While canned pineapple juice can be kept for up to three years unopened, once opened you only have a week to consume it or toss it out. The juice should be poured into a glass or plastic container before storing, and kept in the fridge at or below 40 degrees Fahrenheit.
Prevent Food Poisoning
Canned pineapple juice is pasteurized to kill bacteria that could cause foodborne illness. Once the juice is exposed to air, the potential for bacterial contamination increases. To limit exposure, always cover the pineapple juice tightly when storing it. Temperatures above 41 F will cause the bacterial microorganisms to multiply faster, so never leave the juice sitting out for more than two hours. Symptoms of foodborne illnesses include vomiting, diarrhea, abdominal pain, fever or head or body aches. These can occur as soon as 20 minutes after consuming contaminated juice, or as many as six weeks later.