Digestion fates of different edible oils vary with their composition specificities and interactions with bile salts

The digestion fates of different edible oils are different. The objective of this study was to understand the influences of lipid composition on their digestion fates, and investigate the roles of bile salts (BS) played in emulsified lipid system (whey protein isolate as emulsifier) in the in-vitro small intestine digestion stage. Three typical oils (palm oil (PO), rapeseed oil (RO) and linseed oil (LINO)) were chosen. Results showed that with the BS addition increased from 0.0 to 2.0 mg/mL, the increasing magnitude of the different fatty acid (FA) apparent release rate constants were: PO > RO ≈ LINO. Although the maximum FA release extent changed with BS addition, the order were: PO > RO > LINO. These may probably be attributed to palmitic acids, the most abundant FA in PO, was mostly located on the Sn-1, 3 positions of triacylglycerol (TAG) molecules, which contributed to the pancreatic lipase hydrolysis action. The relatively short chain length and the lower hydrophobicity also favored this process. However, Sn-1, 3 positions of TAGs in RO and LINO were mainly long chain mono- or poly-unsaturated FAs, which restricted the continuous lipid hydrolysis. Furthermore, the lipid composition may also affect the BS behavior on the O/W emulsion droplet surface, thus modulating lipase hydrolysis reaction. These findings can provide some basic understandings of the digestion differences of different oils.