Researchers at Tokyo Institute of Technology have identied 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.
The researchers had previously noted changes in the skin blood flow in the eyelid and nose in response to basic sweet, umami (pleasant savory) 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, close to 40.3 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," say 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.
Source: Tokyo Institute of Technology