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THE PROCESS OF MANUFACTURE. 

 The work of a starch factory may be summarised as follows : — 



Purification of crude starch. 



Purification of waste starch. 

 Drying starch. 

 Preparation of potato meal 

 from residue. 



5. Recovery of starch. lO. Working up or removing the 



waste products. 



(l.) Potatoes are brought by train or water and are stored in 

 heaps, cellars or sheds. 



If the factory is buying potatoes, determinations of the percentage 

 of adherent earth and of starch are made to regulate the price 

 payable. 



(2.) The potato washer consist of a series of troughs in which the 

 tubers are slowly stirred under water to remove the adherent dirt. 



The tubers are then removed and sprayed with clean water and 

 are then ready for 



(j.) The pulping process. — The potato is composed of a mass of 

 small cells in which the starch grains are locked up. The ob- 

 ject to be attained in the pulping process, therefore, is that of as 

 complete a disintegration of the cellular mass as possible. 



This is carried out by means of a revolving drum armed with 

 sharp teeth attached like narrow saws parallel to the axis upon 

 which the drum revolves. 



A velocity of 900-1,200 revolutions per minute is imparted to the 

 drum by suitable machinery. 



The potatoes falling against this revolving drum are rapidly 

 reduced to a fine-grained, foaming reddish pulp. 



It is usual to moisten the tubers with an equal weight of water to 

 facilitate the pulping. 



The pulp consists of the juice of the tubers, free starch granules, 

 fibre and cells still unbroken. In small factories the fibre and 

 whole cells are removed by sieves and after drying used as cattle 

 food, in larger concerns this product is separated and ground up 

 in a mill so as to liberate more starch. In no case can all the 

 starch in the tubers be liberated. 



(4) Washing out the Starch. — The separation of the starch from 

 the juices and the fibre is carried out by a system of sieves. 



Flat sieves are usually constructed so that an engine can be used 

 to shake them to and fro or else a mechanical arrangement of 

 moving brushes is employed to work the starch through the meshes. 



Sometimes revolving cylinders of wire gauze are used. 



The coarser sieves have a mesh of y'- inch, the fine sieves are 

 made of the finest wire gauze or of No. 5 silk gauze. 



Careful attention to the sieves is one of the first essentials for 

 ensuring a high class product. 



The starch " milk" obtained from the last sieve contains, besides 



