A. Fruit may float because pack is too loose or sirup too heavy; or because some air remains in tissues of the fruit after heating and processing.
Q. Is it safe to can foods without salt?
A. Yes. Salt is used for flavor only and is not necessary for safe processing.
Q. What makes canned foods change color?
A. Darkening of foods at the tops of jars may be caused by oxidation due to air in the jars or by too little heating or processing to destroy enzymes. 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.
Iron and copper from cooking utensils or from water in some localities may cause brown, black, and gray colors in some foods.
When canned corn turns brown, the discoloring may be due to the variety of corn, to stage of ripeness, to overprocessing, or to copper or iron pans.
Packing liquid may cause fading of highly colored foods. The use of plain tin cans will cause some foods to lose color ([p. 4]).
Q. Is it safe to eat discolored canned foods?