CEREAL BY-PRODUCTS 165 



161. Rice Starch and Rice Gluten. 



In the case of rice, bruising and washing are insufficient to 

 remove the starch, and it is consequently subjected to treatment 

 with caustic soda. 



About 50 grams of rice are ground to a powder and 

 soaked for twenty-four hours in dilute caustic soda, with 

 occasional vigorous shaking. The grain softens and 

 swells, and a proportion of the protein is dissolved out. 

 The supernatant liquid is drawn off and the residual 

 starch brushed through fine sieves to remove husk, 

 extraneous matter, etc., and well washed with water. 

 The grains should be examined under the microscope. 



The alkaline liquid is just neutralised with dilute 

 hydrochloric acid, and the precipitated protein filtered 

 off, dried, and ground. It consists of rice gluten, which 

 is sometimes used as a feeding stuff. Its protein nature 

 may be shown by the usual tests (see 9, p. 15). 



162. Maize. 



Maize contains from 5 to 7 per cent, of oil — a much 

 higher proportion than most of the other cereals. One 

 hundred grams of ground maize are extracted with 

 ether in a Soxhlet, the solvent evaporated off, and the 

 amount and nature of the fatty material noted. The 

 characteristic tests for oils may be applied. It should 

 be noted that maize oil is not a drying oil. 



163. Cereal By-Products, 



The following cereal by-products should be 

 examined, and their general characteristics noted for 

 identification purposes : — 



Wheat. — Bran, pollards, middlings, sharps. 

 Barley. — Brewers' grains (wet and dried), malt 

 coombs, barley meal 



L 2 



