Determination of trans fatty acids in cold pressed oils

The adulteration of cold pressed oils (CPO) by refining or by blending with refined oils will lead to an increase of trans fatty acids (TFA) in such oils. The regulations of the European Community (EC) demand strict processing conditions without any steam treatment for cold pressed, native olive oils and provide limits for TFA. German regulations, however, allow a "steam washing" for CPO other than native olive oil and offer no limits for TFA. The TFA content of such oils could exceed the limits for cold pressed, native olive oil. Modern capillary GLC serves as a quick tool for the detection of TFA formed during deodorization and other processing. However, care should be taken to avoid the formation of TFA during analysis. We evaluated the content of TFA in several oils labelled as cold pressed and the formation of TFA during "steam washing". Analysis of some seeds indicates that preliminary drying of the seeds may also lead to TFA.