16 BTJLLETIlsr 952, U. S. DEPAKTMElsrT OF AGEICULTURE. 



hopper, where a horizontal rotating screw carries the charge forwarcL 

 and subjects it to great pressure by discharging it over a cone in the 

 throat of the horizontal barrel containing the charge and screw. The 

 oil drips from openings in the barrel and the cake or chips are dis- 

 charged from the throat. 



Owing to the comparatively low oil content of the seed (13 per 

 cent) and also to the very hard seed coat, which tends to cause exces- 

 sive wear on the expeller, it is desirable that the seed be first decorti- 

 cated. Thus, a large part of the hard hulls may be removed and the 

 oil content of the kernels be more readily obtained. The resulting 

 cake has also a much lower fiber content than if the whole seeds were 

 passed through the expeller. 



In the laboratory a successful decortication was effected by passing 

 the seed through a vertical-plate mill set for medium to coarse grind- 

 ing. The ground mass of seeds was then passed through a rotary 

 sifter (of the flour-sifter type) fitted with No. 20 wire mesh. This 

 produced a separation of the coarser particles of the shells or hulls 

 from the finer meaty portion of the seeds. The hulls were found to 

 constitute 44 per cent of the seeds and the kernels with some of the 

 finer particles of shells 56 per cent. The hulls showed an oil content 

 of 4.07 per cent and the kernels 19.9 per cent. 



The kernels were now in condition to permit the oil to be readily 

 extracted, and the shells were in such small quantity as to have only 

 a minimum wearing effect upon the expeller. The yield of oil 

 obtained from the kernels was about 14.5 per cent. This oil was 

 of a dark-green color and had a strong nutlike odor and taste. 

 After being refined it was straw colored with a slight greenish tint 

 and pleasant bland taste and smell. 



Solvent extraction of any oleaginous material depencls upon the 

 solubility of the oil in some volatile solvent, such as benzol. When 

 dry ground grape seeds are treated with a warm benzol solution the 

 latter dissolves the oil, which is then separated from the solution by 

 distillation of the solvent. The recovery of the solvent from the 

 solution is thus effected, enabling it to be used repeatedly. The 

 extracted residue is treated with steam to remove the traces of 

 benzol. By this method from 11 to 12 per cent of oil may be obtained. 

 Such a solvent-extraction plant is shown in figure 10. 



The crude grape-seed oil which was obtained by this method was 

 refined and yielded an oil equal in quality to that obtained by 

 pressure. 



It will readily be recognized that each of these methods has both 

 advantages and disadvantages. The solvent- extraction method pro- 

 duces a greater total yield of oil than the pressure method, but the 

 oil cake resulting from the pressure method possesses valuable stock- 

 feeding qualities which would enable it to be sold to better advantage 



