Refrigeration has long been used to keep microbes from making food hazardous. It slows the growth of potentially deadly pathogens. The fridge also retards deterioration of the flavor, color, and texture of many foods.
The vast majority of fruit and vegetable juices sold in the United States are pasteurized to kill potentially harmful bacteria during the manufacturing process, according to the FDA.
Juice processors who don't pasteurize their products now must take other germ-killing steps such as an ultraviolet light treatment or specially treating peels before squeezing citrus fruit for juice.
Consumers should look for the words "Keep Refrigerated" or "Refrigerate After Opening" on juice labels to know whether the product should be refrigerated.