The best chocolate chip cookie recipes call for softened butter. The mellow taste and soft texture of the room-warmed butter folds easily into the flour and sugar,  making a perfectly smooth dough. The taste is well-worth the time you spend waiting (im)patiently for the normally-refrigerated butter to lose its rock-like consistency. But how long SHOULD you wait? Is it okay to leave the butter out on the counter for an hour, a day, a week? If not, does processing that deliciously smooth spread into your cookie mix put you at risk for foodborne illnesses or poisoning? At Bluegrass Dairy and Food, we firmly believe that an afternoon spent baking cookies should be relaxing, not worrisome! Here, we separate the dairy facts from fiction to give you the lowdown on food safety.


Some concern over butter safety is warranted. The US Food and Drug Administration classifies the whole dairy group (butter, yogurt, milk, cheese, etc.) as Time/Temperature Control for Safety (TCS) foods. Foods under this label pose some risk to human health if eaten after being left out for extended periods of time. The FDA recommends that dairy products be kept at a consistent 41 degrees Fahrenheit or lower at all times to prevent contamination or bacterial growth. As a general rule of thumb, you should try to return all dairy products to the refrigerator within two hours of use – or within one, if it’s a particularly warm summer day.


That said, all dairy products don’t turn rancid equally. Milk should never remain out for longer than an hour or two, but butter can sit out for hours without issue. There is some debate over how long you can or should leave butter to sit at room temperature; however, most food safety professionals agree that leaving a stick out on the counter for a day or two won’t cause any lasting harm. This is partially due to a difference in structure. Unlike milk, butter primarily consists of fat and water molecules. Bacteria needs water to grow; in milk, that water is ready and available. During the churning process for butter, however, the water disperses and settles into small, protected pockets within the fat. This dispersal within the fat makes it difficult for bacteria to access the water pockets, let alone grow. Salted butter is even safer, given the added barrier the salt adds to bacterial growth.


In short: if you want to leave your butter out to soften overnight, you can! That said, you should always try to refrigerate it on hot days or if you don’t need it to be soft. Remember, the butter you leave out is still at risk of being contaminated by airborne dust particles, stray perishable foods, or pests. The best cookies are made with softened butter – but try to return the stick to the fridge once you finish making your dough!