Stability and in vitro digestion of high purity diacylglycerol oil-in-water emulsions

Abstract

In this study, stability and in vitro digestion of sesame oil-based high purity diacylglycerol (DAG) oil-in-water emulsions were investigated. Firstly, the effects of DAG content and the freeze-thaw process on the physical properties of emulsions were assessed. The fresh DAG emulsions exhibited high absolute ζ-potential values (>40 mV), small d4,3 (<0.94 μm), and good stability during 14 days storage. However, DAG promoted partial coalescence of fat globules and the creaming index increased after the freeze-thaw process. Subsequently, the in vitro digestion of DAG emulsions was studied. The d4,3 of emulsions increased from 0.942 μm, 0.754 μm and 0.489 μm to 33 μm (0 g/kg DAG), 30 μm (50 g/kg DAG) and 25 μm (100 g/kg DAG) respectively after digestion in the simulated saliva and stomach, and then decreased to 8 μm, 7 μm and 5 μm respectively in the simulated small intestine. Notably, the variation tendency of ζ-potential was opposite to the d4,3 of emulsions during the simulated digestion. Finally, the free fatty acid release was monitored under simulated intestine digestion and it revealed that higher DAG content favored higher lipolysis. This work sheds light on employing DAG oil to prepare food emulsions.