10 



BULLETIN 867, U. S. DEPARTMENT OF AGRICULTURE. 



sitates in most operations tlie addition of a so-called binder to pre- 

 vent the troublesome squirting of the meats from the presses and 

 at the same time prevent the introduction of excessive meal into the 

 oil. The disadvantages so greatly outweigh the advantages that this 

 practice is not followed to any great extent either here or abroad. 

 (See under "Solvent extraction.") A decorticating machine is 

 illustrated in figure 1. 



HEATING. 



After cleaning, the beans are conducted to the heaters. In 

 contradistinction to other vegetable oleaginous materials, castor 



beans can not be 

 ground and tempered 

 as can flaxseed, pea- 

 nuts, soy beans, cot- 

 tonseed, and copra. . 

 The nonfibrous 

 character of the ker- 

 nel with its attend- 

 ant high oil content 

 so gums up the equip- 

 ment that further 

 grinding is difficult. 

 In addition to these 

 technical difficulties, 

 the bean contains a 

 very active lipase or 

 fat-splitting (sapon- 

 ifying) enzym, which 

 very quickly sets free 

 an excessive amount 

 of fatty acid. Ac- 

 cordingly, every 

 effort is made to 

 deliver the beans 

 to the presses as whole as possible. The reason they are heated 

 at all is to render more mobile the naturally heavy viscous 

 oil. Probably even this would not be done if such treatment served 

 materially to impair the quality of the oil. The temperature to which 

 the beans are raised varies from 100° to 120° F. 



To test the effect of heating undamaged beans, a sample from Santo 

 Domingo was heated for 2\ hours at 70° C. (158° F.). It was then 

 carefully picked over to eliminate any black beans, and cold pressed 

 without any further heating in a laboratory cage press at 1,500 pounds 

 applied pressure per square inch. A sample of unheated beans wa 

 pressed as a control. In each case the first runnings were discarded 



Fig. 1.— A castor-bean decorticator. 



