Since 1970 numerous attempts have been made to replace products derived from petroleum (in particular fuels) by products obtained from vegetable matter so as to reduce the dependency on oil-producing countries and increase the markets and sales of agricultural products. The industrial route utilizing oleaginous plants as starting materials starts from the production of free fatty acids constituting the raw materials for the conversion industries and ends up with fuels, lubricants, etc. The lipids accumulated by the oleaginous plants may be converted into fatty acids by hydrolysis: two processes are currently used industrially to effect this conversion.
The first process consists in hydrolyzing the lipids after extraction by contacting the extracted lipids under conditions of heat and pressure with sulphuric acid/methanol or methanolic potassium hydroxide. Another process consists in carrying out the hydrolysis under similar conditions directly on the crushed seed material without prior extraction. Further details of these processes, which are the only ones used industrially to hydrolyze vegetable oils, may be found in the following reference: K. J. Harrington and C. d'Arcy-Evans, Ind. Eng. Chem. Prod. Res. Dev. 1985, 24, 314-318. The well-known high operating costs, large industrial infrastructure, polluting nature of the effluents, production of glycerol as a by-product without an existing market. These processes are used on account of the lack of simple alternatives.
In addition, experiments have been carried out in the laboratory to effect the hydrolysis of lipids enzymatically by mixing a lipase with the lipids extracted from seeds (G. P. McNeill et al., JAOCS, Vol. 68 No. 1st January 1991, p. 1-5; S. M. Kim and J. S. Rhee, JAOCS Vo. 68 No. 7th July 1991, p. 499-503; C. Gancet, In Heterogeneous Catalysis And Fine Chemicals II 1991, Guisnet Editors, p. 93-104). However, these experiments have remained at the laboratory stage since the technique is incompatible with an industrial exploitation on account of the amounts of enzyme required and the cost of the latter.
It should be emphasized that processes are already known enabling enzymes to be produced from plants (patent WO-A-92/01042 and EP-A-0.449.376). These processes lead to the linexpensive production of enzymes which are then used, after or without having been isolated, in various industrial or food industry conversion processes.
Nevertheless, this teaching is completely unconnected with the problem in question, which concerns the production of fatty acids directly from oleaginous plants.