Mineral availability is modified by tannin and phytate content in sorghum flaked breakfast cereals

摘要

Mineral availability from sorghum grain in some varieties may be low because of the presence of phytates and tannins. However, heat processing of sorghum may lower tannin and phytate levels and thus improve mineral availability. Sorghum has potential in the manufacture of gluten free breakfast cereals, therefore flaked breakfast cereals were manufactured from whole grains of three contrasting sorghum varieties and compared to that manufactured from whole grain wheat The content of tannin, phytate, minerals (Ca, Fe and Zn), in vitro mineral availability and phytate: mineral molar ratios were determined in the raw whole grain flours and the cooked flaked breakfast cereal. For all grain varieties, the in vitro mineral availability of flaked breakfast cereal was higher than the raw flours, an effect most probably related to the concomitant reduction in tannins and phytate levels after processing. The in vitro mineral availability of the flaked wheat breakfast cereal was significantly higher than that of all sorghum breakfast cereals, with that manufactured from the brown sorghum IS8237C having the lowest value (p = 0.05). Given that the sorghum varieties in this study gave lower mineral availability than wheat, other sorghum varieties now require evaluation to identify those with improved mineral availability.