Antioxidative values and customer preference of sweetpotato (ipomoea batatas) flour as compared to wheat (triticum aestivuni) flour

Abstract

Sweet potato is one of the most widely consumed root crops in the tropics especially in Malaysia. This study aims at comparing the antioxidative values of wheat and sweet potato flours and to evaluate customers’ preference towards bakery products made from the flours. The study was divided into 3 phases which were phase 1 (Sampling and flour production), phase 2 (Extraction, determination of components and activity of antioxidants in sweet potato and wheat flours), and phase 3 (Food processing and evaluation). Phase 1 concluded that the recovery rate from fresh sweet potatoes (Ipomoea batatas) roots to flour was about 20-30%. In phase 2, antioxidant activities of MeoH extracts of the flours were evaluated by two in vitro systems, the DPPH radical scavenging and β-Carotene bleaching assays. The extracts had different levels of antioxidant activity in the systems tested where it ranged from 0.09 to more than 10 mg/ml. The antioxidant activities (effective concentration, EC50 mg/ml) of the three varieties of sweet potatoes are in the order of VitAto steam (0.69 mg/ml) > Jalomas steam (0.81 mg/ml) > Telong steam (0.94 mg/ml) and with a p-value of 0.11 when compared to raw-treated sweet potatoes. Also, the phenolic contents ranged from 1.55 to 8.34 mg/g among the sweet potato extracts. Total phenolic concentration, expressed as mg gallic acid equivalents (GAE)/g of methanolic extracts did not show correlation with the antioxidant activity (R2 = DPPH/Phenolics was 0.051). Nevertheless phase 3 showed participants’ preference for buns 1 and 2; and muffins 1 and 2 where (1 = 75% sweet potato flour) and (2 = 100% wheat flour). Results showed a p-value of 0.028 for muffins and 0.006 for buns, concluding that there was a significant difference between preference for buns 1 and 2; and between muffins 1 and 2. In short, our local sweet potato flours have potential as alternatives to wheat flour because of comparable antioxidative values and they can be a source of staple food besides rice in our country.