Deodorization of vegetable oils: Prediction of trans polyunsaturated fattyacid content

Kinetics of the formation of trans linoleic acid and trans linolenic acid w ere compared. Pilot plant-scale tests on canola oils were carried out to va lidate the laboratory-scale kinetic model of geometrical isomerization of p olyunsaturated fatty acids described in our earlier publication. The reliab ility of the model was confirmed by statistical calculations. Formation of the individual trans linoleic and linolenic acids was studied, as well as t he effect of the degree of isomerization on the distribution of the trans f atty acid isomers. Oil samples were deodorized at temperatures from 204 to 230 degreesC from 2 to 86 h. Results showed an increase in the relative per centage of isomerized linolenic and linoleic acid with an increase in eithe r the deodorization time or the temperature. The percentage of trans linole ic acid (compared to the total) after deodorization ranged from <1 to nearl y 6%, whereas the percentage of trans linolenic acid ranged from <1 to > 65 %. Applying this model, the researchers determined the conditions required to produce a specially isomerized oil for a nutritional study. The practica l applications of these trials are as follows: (i) the trans fatty acid lev el of refined oils can be predicted for given deodorization conditions, (ii ) the conditions to meet increasingly strict consumer demands concerning th e trans isomer content can be calculated, and (iii) the deodorizer design c an be characterized by the deviation from the theoretical trans fatty acid content of the deodorized oil.