The One World Blog

One World Roasters' Espresso Workshop with Yale Quantum Institute

Yale Quantum Institute at One World Roasters' Espresso Tasting Stephanie Hessing, second in from the right

Making a good espresso isn’t quantum science—but it can come close. Creating that perfectly intense and invigorating shot of joy requires an intrepid spirit, intensive research, and the insatiable curiosity of the scientific mind.


We recently brought the worlds of coffee and science together in a brilliant fashion with an interactive espresso workshop with Yale Quantum Institute. This special union came together courtesy of the “one normal person” at the organization, Stephanie Hessing, manager of the institute. 


“The rest of the staff are very highly vetted physicists,” Hessing clarifies. “I have a legal background and I’m used to working with very smart … well, nerdy people … so I make sure that things are getting done, information is being communicated, and I help them with inviting people, and handling the logistics— I’m also responsible for creating the atmosphere of the institution … and that’s where the coffee machine comes in.”


Yale Quantum Institute is one of the most prestigious organizations for the study of quantum science within the international community, with visitors from numerous countries frequenting the facility and assisting with development of their many projects.


Rancilo Ergo Espresso Maker The famed Rancilo Egro One can make 200 espressos in one hour!

And for an association as distinguished as Yale Quantum Institute, no regular, ho-hum coffee drip will do. Hessing had to see to it that the “Rolls-Royce of coffee machines,” the elite Rancilo Egro One, was readily available to the scientists, professors, and students of the institute, to keep them from venturing out elsewhere for their coffee and conversation. The venerable machine, capable of firing out 200 top-notch espressos an hour, had the job covered, but beans were still a big question mark.


“I didn’t think about the beans when we first bought the machine, but then we had the machine and I thought “oops we should have beans as well,” Hessing chimes. “I knew that freshness was very important and I’m a green person myself so I wanted to go with organic—I also like to be local. So I searched “organic New Haven coffee roaster” and I guess I just found One World Roasters via Google. I started to have conversations with Eric and he was very service-oriented, very flexible, and very helpful.”


With their forces united, One World Roasters’ Eric Ciolino offered a special opportunity to members of the institute to learn more about an area of study very dear to this clientele—espresso, of course! We thought we’d share some of the key points with you in this month’s blog!

Eric Ciolino serves espresso for coffee tasting Eric Ciolino explains the classic preparation of espresso

Coffee Vs. Espresso


Now, what actually distinguishes espresso from regular, old coffee? You’ve got the little cup, right, and there’s also some foam or something of the like … All true, but none of these common features really get to the bottom of what makes this stuff special. The real answer is far more scientific!

To begin with, we have very different water to coffee ratios. A cup of espresso is far more intense than your average cup of joe, not due to any special beans, but simply because you’re condensing the strength of 9 grams of coffee into 1 fluid ounce, rather than the standard American 5 ounces—which the Dutch native, Hessing, refers snarkily to as “big cups of watery stuff.”


However, what’s more interesting than the proportions alone are the methods through which we access the coffee. For a big cup of watery stuff, we tend to use fairly low tech, but effective tools like drip coffee makers, French presses, and coffee cones to run hot water over coarsely ground coffee beans. The coffee essences diffuse quickly into the water and are separated from the grounds, yielding your standard cup of coffee.


Espresso, on the other hand, is a far more delicate process—the coffee must be finely ground and tightly packed via a process called tamping. An espresso maker then passes very hot, pressurized water (198-205 degrees Fahrenheit) through the coffee—this is chemically where things get interesting. The hot water caramelizes the sugars in the coffee, while the pressure (at least 130 psi) causes the water to dissolve additional carbon dioxide. Once the pressure of the water normalizes upon hitting the cup, CO2 bubbles shoot up from the espresso and are trapped between water molecules at the surface. This is where all the frothy goodness comes from, and there’s a lot of pressure to get this right in the coffee world—no pun intended—in most respectable coffee houses, a crema-less espresso gets dumped!

Espresso Diagram The art of the wet blend illustrated by chart

Espresso—the making of


And there is a lot more to the science of espresso—specifically the composition. Most individual coffees do not have all of the flavor and mouth-feel characteristics necessary for making a balanced and delicious espresso, thus, they are most often combined proportionally to create blends that check off all of the boxes. What those boxes might be are unique to each drinker. This is why we use the "wet-blending method" in our espresso tastings, which allow each taster to customize their own unique coffee.


A wet blend tasting works by using the three-coffee roadmap. As detailed in our table above from the tasting, espressos are generally comprised of three levels of coffee:


I) A base coffee (3 spoons)—we start with an Arabica like a Brazil, Dominican, Mexican, Peruvian, or Sumatra to establish the mouth-feel and color or the espresso.


II) A small ratio coffee (2 spoons)—often high end Robusta coffees like Costa Rican’s, Guatemalan’s, and Venezuelan’s are used to give the coffee a luxurious and frothy crema that is very difficult to obtain with Arabica beans (in this case, due to more carbon dioxide being dissolved as the water passes through these grounds). Used at the right quality level and proportion, Robusta beans can enhance an espresso.


III) The finishing touch (1 spoon)—we add one more coffee on top such as Ethiopian’s, Kenyan’s, Javas, and New Guinea beans to add complexity to the espresso in the form of aroma and aftertaste.


Wet Blending Espresso Demonstration Eric Ciolino demonstrates the "wet-blending" tasting process

Tasters proportionally mix small spoonfuls of the brewed coffees above, taste the ensuing blend, and record their findings—what did they like—what didn’t they like—what do they need to change to make it better? With the data on hand they proceed to the next blend and so on.


“There’s a touch of engineering in the approach,” Hessing remarks. “To start with the foundation and then look for balance and flavors on the coffee wheel— it was all new for me! Eric got us through the whole thing and did a great job.”


Espressos can occasionally be made with only two coffees like One World Roasters’ Black Kat espresso, which is a larger percentage of Sumatra at a dark French roast and a smaller percentage of Ethiopian at a medium-to-dark roast. So what was the Yale Quantum Institute’s favorite blend created from the workshop? 50 percent Colombian and 50 percent Guatemalan—no nonsense, you might say! In general, you don’t want to get carried away with more than three coffees, or the flavor will be too complex to make sense of.


Honing a palate for coffee and espresso can be a gradual process, but it can also be an incredibly enjoyable pursuit as this workshop illustrated. Many artisan roasters like OWR allow customers and clients to sample many different blends to identify the flavor profiles that are just right for them. A word of warning from Hessing though—once you find an amazing espresso, you may have a hard time drinking any other coffee!


“I have a great espresso machine at home, which I always liked, great coffee, but in the last few weeks, I’ve started to hate the coffee—I only want to have the coffee from here, so maybe that’s where it’s slowly setting in. After you get used to this coffee, you start to dislike the others,” Hessing says with a laugh in her voice.


If you’re interested in a private coffee tasting and tour for your business or friends feel free to contact us—we are only too happy share the knowledge and great flavors!


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One World Roasters
967 North High St,
East Haven CT 06512

United States
Phone: 1.203.376.1589

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