270 UNSWEETENED CoNDENSED Mik DEFECTS 
Gritty Plain Condensed Bulk Milk. 
General Description.—Grittiness in the unsweetened goods 
appears usually only in the plain condensed bulk milk. It is a 
defect which renders the product undesirable for ice cream 
making. 
Causes and Prevention.—The chief cause of this defect is 
too great concentration. Plain condensed bulk milk which is not 
condensed over 3.5 parts of fresh milk to 1 part of condensed milk 
does not become gritty. When the concentration exceeds 4:1, 
the milk sugar begins to-crystallize out, making the product 
gritty. Milk sugar requires about six times its weight of water 
for complete solution in cold water. \WWhen condensed at the 
ratio of 4:1 or over, the plain condensed bulk milk contains con- 
siderably less than five parts, by weight, of water to one part 
of milk sugar. ‘This high concentration, together with the prac- 
tice of storing this product at refrigerating temperatures in order 
to preserve it, is responsible for the grittiness. This trouble can, 
therefore, easily be prevented by not condensing to quite as high 
a degree of concentration. 
Metallic Evaporated Milk and Plain Condensed Bulk Milk. 
General Description.—Both, evaporated and plain condensed 
bulk milk may show a metallic and puckery flavor, though this 
defect is rather rare. 
Causes and Prevention.—The metallic flavor may be due 
to the same cause as metallic sweetened condensed milk, 1. e., an 
unsanitary condition of the vacuum pan, in which case its recur- 
rence can be readily avoided by thoroughly cleaning all parts of 
the pan including the dome and the goose neck, and rinsing down 
the whole pan thoroughly with clean water each morning before 
operations begin. 
Unsweetened condensed milk made by the use of the “‘Con- 
tinuous Concentrator’ may have a metallic flavor when the 
scrapers in this machine are improperly adjusted, causing them 
to cut into the copper walls and thereby incorporating metallic 
copper in the product. his source of metallic flavor can be 
removed by proper adjustment of the revolving spider and its 
essential parts. 
