162 PLAIN CONDENSED BULK MILK 



slight and soft curd in his product, that can be shaken out in 

 the shaker in one-fourth to one-half minute. When the curd 

 produced is firm, even prolonged shaking will not prevent the 

 appearance in the finished product of specks and small lumps 

 of curd. Such milk is rejected on the market. 



The formation of curd during the sterilizing process is not 

 desirable and is not necessary as far as the marketable properties 

 of the evaporated milk is concerned. It is unavoidable, however. 

 under many conditions and as long as it can be confined to a soft 

 curd that readily shakes out, no harm is done. 



INCUBATING. 



From the shaker, the cans are transferred to the incubating 

 room. This is a room with a temperature of 70 degrees to 90 

 degrees F. The evaporated milk remains there ten to thirty days. 

 The purpose of incubation is to detect defective milk and de- 

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

 any of the cans have riot been completely sterilized, or if any 

 cans have the minutest leak, the evaporated milk therein will 

 spoil within the time of incubation. Such milk either sours, 

 curdles or becomes solid, or it undergoes gaseous fermentation, 

 causing the appearance of " swell heads." The more nearly per- 

 fect the process of sterilization and the better the construction 

 and seal of the cans, the fewer are the spoiled cans. This incu- 

 bation process is strictly a preventative measure. It is omitted 

 in many factories where the cans are labeled, packed and ship- 

 ped to their destination at once, or put in ordinary storage in 

 the factory. 



CHAPTER XII. 



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 of fluid milk to 

 one part of condensed milk. It is usually superheated to swell 



