Title: Alternative Sweeteners

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Aspartame-Acesulfame: Twinsweet
John C. Fry
Connect Consulting, Horsham, Sussex, United Kingdom
Annet C. Hoek
Holland Sweetener Company, Geleen, The Netherlands
I. INTRODUCTION
Aspartame-acesulfame is the first commercially viable member of a group of
compounds called sweetener-sweetener salts. These salts owe their existence to
the fact that some intense sweeteners form positively charged ions in solution,
whereas others are negative. It is thus theoretically possible to combine two oppositely
charged sweeteners to create a compound in which each molecule contains
both ‘‘parent’’ sweeteners. To look at this another way, many currently permitted
sweeteners are sold as their metal salts, for example, sodium cyclamate, calcium
saccharin, acesulfame potassium. In a sweetener-sweetener salt, the positively
charged metal ion—sodium, calcium, or potassium—is replaced by another
sweetener, which itself carries a positive charge.
Aspartame was probably the first realistic candidate for this role of positively
charged sweetener, although there have since been others, such as alitame.
Despite the availability of aspartame for decades, the practical difficulties of preparing
sweetener-sweetener salts seem to have defeated most researchers. The
patent literature records only one attempt at laboratory synthesis (1) via a route
involving dissolution of an unstable form of the negatively charged sweetener
in a toxic organic solvent, a procedure that produces only small quantities of
poor crystals. Realistic commercial manufacture would require a synthesis that
could be carried out in an aqueous medium and that satisfied both food industry
demands for purity and commercial requirements for economic yield. This was
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