SWEETENED CONDENSED MIUC DEFECTS 203 



which, in the spring of the year, forms a gelatinous coating on 

 the jacket and coils and that part which remains normal. The 

 figures do not show as great a difference, as the physical com- 

 parison of the two products would suggest. Possibly the most 

 significant point these analyses show is that, while the proteids 

 in the coating are higher, the ash is lower than in the normal 

 condensed milk. 



A large portion of the ash of milk is present in chemical 

 combination with the casein, which does not curdle by heat, 

 while the albumin, which is coagulated by heat, contains only 

 a very small amount of ash. Therefore, the fact that an increase 

 in the proteids of this gelatinous coating is accompanied by a 

 decrease in the ash content, would suggest that the proteids of 

 the coating of the jacket and coils consist of more albumin and 

 less casein than the proteids of the normal condensed milk of 

 the same batch. Since this coating of the jacket and coils occurs 

 only in the spring of the year, when most of the cows freshen, 

 it is reasonable to assume that this coating is the result of the 

 acceptance at the factory of milk too soon after calving and 

 which contains excessive quantities of proteids and other sub- 

 stances which are highly sensitive to heat, such as albumin, 

 colostrum, etc. 



Excess of Acid in Condensed Milk and Acid Flux in Tin 

 Cans. The presence in the condensed milk of organic and 

 mineral acids, in excess of the amount which normal fresh milk 

 contains, is conducive of the formation of lumps. 



Excessive amounts of acid in condensed milk may be the 

 result of fermentations, usually due to a poor quality of sugar, 

 or of the use of acid flux in the making and sealing of the tin 

 cans. Condensed milk that shows acid or gaseous fermentation 

 usually contains lumps. The acid which it develops as the result 

 of the fermentation, curdles the casein with which it comes in 

 contact. 



One of the most common channels through which condensed 

 milk may become contaminated with acid mechanically, is the 

 use of cans, in the manufacture and sealing of which acid flux was 

 used. The acid flux generally used contains zinc chloride. The flux 

 precedes the solder and some of it is bound to sweat through the 



