Why You Should Think Twice Before Storing Unsalted Butter At Room Temperature
Softened butter isn't something you can get your hands on in a pinch. If you need butter for baking or simply prefer it for buttering your grilled cheese, you need to wait hours for it to reach that perfectly soft texture. Sure, you can microwave it, but it always results in one part being far more softened (sometimes even melted) compared to the other. If you use the boiling water method to soften butter, it means extra pots you don't always want to deal with.
With that said, it's not uncommon to leave butter out on the kitchen counter so that it maintains that perfectly soft texture and is ready whenever you need it. Although butter is a dairy product, we've always been told it's generally safe to keep it at outside the refrigerator. However, that's not entirely true.
If you plan to keep butter on the counter, make sure it's not the unsalted kind. Keeping unsalted butter out for too long means you could be putting yourself at risk of illness.
Unsalted butter isn't preserved as well as salted butter
It's pretty easy to figure out why salted butter is the safer option when keeping any butter at room temperature. Salt is a natural preservative, and the sodium in salted butter will keep it safer for longer than its unsalted counterpart.
Salt naturally dries up foods; it's the same reason we use it to help create cured meats. And in the process of drying the food, it creates an unfavorable environment for bacteria. It can also kill microbes through something called osmotic shock. The bottom line is that salty foods fare better in higher temperatures. Food with a high salt content will generally last longer in the refrigerator, too.
This does not necessarily mean you can't leave unsalted butter out for any period of time. If it's only a few hours and you plan to cook or bake with it, you don't have much to worry about. But if you're someone who plans to leave it out for a couple of days, you might want to purchase salted butter instead.
Why is it safe to leave butter at room temperature?
We've always been told that dairy products, such as milk and cheese, should not be left at room temperature for more than two hours. What makes butter any different?
The reason butter can be left out is also the reason it tastes so good: lots of fat. Butter has a much higher fat content than other dairy products. That, combined with its lesser amount of water, means it's not as conducive to bacterial growth as milk or cheese. Plus, when you leave the salted kind out, you're only reducing the chances of harmful bacteria growth.
That said, even salted butter does have a room-temperature shelf life and should not be kept out for days on end; it's best if only kept out for no more than two days. If it won't be used within that time, store it in the refrigerator. If you're unsure if the butter has gone bad, check its color.