An artificial sweetener that's 180-200 times sweeter than sugar. It's synthesized from two amino acids (aspartic acid and phenylalanine), the building blocks of protein, and contains about 4 calories per gram. Regular aspartame breaks down and loses its sweetness when heated but is excellent for sweetening cold dishes. A new encapsulated (and therefore heat-stable) form of this sweetener has been developed especially for baking. At this writing, however, it's not available to consumers. See also acesulfame-K; alitame; saccharin; sucralose.