Aspartame

November 04, 2019
I’m a sweetie.
What molecule am I?

The sweetener aspartame is a dipeptide ester sold under the tradenames Equal and NutraSweet, among others. It is formally a condensation product of aspartic acid with the methyl ester of phenylalanine; but the actual synthetic methods are more complex.

In 1968, a South African patent for synthesizing aspartame and other dipeptide sweeteners was awarded to James M. Schlatter and assigned to G. D. Searle (Chicago), now part of Pfizer. The equivalent US Patent (3,492,131) was awarded in 1970. But not until 1981 did the US Food and Drug Administration approve it for use in foods.

At one time, rumors held that aspartame is carcinogenic; but studies performed from 2006 through 2015 refuted this allegation. The FDA and National Cancer Institute supported these studies.

Aspartame’s sweetness is ≈200 times greater than that of sucrose. Its solubility and stability in aqueous media depend strongly on pH. It is most stable at pH 4.3, which makes it ideal for sweetening carbonated beverages. It is unstable at normal cooking and baking temperatures; but it can be used in “no-heat” recipes.

Aspartame is considered to mimic the qualities of sucrose (e.g., flavor, taste duration, and low aftertaste) better than other artificial sweeteners.

Aspartame hazard information

GHS classification*: not a hazardous substance or mixture

*Globally Harmonized System of Classification and Labeling of Chemicals. 

Aspartame fast facts

CAS Reg. No. 22839-47-0
Empirical formula C14H18N2O5
Molar mass 294.31 g/mol
Appearance White crystalline powder or colorless needles
Melting point 246–250 ºC
Water solubility 10 g/La

a. At pH 7.

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