Bone Char

Bone char is a black, granular, porous material produced by charring animal bones at high temperatures in an oxygen-limited environment. It is primarily used in the sugar refining industry as a decolorizing filter to remove impurities and color from raw cane sugar, producing the bright white appearance consumers expect in refined white sugar. Shoppers encounter bone char indirectly whenever they purchase white sugar, powdered sugar, or brown sugar made from refined white sugar.

The production process involves heating crushed cattle bones—typically sourced from slaughterhouse waste—to around 700-900°C in a retort, which carbonizes the organic components and leaves a porous carbon structure rich in calcium phosphate. This material is packed into tall columns, and raw sugar syrup is passed through it; the bone char adsorbs color bodies, ash, and other impurities through physical and chemical interactions. After saturation, the char is cleaned, reactivated by reheating, and reused multiple times before being discarded.

For consumers, bone char matters because it introduces an animal-derived processing aid into a product that appears plant-based, which can conflict with vegan, vegetarian, or religious dietary practices. However, bone char is not listed as an ingredient on labels because it is a processing aid that does not remain in the final product. This means shoppers must rely on brand-specific information or choose alternatives like beet sugar, organic cane sugar, or unrefined sugars to avoid it entirely.