Dairy farmers, processors, and store personnel follow strict practices to protect milk. It should keep for at least 10 days after processing when properly handled. You should purchase milk at least weekly, and preferably twice each week. Pasteurization of milk extends shelf life and assures you of safety without any significant loss of nutrients that are important to our health. Vitamin C is destroyed, but milk contains very little anyway, while small amounts of a B vitamin are lost.
Light is harmful to milk.
It causes tallowy, cardboard-like flavor and destroys some nutrients. Fifteen to 20 minutes of direct sunlight in the back of your car or 1 hour of daylight on your breakfast table are too much. When you purchase milk, go directly to your car and go home as soon possible. Cover milk in your car to prevent light exposure. Use a blanket, a metal or plastic picnic chest, or a cardboard box.