We regularly conduct research here at Sensory
Dimensions. Back in 2011, we began funding our first ever three-year PhD studentship at the
University of Nottingham. The subject under investigation was the
intriguing phenomenon of 'Thermal Tasters', first identified in 2000 by researchers Cruz and Green.
We wanted to find out how widespread Thermal Tasters were in the population and the impact of this on their perception of taste, flavour and mouthfeel of foods and drinks.
The results of the research are now out, so read
on to find out more!
What is a Thermal Taster?
Cruz and Green found that warming the tongue of some people using
a special thermode device can evoke sweetness, while cooling it can evoke
sourness and/or saltiness. Some individuals can experience both heat-related
sweetness and cold-related saltiness, while others only experience one or the
other. These people are known as Thermal Tasters (TTs). People who don't
perceive any 'phantom' taste due to heating or cooling are known as Thermal
Our PhD student, Candy Qian Yang, used our
database of consumers to determine the incidence of thermal tasters in the
population and their responses to a variety of tastes, aromas and oral stimuli.
Previous research has indicated that TTs may
perceive some stimuli as more intense than TnTs. First steps were to determine
if there was a difference in detection thresholds between TTs and TnTs. Candy
screened over 200 respondents for their TT status and classified them into 3
groups: Thermal Tasters (TTs), Thermal non Tasters (TnTs) and uncategorized
(Uncat). TTs detected a taste sensation on both heating and cooling of the tongue,
TnTs did not perceive a taste, and Uncat were inconsistent in their reporting
throughout the classification trials. The most common taste sensations reported
were metallic, sweet, bitter and sour. Amazingly, TTs formed 27% of the study
Candy went on to determine the detection
thresholds of 124 of these people for each of seven taste, aroma and mouth-feel
stimuli. The results showed that sucrose was the only stimulus for which TTs
and TnTs showed a difference in detection threshold: the TTs were more
sensitive. This indicates that the greater sensitivity of TTs at
supra-threshold concentrations reported by earlier researchers does not hold at
detection level. This is not too surprising, as we know that we perceive
things at threshold and above threshold, by different mechanisms.
105 screened respondents participated in the
supra-threshold study. Subjects rated the intensity of five series of taste,
odour and trigeminal sensations, namely sweet, salt, bitter, acid, ethyl
butyrate and capsaicin (heat) plus the intensity of cool and warm.
Results showed that TTs rated cool and warm
sensations more intensely than TnTs. In terms of the taste, odour and
trigeminal sensations, TTs tended to rate intensities higher than TnTs,
although there was no statistically significant difference for any one stimulus.
PROP taster status has long been recognized as
a marker of differences in sensitivity of individuals, particularly to bitter
products. It is genetically determined, and as part of trying to understand the
origins of TT status, Candy’s study investigated if there was any relationship
between the two phenomena.
She found that the two were generally
independent of one another. However, some PROP tasters may have their sensitivity
enhanced if they are also a thermal taster, whereas others (those who are
especially sensitive to PROP) will not have the same enhancement.
Candy’s respondent pool was screened in part from Sensory Dimensions' consumer panel database, so we now have a group of people whom we know have TT status. If you are interested in investigating how this group reacts to your products in relation to a non-taster group then please contact us. Or if you just want more details of any aspects of these studies then please get in touch.