CHEMISTRY AND ENGINEERING OF EDIBLE OILS AND FATS............................................................... Quality of Edible Oils and Fats Traditional and Novel Techniques to Enhance

Polyunsaturated fatty acids (PUFAs) are defined as those having 2 or more double bonds. The common PUFAs found in plant oils are linoleic and linolenic acids. GLA is found in significant quantity in the seeds of borage, evening primrose, blackcurrant [3] and some Onosmodium spe­ cies [4]. Longer chain and more unsaturated fatty acids are rarely found in

plants but eicosapentaenoic acid (Δ-5,8,11,14,17 C20:5; EPA) and docosahexaenoic acid (Δ-4,7,10,13,16,19 C22:6; DHA) occur in some Portu­ laca species [5]. However, these species are not domesticated, so, for commercial purposes, EPA and DHA are usually obtained from fish oils or from microbial sources.