Title: Alternative Sweeteners

226 Kinghorn and Compadre
sweet taste of curculin disappears a few minutes after being held in the mouth,
but a sweet taste occurs on the subsequent application of water to the mouth
(24). The primary structure of curculin monomer contains 114 amino acids, of
molecular weight 12,491, with native curculin being a dimer of two monomeric
peptides connected through two disulfide bridges (24, 47). Because curculin is
stable at 50°C for a year, studies directed toward the commercialization of this
sweet-tasting/sweetness-enhancing protein are in progress (24).
2. Other Sweetness Enhancers
A number of plant constituents have sweetness-enhancing properties, including
cynarin, chlorogenic acid, and caffeic acid (2). Arabinogalactin (larch gum) is
capable of enhancing the sweetness potency and taste qualities of saccharin, cyclamate,
and protein sweeteners such as thaumatin and monellin (1, 2). Recently,
a series of oleanane-type triterpene glycoside esters, strogins 1–5, were described
from the leaves of Staurogyne merguensis Wall. (Acanthaceae). Three of these
compounds, strogins 1, 2, and 4, elicit a sweet taste in water when held in the
mouth, in similar manner to miraculin and curculin, whereas two of the compounds
in this series, strogins 3 and 5, were inactive in this regard (61).
B. Sweetness Inhibitors
1. Phenylalkanoic Acids
Substituted phenoxyalkanoic acids are potent inhibitors of the sweet taste response
without disrupting the taste cell membranes, and their effects are immediately
reversible (62). The sodium salt of 2-(4-methoxyphenoxy)propionic acid
(Fig. 15) is commercially available under the trade name of Cypha ® to modulate
excessive sweetness in formulated products (62). This compound has been found
to be a natural constituent of roasted Colombian Arabica coffee beans and has
been granted GRAS status for use in confectionery and frostings, soft candies,
and snack products, for use up to levels of 150 ppm. A 100-ppm solution of this
Figure 15 Structure of 2-(4-methoxyphenoxyl)propionic acid.