Author
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Warner, Kathleen |
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Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only Publication Acceptance Date: 3/1/2006 Publication Date: 4/30/2006 Citation: Warner, K.A. 2006. Flavor development in high stability oils during frying [abstract]. 97th Annual Meeting and Expo of the American Oil Chemists' Society. p. 44. Interpretive Summary: Technical Abstract: As vegetable oils are modified to produce lower levels of linoleic and linolenic acid and/or higher levels of oleic acid, the flavor profiles of the oils change based on their fatty acid composition. As oils oxidize, they decompose to form flavor-producing compounds such as aldehydes, alcohols and ketones. The more oxidatively unstable the oil, the more flavor compounds that are produced. Linolenic acid is 25 times more oxidizable than oleic acid and linoleic acid is 10 times more oxidizable than oleic acid. Therefore, linolenic acid and linoleic acid produce more degradation compounds than oleic. The types of degradation compounds formed significantly affect the types of flavors that are produced. Because of the high temperature conditions that frying oils are exposed to, the decomposition reactions occur more rapidly than at room temperature. Exposing oils with 8-10% linolenic acid to high temperature oxidizes the oil quickly and produces off-flavors such as fishy; however, by decreasing the linoleic acid content to less than 3%, the fishy flavor is significantly reduced. Oleic acid is fairly stable to frying temperatures and does not decompose like linoleic or linolenic acids. As oleic acid does degrades during frying, volatile compounds such as 2-nonenal and 2-decenal are formed that produce plastic and waxy flavors in the oil. On the other hand, linoleic acid degradation produces both desirable and undesirable flavor compounds. For examples, 2, 4-decadienal is considered a desirable compound because it contributes to the deep fried flavor in fried foods. Linoleic acid also produces hexanal that is undesirable in fried food and frying oils. Therefore, oil with a very high level of oleic acid will be oxidatively stable, but the flavors (waxy and plastic) produced will not be desirable in a fried food. Although linoleic acid does breakdown, it should not be reduced to extremely low levels in an oil. Some of the decomposition products from linoleic acid such as the dienals contribute to the deep fried flavor. Linoleic acid should be present in the composition at least at the 20% level in order for the decomposition of this fatty acid to produce compounds responsible for the deep fried flavor. A mid-oleic/low linolenic acid frying oil will usually have the fatty acid composition necessary to provide the stability needed for long fry life and long shelf life as well as for good deep fried flavor. |
