UNSWEETENED CONDENSED MILK DEFECTS 215 



of the warm grocery store or drug store, etc., it turns brown 

 rapidly. Condensed milk in cold storage retains its natural color 

 indefinitely. Where milk is recondensed (the condensed milk 

 is redissolved either in water or in fresh milk and condensed a 

 second time), the product is always darker in color. This brown 

 color is due to the oxidizing action of heat on both, the lactose 

 and the sucrose, a portion of the sugar caramelizing. Experience 

 has shown that the sugar is more sensitive to the oxidizing 

 action of the heat of recondensing, than when condensed the 

 first time. 



CHAPTER XXIV. 



DEFECTIVE EVAPORATED MILK AND PLAIN 

 CONDENSED BULK MILK 



The following are the chief defects of unsweetened condensed 

 milk : curdy, grainy, separated and churned, blown or fermented, 

 brown, gritty, metallic. 



Curdy, Plain Condensed Milk and Evaporated Milk 



General Description. Curdy, unsweetened condensed milk 

 is a term used for milk in which a part of the casein is precip- 

 itated in the form of lumps of various sizes. The appearance 

 of lumps of curd in this product is a defect that may render the 

 goods unsalable. 



Causes and Prevention. Lumps are usually due to a poor 

 quality of fresh milk, the use of excessive heat in the sterilizing 

 process and too high a degree of concentration. 



Lumps in Plain Condensed Bulk Milk. Lumps are prone to 

 appear in plain condensed bulk milk, as this class of goods is 

 usually made from fresh milk that may be slightly sour, as is the 

 case in creameries and in milk plants where the surplus and the 

 returned milk is often manufactured into plain condensed bulk 

 milk. This defect can be avoided by neutralizing the milk before 

 heating, with an alkali (sodium bicarbonate or. lime water), heat- 

 ing less intensely, by not carrying the condensing process quite 

 so far. If the plain condensed bulk milk comes from the pan in 

 lumpy condition, it can usually be reduced to a smooth body by 

 passing it through an ice cream freezer at ordinary temperatures. 



