Brown sugar is white sugar combined with molasses. That’s the short answer, and it applies to virtually all commercial brown sugar sold in grocery stores. The longer answer involves how much molasses, what kind, and why it matters for cooking.
Two Ingredients, One Sugar
Commercial brown sugar is refined white sugar (sucrose) with cane molasses mixed back in. It contains at least 85% sucrose, with the remainder being molasses and a small amount of moisture. The sucrose itself is a molecule made of two simpler sugars, glucose and fructose, bonded together.
This might seem like a roundabout process: manufacturers refine raw cane sugar into pure white crystals, stripping away the molasses in the process, then add molasses back. But this method gives producers precise control over color, flavor, and moisture content. The result is a consistent product every time.
Light Brown vs. Dark Brown
The only difference between light and dark brown sugar is how much molasses gets added. Light brown sugar contains about 3.5% molasses by weight. Dark brown sugar contains about 6.5%. That small gap creates a noticeable difference in flavor and color. Dark brown sugar tastes more deeply caramel-like with a slight bitterness, while light brown sugar is milder and more versatile.
In most recipes that simply call for “brown sugar” without specifying, light brown is the default. Dark brown sugar works best when you want a stronger molasses presence, like in gingerbread, baked beans, or barbecue sauces.
Why Molasses Matters
Molasses is what gives brown sugar its color, flavor, moisture, and slight acidity. It contains organic acids like acetic and succinic acid that add tangy, complex notes and balance the sweetness. It also contains trace minerals. Brown sugar has about 83 milligrams of calcium per 100 grams, compared to just 1 milligram in white sugar. Iron levels are slightly higher too. These amounts are too small to make brown sugar a meaningful source of any mineral, but they do contribute to flavor chemistry.
The molasses also makes brown sugar slightly acidic, which matters in baking. That acidity reacts with baking soda (a base) to produce carbon dioxide, helping doughs and batters rise. Recipes designed for brown sugar account for this reaction, which is one reason you can’t always swap white sugar in without adjusting the leavening.
The Molasses Source: Cane, Not Beet
Brown sugar molasses always comes from sugarcane, even when the white sugar base comes from sugar beets. Beet molasses has an off-putting flavor that doesn’t work well in food, so brown sugar made from beet sugar still uses cane molasses for coloring and flavor.
Some bakers and pastry chefs insist that brown sugar made entirely from sugarcane performs better than beet-based versions, even when both use cane molasses. The sugar industry maintains the products are identical, but the difference likely comes down to moisture. Cane and beet sugars can hold water differently, and in delicate baked goods, that small variation can affect texture.
“Raw” Brown Sugars Are Different
Not all brown sugar is made by adding molasses back to refined white sugar. Some varieties keep their molasses from the start, never fully refining it away. These are sometimes called “raw” or “natural” brown sugars, though most are still partially refined.
Turbinado sugar comes from the first pressing of sugar cane and retains some of its original molasses. It has large, crunchy crystals with a light golden color. Demerara is similar, with coarse crystals and a mild caramel flavor. Both work well as finishing sugars sprinkled on top of baked goods or stirred into coffee.
Muscovado sugar retains more molasses than turbinado or demerara, giving it a darker color, stickier texture, and more intense flavor. Sucanat goes even further: it’s crystallized pure cane sugar that keeps the highest proportion of its natural molasses. These less-refined options have a more complex, sometimes earthy taste compared to commercial brown sugar’s cleaner sweetness.
Why Brown Sugar Hardens (and How to Fix It)
Brown sugar’s extra moisture, courtesy of molasses, is both its best feature and its biggest storage problem. Sugar is hygroscopic, meaning it absorbs moisture from its surroundings. When brown sugar sits in an open container or a loosely sealed bag, its moisture evaporates. The small amount of water left behind acts like glue, binding the sugar crystals into a solid, rock-hard lump.
The fix is keeping air out. Store brown sugar in an airtight container or a tightly sealed plastic bag. If it has already hardened, place a damp paper towel in the container for a few hours, or microwave the sugar with a small cup of water for 15 to 20 seconds. The goal is to reintroduce moisture so the crystals loosen.
Making Your Own
Since commercial brown sugar is just white sugar plus molasses, you can make it at home in under five minutes. For light brown sugar, mix one tablespoon of molasses into one cup of white granulated sugar. For dark brown sugar, use two tablespoons. Stir or mix until the molasses is evenly distributed and every crystal is coated. The result is functionally identical to store-bought brown sugar and works in any recipe that calls for it.