72 MILK PRODUCTS 



The full analysis of sweetened condensed milk 

 is difficult, and many of the published figures are 

 erroneous. The sucrose interferes with the ex- 

 traction of the fat by solvents. The same 

 difficulty occurs in the analysis of some prepared 

 infant-foods, such as mixtures of milk with malt 

 and glucose. 



For the general operations, a portion of the 

 well-mixed contents of a freshly opened can 

 should be accurately weighed, diluted with a 

 known amount of water, and well mixed, from 

 which mass the portions for analysis may be 

 taken and the results calculated to the original 

 sample. 50 grams mixed with 150 c.c. of water 

 will be a convenient quantity. For the polar- 

 imetric determination of lactose, a special pro- 

 cedure will be necessary ; but for determination of 

 solids, ash, total proteins, and total reducing 

 sugars, the examination may be made as with 

 ordinary milk upon this diluted sample. 



Fat. — The Adams method is not satisfactory 

 under ordinary conditions, owing to the sucrose. 

 The Rose-Gottlieb method is now largely used 

 and generally approved. The following descrip- 

 tion is given by Bigelow and Fitzgerald : 



Weigh from 4.5 to 5.0 grams evaporated or 

 condensed milk into a Rose-Gottlieb tube, add 

 water to make about 11 grams and i34 to i}i 



