Production and evaluation of flours and crunchy snacks from sweet potato (Ipomea batatas) and maize flours

The present study was conducted to assess the suitability of blends of two sweet potato (cream- and yellow- flesh) varieties and maize flours in the preparation of crunchy snacks. Each of the sweet potato varieties was prepared into flour and separately blended with 0, 30 and 50% of maize flour. The blends were evaluated for proximate composition, mineral content, vitamin content, anti-nutrient factors and functional properties. Baked crunchy snacks were prepared from each of the blends and evaluated for physical and organoleptic properties. The results of proximate analysis showed that crude protein (3.40 - 6.57%) was significantly different between the two varieties of sweet potato used and it increased with addition of maize flour to the two varieties. The β-carotene value (345 - 370 μg/100 g) was highest in 100 yellow-flesh sweet potato which slightly decreased with addition of maize flour. The vitamin c content (13.4-17.3 mg/100 g) was also highest for 100% yellow-flesh sweet potato. The cream-flesh sweet potato contained higher amount of phytates (16.0 mg/100 g) but lower amounts of tannins (8.66 mg/100 g) and oxalates 7.0 mg/100 g) compared with the yellow-flesh varieties. The tannins, phytates and oxalates values decreased with addition of maize flour to both varieties of the sweet potato used. The bulk density values (0.523 - 0.683 g/cm3), water absorption capacity (123 - 143%) and oil absorption capacity (13.3 - 15.3%) were significantly (p < 0.05) different among the samples. The specific height was highest for 100% yellow flesh sweet potato and it decreased with addition of maize flour. The sensory evaluation revealed that all the samples were scored within the acceptable attribute limits except the sample from 100 cream-flesh sweet potato which was scored lowest in all attributes.