420 Keeping Qualities of Oil-cakes 



In view of these facts and of the endeavours which are being made 

 to increase the use of these cakes in this country, it was thought ad- 

 visable to re-examine the whole subject of the keeping qualities of these 

 cakes and to compare them, in this respect, with other cakes, which 

 are already widely used by British farmers. The three nut- cakes were 

 therefore compared with linseed, undecorticated cottonseed, "soycot" 

 and soya cakes, the cakes being kept 



(a) under ordinary farm conditions in the cake store at The 

 Manor Farm, Garforth ; 



(6) in the laboratory under conditions most likely to promote 

 decomposition. 



Of each particular kind of cake four adjacent cakes from the middle 

 of a press were obtained fresh from the crushers. Of these four cakes, 

 two were stored at Garforth in the cake store, stacked in the usual way 

 alongside the cakes then being fed on the farm, whilst, of the other two, 

 one was used for the laboratory trials and the other kept in reserve. 

 When the cakes were sampled for analysis, strips about eight inches 

 wide were taken from the middle of each cake, ground up, mixed 

 separately and sampled by quartering in the usual way. 



In addition to careful observation of the appearance, physical con- 

 dition and other external characteristics of the cakes, the following 

 points were examined : 



(1) The changes in the composition of the cake with respect to 

 {a) crude protein, (6) true protein, (c) oil, due allowance being made 

 for the variation in the moisture content of the cake during storage. 



(2) The increase in the amount of the free fatty acids in the 

 oil during storage. 



(3) The part played by the oil in any changes undergone by the 

 nitrogenous constituents of the cake. 



Faem Tests. 



The two cakes of each kind were put into the cake store on 

 March 28th, 1916, the first cake being sampled on June 15th, and the 

 second on September 13th, 1916, by the method described above. The 

 samples were thus obtained, roughly after three and six months storage 

 respectively. The six months storage covered the whole of the summer 

 months, the cakes thus being kept at temperatures very suitable for the 

 activity of micro-organisms. The percentage composition of the dry 

 matter of the cake^ at each stage is given in Table I. 



