Butter may seem like one of those foods that never really expires and can just quietly stay in the fridge until you decide to use it. A lot of us were brought up with the idea that butter is a durable product that hardly ever goes bad. However, the fact is that butter has a limited shelf life, and when it happens, it usually emits very faint odors and flavors. Breathing those aromas can not only ruin the taste of the food that you are preparing but can also cause you stomach problems. Having knowledge about things that can signify that your butter is not good can save you from an unwanted surprise in your food. Here are some very real and easy-to-notice signs that your butter has gone bad.
A sour or sharp smell

Fresh butter is soothing with a pleasant, creamy smell. When it suddenly smells sour or sharp or simply out of place, that is the first indicator. Butter must not have an offensive smell.
Brown or dark yellow discoloration

New butter is yellow, of an even and pale hue. Oxidation is probably established when portions of it become darker or brown in color. This transformation usually has an influence on taste and quality.
Too much softness at cold temperatures

Butter usually hardens in the refrigerator. When it remains unusual even when cold, then something has been wrong. This tends to indicate structural failure as a result of rottenness.
A soapy or chemical-like smell

When the butter smells like soap or cleaning products, then it has oxidized. This occurs when fats decompose with time. Even when it appears all right, it must be thrown away.
A chalky or crumbly feel

Butter that is spoiled may become hard and dry or chalky. This transformation renders its distribution difficult and unacceptable to use. Flavor loss is normally followed by texture changes.
Butter rapidly absorbs strong odors

Butter picks up smells readily. Whether it smells of onions or spices or some other pungent food, its quality has already been affected. It may not be dangerous, but it is better not to use it.
Strange smell left on your fingers

When you touch butter, and your hands are stinky, then that is not normal. Fresh butter does not leave much or any smell. The presence of lingering smells implies that the fats have decomposed.
Foams or a strange reaction on heating

Butter generally melts easily as it is heated. When it foams too much or produces an unpleasant smell immediately, it can be spoiled. Bad butter will not be corrected through cooking.