252 UNSWEETENED CONDENSED MILK DEFECTS 



Causes and Prevention. All sweetened condensed milk not 

 held at a low temperature grows darker in color with age. If 

 manufactured properly and not exposed to unfavorable condi- 

 tions, this brown color appears very gradually and not until the 

 condensed milk is many months old. If exposed to high tem- 

 perature in storage or transportation, when stowed against the 

 boiler room in the hold of the steamer, or lying on the shelves 

 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 XXIII. 



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 



