252 UNSWEETENED CoNDENSED Mik Drrrcrs 
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 condt- 
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. 
‘Ihe 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 
