We investigated the effect of neutral lipids, polar lipids, and an emulsified formulation (EMF) on carotenoid bioaccessibility in an in vitro digestion assay of vegetables. These reagents enhanced carotenoid bioaccessibility. Contrary to our previous report, they also exhibited effects on lutein. Bile extracts/pancreatin concentrations also participated in the bioaccessibility. The EMF, which consisted of lower amounts of oil, had the same effect on lutein as rapeseed oil. These reagents also showed effects in the aging model, with more reduced bile extract/pancreatin concentrations, suggesting that lipids and EMF contributed to carotenoid bioaccessibility in bile/pancreatic juice secretions due to aging and disease.

The flavor deterioration of mayonnaise is induced by iron, which is released from egg yolk phosvitin under acidic conditions and promotes lipid oxidation. To prevent oxidative deterioration, natural components, rather than synthetic chemicals such as ethylenediaminetetraacetic acid have been required by consumers. In the present study, we evaluated the inhibitory effects of three egg white components with the same amino acid composition, namely egg white protein, hydrolysate, and the amino acid mixture, on lipid oxidation in mayonnaise and an acidic egg yolk solution as a model system. We found that the hydrolysate had the strongest inhibitory effect on lipid oxidation among the three components. The mechanism underlying the antioxidant effect was associated with Fe²⁺-chelating activity. Thus, egg white hydrolysate may have the potential as natural inhibitors of lipid oxidation in mayonnaise.

To assess the effect of rice bran oil emulsified formulation (EMF) on cooked rice, a single-arm open clinical trial and in vitro testing for digestion and glycemic response were performed. Fifteen Japanese men consumed 200 g of packed rice, cooked with or without EMF. Blood samples were collected 0, 30, 60, and 120 min post-consumption and analyzed for glucose, insulin, and triglyceride levels. Continuous glucose monitoring (CGM) and sensory evaluation were also performed. A two-step in vitro digestion test, simulating gastric and small intestinal digestion was conducted. EMF-added rice group showed higher insulin response levels at 60 min than the placebo group. Stratification of participants with HbA1c ≥ 5.6 or an insulinogenic index ≤ 0.4 revealed a significant reduction in C_max glucose levels. A significant correlation was observed between venous and CGM blood glucose levels and no significant sensory differences were observed. The in vitro test revealed significantly lower C_∞, equilibrium starch concentrations, with EMF. Clinical trial suggests that EMF may stimulate insulin secretion and reduce blood glucose levels in participants with lower insulin responses. In vitro tests suggest that EMF inhibits glycemic digestion. This trial was registered at the UMIN Center (UMIN000053495; registered 31 January 2024).

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.