NMR study on the oxidation of vegetable oils for assessing the antioxidant function of trehalose

Abstract

The objective of this study was to investigate the antioxidant activity of trehalose in vegetable oils after 16 h deep-frying at 180 °C by using nuclear magnetic resonance (NMR) spectroscopy. 1 H NMR spectroscopy is a useful technique for determining structure which requires small sample volumes and short processing time. The results of this study indicate the oxidation stability of vegetable oils can be improved with the addition of trehalose at 0.05% (w/w) concentration. The antioxidant activity of trehalose positively affected all vegetable oils studied with notable differences when used in conjunction with soybean oil. For example, the measured percent loss of olefinic protons in soybean oil (oil-0 control) changed from 6.17 to 2.52 (integral value) in sample soybean oil-1 with the addition of trehalose. Similarly, the percent loss of bisallylic protons changed from 8.19 to 3.32. Further, with respect to the percent loss of allylic protons changing from 3.02 to 0, the oxidation of an allylic proton was greatly depressed. Trehalose improved the oxidation stability of soybean oil much better than that of corn oil, canola oil, cottonseed oil and peanut oil. In summary, trehalose can be used as a safe and effective antioxidant for these edible oils. • Efficiently antioxidant activity of trehalose in deep-frying vegetable oils. • 1 H NMR spectroscopy is a useful technique for determining structure change of oil. • Trehalose improved greatly the oxidation stability of vegetable oils.