Aspartame

Aspartame
Chemical nameIIII	N-(L-α-Aspartyl)-L-phenylalanine, 1-methyl ester
Other names	NutraSweet Canderel Equal
Chemical formula	C14H18N2O5
Molecular mass	294.301 g/mol
CAS number	[22839-47-0]
Melting point	246-247 °C
Boiling point	decomposes
SMILES	[NH3+] [C@@H](CC([O-])=O)C(N[C@@H] (CC1=CC=CC=C1)C(OC)=O)=O
NFPA 704	NFPA 704 safety square 1 1 0
Disclaimer and references

Aspartame (or APM) (IPA: /ˈæ.spɚˌteɪm/ or /əˈspɑɹˌteɪm/) is the name for an artificial, non-saccharide sweetener, aspartyl-phenylalanine-1-methyl ester; i.e., the methyl ester of the dipeptide of the amino acids aspartic acid and phenylalanine.

This sweetener is marketed under a number of trademark names, including Equal, NutraSweet, Canderel, and is an ingredient of approximately 6,000 consumer foods and beverages sold worldwide. It is commonly used in diet soft drinks, and is often provided as a table condiment. It is also used in some brands of chewable vitamin supplements and common in many sugar-free chewing gums. However, aspartame is not always suitable for baking because it often breaks down when heated and loses much of its sweetness. In the European Union, it is also known under the E number (additive code) E951. Aspartame is also one of the sugar substitutes used by diabetics.

Aspartame is a subject of a public controversy due to perceived health risks (see aspartame controversy). It has lost market share in recent years to sucralose, (Altern, which is EU permitted food additive E955.[1]) ,sold under the brand name Splenda.

Chemistry

Aspartame is the methyl ester of the dipeptide of the natural amino acids L-aspartic acid and L-phenylalanine. Under strongly acidic or alkaline conditions, aspartame first generates methanol by hydrolysis. Under more severe conditions, the peptide bonds are also hydrolyzed, resulting in the free amino acids. It is a nonpolar molecule.

Properties and use

Aspartame is an attractive sweetener because it is 180 times sweeter than sugar in typical concentrations, without the high energy value of sugar. 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, and some consumers find it unappealing. Blends of aspartame with acesulfame potassium — usually listed in ingredients as acesulfame K — are alleged 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.

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.

Discovery and approval

Aspartame was discovered in 1965 by James M. Schlatter, a chemist working for G.D. Searle & Company. Schlatter had synthesized aspartame in the course of producing an anti-ulcer drug candidate. He discovered its sweet taste serendipitously when he licked his finger, which had accidentally become contaminated with aspartame.

Following initial safety testing, there was debate as to whether these tests had indicated that aspartame may cause cancer in rats; as a result, the U.S. Food and Drug Administration (FDA) did not approve its use as a food additive in the United States for many years. In 1980, the FDA convened a Public Board of Inquiry (PBOI) consisting of independent advisors charged with examining the purported relationship between aspartame and brain cancer. The PBOI concluded that aspartame does not cause brain damage, but it recommended against approving aspartame at that time, citing unanswered questions about cancer in laboratory rats. In 1981, U.S. President Ronald Reagan appointed Arthur Hull Hayes as FDA commissioner. Citing data from a Japanese study that had not been available to the members of the PBOI, Hayes approved aspartame for use in dry goods. In 1983 FDA further approved aspartame for use in carbonated beverages, and for use in other beverages, baked goods, and confections in 1993. In 1996, the FDA removed all restrictions from aspartame allowing it to be used in all foods.

In 1985, Monsanto bought G.D. Searle — and the aspartame business became a separate Monsanto subsidiary, the NutraSweet Company. On May 25 2000 Monsanto sold it to J.W. Childs Equity Partners II L.P. The U.S. patent on aspartame expired in 1992. Since then the company has faced hot competition in market for aspartame from other manufacturers, including Ajinomoto, Merisant and the Holland Sweetener Company, which stopped making the chemical in late 2006 because "global aspartame markets are facing structural oversupply, which has caused worldwide strong price erosion over the last 5 years" making the business "persistently unprofitable”.

Metabolism

Upon ingestion, aspartame breaks down into several residual chemicals, including aspartic acid, phenylalanine, methanol, and further breakdown products including formaldehyde and formic acid. There is some controversy surrounding the rate of breakdown into these various products and the effects that they have on those that consume aspartame-sweetened foods. (See Aspartame controversy)

The naturally-occurring essential amino acid phenylalanine is a health hazard to those born with phenylketonuria (PKU), a rare inherited disease that prevents phenylalanine from being properly metabolized. Since individuals with PKU must consider aspartame as an additional source of phenylalanine, aspartame-containing foods sold in the United States must state "Phenylketonurics: Contains Phenylalanine" on their product labels.

Aspartame controversy

Main article: Aspartame controversy

Aspartame has been the subject of controversy regarding its safety and the circumstances of its approval by the American FDA and European FSA. Some studies have also recommended further investigation into possible connections between aspartame and negative effects such as headaches, brain tumors, brain lesions, and lymphoma. These findings, combined with possible conflicts of interest involving CEO Donald Rumsfeld in the approval process, have engendered vocal activism regarding the possible risks of aspartame. The 2004 documentary Sweet Misery: A Poisoned World voices these same concerns.

The results of this carcinogenicity bioassay not only confirm, but also reinforce the first experimental demonstration of APM’s multipotential carcinogenicity at a dose level close to the acceptable daily intake (ADI) for humans. Furthermore, the study demonstrates that when lifespan exposure to APM begins during fetal life, its carcinogenic effects are increased.

Further reading

• Morando Soffritti, Fiorella Belpoggi, Eva Tibaldi, Davide Degli Esposti, Michela Lauriola (13 June 2007). "Lifespan Exposure to Low Doses of Aspartame Beginning During Prenatal Life Increases Cancer Effects in Rats". doi:10.1289/ehp.10271. {{cite journal}}: |format= requires |url= (help); Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link)

External links

• The European Foundation of Oncology and Environmental Sciences