THE GROUND-NUT. 53 



vantage of local extraction is that oil can be prepared 

 from nuts in a fresh condition, freight charges are lessened, 

 and the residual cake becomes available for local use. 



A short description of the machinery and processes for 

 more scientific extraction of the oil may here be desirable* 



In preparing ground-nut oil, the outer husk is generally 

 removed, although oil can be expressed from unshelled 

 nuts. Where native women and children are available 

 this labour can be done by hand, but small hand machines 

 are obtainable and more effective. Such machines break 

 the husks between rollers set at such distance as to 

 prevent the crushing of the kernels in the process ; the 

 husks and as much as possible of the red " skin " of the 

 kernel being removed by a blast of air. The husks can 

 be blown to the engine and used as fuel, or, mixed with 

 meal, they may be made into cakes. 



The cleaned kernels are ground between rollers, then 

 placed in hydraulic presses. The first pressing takes 

 place at ordinary temperature, yielding as much as 

 30 per cent, of pale-coloured oil. This " cold-drawn " 

 oil is known as " huile surfine " de Rufisque, Gambia, 

 etc., according to the origin of the nuts. This is used 

 for edible purposes. A further 6 or 8 per cent, of oil 

 inferior in quality, but still useful for edible purposes, 

 can be obtained by moistening and warming the cake 

 in steam kettles at a temperature of 30 to 32 C. An 

 additional 5 to 7 per cent, of oil, unfit for edible use, but 

 very good for soap, can be obtained by a third expression 

 at a temperature of from 48 to 50 C. The second and 

 third expressions are usually made in open Anglo- 

 American presses, which employ bags or cloths to hold 

 the cake. 



