The Science of Tea

AVEIRO, Portugal —

Medical advances get the biggest headlines but scientists worldwide are also exploring the chemistry, metabolomics and advancing the technology of tea production.

CoCoTea2015-LOGOLast week more than 200 scientists, physicians, nutritionists and food technologists from 37 countries gathered at the University of Aveiro in Portugal for the 3rd International Congress on Cocoa Coffee and Tea 2015 (CoCoTea).

The congress convenes every two years “to offer an inter-disciplinary area of discussion for scientists dealing with different aspect of three popular foods stimulating the central nervous system and whose consumption is related with many social and cultural implications,” said Prof. Manuel Coimbra, who chaired the event. His remarks opened three days of oral presentations and the display of almost 200 scientific posters that described some very interesting work in the science of tea.

Research presentations were detailed and highly technical, well beyond the scope of this reporter, but several generalizations may be of interest to those in the business of producing and marketing tea.

WTN150629_University of Aveiro-LOGOThe first involves a better understanding of taste. One paper described the influence of emotions on our sensory perception. Taste is more than its chemical components due in part to the variance in receptors within individuals (30% of Caucasians for example do not experience bitter). Taste is also influenced by emotional state. Pieter Desmet and Hendrik Schifferstein, in the journal Appetite 2008, revealed that smell and taste are the most often mentioned (49%) aspect correlated with human emotions. The perception of food quality was mentioned by 23% of respondents and the anticipated consequence of experiencing food and beverages (10%) was also tied to emotions.

“Context is also very important to triggering emotions – the ambiance of a restaurant, if you are not comfortable in a setting you might not like your meal,” according to Prof. Koushik Adhikari, at the University of Georgia, whose team recorded the immediate emotion induced by the coffee drinking experience.

Essentially this team of scientists at Kansas State University asked about 100 consumers over several weeks to express how drinking different coffees made them feel… some experienced “warm” for example while others expressed “wild.”

During his oral presentation Adhikari described 44 emotions used by consumers in describing their taste experience. Expressions included “boring” and “joyful” and “good” and “satisfying.” Subjects were given six coffees prepared with their choice in condiments which were kept constant during throughout the study. “Our focus was not the coffee but the drinking experience and hence we decided that consumers could choose their own preference in milk, creamer, sugar and sweetener,” said Adhikari. Responses appear in clusters ranging from low energy emotions to high energy emotions.

The top five emotions based on frequency of response included “energetic, jolted, boosted, productive and jump-start.”

I learned in discussions with professors and corporate scientists that much remains to be explored in describing the basics of tea. Medical research into the health benefits of tea has produced more than 5,000 favorable findings in both animal and human studies in the past few years. Here in Aviero the emphasis was on understanding flavonol glycosides, for example or describing the stability of black tea theragubigins.

Theragubigins are polymeric flavanol-derived compounds formed during the fermentation of tea leaves “that may contribute majorly to its beneficial effects on health,” according to researchers at Jacobs University in Bremen, German. These compounds comprise approximately 70% of total polyphenols in black tea.

A report by the Catalan Institute of Oncology in Spain addressed the risk of esophageal cancer (EC) adenocarcinoma (EAC) and squamous cell carcinoma (ESCC) from tea and coffee consumption.

“Data did not show a significant association between tea and coffee consumption and EC, EAC and ESCC, although a decreased risk of ESCC among men and current smokers is suggested, but need to be confirmed in further prospective studies including more cases,” writes lead researcher Raul Zamora-Ros.


University of Aveiro, Portugal

  • Unraveling the Grind: Do Emotions Influence Coffee Drinking? Koushik Adhikari, University of Georgia, Natnicha Bhumiratana, PepsiCo, Thailand and Edgar Chambers IV, Kansas State University.
  • Analyzing of flavonol glycosides in black, green and oolong teas, H. Jiang, U.H. Engelhardt, C. Thräne, B. Maiwald, J. Stark
  • Tea Research Institute, Chinese Academy of Agricultural Sciences, China, Technische Universität Braunschweig, Germany
  • Investigation of stability of black tea thearubigins, A. Shevchuk, N. Kuhnert, Jacobs University, Bremen, Germany.
  • Tea and coffee consumption and risk of esophageal cancer: The European prospective investigation into cancer and nutrition study. Int J Cancer. 2014 Sep 15;135(6):1470-9. doi: 10.1002/ijc.28789. Epub 2014 Feb 28.