SUGAR SUBSTITUTES NOT SO SUPER SWEET AFTER ALL
The taste of common
sugar substitutes is often described as being much more intense than sugar, but
participants in a recent study indicated that these non-nutritive sugar
substitutes are no sweeter than the real thing, according to Penn State food
scientists.
In the study,
participants compared the taste of non-nutritive sweeteners that are often used
as low- or no-calorie sugar substitutes with those of nutritive sweeteners,
such as sugar, maple syrup and agave nectar. The participants indicated they
could perceive the non-nutritive sweeteners -- such as aspartame, marketed as
NutraSweet; acesulfameK, often called AceK; and RebA, a compound found in the
stevia plant -- at lower concentrations than real sugar, but the intensity of
these sensations was no sweeter than sugar and other nutritive sweeteners.
"While you can
detect non-nutritive sweeteners at lower levels than sugar, that doesn't really
tell us anything about the perceived intensity of that sweetness," said
John Hayes, assistant professor, food science and director of the sensory
evaluation center.
The assumption that
these sweeteners are excessively sweet may be the result of confusing potency
and intensity, said Hayes, who worked with Rachel Antenucci, a graduate student
in food science.
"In terms of receptor
biology, the potency of a substance describes the lowest concentration that
activates a taste receptor, but this does not predict the intensity, or
magnitude, of the response," said Hayes.
The ability to detect
sweetness of non-nutritive sweeteners at low levels, then, is related to their
potency, but not their intensity, he added. Sugar, on the other hand, is less
potent but causes more intense sensations of sweetness.
"These
ingredients are often marketed or described as 'high-intensity' sweeteners, but
that's misleading," said Hayes. "Our data confirm other work showing
the maximal sweetness of low-cal sweeteners is often much lower than that of
table sugar or other natural sweeteners, like maple syrup."
The researchers, whose
findings are available online in the International Journal of Obesity,
said these sweeteners did not seem to act as supernormal stimuli -- a term
first used by Nobel laureate Niko Tingergen to describe exaggerated stimuli
that serve as triggers for innate behaviors.
Some psychologists
have suggested that supernormal stimuli and the responses they provoke could be
a factor in the obesity epidemic, said Hayes.
"We have evolved
to like sweetness from before birth, so some people assume so-called 'high
intensity' sweeteners hijack or over-stimulate our natural drive to consume
sweet foods, causing us to overeat," said Hayes. "However, this view
assumes that foods we eat today are more intense than those we would have been
exposed to evolutionarily, and our data imply this isn't the case."
Hayes also said the
availability of highly desired foods may play a more important role in the
obesity epidemic.
The researchers
recruited 401 participants to take part in a series of taste tests held at the
Sensory Evaluation Center at Penn State. Once the subjects were briefed on the
study, they tasted between 12 and 15 separate samples that contained maple
syrup, agave nectar and sucrose, as well as various concentrations of
aspartame, sucralose, AceK and RebA. Participants indicated that the caloric
sweeteners all had higher sweetness ratings than the non-nutritive sweeteners.
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