Effect of food processing of pearl millet (Pennisetum glaucum) IKMP-5 on the level of phenolics, phytate, iron and zinc

Pearl millet is consumed as a staple food in semi-arid tropical regions. With a view to upgrading the micronutrient status of pearl millet-based foods, the effects of single operations and of porridge preparation scenarios on levels and in vitro solubility (IVS) of iron and zinc and mineral complexing factors (phytates: inositol phosphates and phenolic compounds) were tested. Disc milling of grain may add significant iron but this is not necessarily IVS iron. Soaking of grains results in a 25% loss of iron, but also facilitates endogenous phytate degradation, particularly when combined with milling and cooking. Germination and lactic acid fermentation both result in partial phytate degradation. Cooking does not decompose phytates, but results in complex formation of phenolic compounds as measured by a significant reduction in reactive hydroxyl groups. Because of its different distribution in the grain, zinc is generally less affected than iron. Phytate reduction by endogenous phytases is inhibited at low pH as caused by fermentation. Kanwa (alkaline rock salt) could be a functional cooking ingredient as a source of minerals and to react with phenolic substances. The relative IVS of iron was doubled by germination of grain and increased 3-fold by fermentation of wholemeal slurry. Zinc IVS tended to increase on cooking with kanwa, but decreased in cooked fermented flou