Soy milk, once opened, requires refrigeration and should be consumed within five days . Prior to being opened, however, soy milk actually doesn't require chilling, and has an unrefrigerated shelf life of at least one year. Then why, might you ask, is it is sold refrigerated in the milk aisle while other brands go unrefrigerated next to rice milk?
The answer might surprise you: It's primarily for marketing reasons. When it entered the market more than a fifteen years ago, the now-bestselling soy milk brand, White Wave , aimed to compete head to head with cow milk . They arranged for the product to be sold in traditional gable-top milk cartons and lobbied for grocers to place its product, Silk  soy milk, in the dairy case, to convey the image of being freshly made. In reality, there is little nutritional difference between refrigerated and unrefrigerated soy milk — both are made by mixing a dry soy mixture with water.