ヒマシ粕

Castor pomace was left unavailable until today due to its serious toxic damage to the animals, despite of its valuable protein content. Ricin which was a toxic protein in castor bean was considered responsible for the powerful toxic action of castor pomace after a regular heat-treatment in the extraction process of its oil. However, it was expected that the pomace might be completely detoxified by an additional heat-treatment. Thus, various attempts were made of treatment under different conditions of heating in order to detoxify the pomace, resulting in that the pomace could be completely detoxified by heating at 125℃ in an autoclave under a pressure of 2 kg/cm2. for 5 minutes, whereas heating in an open vessel was not able to completely detoxify the castor pomace even at 165℃. Furthermore, it was found that detoxification was carried out more efficiently when the pomace was autoclaved in the presence of excess water. Through these experiments the toxicity of the pomace was assayed on chicken by intraperitoneal injection of an aqueous solution of the toxic principle which was extracted from the pomace with 10 % sodium chloride solution, dialyzed against water, subsequently precipitated with saturated ammonium sulfate, and then dialyzed against water or 0.9 % sodium chloride solution. For the purpose of an indirect and rapid determination of the toxicity remained in the heat-treated pomace, an attempt was made to correlate the loss of toxicity on heating to the inactivation of the other physiologically active proteins, i.e. hemagglutinin and protease. No correlation was found between these activities. However, the amounts of water-soluble proteins remained after the heat-treatment was found to be approximately proportional to the degree of detoxification of the pomace, so that it became possible to determine the degree of detoxification indirectly by measuring the amounts of water-soluble proteins remained in the treated pomace. A turbidimetric method was employed for a rapid determination of the water-soluble protein which was extracted under a certain condition. On the other hand, allergic symptoms observed on chicken fed pomace was examined, since allergen is usually so heat-stable that it is possible to remain intact even after the heat treatment. No allergic symptoms was observed on the chicken during 7 weeks of feeding with the heat-treated pomace. At the beginning of the 8th week a partially purified allergen which was prepared from castor bean was injected into the chicken. Any allergic symptoms did not even appear. Therefore, it could be concluded that even if a small amount of allergen was still contained in the treated pomace, it did not give any damage to the chicken at all. Consequently, it was found that an appropriate heat treatment could make the castor pomace free from ricin toxicity and utilizable for an animal feed.