Aro A, Amaral E, Kesteloot H, Rimestad A, Thamm M, Poppel G van (1998): Trans fatty acids in french fries, soups, and snacks from 14 European countries: the TRANSFAIR study
J. Food Comp. Anal. 11 (2): 170-177.

The trans fatty acid content in french fried potatoes from fast-food restaurants and supermarkets ranged from 12 to 35%. Popcorn with added fat and salt, for preparation in microwave ovens contained high proportions of trans fatty acids in Denmark, Finland and Iceland, however, ready made popcorn was low in trans fatty acids but contained high saturated fatty acids in Iceland and Sweden. Other foods that contained >10% trans fatty acids included soup concentrates and instant soups and high-fat frosted breakfast cereals from Sweden and Finland. It is concluded that deep-fried products may contain high proportions of isomeric trans fatty acids. These foods contain less saturated fats and more cis-unsaturated fatty acids than foods prepared with low-trans saturated fats.