Free-flowing granulated white sugar is a trouble-free ingredient in most climates, but the same can’t be said for brown sugar. The molasses that gives brown sugar its fragrance and color can eventually dry out and harden, turning your sugar into a solid and unusable lump. It’s relatively quick and easy to restore your brown sugar to its normal soft and fluffy consistency, either immediately by heating it or overnight by adding moisture.
Things You'll Need
Softening as Needed
Separate approximately as much lumpy, hardened sugar from the package as you’ll need for your recipe, and place it in a heatproof bowl.
Moisten two or three thicknesses of paper towel under the tap; then squeeze out any excess water. The towel should be damp, but not dripping. Place it inside the bowl with your sugar; then cover the bowl with a plate or a sheet of plastic film wrap and put it in the microwave. Alternatively, instead of paper towels, pour boiling water into a second bowl and place it in your microwave alongside the first. If you use this method, don’t cover the sugar.
Microwave the sugar on High for 1 minute; then break it up with a wooden spoon. If it hasn’t completely softened, return it to the microwave and continue to heat it in 30-second increments.
Remove the softened sugar from your microwave, and stir it thoroughly with your wooden spoon to ensure that no lumps remain. Let the sugar cool to room temperature before you use it, so it doesn’t alter the results of your recipe. If necessary, you can break up or remove any remaining lumps with your fingers before use.
Softening In the Pantry
Transfer your hardened brown sugar to a sealable, airtight container or glass sealer jar. If necessary, first place it inside a heavy plastic bag and rap it sharply a few times with a rolling pin to break it into manageable pieces.
Soak a terra-cotta sugar softener, available at most department stores or kitchen retailers, in hot water for 15 minutes. Remove it from the water, and blot it dry with clean paper towels.
Nestle the sugar-softener into your container of sugar, and seal it tightly. After 24 hours, shake the container vigorously to assess whether it has softened completely. If it hasn’t, use the handle of a wooden spoon or other suitable implement to break up large lumps and then re-seal the container. By the second day, your sugar should be usable once more.
Leave the terra-cotta softener in the container with your sugar permanently, to prevent the problem recurring. Remove it, re-soak it and return it to your sugar at least once every six months, for the best results.
References and ResourcesU.S. Sugar Company: Soften Hard Brown Sugar
The Kitchn: Best Product -- Brown Sugar Saver