Aspartame is an artificial sweetener. It is 200 times sweeter than sugar in typical concentrations , without the high energy value of sugar . [ citation needed ] While aspartame, like other peptides , has a caloric value of 4 kilocalories (17 kilojoules) per gram , the quantity of aspartame needed to produce a sweet taste is so small that its caloric contribution is negligible, which makes it a popular sweetener for those trying to avoid calories from sugar. The taste of aspartame is not identical to that of sugar: the sweetness of aspartame has a slower onset and longer duration than that of sugar. Blends of aspartame with acesulfame potassium a usually listed in ingredients as acesulfame k aare alleged [ who? ] to taste more like sugar, and to be sweeter than either substitute used alone.
Like many other peptides , aspartame may hydrolyze (break down) into its constituent amino acids under conditions of elevated temperature or high pH . This makes aspartame undesirable as a baking sweetener, and prone to degradation in products hosting a high-pH, as required for a long shelf life. The stability of aspartame under heating can be improved to some extent by encasing it in fats or in maltodextrin . The stability when dissolved in water depends markedly on pH . At room temperature, it is most stable at pH 4.3, where its half-life is nearly 300 days. At pH 7, however, its half-life is only a few days. Most soft-drinks have a pH between 3 and 5, where aspartame is reasonably stable. In products that may require a longer shelf life, such as syrups for fountain beverages , aspartame is sometimes blended with a more stable sweetener, such as saccharin . [10]
In products such as powdered beverages, the amine in aspartame can undergo a Maillard reaction with the aldehyde groups present in certain aroma compounds . The ensuing loss of both flavor and sweetness can be prevented by protecting the aldehyde as an acetal .
Some claim that aspartame leaves an odd after-taste, while others describe it as a non-flavor or watery after-taste