How do I create an experiment from the following scenario:
"When opening a container of cranberry juice you notice the label 'refrigerate after opening.' you also noticed this label on a variety of other food containers such as mayonaise bottles and tuna cans. why does the food have to be refrigerated once they can or bottle is open but not before? what would happen if the food were not refrigerated after opening? what is refrigeration do?
Since your question has already been answered by june, I will say that since moist foods are sealed off to kill off and prevent any bacteria, mold, and further growth, when they are opened, it is immediately exposed to the atmospheric oxygen and the bacteria probably carried by floating dust particles. By refrigerating the can, it should slow the growth of bacteria that can cause food poisoning. This has nothing to do with the question, but I am bored :).
To create an experiment from foods that need to be refrigerated after they are opened, one needs to document the changes in the foods after they are unsealed.
A simple visual test would be to have three identical containers of a chosen food. It would be easiest to do a visual test with food that is in a clear container, such as mayonnaise or juice.
Keep one sample untouched. Open the second sample, and do not refrigerate it. Open the third sample, and refrigerate it.
After a set passage of time (eg. 5 days), visually compare the three samples. Repeat this process every 5 days, and record your observations.
With the introduction of bacteria, due to the unsealing of the container, there should be a noticeable difference.
Should you want to introduce a more intense differentiation, you could use a simple litmus test.