91C-17 |
Quantifying and importance of MDA concentration in vegetable oils and frying |
D. DANA, Institute of Biochemistry, Food Science and Nutrition, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100, Israel and I. S. Saguy. Malondialdehyde (MDA), known to be mutagenic and carcinogenic, is a secondary lipid oxidation product. MDA measurement in vegetable oils could be utilized to assess mutagenic activity of the oil, as well as a marker for lipid deterioration. Although various methods to quantify thiobarbituric reactive substances (TBARS), which include MDA, are used, a method for direct determination of MDA concentration in vegetable oils has not been reported. The objective was the development of a specific, sensitive and rapid method for quantifying MDA concentrations in vegetable oils. A novel procedure has been developed for monitoring MDA in various vegetable oils and during deep fat frying. The method is based on optimal MDA extraction, which depends on sample weight and homogenization time. Measurements were performed on a variety of oils including simulating a deep fat frying process using corn oil at 170°C for up to 40 h. Third derivative absorption spectrum of the reaction mixture circumvented interference from other complexes and allowed direct determination. Sample weight, homogenization time and the procedure were found to affect the derived MDA concentration. Optimal conditions were 0.1 g sample and 60 s homogenization. MDA concentrations for 15 various commercial vegetable oils were 609 - 913, 674 - 800, 615 - 1187, 789 - 847, 1204 - 1346 and 1253 ppb for soybean, corn, canola, sunflower, olive and safflower oil, respectively. MDA concentration increased by ca. 4-fold (363 to 1267 ppb) during a simulated deep fat frying process at 170°C for up to 40 h. MDA detection limit and sensitivity of this method is comparable with other reported HPLC methods. The measurement of MDA concentration indicates the extent of oil oxidation, and due to its health related significance, it should be also utilized as an oxidation criterion for monitoring oil deterioration during deep fat frying.
Session 91C, Food Engineering: Food process engineering
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