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W. Jeffrey Hurst, BA ‘69

In the 1980s, Hershey chemical analyst W. Jeffrey Hurst, BA ‘69.

Photographer: Ross Mantle

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Sweet Science: Unearthing chocolate’s ancient history

Look closely at the back wrapper of a Hershey’s chocolate bar and you will find the company’s consumer information 800-number. People typically call this number to ask about ingredients or recipes or nutrition or where they can buy Kit Kat bars. But in the mid-1980s, a call came into Hershey from anthropologists at the University of Texas at San Antonio.

They had been working on a dig at Río Azul in northeastern Guatemala. At its peak in the 5th century, Río Azul was inhabited by 3,500 Mayans. In 1984, archaeological excavators uncovered what they designated as Tomb 19. It contained the remains of a middle-aged man who had died around 460 AD, plus a trove of ceramic vessels. One of them bore the hieroglyph for the Mayan word ka-ka-wa — in English, cacao, chocolate’s primary ingredient.

Furthermore, several vessels contained residue of what the anthropologists suspected was chocolate. But they did not know how to test for that. So they dialed the 800-number of the company synonymous with chocolate candy. Somebody there ought to know, right?

The query made its way to an analytical chemist named W. Jeffrey Hurst.

One of his specialties was figuring out new analytical methodologies, and he liked solving problems. So his boss gave him permission to work on this one for the anthropologists from Texas. Cacao consists of more than 500 chemical compounds. Hurst needed to find some that not only were unique to Mesoamerican cacao and therefore useful as markers, but stable enough to be present in detectable amounts after 1,600 years in Tomb 19. By process of elimination, he settled on caffeine and theobromine, the latter a bitter-tasting compound that can be found in some tea leaves and the kola nut, but usually indicates cacao. Hurst assembled some off-the- shelf components to conduct a form of analysis known as high-performance liquid chromatography, and tested the Río Azul residue. His verdict? Whoever had placed those Mayan vessels in the tomb had indeed used them for an ancient variety of liquid chocolate.

Hurst tells this story in his office at the Hershey Company Technical Center, which is found on Reese Avenue, as in Reese’s Peanut Butter Cups. The street lamps high over the parking lot are shaped like Hershey’s Kisses. Hurst’s office is cluttered

— scientists may have orderly minds, but their offices inevitably are a jumble — with computer equipment, books, stacked paper, a giant stuffed frog given to him by his wife, Deborah, two framed pieces of her fabric art and a cacao seed pod.

Hurst, a 1969 graduate of Ohio University, ordinarily does not spend his time in the office researching ancient uses of chocolate. That is not his job at Hershey. His condensed professional biography notes that his “emphases are in separation science using standard, micro and nanotechniques, laboratory automation, the evaluation of new and emerging analytical technologies, the development and evaluations of methods for the determination for food allergens and the application of nontraditional analytical methods to food analysis.” This work produces scientific papers with titles like “Use of o-Phthalaldehyde Derivatives and High-pressure Liquid Chromatography in Determining the Free Amino Acids in Cocoa Beans” and “Determination of Aflatoxins in Peanut Products Using Reverse Phase HPLC” and the more comprehensible, to a layperson, “Carbohydrate Composition of Candy Bars.”

But Hurst has a long-standing deep interest in history, and so has enjoyed a 25-year sideline in analyzing samples of pottery made and used long before Columbus sailed into view. In the process he has contributed methodology and knowledge to archaeology, anthropology, ethnobotany and the history of cacao in the New World.

After he produced a 1989 paper in the Journal of Chromatography from his work with the Texas anthropologists, he went back to his more conventional work for Hershey. But a dozen years later, Texas was on the line again. This time a trio of anthropologists from the University of Texas at Austin — Terry G. Powis, Fred Valdez Jr. and Thomas R. Hester — had unearthed, at the Colha archaeological site in northern Belize, some Mayan ceramic vessels with near-vertical spouts and half-circle handles.

Scientists knew that starting about 400 AD, Mayans had used similar vessels to pour liquid chocolate back and forth to produce a froth considered the most desirable part of the beverage. These artifacts from Colha were centuries older than the first known use of chocolate, but they bore a dark residue that had aroused the curiosity of the anthropologists.

Hurst and a colleague at Hershey, Stanley Tarka, applied the technique he had developed to test the Río Azul samples, and sure enough found theobromine, in one case from a vessel date circa 600 BC. He says, “The joke was that meant ‘600 years before chocolate.’” This piece of lab work established that people were drinking cocoa in Mesoamerica a thousand years earlier than previously known. Hurst, Tarka and the anthropologists co-authored a Nature article based on that research, and it caught the attention of science reporters who knew that Mayans drinking cocoa in 600 BC would catch the attention of readers.

Newspapers, popular science magazines and the BBC came calling. “I think I spent a week working with someone from our communications staff fielding interviews,” Hurst recalls. There was one more lasting effect: He became the man to call if you had some very old North American or Central American pottery with what looked like chocolate residue on the inside.

With Stephen Bergmeier, professor of chemistry and biochemistry at Ohio University, alumnus W. Jeffrey Hurst has studied the beneficial antioxidant properties of chocolate. To learn more about their collaboration and Hurst’s continuing research on Mayan chocolate and a pre-Columbian American beverage known as the “Black Drink,” please continue reading the full version of this article in the Spring 2014 issue of Ohio Today, which is published by the Ohio University Division of University Advancement for alumni and friends of Ohio University.

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