Effect of local food processing on phytate levels in cassava, cocoyam, yam, maize, sorghum, rice, cowpea, and soybean

Abstract

Phytate levels in the unprocessed foods were 6.24 ± 0.22 mg of phytate/g of sample (cassava), 8.55 ± 0.45 mg/g (cocoyam), 6.37 ± 0.32 mg/g (yam), 7.34 ± 0.31 mg/g (white maize), 6.86 ± 0.12 mg/g (yellow maize), 8.86 ± 0.20 mg/g (red sorghum), 4.49 ± 0.22 mg/g (rice), 8.24 ± 0.22 mg/g (cowpea), and 6.88 ± 0.52 mg/g (soybean).Seventy-two hours of fermentation substantially reduced phytate levels in these foodstuffs, ranging from 80% to 98% for rice, cassava, and cocoyam and from 52% to 65% for sorghum, maize, soybean, cowpea, and yam.Lowering of phytate levels was most rapid within the first 48 h of fermentation.Cooking had little reducing effect on phytate levels in whole cereals and legumes but had considerable reducing effect on phytate levels in the tubers.Further processing of all the intermediate products to ready-to-serve foods achieved reductions in phytate levels.The pH of the maize dough fell from pH 6.21 to pH 3.10 during fermentation.