Vitamin C in an opened orange juice deteriorates rapidly. If it is fresh, drink it up immediately. If it is processed, drink it within a few days.

Orange juice contains a high percentage of Vitamin C, which helps in boosting your immune system. According to a recent study at Arizona State University, the levels of vitamin C in an opened orange juice deteriorates rapidly even when it is refrigerated. If a fresh orange juice has to be stored, do so in the refrigerator, but within 24 hours the taste of the juice changes.