New seed oils for oleochemical industry: evaluation and enzyme-bioreactor mediated processing

Abstract

The introduction of new oilseed crops for the production of vegetable oils for oleochemical uses is currently under investigation. Crops like Crambe abyssinica, Limnanthes alba, Dimorphotheca pluvialis and Euphorbia lagascae contain oils with high proportions of industrially interesting, and sometimes unusual fatty acids, such as erucic or other very long-chain fatty acids, hydroxy fatty acids or epoxy fatty acids. In this paper we present an overview of our investigation of aspects of the processing of the new oilseeds and their oils. The optimal oil quality and content from the new seeds was studied with respect to sowing date and harvest time. Oil from the harvested seeds was recovered with both mechanical expelling and solvent extraction techniques. It was found that for Euphorbia and Crambe seeds cold-pressing resulted in acceptable oil yields and qualities. Cold-pressing was found to be unsatisfactory for oil recovery from Dimorphotheca and Limnanthes seeds. For the latter, optimal conditions for solvent extraction are presently explored. The recovered oils were subjected to enzymatic hydrolysis to isolate the fatty acids of interest. We were particularly successful in isolating the highly reactive hydroxy and epoxy fatty acids. This is especially relevant since these fatty acids can be isolated by conventional chemical techniques only with great difficulty, due to their thermal instability. When 1,3-positional specific lipases were employed, erucic acid could be recovered at high purity from the highly symmetric Crambe oil triglycerides, thus facilitating the down-stream processing of the erucic acid. New developments in membrane technology lead to highly efficient enzyme supports to permit a continuous enzymatic oil hydrolysis.