In new research, Professor Orians explores effects of climate change on tea

The tea tasters sip the tea and record their observations about its taste and aftertaste. Alex Cherry / The Tufts Daily

Organisms all over the planet,  from walruses to bumblebees to shellfish, have been affected by climate change. Tea, its drinkers and its growers have earned their place on that list according to ongoing research by Professor of Biology Colin Orians.

Orians has launched a new study that explores the relationship between climate change and the cultivation of tea in China. In a four-year study funded by a $931,000 grant from the National Science Foundation (NSF), Orians and his colleagues are testing the impact of extreme precipitation on tea by looking at the differences between teas harvested during the dry season and those harvested during monsoons.

The research team looks at the chemical composition of tea, as well as more consumer-oriented factors such as taste and mouth-feel (the tea tasting term for texture). They hope to use their findings to help tea farmers mitigate the effects of climate change in order to more consistently produce the high-quality teas that consumers like.

Part of the research process includes bi-weekly tea-tasting meetings, during which Orians and Co-Principal Researcher Selena Ahmed, among other colleagues, gather to taste a particular tea and rate various aspects of its palatability.

One such meeting occurred last Thursday, Oct. 16. Orians was in attendance, as well as graduate students at the School of Arts, Sciences and Engineering Nicole Kfoury, Amanda Kowalsick, Nick Wilton, Eric Scott and Julia Pilowsky; postdoctoral scholar Patrick Antle; Associate Professor of Chemistry Al Robbat; Associate Professor of Biology George Ellmore; Program Administrator of Environmental Studies Sara Gomez; and Rebecca Boehm, a graduate student at the Friedman School of Nutrition Science and Policy.

Kowalsick explained that the research is essentially a two-step process.

“What we’re first looking at is how the climate factors such as rainfall are affecting the tea chemistry itself, so what’s … changing from the spring dry harvest to the monsoon wet harvest,” she said. “The second part of the project is looking more at what the consumers are tasting, which is what we’re doing now. So we have two different techniques … We’re able to see the effects of rainfall on actual tea that a consumer would drink as well.”

According to Kfoury, one way that the researchers are able to analyze the chemical components of the different teas is by assembling a library of the various compounds. Kfoury said that this library allows them to scan through the different components of each tea, which helps to speed up the analysis.

“What we do first is we take one of the teas and we do what’s called a two-dimensional GCS analysis, so we can basically pick apart the teas and generate a library of every compound that we find in the teas,” Kfoury said. “By creating this library, one library for each kind of tea — one spring library and one monsoon library for each year — we can then use that library to scan through all of our other samples very quickly … by comparing against our library and using data analysis software that Dr. Robbat has developed.”

Orians said that the tea-tasting meetings are a way to qualify the more quantitative aspects of their research.

“We wanted to put together a sensory expert panel to evaluate teas, because we can measure the chemistry, but how do we know how that affects our sensory properties?” Orians said. “We are a panel of people who are a part of the project and people who are tangential to the project who are just really interested in … exploring the chemistry and sensory properties of tea as a consequence of environmental variability and climate change.”

The tea-tasting process is something that the researchers have honed to an exact science, Orians said. According to their brewing protocol, each tea sample must be brewed for three minutes exactly with water at 90 degrees Celsius. After the three minutes are up, the team begins tasting the tea and ranks its various aspects, such as balance, fullness, mouth-feel and total intensity of flavor. Then, at various time points after the tea has been brewed, they rank other aspects, such as aftertaste.

“We have to time it right down to the second because the flavor changes as the tea cools down,” Pilowsky said.

Ellmore described how the flavor of tea would be compromised if the brewer is not careful with time and temperature.

“If the tea is made correctly, if it’s brewed correctly with the Chinese method, there would not be any bitterness,” he said. “Some people taste flowers and honey, and all sorts of different things — bitterness is not one of [them]. If you leave the water in there for too long or too hot, all the sudden there’s this bitterness that comes through.”

In general, the research team has found that tea from the dry season is higher-quality than tea from the monsoon season. This means that consumers tend to like tea from the dry season better, which creates a demand that tea farmers are incapable of filling, due to the uncontrollable nature of the weather.

“It’s shown that the higher-quality tea, the tea that most consumers like, is from the dry season, not the monsoon season,” Robbat said. “Farmers actually get much less money for monsoon-harvested tea, so we’re trying to take a holistic approach. There are environmental factors that influence what the plant does.”

Robbat also mentioned the implications of these findings, especially as they relate to the effects of climate change today.

“We’re beginning to see longer and longer monsoon seasons, which means poorer and poorer quality and less quantity of the tea,” he said. “So this is a project where we’re trying to really understand what all these interactions are.

The researchers hope to use their findings to come up with ways tea farmers can mitigate the negative effects of climate change on their crops. Orians described one such possibility: allowing insects to feed on the growing tea leaves, especially during monsoon seasons.

“One of the things that we know is that plants produce … chemicals, but these chemicals can change in response to insects feeding on them,” he said. “There have been reports that tea leaves that have been fed upon by insects are often the most valued. In fact … there’s a particular tea in Taiwan which is incredibly sought-after because insects have [been] feeding on them, changing the chemistry of those leaves.”

Orians explained that this finding could help tea farmers to grow tea that consumers would like better, and therefore buy in higher quantities.

“So one of the things that’s part of the project is to look at whether or not a little bit of insects feeding on your plant is a good thing, especially as the monsoons hit,” Orians added. “It turns out that when the rains hit, it’s also the time the insects tend to come out, so … perhaps farmers wouldn’t want to spray against the insects when the monsoons hit because they can actually increase the quality of tea for those first few harvests during the monsoons.”

Toward the beginning of the meeting, as Kowalsick and Kfoury poured the tea, spirits were high, and it was clear that the researchers were enjoying this project.

“Ah,” Ellmore said, inhaling the aroma from his cup. “Another relaxing day of tea here at Tufts University.”