Condensed Milk and Milk Powder 99 



cause most vigorous agitation. The stroke should be not less than 

 two and one-half inches and the eccentric should revolve not less 

 than three hundred to four hundred times per minute. In order to 

 accomplish this without wrecking the- machine, the shaker must be 

 fastened securely to a solid foundation. 



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

 to completely break down a soft curd 1 . When shaking for five min- 

 utes does not produce a smooth milk, the product is usually hope- 

 lessly 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 certain 

 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. Experience has shown, how- 

 ever, 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 produced is firm, 

 even prolonged shaking will not prevent the appearance in the fin- 

 ished 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 de- 

 sirable 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 pur- 



