iob Condensed Milk and Milk Powder 



pose of inculbation is to detect defective milk and defective cans 

 before they leave the factory. If the contents of any of the cans 

 have not been completely sterilized, or if any cans have the minutest 

 leak, the evaporated milk therein will spoil within the time of incu- 

 bation. Such milk either sours, curdles or becomes solid, or it 

 undergoes gaseous fermentation, causing the appearance of "swell 

 heads." The more nearly perfect the process of sterilization and 

 the better the construction and seal of the cans, the fewer are the 

 spoiled cans. This incubation process is strictly a preventative meas- 

 ure. It is omitted in many factories where the cans are labeled, 

 packed and shipped to their destination at once, or put in ordinary 

 storage in the factory. 



CHAPTER XIII 



PLAIN CONDENSED BULK MILK 



Definition. — This is an unsweetened condensed milk made from 

 whole milk, or partly, or wholly skimmed milk, condensed in vacuo 

 at the ratio of about three or four parts oi fluid milk to one part of 

 condensed milk. It is usually superheated to swell and thicken it, 

 and it has the consistency of rich cream. It is sold in io-gallon 

 milk cans to ice cream factories and in milk bottles to the direct 

 consumer. Plain condensed bulk milk is not sterile, nor is it pre- 

 served by sucrose. Its keeping quality is similar to that of a high 

 quality pasteurized milk. 



Quality of Fresh Milk. — The sweeter and purer the fresh milk 

 or skim milk, the better will be the quality of this product. Old milk, 

 or skim milk in which the acid development has made considerable 

 headway, tends to form a lumpy, plain condensed bulk milk. How- 

 ever, since this milk is not subjected to sterilizing temperatures and 

 is used up quickly after manufacture, the quality of the fresh milk 

 from, which it is made, is not of such magnitude as in the case of 

 evaporated milk. 



Heating. — In the manufacture of plain condensed bulk milk the 

 heating is accomplished much in the same manner as in the case of 

 sweetened condensed milk and evaporated milk. The milk is usually 

 heated by turning steam direct into it. 



