THE MILK CONTRACTOR 337 



till it is needed, when it is melted for use, and the other is to hold large 

 quantities of sweet butter in cold storage and homogenize it with skim- 

 milk or milk powder as it is needed. The success of homogenizing for 

 these purposes has led to the introduction of machines called emulsors 

 which emulsify cream products in such a way that the fat is not broken up 

 enough to prevent cream and butter being again separated. Ice cream 

 made from homogenized cream is believed by some to be superior because 

 of its smooth consistency. 



One milk dealer is reported to have lost much of his trade by tricking 

 his customers by separating his milk and homogenizing the cream sepa- 

 rately and then returning it to the milk where it formed a more bulky 

 cream than before, which deception cost him heavily when at last it was 

 discovered. Also, it is possible to homogenize other fats than butter- 

 fats with skim -milk and so to deceive the public. Thus while homo- 

 genizing may be misused by the unscrupulous, in the hands of honest 

 men it has its proper applications. 



Milk Beverages. Much of the skim-milk in milk plants is made into 

 milk beverages which are used in increasingly large quantities by the 

 public. 



Recovery and Use of Casein. In the smaller milk plants there may 

 be considerable loss from skim-milk for often the only way of disposing 

 of it is to sell it to the farmers. In other plants the casein is recovered 

 in the following manner; 2,500 Ib. of skim-milk are heated to 120F. and 

 11.5 Ib. of sulfuric acid of a specific gravity 1.83 are added, care being 

 taken to dilute the acid well before putting in the skim-milk, other- 

 wise it will burn and discolor the curd. As the acid is added the 

 skim-milk is stirred. If too little acid is added a soft curd, which 

 does not press well, results. The curd is pressed, after which it is 

 ground and then dried at 145F. If the temperature rises to 150F. the 

 curd burns. The dried curd is then shipped to large manufacturers of 

 casein products. 



Care of Milk Plant and Creamery Wastes. The care of the wastes of 

 a city milk plant or of a creamery is important. If they are permitted 

 to flow out on the ground, a nuisance results. Whenever it is possible 

 connections should be made to the public sewer. Where this cannot be 

 done other methods of sewage disposal must be adopted. In some cases 

 the sewage may be disposed of by dilution, that is, by discharging it into a 

 running stream. Sometimes local or State laws prohibit such a practice 

 and sometimes the volume of the stream is not great enough to dilute 

 the creamery effluent to such a degree that no nuisance will result. This 

 is the more likely to be the case from the fact that the volume of waste is 

 likely to be largest when that of the stream is smallest. In such cases 

 recourse must be had to sewage treatment. 



Two methods have been found applicable to creamery wastes, viz.: 



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