30A-31 | |||||||||||||||||||||||||
Quality assessment of frying oil by quantitative 1H and 13C NMR spectra | |||||||||||||||||||||||||
M. LI1, K. M. Keener, and B. E. Farkas. (1) Department of Food Science, North Carolina State University, 129 Schaub Hall, Box 7624, Raleigh, NC 27695
Degradation of oil quality during immersion frying has numerous effects on the product and process. These effects include changes in oil uptake by the product and rate of heat transfer at the oil/product interface. Several methods are available for assessment of frying oil quality. Traditional chemical analysis such as measurement of total polar materials, free fatty acids, and iodine value are time consuming and harmful reagents are often required. Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique used to determine structural and dynamic information at the molecular level. NMR can be used to determine changes in the chemical structure of frying oil caused by degradation. These changes may then be related to changes in oil performance including heat transfer capability and absorptivity. The objective of this research was to determine the changes in chemical structure of frying oil and quantitatively determine the composition in fresh and used frying oils. The 1H and inverse-gated proton decouple 13C spectra of fresh and used canola and soybean oil were run on a Bruker Avance-500 NMR spectrometer. The integral of the resonance peaks were utilized to calculate the fatty acid composition. NMR analysis of changes in oil composition (%) are as follows:
These results suggest that the C18:3 and C18:2 fatty acid components decrease while C18:1 and saturated fatty acids increase as frying oil degrades. The NMR results are consistent with that of traditional chemical methods. It was shown that NMR is a potential method for fast and reliable monitoring of oil degradation.
Session 30A, Food Chemistry: Lipids
|