Myo-inositol phosphates profile of buckwheat and quinoa seeds: Effects of hydrothermal processing and solid-state fermentation with Rhizopus oligosporus

Abstract

Phytate content, bioavailability and myo-inositol phosphates profile were analysed in pseudocereals (i.e., white and coloured quinoa, buckwheat) subjected to thermal processing and solid-state fermentation with Rhizopus oligosporus. Fair buckwheat groats were characterised by the highest level of phytate (18.3 µmol/g), with 54% share of InsP6 fraction. Processing (cooking, roasting, tempe-type fermentation) resulted in the significant decrease in phytate content, its bioavailability and the share of higher phosphorylated forms of myo-inositol (InsP6-5) in the profile of all the samples. Fermentation of cereals resulted in generation of high amounts of inositol triphosphates, particularly in the case of buckwheat (32% share in the whole profile). The path of dephosphorylation, identified after fermentation of quinoa seeds including intermediate products–Ins(1,2,4,5,6)P5 and Ins(1,2,6)P3–confirmed that the dominant phytase activity could be attributed to the presence of microbial 3-phytases from R. oligosporous.