67D-17 |
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P. C. OSIDACZ and W. E. Artz. Food Science and Human Nutrition, University of Illinois, 382 AESB, 1304 W. Pennsylvania Ave., Urbana, IL 61801 Deep fat frying is a popular method of food preparation in many parts of the world, due to the very desirable flavor and textural produced in the fried food. As a result of strong consumer preferences for fried food, the oxidation of frying oils and fats has an important role in the production of both desirable and undesirable flavor compounds in the oil. Transition metals, such as iron, occur naturally in meats and could decrease the stability of the frying oil if significant amounts leach into the oil and accelerate oxidative reactions. The objective was to examine the thermoxidative stability of partially hydrogenated soybean oil after addition of heme-iron. Heme-iron (2.7 ppm) was added to the oil, and then samples were heated at 160, 180 and 200ºC continuously for 72 hours and sampled every 12 hours. The p-anisidine values, acid values, color, dielectric constant and the triacylglycerol (TAG) polymer content of the oil samples were compared to the oil sample heated without added iron. Generally, the value of each oxidative index increased with 1) an increase in temperature, 2) an increase in heating time, and/or 3) addition of iron. The differences between the samples heated with and without added iron were often negligible at 160ºC and 180ºC, but the differences between the control and the samples with added heme-iron were much greater for samples heated at 200ºC. The target discard point (20% TAG polymer) was reached in the oil sample that contained added iron after 30 hours of heating at 200ºC, while the samples heated at 160ºC and 180ºC did not contain 20% polymer even after 72 hours of heating. The results demonstrate that heme-iron in frying oil can increase the rate of oxidation and that at very high frying temperatures, the reduction in the frying life of the oil can be substantial.
Session 67D, Food Chemistry: Lipid and carbohydrate chemistry
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