OILCAKES, ETC. 155 



CHAPTER XVI 



Concentrated Food-stuffs — Oilcakes, Pulses, 

 Cereals, etc. 



Oilcakes. 



148. Qualitative Examination. 



Oilcakes should be subjected to the following 

 qualitative tests : — 



[a) The cake should be broken up in a mortar, its 

 hardness or other characteristics noted, and an 

 examination made with a lens for the presence 

 of strange husks and seeds, fibre, pieces of wood 

 or other extraneous material, mould, insects, etc. 



{b) The ground cake is mixed with water in a 

 porcelain dish, stirred with the little finger, and 

 presence of any grit or sand noted. 



{c) The ground cake mixed with water is warmed on 

 the water-bath and the smell observed. It 

 should be perfectly fresh, and free from 

 mouldiness. 



{d) The cake and water mixture is boiled, allowed 

 to cool, and tested with a solution of iodine in 

 potassium iodide for starch. Most of the oil- 

 seeds contain no free starch, and its presence in 

 any quantity, as e.g,^ in linseed cake, is strong 

 indication of adulteration with flour or milling 

 by-products, or the presence of immature seeds. 



The above tests should be applied to all samples of 

 oilcake which are accessible. 



Formation of Prussic Acid from Linseed Cake. 



Linseed and linseed cake contain a cyanogenetic glucoside (see 

 p. 42) named phaseolunatin, and coexistent with it a specific 



