How Long Does Brown Sugar (Packed) Last?

Brown sugar rarely spoils in a food-safety sense, since its molasses content and low overall moisture still don't offer bacteria much to work with, but it does have a real practical shelf-life issue that plain sugar doesn't: hardening into a solid, unusable block as its moisture slowly evaporates into the surrounding air through a loosely sealed bag.

A rock-hard block isn't spoiled and doesn't need to be thrown out — a few minutes in the microwave with a damp paper towel draped over it, or an overnight stay in a sealed container with a slice of bread or a piece of moist terra cotta, restores most brown sugar back to a scoopable texture. Genuine spoilage (mold, an off smell distinct from its normal molasses aroma) is rare enough for a dry sugar like this that hardening, not decay, is almost always the actual issue behind a bag that seems to have 'gone bad.' A bag stored in a particularly humid kitchen, or one that's been opened and left loosely folded shut rather than resealed tightly, hardens noticeably faster than one kept in a genuinely airtight container from the start. Dark brown sugar, with its higher molasses content, tends to dry out and harden a bit faster than light brown sugar once opened, simply because it's carrying more of that moisture-rich molasses to begin with.

See Brown Sugar (Packed)'s full storage & shelf-life guide (with spoilage signs) →