Impact of diacylglycerol and monoacylglycerol on the physical and chemical properties of stripped soybean oil

In this study, we determined the effect of diacylglycerol (DAG) and monoacylglycerol (MAG) on the oxidative stability of stripped soybean oil (SSO) and on the antioxidative effectiveness of alpha-tocopherol in SSO. We also examined the influence of DAG and MAG on the physical properties of SSO. DAG (0-2.5 wt%) had little effect on the chemical stability of SSO and on the antioxidative activity of 40 mu M alpha-tocopherol in SSO (55 degrees C). MAG (0-2.5 wt%) had no remarkable impact on the chemical stability of SSO. The addition of MAG (0.5 wt%) suppressed the effectiveness of alpha-tocopherol (40 mu M) in SSO. The addition of DAG did not cause an appreciable change in the interfacial tension (IFT) of SSO, indicating that it was not strongly surface active. MAG significantly decreased the interfacial tension of SSO, due to its strong surface active properties. Wide angle X-ray scattering (WAXS) analysis showed that DAG did not alter the structured organisation of SSO, which remained in an amorphous form, whereas MAG led to strong scattering, indicating the formation of crystals. The physical properties of DAG and MAG in the SSO may be related to the chemical stability of SSO and the effectiveness of antioxidants incorporated. These results can be used to better understand the physicochemical mechanisms by which minor components impact oxidation of bulk oils. (C) 2013 Elsevier Ltd. All rights reserved.