The cocoa craze: Experts spill the beans on the science of chocolate

Stanford students love to live the sweet life, and eating chocolate is no exception. “Chocolate is a marvel — the eighth wonder of the world,” Carter Rosenthal ’27 said. 

Rosenthal and other Stanford students are clearly chocolate fans, as evidenced by the hundreds of students who flock to Ricker Dining Hall for its beloved “Death by Chocolate” special. Touted as a potential health supplement, TikTok-famous aphrodisiac and quintessential romantic gift, chocolate has cemented a spot as a bona fide favorite dessert of many who sample.

According to Markus Covert, chair of the bioengineering department, chocolate’s signature mouthwatering melt is part of its appeal.

“The melting point of chocolate is almost the same temperature as our body,” he said. This melting is accompanied by the “release of aromatic compounds,” enfolding the consumer in a rich sensory experience.

To John Hong ’23 M.S. ’25, the significance of chocolate aligns with the romance of Valentine’s Day. “Chocolate’s melt is a lover’s warm embrace, softly melting your heart in a whisper of sweetness,” Hong said.

Deeming chocolate the “best food of all time,” Rosenthal echoed Hong, saying, “the exquisite concoction transcends our mere sense of taste and brings about a brief moment of enlightenment.”

But despite the transient tastiness, Americans are actually eating cheaper-quality chocolate than consumers in other parts of the world. In the United States, a chocolate product can “have only 10% cocoa content and still be called chocolate,” Covert said. In Europe, this threshold may not fall below 35%. Those with a well-traveled chocolate palate may notice Hershey’s chocolate has a signature light hint of acidity, which Covert attributed to a cost-cutting decision made by founder Milton S. Hershey. 

According to Covert, legend has it that Hershey capitalized on Americans’ naivete regarding chocolate’s true taste and used milk that was spoiled or on the verge of spoiling in its chocolate recipes. To stabilize the milk, Hershey added butyric acid, causing the sour tang. 

Although Hershey reports they do not add butyric acid to their chocolate recipe today, and others say it was only added to improve shelf life, the tang in Hershey’s bars lingers. This may be the result of butyric acid naturally forming in dairy milk, according to Hershey’s director of corporate communications Jeff Beckman.  

Hershey’s mass-produced chocolate bars fall on the lower end of chocolate prices, which can vary  widely depending on cocoa content and caliber. In an email to The Daily, Olga Khessina, an associate professor of business administration at the University of Illinois Urbana-Champaign, wrote that the mass market is associated with high volume and low prices, typified by brands like Hershey, Mars Wrigley and Nestle.

On the other hand, craft chocolate is higher-quality, low volume and more expensive, she wrote. Such chocolate is “usually made bean-to-bar,” meaning the chocolate maker handles the entire production process from raw cacao bean to solid bar. 

The chocolate-making process begins, according to Covert, with fermenting cacao beans over several days, either naturally through existing microbes in cacao or by inoculation, or mixing in a microbe cocktail. He said that similar to wine, the microbiome used in cacao bean fermentation impacts the chocolate product’s terroir, or the taste of the bean’s origin as influenced by intermingling factors like soil and climate.

Chocolate makers “roast the beans before grinding them and separating them into fat and powder,” Covert said. The resulting solids may be combined with ingredients like milk and sugar to create the final chocolate product. 

But students should not scarf down this confection at whim. Christopher Gardner, director of nutrition studies at Stanford Prevention Research Center, wrote that chocolate “may be healthier than straight table sugar, but almost all chocolate contains sugar.” 

 “Chocolate is NOT a health food,” he wrote.

According to Gardner, any type of milk chocolate or chocolate with less than 100% dark or cacao will contain added sugar, which can “increase oxidative degradation,” he wrote. “There is no agreed upon amount of chocolate that is ‘advisable’ for health benefits,” according to Gardner, regardless of chocolate’s alleged health benefits due to its antioxidant content. 

Regardless of chocolate’s true health value, Stanford students cannot resist the tempting treat. “There’s nothing like that something sweet after something salty. And dark chocolate hits the spot,” Daniella Lumkong ’23 M.S. ’24 said.