Leaving goat milk unrefrigerated for more than two hours is not recommended. Even pasteurized milk is susceptible to the growth of harmful bacteria and food-borne pathogens, all of which thrive on milk's many nutrients and natural sugar. When serving goat milk with breakfast or during any occasion at the table, it is best to use it promptly and return it to your refrigerator at once.
Unrefrigerated Shelf Life
Goat milk contains several macro- and micronutrients essential for human health, including calcium, protein and fat. Like cow's milk, goat milk also provides sugar in the form of lactose. This nutrient-dense environment allows bacteria and pathogens to flourish rapidly, especially if the milk's temperature rises beyond the ideal temperature for storing, which is usually as cold as your refrigerator. This is why milk tends to spoil quickly, almost as soon as it approaches room temperature.
Best Storage Temperature and Conditions
The optimal temperature window at which goat milk remains freshest up to and for some time after its best-by date is 35 F to 40 F. For every 5 F rise in temperature over 39 F, its shelf life is shortened by 50 percent. The lower end of 35 F is recommended for food-service providers. This lower temperature allows some leeway in case the milk must sit out and away from any source of cold for a time before service, such as in a cafeteria or during buffet-style catering.
Buying and Keeping Goat Milk Fresh
When purchasing goat milk, opt for products sold in enclosed cabinets. If your supermarket's dairy section features open shelves, select cartons closest to the back of the shelf. These cartons have been maintained at cooler temperatures more consistently and have not been exposed to as much light, another form of heat. Transport any goat milk-based products immediately and refrigerate them as soon as possible. Milk picks up other smells easily, so store your goat milk away from foods with strong odors. Because home refrigerators are typically set at 40 F, keep your milk in the main compartment and not in the door to protect it from temperature fluctuations.
Good Versus Bad Bacteria
It is particularly important to store raw, unpasteurized goat milk at 35 to 40 F or as close to this temperature as possible. Raw, unpasteurized goat milk retains all of its strains of good bacteria like Lactobacillus acidophilus, but the belief that these bacteria are capable of fighting off bad bacteria and protecting the freshness of any unrefrigerated dairy is unsubstantiated by science. Raw, unpasteurized goat milk is more likely to also contain harmful bacteria, such as salmonella and Escherichia coli, and these are quite capable of multiplying to critical masses sufficient to cause illness when their host environment is allowed to warm.