August 2014

Dear Reader,

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!

Best wishes,

The Team at Sensory Dimensions

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 non-Tasters (TnTs).

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.

Candy’s Research

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 population!

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.

Do TTs Perceive Stimuli More Intensely at Supra-threshold Concentrations?

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.

How does TT Status Relate to PROP Taster Status?

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.

How will our TT Group React to your Products?

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.

Talking Sense about...TTs

This research offers some fascinating insights, not only to those who are interested in the mechanisms of sensory perception, but also for the product developer working on products that rapidly cool or heat the tongue such as ice creams, cold beers and curries. The elicitation in thermal tasters of a metallic sensation on this heating or cooling is of particular note, as this is normally an unwanted characteristic. Given the high incidence of TTs in the population (over 25%) this could have practical consequences for the industry.

Sensory News

Interested in being a big fish in a small but rapidly growing pond?

We have vacancies at both our Nottingham and Reading sites for Sensory and Consumer Scientists at all levels. Contact Tracey Sanderson for more details.

New Starters

Welcome to Liz Harington, Arran Abbiss, Kyle Ogle and Amanda Kirkham who have joined our team of technicians in Nottingham and Sarah Bonham, our new deputy Recruitment Manager in Reading.

Eurosense 2014

We are very much looking forward to Eurosense in September. We will be exhibiting so hope to see you there.

Great British Bake Off

To mark the new series of the Great British Bake Off our Nottingham team held their own bake off competition.  Against strong competition, Star Baker was awarded to Weronika for her stunning chessboard creation!