DETECTIOlSr OP LIME USED IN DAIRY PRODUCTS. 3 



While it is probable that the percentage of calcium oxid in the 

 ash of pure cream and butter would correspond closely to the figures 

 quoted above, it is important to prove this point before proceeding 

 with the interpretation of analyses of commercial milk products to 

 determine whether lime may have been added. 



METHODS OF ANALYSIS. 



Samples of milk, buttermilk, or cream require no particular prep- 

 aration for analysis. All samples of butter analyzed in this in- 

 vestigation were prepared in the following way: About 1 pound 

 of butter was melted at as low a temperature as possible in a well- 

 stoppered, wide-mouthed bottle and then cooled. The melted fat, 

 curd, water, and salt were violently shaken together before and 

 during the "setting" of the butter. If the sample subsequently is 

 kept cool, it will not leak buttermilk, thus causing variations in 

 sampling. 



In order to prove the addition of lime to dairy products a careful 

 analysis of the ash is essential. To determine total ash, 10 grams of 

 milk, cream, or butter are weighed out in a platinum dish, the water 

 evaporated on a^ steam bath or air oven, the fat then burned off, and 

 the dish heated in a muffle at a low heat until a white ash remains. 

 The water must be completely evaporated before the fat is ignited, 

 otherwise there will be loss by spattering. In the case of salted but- 

 ter, after weighing the ash add dilute nitric acid and determine the 

 sodium chlorid by precipitation with silver nitrate. All results 

 reported in this bulletin were determined gravimetrically, with the 

 exception of alkalinities. Unless the percentage of salt is more than 

 5 it is best determined without taking an aliquot. The difference 

 between the total ash arid the sodium chlorid in the ash is the salt- 

 free ash. In duplicate determinations there may be a noticeable 

 difference in the total ash, but the percentages of salt- free ash agree 

 very closely. Examples of some of the results obtained are given 

 in Table 2. No effort was made to select especially favorable results. 



Table 2. — Agreement in percentages of salt-free asJi in dairy products. 



Sample 



Total 



Salt. 



Salt-free 



Sample 



Total 



Salt. 



Salt-free 



No. 



ash. 



ash. 



No. 



ash. 



ash. 





Per cent. 



Per cent. 



Per cent. 





Per cent. 



Per cent. 



Per cent. 



1 



2.117 



2.004 



0.113 



6 



3.430 



3.285 



0.112 





2.066 



1.956 



.110 





3.400 



3.258 



.142 



2 



3.887 - 



3.735 



.152 



7 



3.840 



3.694 



.146 





3.863 



3.718 



.145 





3.840 



3.700 



.140 



3 



4.860 



4.660 



.200 



8 



4.784 



4.654 



.130 





4.779 



4.577 



.202 





4.758 



4.629 



.129 



4 



4.768 



4.647 



.121 



9 



4.780 



4.620 



.160 





4.640 



4.518 



.122 





4.808 



4.644 



.164 



5 



4.847 



4.675 



.172 



10 



4.822 



4.721 



.101 





4.870 



4.693 



.177 





4.753 



4.655 



.098 



