The appearance of pure rapeseed oil, UA powder, blend of UA and rapeseed oil and UA emulsion were photographed after in vitro simulated digestion, and the results are shown in Fig. 1 A ~ D. All digestive systems were turbid and delamination occurred after a period of placement. The digestion of UA alone produced only a thick milky white deposit at the bottom, while the other three digestion medium involving rapeseed oil produced a white cream layer (probably composed of undigested oils and other materials) at the top in addition to the deposit (Zhang, Zhang, Zhang, Decker, & McClements, 2015). The deposit may be due to the presence of calcium ions in the digestion medium, which promotes the deposit of anionic components such as bile salts and free fatty acids (Tzoumaki, Moschakis, Scholten, & Biliaderis, 2013). The white cream layer at the top of the digest seems to reflect the degree of hydrolysis of rapeseed oil. Comparison of the appearance of the three digestion medium of rapeseed oil alone, UA-oil blend and UA emulsion showed that the top layer of the UA-oil blend was slightly less than that of the other two systems, while the single rapeseed oil contained more undigested top layer (Fig. 1 A). This phenomenon was consistent with the FFA % after 2 h of intestinal digestion in several systems, that is, UA + oil > UA emulsion > oil (Fig. 1 E).