Acesulfame potassium

Acesulfame potassium (ay-see-SUHL-faym) is a calorie-free artificial sweetener, also known as Acesulfame K or Ace K (K being the symbol for potassium), and marketed under the trade names Sunett and Sweet One. In the European Union, it is known under the E number (additive code) E950. It was discovered accidentally in 1967 by German chemist Karl Clauss at Hoechst AG (now Nutrinova). In chemical structure, acesulfame potassium is the potassium salt of 6-methyl-1,2,3-oxathiazine-4(3H)-one 2,2-dioxide. It is a white crystalline powder with molecular formula C4H4KNO4S and a molecular weight of 201.24 g/mol.

Properties
Acesulfame K is 200 times sweeter than sucrose (table sugar), as sweet as aspartame, about 2/3 as sweet as saccharin, and 1/3 as sweet as sucralose. Like saccharin, it has a slightly bitter aftertaste, especially at high concentrations. Kraft Foods has patented the use of sodium ferulate to mask acesulfame's aftertaste. Acesulfame K is often blended with other sweeteners (usually sucralose or aspartame). These blends are reputed to give a more sugar-like taste whereby each sweetener masks the other's aftertaste, and/or exhibits a synergistic effect by which the blend is sweeter than its components.

Unlike aspartame, acesulfame K is stable under heat, even under moderately acidic or basic conditions, allowing it to be used in baking, or in products that require a long shelf life. In carbonated drinks, it is almost always used in conjunction with another sweetener, such as aspartame or sucralose. It is also used as a sweetener in protein shakes and pharmaceutical products, especially chewable and liquid medications, where it can make the active ingredients more palatable.

Discovery
Acesulfame Potassium was developed after the accidental discovery of a similar compound (5,6-dimethyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide) in 1967 by Karl Clauss and Harald Jensen at Hoechst AG. After accidentally dipping his fingers into the chemicals that he was working with, Clauss licked them to pick up a piece of paper. Subsequent research showed that a number of compounds with the same basic ring structure had varying levels of sweetness. 6-methyl-1,2,3-oxathiazine-4(3H)-one 2,2-dioxide had particularly favourable taste characteristics and was relatively easy to synthesize, so it was singled out for further research, and received its generic name (Acesulfame-K) from the World Health Organization in 1978.

Safety
As with other artificial sweeteners, there is concern over the safety of acesulfame potassium. Although studies of these sweeteners show varying and controversial degrees of dietary safety, the United States Food and Drug Administration (US FDA) has approved their general use. Critics say acesulfame potassium has not been studied adequately and may be carcinogenic, although these claims have been dismissed by the US FDA and by equivalent authorities in the European Union.

Some potential effects associated with Acesulfame K have appeared in animal studies. Acesulfame K has been shown to stimulate dose-dependent insulin secretion in rats, though no hypoglycemia was observed.

One rodent study showed no increased incidence of tumors in response to administration of acesulfame K. In this study, conducted by the National Toxicology Program, 60 rats were given acesulfame K for 40 weeks, making up as much as 3% of their total diet (which would be equivalent to a human consuming 1,343 12-oz cans of artificially sweetened soda every day). There was no sign that these (or lower) levels of acesulfame K increased the rats' risk of cancer or other neoplasms. However, a similar study conducted with p53 haploinsufficient mice showed signs of carcinogenicity in males but not females. Further research in terms of food safety has been recommended.

Research suggests that acesulfame K may affect prenatal development. One study appeared to show that acesulfame K is ingested by mice through their mother's amniotic fluid or breast milk, and that this influences the adult mouse's sweet preference.

Compendial status

 * British Pharmacopoeia