of red kidney bean (RKB) powder were studied before and after the incorporation of red kidney bean in the biscuits. The bean powder was mixed with wheat flour at a level of 0% as control, 10%, 20%, and 30% during dough preparation. Results revealed that RKB powder is a rich source of protein (26.25%) together with carbohydrate (59.7%), fat (2.4%), and ash (3.27%). The total phenolic content of bean powder was 14.15 mg GAE/g. Kidney bean powder showed good functional properties including water absorption capacity (149.7%), oil holding capacity (99.54%), swelling capacity (4.6%), and bulk density of 0.74 g/ml. After increasing the percentage of RKB with control, there were significant increases (p < 0.05) in the levels of protein, moisture, ash, fat, while carbohydrate content and total gross energy decreased significantly. Investigation of total phenolic content showed the increasing trend with the higher RKB fortification, which amounted to 10.31 mg GAE/g for control and 12.50 mg GAE/g for 30% RKB. DPPH radical scavenging activity was investigated for all the samples at five different concentrations. As there was an increase in the percentage of RKB and concentration of the samples, the antioxidant activity also increased significantly (p < 0.05), where IC50 value decreased from 0.0228 mg/ml for control to 0.0289 mg/ml for 10% RKB, followed by 20% and 30% RKB, respectively. In sensory test, the control cake secured the highest score in color, flavor, texture and overall acceptability followed by the cake incorporated with 10% freeze-dried mushroom powder.