Effect of milling, soaking, malting, heat-treatment and fermentation on phytate level of four Sudanese sorghum cultivars

Four cultivars of Sudanese sorghum (Sorghum bicolor) were analysed for their phytate content, with respect to effects of processing operations, namely milling extraction, water soaking, malting, heat-treatment and fermentation. The conditions of processing used were: decortication to give an 80% extraction meal; 12 and 24 h soaking in tap water; 96 h germination; fermentation for 3,6,9 and 12 h; and cooking at 95°C until starch gelatinized. Total phosphorus, phytate phosphorus and phytic acid were determined. Results showed that phytic acid phosphorus formed >85% of total phosphorus of the sorghum cultivars studied. All treatments investigated caused phytic acid reduction to various extents. Enzymic methods of phytic acid removal (fermentation and malting) were found to be more effective than physical extraction methods, i.e. milling, soaking and heating.