A novel process for the production of castor oil by direct solvent extraction

Abstract

This research was undertaken to: develop a process for the direct solvent extraction of castor oil seeds. A literature survey confirmed the desirability of establishing such a process with emphasis on the decortication, size, reduction, detoxification-deallergenization, and solvent·extraction operations. A novel process was developed for the dehulling of castor seeds which consists of pressurizing the beans and then suddenly releasing the pressure to vaccum. The degree of dehulling varied according to the pressure applied and the size of the beans. Some of the batches were difficult-to-hull, and this phenomenon was investigated using the scanning electron microscope and by thickness and compressive strength measurements. The other variables studied to lesser degrees included residence time, moisture, content, and temperature.The method was successfully extended to cocoa beans, and (with modifications) to peanuts. The possibility of continuous operation was looked into, and a mechanism was suggested to explain the method works. The work on toxins and allergens included an extensive literature survey on the properties of these substances and the methods developed for their deactivation Part of the work involved setting up an assay method for measuring their concentration in the beans and cake, but technical difficulties prevented the completion of this aspect of the project. An appraisal of the existing deactivation methods was made in the course of searching for new ones. A new method of reducing the size of oilseeds was introduced in this research; it involved freezing the beans in cardice and milling them in a coffee grinder, the method was found to be a quick, efficient, and reliable. An application of the freezing technique was successful in dehulling soybeans and de-skinning peanut kernels. The literature on the solvent extraction, of oilseeds, especially castor, was reviewed: The survey covered processes, equipment, solvents, and mechanism of leaching. three solvents were experimentally investigated: cyclohexane, ethanol, and acetone. Extraction with liquid ammonia and liquid butane was not effective under the conditions studied. Based on the results of the research a process has been suggested for the direct solvent extraction of castor seeds, the various sections of the process have analysed, and the factors affecting the economics of the process were discussed.