This project aims to develop a complete process engineering concept for the recovery of vegetable oils and fats for industrial purposes with the help of enzymes. The proposed enzymatic process is an alternative to or partial substitute for solvent extraction. Such a recovery process, without solvent extraction, would enable a simplified extraction plant to be used. From the environmental point of view an enzymatic process has a number of advantages in handling, recovery and disposal of solvent, as well as reducing other inherent risks - such as the danger of explosion. The application of the enzymatic extraction of the following new oilseeds was planned: Calendula officinalis, Coriandrum sativum, Crambe abyssinica and Euphorbia lagascae. However, a possible problem arose with Euphorbia. This was being processed at a pilot plant in France when two members of the staff fell ill and one had to be treated as an in patient for a week. The symptoms did not correspond to known diseases and diagnosis was difficult. Hence, the literature was investigated. However, it was only possible to obtain the well known descriptions concerning the toxic effects of this plant. Information concerning safety during the processing of Euphorbia and the symptoms of the effects of the poison on humans in the event of contamination has not apparently been reported. Linked to this was the necessity of a very costly cleaning of the equipment and pilot plant after use. Hence, this area is not being pursued. Results, so far, for the other crops are described below.
The project will determine the required parameters and peripheral conditions for the use of enzymes in the recovery of vegetable oils and fats from new oilseeds without solvent extraction: yields of the recovery of more than 90 % expected: the project deals with new oilseeds which include fatty acids with a special design which are very important for oleo-chemistry. The oilseeds are from plants which have been discontinuous, cultivated for this purpose up to now as well as from plants with only a small level of cultivation. In addition genetically manipulated plants will become more significant for this purpose in the future.
To ensure positive results for this project : a partnership will be arranged between two European participants. The participants are the Frech institution Gerdoc and the German association pilot pflanzenoeltechnologie Magdeburg E.V. (PPM E.V.) The operator of the project UEPNO will be the PPM E.V.
The result of the project will be complete process engineering conception for the enzymatic extraction of vegetable oils and fats from new and conventional oilseeds: the enzymatic extraction will be an important part within the recovery and processing of renewable raw materials. The investigations include the process engineering; the environmental effects as well as the analyses of the intermediate; final and byproducts. The new extraction step will be a "smooth process" from the product's and environmental point of view.
Using the conventional process with whole seeds of Calendula the oil yield was around 50%. Milled seed was also pressed. However, no oil could be extracted. In order to determine the cause, various investigations were carried out, indicating that one reason probably reflected the structure of the seed. Traditional press tools are designed for use with hard and brittle seeds and also for seeds with a high oil content, rather than high hull mass. A hard hull is necessary for successful pressing because it aids the power transfer from the press screw into the seed. Calendula seed has a lower oil content of 15 20%. The hull constitutes 60 70% of the mass and has a soft and elastic structure. This hull structure is unfavourable for pressing because of unequal force transmission into the seed. As a result, within the press, the seed is transported and compressed, thus expressing some of the oil. At the end of the pressing canal, the seed expands and soaks up a large part of the expressed oil. During the milling of Calendula the harder seed component (fibres) is destroyed and so impairs the pressing process and no oil is yielded. Different grades of milled seeds were investigated with the same negative result.
The enzymatic treatment of Calendulawas carried out in a container fitted with an electric mixer. For optimal enzyme treatment, the water/seed ratio was to be determined. With milled seed the best ratio was found to be 6:1. For whole seed this was 7:1. The enzymes used included two cellulases, two pectinases and two proteases. The experiments were carried out first with single enzymes and then with an equi mixture of all enzymes. The enzymes were provided in solution. They were added to the seed/water mixture at varying concentrations in the range of 0.1 1.0% of the quantity of seed. The experiments were carried out at a temperature of 55°C and a pH of between 4 and 4.5. After incubation the seed was dried to 6 10% moisture and pressed. The press cakes were extracted using hexane. The total oil yields were around 96%. Pressing of enzymatic treated milled seeds delivered no oil. The results of pressing of whole and enzymatic treated seeds were the same as those of the traditional processed seeds. Investigations were carried out using varying incubation periods (of up to 12 hours) and enzyme concentrations (up to 2%). However, the results showed no great increase in oil yield with any one combination. To determine the activities of enzymes on the oil containing kernels of Calendula, the seeds were flaked, not milled. The flaked kernels were separated from the hulls and enzymatically treated under standard conditions. Enzyme treated whole seeds and the flaked kernels were extracted using hexane. The oil yields of extracted flaked kernels were 5% lower than the yields of extracted whole seeds. The reason for the difference in yields is due to the cell wall breaking during the enzyme treatment of the flaked kernels, which results in oil being lost into the aqueous enzyme solution. Flaked Calendula seeds without enzymatic treatment were pressed. The oil could be extracted during pressing. Analysis of recovered oils showed that the use of enzymes had no influence on the fatty acids. The oil recovered after enzyme treatment contained more seed fibres than the conventionally recovered oils. These fibres, however, are easy to separate from the oil by filtration. Parallel enzymatic investigations at a laboratory scale carried out with Crambe and Coriandrum enabled oil to be extracted following enzyme treatment without pressing.
The extraction and crushing methods used for rape and sunflower are not suitable for Calendula. The enzymes used were chosen because of their beneficial effects on processing with rape seed. The processing of the enzyme treated milled and whole Calendula seed indicates that the results from rape seed are not repeatable with all types of oil seeds. Further investigations with the use of enzymatic and conventional processes will be carried out with flaked Calendula.
This project aims to determine the effectiveness and conditions of use for the application of enzymes in the recovery of vegetable oils and fats from new and conventional oilseeds without the need to use solvents. In this way it is hoped to get recovery yields of more than 90%. The project deals with new oilseeds which include those containing fatty acids of unusual composition suited for use in oleo chemistry. The oilseeds under investigation are from plants which have been cultivated rather erratically in the past, or from novel crops, cultivation of which is just beginning. MATERIALS AND METHODS
Problems were experienced in obtaining some of the equipment and measuring devices required, but in general such problems were overcome by hire of equipment. As planned, seeds of Calendula (with an oil content of around 17%) were extracted using conventional methods and also using an enzymatic treatment. The conventional method involved pressing, with a screw press, of whole or milled seeds. Alternatively, milled and unmilled seeds were treated with enzymes.
Funding SchemeCSC - Cost-sharing contracts