Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How tastes are linked with facial expressions

07.01.2014
Researchers at Tokyo Institute of Technology identify links between the palatability of various tastes and circulation in different parts of the face.

Tastes deemed ‘pleasant’ increase blood flow in the eyelid according to a recent study by Hideaki Kashima, Yuka Hamada and Naoyuki Hayashi from the Prefectural University of Hiroshima, Kyushu University and Tokyo Institute of Technology. The research identifies links between the subjective perception of palatability with circulatory responses.


Change in facial blood flow before (left panel) and during eating consommé soup. This subject felt tasty to consommé soup. Red shows greater blood flow and blue shows lower blood flow. Note that blood flow in eyelid increased with eating tasty soup.

The researchers had previously noted changes in the skin blood flow in the eyelid and nose in response to basic sweet, umami (pleasant savoury) and bitter tastes.

Now the researchers have extended the study to identify a correlation between changes in circulation in specific parts of the face and the subjective palatability of different complex tastes such as the sweet and sour taste of orange juice.

They studied the responses of 15 test subjects to the taste of sweet chilli sauce, orange juice, bitter tea, coffee and soup, and a water control. All samples were tasted by pipette at the same lukewarm temperature, 40.3 ± 0.2 °C. A conductance index was calculated from the measured skin blood flow as a ratio of the mean arterial pressure.

Chilli was found to increase blood flow in all measured areas irrespective of the palatability rating given by the subjects. However, as the researchers point out, when changes induced by chilli sauce were excluded there was a significant correlation between the palatability ratings the test subjects gave and the conductance index values in their eyelids.

“These results suggest that the facial circulatory response reflects the degree of palatability of a foodstuff,” conclude the researchers.

Since smell also contributes to the palatability of food, it will be interesting to study further the study to consider the influence of different smells on skin blood flow.

METHODS

Circulation measurements

The researchers collected skin blood flow data from the test subjects’ forehead, eyelid, nose and cheek using laser speckle flowgraphy. The data was recorded 5 s before stimulation and 20s after stimulation. In addition the skin blood flow in the right index finger was measured by laser Doppler flowmetry.

The researchers also continuously monitored the heart rate and mean arterial pressure using an automatic sphygmomanometer applied to the subject’s left middle finger.

Subjective test subjective scoring

The test subjects retained the taste sample fluids in their mouths for 30s before swallowing and then rinsed their mouths with pure water at 40 °C until the taste had gone. They rated the tastes on six eleven-point visual analog scales, one for palatability and one for the intensity with respect to each of the five tastes sweet, sour, salty, bitter and spicy. The ratings scaled from +5 (the most pleasant) through 0 (no change) to -5 (the most unpleasant).

Results and suggestions

CI in the eyelid increased significantly in response to chilli sauce, orange juice and soup, while CIs in the forehead, nose and cheek decreased in response to bitter tea.

There was a significant correlation between the palatability scores and CI values in the eyelid when changes induced by chilli sauce were excluded. These results suggest that the facial circulatory response reflects the degree of palatability of a foodstuff.

The conductance index in the nose was not found to be related to palatability scores, however bitter tea caused vasoconstriction in the nose. Similar vasoconstriction in the nose has been observed in response to the discomfort of electrical stimulation of a finger or teeth. Temperature decreases have also been noted around the noses of rhesus monkeys in response to negative emotions, and are likely the cause of the observed vasoconstriction in the nose in response to bitter tea. The researchers explain the mechanism in terms of the nose’s high quantities of arteriovenous anastomoses controlled by adrenergic vasoconstrictor nerves. While the vasoconstriction is strongest in the nose, previous studies have noted sympathetic vasoconstrictor activity in the forehead and cheek, as noted by the researchers in the current study.

In the current study orange juice was found to significantly increase skin blood flow in the cheek but did not alter the conductance index as the mean arterial pressure also increased possibly via sympathetic activation. In contrast skin blood flow in the forehead was not found to increase at the taste of orange juice although it had been noted in response to cold pressor tests.

Further information

Yukiko Tokida, Miwako Kato
Center for Public Information, Tokyo Institute of Technology
2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
E-mail: media@jim.titech.ac.jp
URL: http://www.titech.ac.jp/english/
Tel: +81-3-5734-2975 Fax: +81-3-5734-3661
About Tokyo Institute of Technology
As one of Japan’s top universities, Tokyo Institute of Technology seeks to contribute to civilization, peace and prosperity in the world, and aims at developing global human capabilities par excellence through pioneering research and education in science and technology, including industrial and social management. To achieve this mission, we have an eye on educating highly moral students to acquire not only scientific expertise but also expertise in the liberal arts, and a balanced knowledge of the social sciences and humanities, all while researching deeply from basics to practice with academic mastery. Through these activities, we wish to contribute to global sustainability of the natural world and the support of human life.

Journal information

Hideaki Kashima, Yuka Hamada, Naoyuki Hayashi, “Palatability of tastes is associated with facial circulatory responses” Chemical Senses, 2014, DOI: 10.1093/chemse/bjt074 (Article first published online: 5 Jan 2014).

Adarsh Sandhu | Research asia research news
Further information:
http://www.titech.ac.jp/english/
http://www.researchsea.com

More articles from Studies and Analyses:

nachricht When a fish becomes fluid
17.12.2018 | Institute of Science and Technology Austria

nachricht Some brain tumors may respond to immunotherapy, new study suggests
11.12.2018 | Columbia University Irving Medical Center

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data storage using individual molecules

Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.

Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Pressure tuned magnetism paves the way for novel electronic devices

18.12.2018 | Materials Sciences

New type of low-energy nanolaser that shines in all directions

18.12.2018 | Physics and Astronomy

NASA research reveals Saturn is losing its rings at 'worst-case-scenario' rate

18.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>