KOYOTO, Japan
It is thanks to the work of Professor Kanzo Sakata that we are beginning to understand why certain teas develop wonderful aromas and flavors during the manufacturing process. His research and willingness to share what he discovers is adding so much to our appreciation and knowledge about tea flavor profiles, particularly of oolong, pu-erh and other dark teas.
Professor Sakata retired from the Institute of Chemical Research at Kyoto University in 2007 but is busier with his work in tea than ever before. Now Professor Emeritus, he is asked more and more often to speak at seminars and to play a vital role in explaining aspects of tea science that to date we have known very little about. His most recent assignment was to give a talk entitled
Molecular bases of tea aroma formation and tea manufacturing technology to a group mainly composed of tea farmers and tea traders in Shizuoka. The
Special Seminar for Fermented Teas and Selected-microbe Fermented Tea was extremely topical, as Japanese tea farmers explore ways of making their own ‘dark teas’ to meet a growing interest in the perceived health benefits of aged and microbially-fermented teas.
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| Professor Sakata |
“Because Shizuoka is a leading prefecture for green tea production in Japan,” explains Sakata, “the tea industry had never supported anything other than green tea manufacturing. But recently, they realized that many tea farmers are interested in manufacturing other types of tea – black and oolong, etc. – but the quality has not been good enough. I was never asked before by local government to give a talk, although I have been teaching many tea farmers in other parts of the country how tea aroma is produced during manufacture.”
Professor Sakata studied at Kyoto University’s Department of Agricultural Chemistry and won a prize in 1977 for young researchers from the Agricultural Society of Japan for his
Chemical Studies on Ezomycins for Agricultural Use. He went on to work as a researcher at the RIKEN Institute of Physical and Chemical Research in Japan, at the Research School of Chemistry at the Australian National University, and in 1981 became Associate Professor, then Professor at Shizouka University’s Faculty of Agriculture. From 1998 until his retirement in 2007 he was Professor at the Laboratory of Molecular Biocatalysts at Kyoto University’s Institute for Chemical Research.
Sakata’s main interest in the 1970s and early 80s was in marine organisms and in particular the feeding behavior of abalone and sea urchins. “But then I met Ms. Luo Saojun, a researcher from Hanzhou Tea Research Institute in China and a specialist in tea manufacture and especially oolong tea. She taught me about the wonderful flavor of high quality oolong tea and the lovely floral aroma that is produced during manufacturing. She told me also how important chemical studies are in tea manufacturing. This for me was a great ‘chaen’.”
‘Chaen’ is a Japanese word invented by Sakata to mean the special relationship established between people through tea! “I feel so happy that I got to know the world of tea, which is so wide and so deep, and I’ve met so many good people through tea. I once looked in several dictionaries for a word that sums up the way we communicate via tea and I couldn’t find anything. So I call it ‘chaen’.”
After working with Luo Saojun, Sakata decided to turn his attentions to tea chemistry, but “I was aware that tea has been studied for thousands of years and I really thought that there were no exciting themes still to be studied. However, since Shizuoka prefecture is Japan’s most important tea producing region, I thought I should concentrate on tea. I soon realized that there are so many things that are unknown and so far we have only clarified a part of tea aroma formation during manufacturing. It’s the tip of the iceberg! There are many kinds of important tea aroma compounds that we don't yet understand.”
Sakata became particularly interested in what happens during the manufacture of oolong tea to produce its very special floral tea aroma. “Oolong is manufactured by very special processing, involving solar withering and turning of the leaf. During this part of the process, plenty of aroma, especially floral aroma, is generated. I was very interested in this, not only from the food processing but also from the plant physiological point of view – for example the response of the tea leaves to the stresses of water deficiency and injury.”
When Luo Saojun returned to her work in China, she had sent a young chemist (Dr. Guo Wenfei) from her department in Hangzhou to work with the Professor at his laboratory in Shizuoka. Together the two men researched the molecular mechanism of aroma formation in tea and broke new ground when they realized that a new enzyme is involved in the formation of aroma in oolong tea. Their work showed that the enzyme is produced as a result of the self-defense mechanism in the plants themselves. This kicks in when they need to ward off attack by a fungus called Colletotrichum theae-sinensis which causes a serious disease in tea bushes!
Professor Sakata played a fascinating and crucial role at World Tea East in Philadelphia in September 2011 when he explained aroma development in pu-erh tea. The session offered the chance to taste five different pu-erh teas (some from young cultivated bushes and some from ancient trees, some ‘raw’ made by the traditional raw pu-erhs that are aged for at least 7 – 10 years, and other ‘cooked’ pu-erhs made by the more modern, method which wets and piles the leaf prior to a briefer period of ageing). Sakata was able to explain not only the chemical processes that takes place during fermentation but also the results of health studies linking pu-erh tea to a reduction in cholesterol levels and body mass index in those taking part in the study.
Everyone was fascinated by his knowledge and understanding of these important areas and he was delighted at the success of the session: “All the people there did not really know ‘dark tea’. They knew the word ‘pu-erh’ but they had the wrong image of pu-erh. After we explained the two types and let them taste the teas, I recognized changes on several people’s faces – especially when they tasted the aged raw pu-erh. They clearly recognized that the tea they were used to was ripened or cooked pu-erh. They were not used to raw pu-erh teas.”
What is important for Professor Sakata in the world of tea research now? A current topic is the production of theaflavin, the important red pigment in black tea. “Mass production of theaflavin will soon be possible and the health benefits of this particular constituent of black tea will also be more clearly understood in the future. A new tea drink may be possible! This technology will open a new page for black tea, I think!”
The Professor recognizes that there are many other problems to solve. “There are so many kinds of tea in the world and many possibilities to produce new types. However, most people just enjoy a limited variety in their daily life and we should help them to know more about the diversity of tea and the culture of tea.” His work is certainly helping tea drinkers around the world to understand some of the mysteries of the plant and the beverage, and to appreciate the part that nature plays in creating the individual character of some of our favorite teas.
Jane Pettigrew is a tea specialist, historian, author of 13 books and consultant to tea companies. She lives in London.
