Preparation of Pickering emulsions with short, medium and long chain triacylglycerols stabilized by starch nanocrystals and their in vitro digestion properties

Food-grade Pickering emulsions are receiving more attention in the development of new delivery systems in food and pharmaceutical areas. In this study, starch nanocrystals (SNCs) prepared via acid hydrolysis of waxy maize starches were used as food-grade particle emulsifiers, to stabilize three typical edible oils with different chain lengths of fatty acid: short, medium and long chain triacylglycerols (SCT, MCT and LCT, respectively). On increasing the SNC concentrations from 0.1 to 3.0 wt%, the droplet size of these three Pickering emulsions decreased until 1.0 wt%. At this concentration, these three emulsions showed high stability against Ostwald ripening (for SCT) and coalescence (for MCT and LCT) for 90 days at 25 degrees C. However, the in vitro digestion properties of these three emulsions were significantly different. The rate of lipid digestion increased in the order LCT < MCT < SCT, whereas the percentage of SNC digested decreased in the order LCT > MCT > SCT. The inverse relationship between lipid and SNC hydrolysis rates may be due to, with the higher rate of lipid hydrolysis, more SNCs being displaced from the interface which would decrease the surface areas to enzymes. At the same time, calcium in digesta may absorb to SNCs to reduce the digestibility. These results may provide information about the physical and digestive properties of food-grade Pickering emulsions of different chain length triacylglycerols.