Physicochemical compositions, nutritional and functional properties, and color qualities of sorghum–orange‐fleshed sweet potato composite flour

Abstract

Sorghum and orange‐fleshed sweet potato (OFSP) flours were blended to produce composite flours at eight different ratios of 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, and 20:80, respectively, whereas 100% sorghumflour was used as control. The physicochemical compositions, nutritional and functional properties, as well as color attributes of the composite flour blends were evaluated. The acquired data were analyzed using ANOVA, and the means were separated using the Duncan multiple range test. Significant differences (p < .05) were observed in the physicochemical and nutritional properties of the flour blends. The protein levels in the composite flour decreased as the proportion of OFSP flour increased. However, the levels of vitamins, particularly vitamins A and C contents of the composite flours increased with higher proportions of OFSP, ranging from 0.27 and 1.74 mg/100 g in sample S100 to 2.13 and 2.12 mg/100 g in sample S20O80, respectively. In contrast, an increase in the percentage of OFSP flour resulted in a decrease in the contents of vitamin B‐complex, particularly vitamins B2 and B6. These values decreased slightly from 0.19 and 1.98 mg/100 g in sample S100 to 0.16 and 0.03 mg/100 g in sample S20O80, respectively. Furthermore, as the proportion of OFSP flour increased, there was a reduction in the calcium levels from 17.39 mg/100 g in the 100% sorghum sample to 13.52 mg/100 g in the S20O80 sample. However, no particular trend was observed in, magnesium, iron, and phosphorus levels. Sample S50O50 had the highest percentage of essential and conditional amino acids, except for cysteine, valine, and phenylalanine. The findings also revealed significant variations (p < .05) in the composite flour samples' functional properties and color measurements. Substituting sorghum with OFSP in sorghum‐based food products would significantly increase their vitamin A content.