Location: Functional Foods Research Unit
Title: Enhancing antioxidant activity of sesamol at frying temperature by addition of additives through reducing volatility Authors
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 13, 2014
Publication Date: November 1, 2014
Citation: Hwang, H.-S., Winkler-Moser, J.K., Vermillion, K., Liu, S.X. 2014. Enhancing antioxidant activity of sesamol at frying temperature by addition of additives through reducing volatility. Journal of Food Science. 79:C2164-2173. Interpretive Summary: Sesamol, a natural antioxidant found in sesame oil, has drawn a considerable interest as an antioxidant in frying oil for its health promoting benefits and relatively low cost. However, due to its high volatility at the frying temperature (about 180 °C), at this temperature its antioxidant activity is considerably reduced. In this study, it was hypothesized that an additive chemically binding sesamol could reduce volatility of sesamol. From the experiments with twenty two additives, it was found that these additives could effectively bind sesamol and reduce its volatility. The reduced volatility of sesamol could also improve its antioxidant activity to prolong the life time of frying oil. It is believed that this method can also be used for many other antioxidants of which volatility is a problem.
Technical Abstract: Additives were evaluated to investigate their effects on volatility of sesamol at frying temperature with the hypothesis that the interaction between an additive and sesamol would reduce sesamol volatility. Twenty-two additive:sesamol combinations were examined by thermogravimetric analysis (TGA) under nitrogen in neat form and in soybean oil. The results indicate that these additives could bind to or interact with sesamol and consequently reduced its volatility. 1H NMR study provided evidence for hydrogen bonding between sesamol and a hydroxyl group, an amino group, and ether groups. Subsequent heating tests were conducted to investigate the effect of the reduced volatility of sesamol on antioxidant activity in soybean oil at 180 °C. Oxidation of soybean oil was monitored with gel permeation chromatography for formation of polymerized triacylglycerols and with 1H NMR for loss of olefinic and bisallylic protons. Sesamol retained in soybean oil during the heating process was determined by HPLC. A strong correlation between the retained sesamol and the antioxidant activity was observed. The mixture of 830 ppm sesamol and mono-/diglycerides, polysorbate 20 or L-carnosine showed much improved antioxidant activity compared to sesamol itself and slightly better antioxidant activity than 200 ppm TBHQ (tert-butylhydroquinone). It is believed that this method can also be used for many other antioxidants for which volatility is a problem.