Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2002
Publication Date: 6/2/2002
Citation: WARNER, K.A., NEFF, W.E., ELLER, F.J. ENHANCING QUALITY AND OXIDATIVE STABILITY OF AGED POTATO CHIPS WITH GAMMA TOCOPHEROL. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY. 2002. Interpretive Summary: Many fried foods are packaged and sold in grocery stores where they must be able to maintain good quality. Fried foods sometimes cannot withstand these storage conditions and will develop off-flavors, such as rancid, and be unacceptable to consumers. Researchers have been developing new knowledge about how to keep packaged fried food from becoming rancid. One method is to use oils that have compositions that help prevent rancidity. For example, some oils such as soybean, contain natural antioxidants known as tocopherols that help keep stored foods from developing off- flavors. One type of tocopherol, called gamma tocopherol, is known to be a very good antioxidant. In this study, we investigated not only how much gamma tocopherol is left in fryer oil and in stored potato chips; but also how much gamma tocopherol is needed to keep potato chips from becoming rancid. We found that if the fresh frying oil has a large amount of gamma tocopherol, that enough of this antioxidant will remain in the potato chip to prevent it from becoming rancid. This information will help ensure good quality, healthful fried foods and will benefit both consumers and food manufacturers.
Technical Abstract: To determine effects of gamma tocopherol on the stability of fried food, potato chips were fried in triolein with 0, 100 or 400 ppm gamma tocopherol. Potato chips, sampled after 1, 3 and 6 hours of frying time, were aged for 0, 2 and 4 days at 60C, then evaluated for odor by sensory analysis and for volatile compounds by purge and trap gas chromatography-mass spectrometry. Oil sampled after 1, 3 and 6 hours of frying time from the fryer was evaluated for total polar compounds and retention of gamma tocopherol. Oil extracted from the potato chips was also analyzed for retained gamma tocopherol. Gamma tocopherol inhibited polar compound production in the triolein. Results showed that gamma tocopherol inhibited oxidation of the fried food even when only very low levels of retained gamma tocopherol were present in the frying oil or potato chips. Gamma tocopherol disappeared rapidly with only slight amounts of the original 100 ppm level detectable after the triolein was used for frying. Nonanal formation was inhibited by gamma tocopherol in chips aged for 4 days at 60C. Odor analysis of the aged potato chips showed that samples with 0 ppm gamma tocopherol had a rancid odor after aging for 4 days. Potato chips with 400 ppm gamma tocopherol had no rancid odors; however, as the level of gamma tocopherol decreased in the triolein and in the potato chips, a plastic odor characteristic of oxidized triolein was detected.