Effect of traditional fermentation and malting on phytic acid and mineral availability from sorghum (Sorghum bicolor) and finger millet (Eleusine coracana) grain varieties grown in Kenya

Abstract

Sorghum and finger millet grains are traditional staple foods in Kenya. However, they have naturally occurring anti-nutritional factors, such as phytic acid, that decrease their dietary availability. This work determined the effect of fermentation and malting on the phytic acid content of, and mineral availability in five varieties of sorghum and four varieties of finger millet grain grown in Kenya. Phytic acid ranged from 875.1 to 2,211.9 mg/100 g in sorghum. The levels in finger millet ranged from 851.6 to 1,419.4 mg/100 g grain. Fermentation resulted in a mean decrease of phytic acid in of 64.8% after 96 hours and 39.0% after 72 hours in sorghum grain. In finger millet, there was a mean decrease of 72.3% and 54.3% after 96 and 72 hours, respectively. Malting also resulted in a mean decrease of 23.9 and 45.3% after 72 and 96 hours, respectively. The extent of decrease of phytic acid differed among the grain varieties. Fermentation increased the rate of available iron, manganese, and calcium in both sorghum and finger millet. The available minerals were generally higher in finger millet than in sorghum after fermentation. Fermentation was also more effective than malting in reducing phytic acid in sorghum and finger millet. Simple traditional food processing methods can therefore be used to increase mineral availability.