Effects of soaking, germination and fermentation on phytic acid, total and in vitro soluble zinc in brown rice

Abstract Rice is an important staple food in Asian countries. In rural areas it is also a major source of micronutrients. Unfortunately, the bioavailability of minerals, e.g. zinc from rice, is low because it is present as an insoluble complex with food components such as phytic acid. We investigated the effects of soaking, germination and fermentation with an aim to reduce the content of phytic acid, while maintaining sufficient levels of zinc, in the expectation of increasing its bioavailability. Fermentation treatments were most effective in decreasing phytic acid (56–96% removal), followed by soaking at 10 °C after preheating (42–59%). Steeping of intact kernels for 24 h at 25 °C had the least effect on phytic acid removal ( In vitro solubility, as a percentage of total zinc in soaked rice, was significantly higher than in untreated brown rice while, in steeped brown rice, it was lower ( p in vitro soluble zinc. This may result from zinc complexation to other food components.