29B-14

E. VITTADINI, J. H. Lee, D. B. Min, and Y. Vodovotz. Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., 110 Parker Food Science Bldg., Columbus, OH 43210-1007

Differential Scanning Calorimetry (DSC) monitors the changes of physical or chemical properties of a material as a function of temperature by detecting the heat changes. Oxidized oils produce many volatiles and non-volatile compounds, which can change the physical or chemical properties of oils, compared to the non-oxidized oils. DSC has numerous advantages compared to the standard chemical methods for the evaluating oil oxidation, including short experimental times, small sample size, no use of solvents, and simple operation.

The objective of this study was to evaluate DSC as an analytical method to evaluate the autoxidation at 50°C and thermal oxidation of extra virgin olive oil at 93 and 180°C in air-tight model systems.

Extra virgin olive oil was placed in 10-mL air-tight vials and held in the dark at 50, 93 and 180°C. Oxidized olive oil was analyzed for the headspace oxygen depletion, the amount of headspace volatiles, and the DSC phase transitions. DSC parameters were compared with the headspace oxygen depletion and the amount of headspace volatiles in oxidized oil samples.

A single crystallization peak was found in olive oil by DSC. The crystallization peak shifted to lower temperatures its enthalpy decreased as the exposure time increased at 93 and 180oC. DSC peak enthalpy in olive oil at 50, 93, and 180oC showed a correlation of 0.84, 0.91, and 0.95, respectively, with headspace oxygen depletion in sample bottles. Correlation of DSC initial peak temperature with headspace oxygen depletion was 0.53, 0.87, and 0.95 at 50, 93, and 180°C, respectively.

DSC is a sensitive and reproducible analytical method to evaluate the oxidative stability of oils at frying temperature at 180°C.

Session 29B, Food Chemistry: Lipids, antioxidants and emulsifiers
2:00 PM - 5:30 PM, Sunday PM

2003 IFT Annual Meeting - Chicago,