The impact of wheat sprouting on iron and zinc bioaccessibility and bioavailability to Caco-2 cells

While wheat is a good source of iron (Fe) and zinc (Zn), their bioaccessibility is limited due to chelation with phytic acid. Sprouting wheat at 26 °C reduced the phytate content by 25-40 % and increased bioaccessibility (determined with an in vitro digestion assay) 1.5-2.7 times (Fe) and 1.6-2.3 times (Zn), depending on the sprouting time (48-120 h). Subsequent application of in vitro digests to Caco-2 cells showed that sprouting for 120 h at 26 °C did not enhance wheat Fe bioavailability, while it increased Zn bioavailability 1.6-fold. When the in vitro digests were exposed to diffusive gradients in thin film (DGT) with Chelex resin, which binds free mineral ions, sprouting was found to have caused release of non-labile Fe complexes and some labile Zn complexes. The latter resulted in higher levels of bioavailable forms of Zn in wheat.