128 EVAPORATED MILK INCUBATING 



volve not less than three hundred to four hundred times per 

 minute. In order to accomplish this without wrecking the ma- 

 chine, the shaker must be fastened securely to a solid foundation. 



From one-fourth to two minutes' shaking is usually suffi- 

 cient to completely break down a soft curd. When shaking for 

 five minutes does not produce a smooth milk, the product is 

 usually hopelessly curdy and no amount of additional shaking 

 will remedy the defect. 



In some cases it has been possible, however, to improve the 

 curdy product by shaking again after a day or two. Under cer- 

 tain conditions, age seems to have a slight mellowing effect on 

 the curd. 



Efficiency of Different Types of Shakers. Some shakers 

 have a straight, horizontal, back and forth motion. Others have 

 a rotary or elliptical motion; the latter are not considered as 

 effective in their work as the former. Some of the sterilizers in 

 which the interior frame holding the cans, moves back and forth, 

 are advertised to shake the milk as well as sterilize it. Ex- 

 perience has shown, however, that the shaking performed by 

 these sterilizer-shakers is not sufficient and that the use of a 

 separate shaker is necessary. 



Formation of Curd not Desirable nor Necessary. It should 

 be understood that the processor should aim to get only a very 

 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 prod- 

 uced is firm, even prolonged shaking will not prevent the appear- 

 ance 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. 



