In Vitro Bioaccessibility and Caco-2 Cell Uptake of γ-Oryzanol from Cooked Rice Containing an Emulsified Formulation

We used a prototype of packaged cooked rice based on white rice using an emulsified formulation (EMF) containing γ-oryzanol, a compound with various biological activities. We compared the bioaccessibility of γ-oryzanol after in vitro digestion and its subsequent uptake by Caco-2 intestinal model cells. γ-Oryzanol bioaccessibility was higher in cooked EMF rice and cooked white rice than in cooked brown rice. Because EMF contains phospholipids, which influence the bioaccessibility and intestinal absorption of fat-soluble components, we examined their effects on uptake. Lysophospholipids enhanced γ-oryzanol uptake by the cells. Rice oil was added to cooked EMF rice to adjust its γ-oryzanol content to that of cooked brown rice. Cooked EMF rice showed greater γ-oryzanol bioaccessibility than cooked brown rice. The bioaccessible γ-oryzanol fraction was diluted and applied to cells using a combined model of in vitro digestion and cellular uptake. Cellular uptake of γ-oryzanol from the bioaccessible fraction was greater when the fraction was derived from cooked EMF rice than from cooked brown rice. Finally, the biological activities of γ-oryzanol constituents were estimated using online computer simulations. The results suggested that free ferulic acid and ferulic acid esters, as well as the free triterpene alcohols, may exhibit biological activity.