What Is Thaumatin? The Zero-Calorie Protein Explained is a natural sweetener and flavor enhancer extracted from the West African katemfe fruit (Thaumatococcus daniellii). Unlike artificial sweeteners, thaumatin is a protein, not a carbohydrate, which means it delivers intense sweetness without calories. This unique characteristic makes it a favorite among health-conscious consumers and food manufacturers seeking natural alternatives to sugar and chemical-based sweeteners.