»S = Cane Sugar 

 Lactose 



22D 



26.44 



If no cane sugar is present 



Lactose = v ^-~ X 100 



26.44 



If no polariscope is available the following method has been 

 found by one of us to give satisfactory results. The milk solution 

 is curdled with acetic acid, and, after filtering, lead acetate is 

 added. Excess of lead is removed by sodium sulphate, and the 

 lactose estimated by direct reduction of Fehling's solution. After 

 inversion the total sugars can be estimated. 



In addition physical constants such as viscosity and colour 

 tests, and sterilisation standards are carried out in the laboratories 

 of the big American condensed milk factories. 



It will be apparent from these examinations if the milk will 

 "keep" for a long period (in airtight tins of course), and, of equal 

 importance, whether they will pass the legal standards of the 

 different States. 



While on this subject we must refer to the inconvenience and 

 unfairness of having different standards in different Provinces, 

 and in different countries for that matter. Sweetened condensed 

 milk in Natal must contain 31 per cent, milk solids, 28-5 per cent, 

 of which must be fat. No extraneous matter except sugar is per- 

 mitted. So far as we know, different percentages apply in the 

 other three Provinces of the Union. In the United States 

 standards vary from 24-5 to 34-3 per cent, solids, with correspond- 

 ing amounts of fat. It is surely time that international standards 

 for milk, condensed milk, and essential foods were laid down. 



In the writers' opinion minimum and maximum fats and 

 total solids should be abolished as regards condensed milk. The 

 main criterion as to suitability for sale should be whether or not! 

 the sample is prepared from whole fresh milk (this, of course, in 

 addition to its wholesomeness at the time of sale). Original fresh 

 milk should be of the standard 11-8 per cent, total solids and 3-3 

 per cent, of fat. These figures may not be the best, but figures to 

 guide the analyst should certainly be provided in a schedule. 

 Relation of fat to protein matter is a very important indication 

 of skimming. It is very seldom that the proportion fat : protein 

 is less than 1 : 0-82 in condensed milk, and an experienced analyst 

 will make very few mistakes in his conclusion. 



The law should further compel the manufacturer to state on 

 each tin to what extent the article must be diluted with water in 

 order to bring it to the standard of fresh milk laid down. The 

 current instructions on tins are to mix with from two to four parts 

 of water, or to mix water until the desired consistency is obtained. 

 These instructions are not only vague, but definitely harmful 

 where young children are being fed with condensed milk. 



