Chemistry major researches exactly what’s in cold brew coffee during internship

By Chuck Gordon

Neither Todd Griffin nor Caleb Lethgo drinks coffee, but they sure know a lot about it.

During a summer internship overseen by Griffin, Wingate's chemistry safety officer, Lethgo, a junior chemistry major, tested cold-brew coffees from the Daily Grind brewery in Statesville to determine their caffeine and selected chlorogenic-acid levels. He then tested cold brews from other manufacturers to compare and contrast, in order to give the Daily Grind some baseline numbers.

Based on a process co-developed by Griffin and his company, G2 Analytical, Lethgo found that the Daily Grind brews contained substantial caffeine and higher concentrations of the chlorogenic acids measured than the comparison products. Chlorogenic acids are naturally occurring coffee compounds that are being studied for their potential antioxidant and anti-inflammatory activity.

"People are starting to do these energy drinks that are coffee based," Griffin says. "And they advertise them at, like, 300 milligrams of caffeine per 15-ounce can. We demonstrated that Daily Brew coffees are very close to 300 milligrams per 12-ounce can while retaining substantially more of the chlorogenic acids."

In the research lab in the Levine Health Sciences Building, Lethgo worked six hours a day over the summer feeding samples into a high-performance liquid chromatography (HPLC) machine, which is used to separate and analyze components in liquid mixtures.

First, he had to learn how to read the information supplied by the HPLC machine, but he quickly got the hang of it.

"Like, a day or two, maybe," Lethgo says. "The process is pretty straightforward."

Lethgo says he liked the routine of working in the lab and that he understood the work and could focus on it for hours at a time. But he said it provided variety too.

"We tried variations on it to determine what was the best method for preparing and for getting the best peaks," he says. "And then there's also just organizing samples and things like that."

Companies hire G2 to measure expected ingredients and investigate products with unexpected chemical compositions. In one recent investigation prompted by a reported adverse event, G2 detected THCP in a product represented as a CBD product. THCP is a psychoactive cannabinoid that has a brain-receptor binding that is 33 times as strong as Delta-9 THC.

Alongside the Daily Grind, Griffin developed a process for pressurizing ground coffee beans in order to extract the good stuff - the caffeine, the chlorogenic acids, the roasted-bean taste - in the most efficient way possible. It had a side benefit in that it condensed the time it takes to produce cold brew from the typical two to four days to about 40 minutes. The Daily Grind is a white-label company, producing cold-brew coffee that is sold under various names around the country.

"We control key variables in the process so that we don't get the bad stuff, the astringent quality, the acidity, into the product," Griffin says. "We leave behind a lot of the oils that give you the astringent flavor on your tongue."

He says that the work Lethgo and G2 Analytical did has given the Daily Grind good information that will help them plan and market their coffee better. They investigated the temperature stability of the company's products, to see whether the chlorogenic acid degraded during the extraction process.

"Once we get it into liquid form, it's pretty stable. It's hard to degrade it," Griffin says. "That helps the Daily Grind with understanding shelf life and marketability."

They also studied batch-to-batch variability, to see how reproducible the process is.

Lethgo says he enjoyed the work in the lab, but part of the internship also involved presenting his findings to the Daily Grind and their bean supplier, Haerfest (pronounced "Harvest"). Public speaking is "not my favorite," Lethgo says, but Griffin says that he "did great."

"I know I have problems speaking up loudly, and it is difficult for everyone to hear me," Lethgo says. "I have to focus more on that. And I also practiced my presentation many times. That way I already knew the tempo and pace I should be speaking at and what worked."

Lethgo also worked closely last semester with students in the Benchmark Laboratory Scholars program, which helps students develop practical laboratory and professional skills.

"We're slowly building those soft skills that have to go along with the scientific skills," Griffin says.

Sept. 17, 2026