Physical properties and cellular antioxidant activity of vegetable oil emulsions with different chain lengths and saturation of triglycerides

Abstract

Lipid concomitants are the main trace substances that determine the oxidative stability of oils. Over 90% of oils are composed of triglycerides, which affect oxidative stability. Oils typically enter living organism as emulsions. This study investigated the physical properties and cellular antioxidant activity (CAA) of emulsions in two model oils, namely, rice bran oil (RBO) with long-chain unsaturated triglycerides and coconut oil (CNO) with medium-chain saturated triglycerides. The results were as follows: the mean particle sizes were all approximately 250 nm; the polydispersity index (PDI) values were below 0.2; and the zeta potential values were more negative than −30 mV. The droplet size distribution of CNO emulsions was more concentrated than that of RBO emulsions. Rice bran oil-S (RBO-S) emulsions exhibited the highest CAA value, but the CAA value of coconut oil-C (CNO–C) emulsions was higher than that of rice bran oil-D (RBO-D) emulsions, indicating that CAA was influenced by the combined effect of triglycerides and minor constituents. Moreover, the medium-chain saturated triglycerides in vegetable oil emulsions resulted in a stronger CAA than that of long-chain saturated triglycerides.