You probably already assumed that light brown and dark brown sugar are more closely related to each other than either variety is to white sugar. So what sets them apart, besides hue?
Brown Sugar vs. White Sugar
Before we get to that, let’s talk about the relationship between white and brown sugar. White sugar is, to simplify a very complex process, crystals extracted from sugar beets or sugar cane. That refinement involves stripping them of moisture, which leaves behind a dark, thick syrup we know as molasses. To make brown sugar, as HowStuffWorks explains, some molasses is either left in the sugar crystals—or it’s re-added after the fact.
Light Brown Sugar vs. Dark Brown Sugar
The difference between light and dark brown sugar boils down to one simple factor: the amount of molasses. Light brown, unsurprisingly, has less—typically around 3.5 percent. Dark brown boasts nearly twice that: 6.5 percent (though the exact percentage varies by brand and product). Because of its higher molasses content, dark brown sugar is slightly more moist and acidic. According to Imperial Sugar, dark brown sugar also has “a stronger flavor with more pronounced caramel undertones.”
Can You Substitute Dark Brown Sugar for Light Brown Sugar?
In short, you don’t have to run to the store because your recipe calls for dark brown sugar and you only have light. Nor do you need to reach for your car keys if your brown sugar—light or dark—is hard as a rock. Here’s how to soften it.
[h/t Bon Appétit]