The "Percent Sucrose
Equivalent" scale
Sweetness is commonly measured by
comparison to
reference solutions of sucrose. Sucrose is the standard to which all
other sweeteners are compared. Humans can recognize sweetness in about
1 or 2% sucrose solution. Coffee is typically sweetened to about the
level of 5% sucrose. Soft drinks are usually about as sweet as 10%
sucrose. 15% sucrose is
really
sweet and starts to feel a little syrupy. Taste panelists usually are
trained to quantitate sweetness on a 15 cm line scale, using
2-15%
sucrose solutions as references.

Other sweeteners are then tasted at a
series of
dilutions to determine the concentration that is as sweet as a given
percent sucrose reference. For example, if a 1%
solution of
sweetener X is as sweet as a 10% sucrose solution, then sweetener X is
said to be 10 times as
potent
as sucrose.
For a detailed discussion, see "A
Systematic Study
of Concentration-Response Relationships of Sweeteners," G.E. DuBois,
D.E. Walters, S.S. Schiffman, Z.S. Warwick, B.J. Booth,
S.D. Pecore, K. Gibes, B.T. Carr, and L.M. Brands, in
Sweeteners: Discovery, Molecular
Design and Chemoreception, D.E. Walters, F.T. Orthoefer,
and G.E. DuBois, Eds., American Chemical Society,
Washington, DC (1991), pp 261-276.