Molasses is a byproduct of sugar production. As the juice — from sugar cane or sugar beets — cooks, it forms crystals of sugar and molasses. The manufacturer uses a machine to spin out the liquid, leaving the sugar crystals. The juice goes through three boiling processes, producing three grades of molasses.
The liquid remaining after the first boil is light molasses. It is lightest in color and contains the most sugar. Light molasses is less viscous than other molasses products. The second boil produces dark molasses, which contains less sugar and is more viscous. The third boil produces blackstrap molasses, the darkest product with the most intense flavor.
The process of refining sugar from cane or beets leaves a product high in nutrients, particularly iron. Blackstrap molasses, with the lowest sugar content, has the highest nutritional content. Molasses provides other minerals, including calcium, potassium and magnesium. Because manufacturers vary their production methods, the nutritional content of molasses differs among brands, so the nutritional label of the product is the best way to determine its exact nutritional content.
When manufacturers use young sugar cane to produce molasses, they sometimes use sulfur dioxide as a preservative to treat the product. Unsulfured molasses is generally lighter and cleaner in flavor than the sulfured product.