30A-18 |
Application of modulate differential scanning calorimetry and dynamic thermal stripping-thermal desorption – gas chromatography to describing oxidation byproducts in extra virgin olive oil |
A. KANAVOURAS and R. J. Hernandez. School of Packaging, Michigan State University, East Lansing, MI 48824 Modulated differential scanning calorimetry (m-DSC) can provide very useful information regarding the degree of oxidation of edible oils. Since m-DSC is sensitive to composition changes resulting from oxidation, this technique could be used as a rapid and effective method to characterize the quality of olive oil at different degree of oxidation. The objective of this study was to correlate m-DSC measurements with dynamic-thermal-stripping/thermal desorption/gas chromatography of oxidized virgin olive oil. M-DSC thermograms were obtained on oil subjected to different oxidation treatments and selected flavor and off-flavor compounds of oil were quantitatively determined during the oxidation period. Extra virgin olive oil was subjected to the following thermo-oxidizing treatments: a) oil samples were purged with air using glass washing bottles at two flow rate values at 20-22 °C; b) oil samples were heated in a conventional oven at two area/oil mass ratios; and c) oils samples were heated in a microwave oven also at two area/oil mass ratios. Samples were withdrawn and analyzed at predetermined time intervals. Flavor and off-flavor compounds were isolated using a dynamic thermal stripping apparatus and transferred into a gas chromatograph by using a thermal desorption unit. All oil samples were analyzed by m-DSC from 25°C to -80°C at 7°C /min, and heating back to 40°C at 10 °C /min. We obtained high correlation values between the different m-DSC thermogram parameters and the chemical composition of oil from gas chromatography analysis. Results showed that m-DSC can be used as a simple method to indicate compositional changes in olive oil due to oxidation.
Session 30A, Food Chemistry: Lipids
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