iv PRESERVED MILK 203 



except the water. Before the manufacture of condensed milk 

 was commenced, an attempt was made in America to make a 

 dry preparation of milk which was pressed into tablets, but the 

 attempt was not successful. Since then many more or less 

 successful attempts have been made, but it is only during the 

 last few years that the manufacture of a satisfactory material 

 has been in operation on a large scale. The difficulties and 

 failures which had previously attended the manufacture of 

 dried milk or milk meal were due either to the fat becoming 

 rancid, or the casein, which is ordinarily present in milk in a 

 collodial state, became changed by the heat, and was then 

 insoluble in water. A good dried milk when stirred with water 

 ought to give a fluid which, in taste and appearance as well as 

 in its chemical and physical properties, exactly resembles milk. 



Even now there is no dried milk preparation which exactly 

 fulfils these ^ conditions, but there are several which approach 

 closely to the ideal, and they are used in large quantities both 

 for baking and in the manufacture of such foods as chocolate. 

 Every advance in this branch of the subject is to be welcomed, 

 for success means a solution of that very important problem in 

 modern dairy work, viz., the disposal of the ever- increasing 

 quantity of separated milk. Up to the present, separated milk 

 has been used in far larger quantities for this preparation than 

 whole milk, for the material made from the latter has not 

 found such a ready sale. 



The best known preparations of dried milk at the present 

 time are those of Dr. M. Ekenberg (Sweden) and Just- 

 Hatmaker (America), the manufacture being essentially 

 different in each case. 



In the Ekenberg method the mill! is evaporated in a drum 

 at 40-45 C. in vacuum. A nickel cylinder heated internally 

 by steam revolves inside the drum. The milk dries on the 

 surface of the cylinder to a thin layer, which is automatically 

 scraped off and falls into a special receiver, and this dried milk 

 is then ground to powder after being cooled, and further dried 

 in warm air. 



In the Just-Hatmaker method, on the other hand, the 

 milk is allowed to flow between two iron cylinders which 

 rotate in opposite directions and are heated by steam to about 

 130-140. The milk dries almost instantaneously on the outer 



