Butter’s main enemies are heat and light. Stored sealed in a cool, stable place, butter lasts longer than many expect, but it will eventually go rancid. Unsalted butter keeps about 1–3 months in the fridge; salted butter up to 5 months (salt inhibits microbes). At room temperature, use within ~2 weeks. Signs to discard include sour, metallic, or bitter tastes; rancid or unpleasant oily smells; visible black spots, mold, or overly dry surface—if any of these appear, throw the whole block away. Keep butter in the coldest part of the fridge (not the door) to avoid temperature swings. For bulk purchases, freeze butter in individual sticks inside sealed bags—this can preserve quality up to a year; thaw slowly in the fridge overnight for best results. Even butter past its printed date may be usable if it looks and smells fine, but if packaging was damaged or it was exposed to heat or light, it’s safer to discard.
