Dunkin’ Donuts coffee tester has clout

Hélène Marsot shakes and sniffs a dozen cups of dry ground coffee. There’s no talking when you “cup,” she explains.

Boiling water is added and, four minutes later, she brings her face so close to the liquid it leaves a tiny brown stain on her nose. She inhales deeply. Five more minutes pass and she dips her spoon into the coffee. Then she slurps in a short and powerful burst, sucking in air with the coffee to “bring a boost in the sensory effects.” She spits the coffee into a bowl.

Marsot is the one of two chief coffee taste-testers for Dunkin’ Donuts, responsible for ensuring that millions of cups of coffee the company serves each day taste exactly the same. In a room filled with expensive coffee grinders, brewers, and plastic bags of raw beans at Dunkin’s headquarters in Canton, she tastes about a 100 cups of coffee a week — and sometimes just as many in a day.

“My job is to make sure that the coffee that is delivered to our stores is consistent all year around,” Marsot said in a French accent that remains strong more than a decade after she left Paris. “For us to always end up with a consistent product, we have to control the quality from the tree to the cup. That’s what I do.”

The samples she tests are pulled out of the shipping containers full of beans that Dunkin’ buys from Central and South America. The company operates labs in nearly every country from which it buys coffee, where people taste-test and machines determine the moisture content and other measurable qualities of the beans. Marsot repeats the tasting process on many of those samples stateside as a final layer of quality control before the coffee is sold to consumers.

When Marsot was hired, she said, the company’s quality assurance system was based on in-house experts and a shared understanding of the Dunkin’ taste. But the coffee chain had big plans to expand and grew from roughly 6,100 restaurants worldwide in 2005 to about 11,300 today. Marsot thought the company needed a more scientific approach to sustain that growth.

So she introduced a standardized system to score coffee on a scale of 1 to 7, for acidity, aroma, sweetness, finish, fragrance, body, and balance.

Depending on the origin of the beans, Dunkin’ gives each coffee an acceptable scoring range. If just one attribute in one cup of coffee is out of range, or “defective,” as Marsot describes it, the entire cargo ship container the sample came from can be sent back to the roaster.

“Dunkin’ has a very strict protocol,” the 39-year-old Marsot said. “We don’t give much room for error.”

John Tlumacki/Globe Staff

Marsot earned degrees in food microbiology and sensory evaluation in France. Before joining Dunkin’ Brands Group, she trained employees of a liquor company to taste-test spirits and worked in quality assurance at a ham and sausage plant. When she moved to America, Marsot first worked for Au Bon Pain.

She said that maintaining the same taste of the Dunkin’ coffee is difficult because beans are sourced from many countries and are subject to seasonal variations that affect the flavor.

Another big challenge: the process of translating senses into numbers and then training others employees to “speak the same language from Latin America to Canton to the roasting facilities.”

Marsot has trained hundreds of people to detect specific scents and score them, a process that takes months to learn and about three years to perfect, she said.

“I don’t want you to invent new words,” she said. “I don’t want you to call fruity cherry. You have to learn this new language, find it in the cup, and know what word to put behind it.”

Palmer Potter, the director of food and wine experiential programs at Boston University, compared the process to teaching someone to taste wine. Building a system isn’t difficult, but it is hard for everyone to agree on the tastes.

“The science of taste is complex and is influenced by genetics as well as aspects like mood,” Potter said. “There are studies that say music can impact how you taste things.”

Potter said that the more people practice, the better they become at reducing subjectivity.

Dunkin’ cups with at least three trained testers to help eliminate personal differences.

Over the years, Marsot has become a human calibration tool. She often travels to exporters and labs in other countries to teach the sensory evaluation system or provide refresher sessions. She also speaks with growers about upcoming crops and expectations.

“We can spend hours around a cupping table talking about one cup of coffee,” said Marsot, who grows coffee plants at her home in Weston. “Why? Because we love it.”

More coffee features:

• Dunkin’ Donuts executive chef Jeff Miller

• A peek inside Starbucks headquarters

• The mission: Taste up to 500 cups of coffee a day

• Double Shot: Coffee-related features