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By Peter Skarpelos As with so many innocent vices, it all started in the Berkeley dorms. One night after studying late, the girls next door peeked in and offered me some coffee they had just made. "Sure!" I said, and they went back to pour me a cup. I could smell the aroma even before I walked into the room. Their rich and complex brew was better than any I had ever tasted; I was hooked. And I couldn't get to sleep that night, no matter how hard I tried. It was my first encounter with Peet's French Roast, and my eyes had been opened. Literally. My mom unwittingly fanned the flames of my growing passion when she gave me my own espresso maker for Christmas, with the comment: "It looks like a neat engineering contraption for my engineer son." Now I was equipped to do some serious research on my own. There is an art to making a great cappuccino, and I was going to learn it. Throughout my student years, and especially as a grad student in materials science and engineering, I could always find someone to talk to about the finer points of pulling a shot or the proper consistency of foam. Especially over a cup. One of the most enthusiastic of these was Harold Ackler '87, a student of ceramics. Harold drank so many mochas from Peet's that one of his labmates brought an espresso maker into the lab and charged Harold a buck for each mocha. After a while, Harold had bought so many drinks that he had paid for the machine, which his labmate ceremoniously presented to him as a gift.
One of Harold's pet peeves was that he could never get decent coffee when he went camping. He couldn't bring all the paraphernalia to make a mocha, but what he really needed was instant coffee. The trouble was that instant coffee-the "freeze-dried crystals" you buy at the grocery store-doesn't taste even remotely like the fresh stuff, let alone a good strong shot. As engineers and gourmets we wondered why this was. Does the freeze-drying process inherently degrade the coffee flavor, or did the big coffee companies figure that anyone who drank instant wouldn't know the difference if they used the worst coffee beans? To put these ideas to the test we needed to experiment, and Harold had the key. When making engineering ceramics, shrinkage and cracking is carefully controlled by first pre-drying the "green" ceramics in a freeze dryer-a piece of machinery that was conveniently available in Harold's lab. We thought, as long as no one was using it and we cleaned up afterward, why not use Berkeley's resources in an interdisciplinary way and advance the body of scientific knowledge? So we bought a pound of Peet's, and I brought my espresso maker in to join Harold's. Then we started pulling shots and pouring them into a large steel bowl. We froze the coffee rapidly by pouring in liquid nitrogen, which boils at -196ºC. Within a minute, all the nitrogen had bubbled away, leaving a bowl of what looked like coffee-ice popcorn. We crushed the "popcorn" into fine bits, packed it into the freeze dryer, and waited. After several days, the machine had finished sucking the water out, and we finally had our precious powder. Now for the taste test. But how much water did we need to add? How much dry coffee per cup? We did what all good engineers do at such moments: We guessed. Harold and I put one flat teaspoon in each of our mugs and filled them to the rim with hot water. Success-the reconstituted coffee smelled heavenly, and it tasted just like it had when we'd made it days before! After Harold left to study at MIT, he complained that you couldn't get a real mocha in Cambridge like the ones at Peet's. Instead of going through the entire freeze-drying process again, Harold's old labmates went straight to the source: We went to Peet's, bought a thermos, and filled it with mocha at 5 p.m. We then rushed to FedEx, shipped the package to MIT, and called Harold to tell him to be in his office to receive a package at 10 a.m. the next morning. I believe he was the happiest person in all of Boston that day. Back to Top |
Peter Skarpelos ’89, M.S. ’94, is an engineer living in Berkeley. He continues to refine his appreciation for fine coffee. We invite alumni to write about their Cal experiences for "Recalling Cal," California Monthly, Alumni House, Berkeley 94720. Contributors will be paid $100 upon publication.
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