Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2000
Publication Date: N/A
Interpretive Summary: Vegetable oils are usually processed when they are intended for use in frying operations or for margarines and shortenings. However, this type of processing can produce high amounts of trans fatty acids that are believed to increase cholesterol. By using a new oil processing procedure, oils can be made that have greatly reduced levels of trans fatty acids. Results of composition studies on these new oils showed that they could be utilized for commercial-grade margarine and shortening basestocks as well as for frying oils. Evaluation of the odor of these new oils as they are heated prior to deep-fat frying showed that they had less undesirable odors than oils processed in the current manner. Development of these new low trans fatty acid oils would create an alternative to current high trans fatty acid oils now used for frying and baking by the food industry. This information will be of interest to oil processors, food manufacturers, and nutritionists.
Technical Abstract: To determine composition and sensory characteristics of electrochemically hydrogenated soybean oils, oils were evaluated for triacylglycerol structure and for odor attributes in room odor tests. Soybean oils were either electrochemically hydrogenated with Pd at 50 deg C or 60 deg C to iodine values of 104 and 90 or were commercially hydrogenated with Ni to iodine values of 94 and 68. Trans fatty acid contents were 17% and 43.5% for commercially hydrogenated oils and 9.8% for both electrochemically hydrogenated products. Compositional analysis showed higher levels of stearic and linoleic acids in electrochemically hydrogenated oils and higher oleic acid levels in the chemically hydrogenated products. Chemical analysis indicated little hydrolysis or oxidation in electrochemically hydrogenated oils because both free fatty acid values and peroxide values were low. Solid fat index profile of a 15:85 blend of electrochemically hydrogenated soybean oil (iodine value of 90) with liquid soybean oil was equivalent to that of stick margarine. In odor tests of oils heated at frying temperature, chemically hydrogenated soybean oils showed strong intensities of an undesirable hydrogenation odor (waxy, sweet, flowery, fruity, crayon-like) However, electrochemically hydrogenated samples showed only weak intensities of this odor indicating that the hydrogenation flavor would be less detectable in foods fried in these oils than in chemically hydrogenated soybean oils. Electrochemical hydrogenation produced oils with lower levels of trans fatty acids and lower intensifies of off-odors, including hydrogenation odor, when heated to 190 deg C than did commercially hydrogenated oils.