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What causes cloudy liquid in canned fruits and vegetables? 
oudy liquid may be a sign of spoilage. Or it may be caused by the 
inerals in hard water, or by starch from overripe vegetables. 
Q. How can you tell whether food with cloudy liquid is spoiled? 
A. Boil the food and note the odor. Do not taste or use any food having 
an off odor (p. 21). 
- Q. Why does canned fruit sometimes float in jars? 
__ A. Fruit may float because the pack is too loose or the sirup too heavy. 
Or perhaps air in the tissues of the fruit has not all been forced out 
during heating and processing. 
Q. What makes canned foods change color? 
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A. Darkening of foods at the tops of jars may be caused by oxidation due 
fo air in the jars or by too little heating or processing to destroy en- 
zymes. Overprocessing may cause discoloration of foods throughout 
*the containers. 
Pink and blue colors sometimes seen in canned pears, apples, and 
peaches are caused by chemical changes in the coloring matter of 
the fruit. 
_-lron and copper from utensils used in preparing foods, or from the 
_ water in some localities, may. cause brown, black, and gray colors in 
CANNING??? 
‘that has an unusual color should be examined carefully before use 
(p. 21). 
.[s it true that ascorbic acid helps keep fruits and vegetables from 
darkening? 
. The addition of 250 milligrams of ascorbic acid (vitamin C) to a quart 
of fruit or vegetable before it is processed retards oxidation, which is 
one cause of darkening of canned foods. 
. Is it all right to use preservatives in home canning? 
. Do not use canning powders or other chemical preservatives—some 
of them may be harmful. Sterilization by heat is safer and more certain. 
. Why does the under side of metal lids sometimes discolor? 
. Natural compounds in some foods corrode the metal and make a brown 
or black deposit on the under side of the lid. This deposit is harmless 
and doesn't mean that the food in the jar is unsafe to eat. 
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. When canned or frozen fruits are bought in large containers, is it Pos: 
sible to can them in smaller containers? 
. Any canned or frozen fruit may be heated through, packed, and proc- 
essed the same length of time as recommended for freshly prepared 
food. This canned food may be of lower quality than if it had been 
canned when fresh. 
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. Is it safe to leave food in tin cans after opening? 
. Yes, but like fresh-cooked food, food in tin cans needs to be covered 
“and kept in a refrigerator or other cold place. 
. Why have processing times for mixtures of food like mixed vegetables, 
soups, and stews not been included in this pamphlet? And why are 
only pint and quart glass jars and No. 2 and 21/2 tin cans recommended? 
. Processing times have been given for only those low-acid vegetables 
and sizes of containers on which research has been completed by this 
_ Bureau. Processing times for some mixtures are now being studied. 
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