My daughter left a crockpot of food in the refrigerator for over a month. Mold was crazy bad in the crockpot. 3 packages of unopened butter were in the refrigerator also. Should they be thrown out?
Butter is mainly fat - no nitrogen. (It is about 0.8% protein by weight.) So it is not a very nutritive environment. But its principle protection is that it is “dry”. Although it is about 16% water, that water is emulsified and therefore protected from contamination. The original wax paper wrapping, and the surrounding container, as well as the temperature of the fridge, would make it very difficult for microbial contamination or growth to occur.
Mold spores are in the air around us. Having a high concentration of mold nearby in a crockpot could increase the concentration in the fridge but there are other factors that influence whether the butter has spoiled and the butter may be unaffected. If anything concerns you and your health is at risk, when in doubt, throw it out. Here are some factors to consider
- Has the manufacturer's suggested sell-by date passed?
- Are there discolorations or mold on the surface if the butter?
- Has the butter become soft, or hard and difficult to spread?
- Does the butter smell stale, cheesy or decomposed?
- Is the butter unsalted (salt acts as a preservative)?
If several of these apply in your situation, you may want to throw the butter out as it doesn’t make much sense to risk food-born illnesses.