The Research That Aims to Cheese

On a recent Tuesday at the University of Wisconsin at Madison, sample number 435 lies supine on a lab table where it surrenders to a gauntlet of measurements.

Brandon Prochaska slides a thermometer into the pizza’s abdomen, and the digits tick upward to 205 degrees Fahrenheit. He and a group of other trained professionals jot the number down.

While the pie cools, they inspect its blisters and score their size, quantity, and color. Are the spots as fat as quarters? That’s an 8.5 on a 15-point scale. As prevalent as the pattern on a Dalmatian’s coat? A four. As dark as a worrisome mole? A 14.

Next, the mozzarella is manipulated. With a fork, Prochaska, who is today’s designated stretcher, rakes cheese into a small pile, slides a tine into that pile, and lifts skyward. Someone else crouches to gauge the precise height at which the gooey strand breaks apart — 12 inches. At the Center for Dairy Research, 12 inches is nothing special.

Prochaska repeats this motion twice more, attempting to apply consistent force and speed. He also produced a strand so that the group could determine its thickness. “Judge it before it’s gone, people,” he says, holding still so that the string of cheese — slightly wider than a cobweb, or, to use the center’s scale, a 2.5 — does not collapse before everyone gets a good look.

Precision is the pursuit of the descriptive sensory panel, which meets every week here in Babcock Hall to analyze pizza, cheese, and other dairy products. This might not sound like much of a job at all, but the task is more complex than it seems. The panel, which Prochaska oversees, translates the subjective experience of interacting with food into objective data that researchers can use to test their hypotheses about, say, milk coagulation or meltability. It’s through these translations that dairy science — and your cheese-eating experience — advances, one chew at a time.

Speaking of chewing, it’s time to eat — sort of.

Sample 435 is sliced into squares and distributed on paper plates. Panelists peel the cheese off the crust, fold it into quarters, and chomp, rating the cheese’s “first chew hardness” and other chewing metrics. Noses plugged, they suss out the mozzarella’s level of salt, bitterness, and acidity. Then they open their nostrils to search for aromatics like milk fat and butter.

Once the panelists select scores that feel right, the evaluation is complete. But before moving on to the next pizza and the next round of measurements, they must empty their mouths. If you thought they’d swallow, you thought wrong. Everyone spits, demurely, into a cup.

Here, the scientific method is occasionally disgusting.

Millennia before there was such a thing as a descriptive sensory panel or the state of Wisconsin, Neolithic human beings discovered cheese to be a fantastic answer to a gastronomic problem. Like many people today, as adults they were intolerant to the lactose present in animal milk. But when milk turns into cheese, much of the lactose either is carried away in the whey or is converted into lactic acid, making it easier to digest than milk.

As animal husbandry developed in the Fertile Crescent region, people began milking sheep and goats and leaving that milk in unrefrigerated conditions. There was likely an “aha moment” in which people realized that though they could not consume the liquid, they could eat “the chunky part,” also known as the curd, says Liz Thorpe, a cheese expert who wrote The Book of Cheese: The Essential Guide to Discovering Cheeses You’ll Love.

People have treasured cheese ever since — a “solidified whitish mass” of it was even discovered inside the tomb of Ptahmes, an important Egyptian official in the 13th century B.C. Today, cheese is a linchpin of Wisconsin’s economy. The state is home to well over a million dairy cows that produce 2.62 billion pounds of milk a month. A month!

As in any booming industry, research and development fuels innovation. Enter the Center for Dairy Research. Founded in 1986, it has more than 50 employees based on the Madison campus, receiving some university money but primarily supported by a dairy farmer funding program, federal grants, and its own generated revenue. Its focus is on milk and products made from milk, particularly “specialty cheeses,” or those that are not mass produced and bring in higher sales returns per item, says John A. Lucey, the center’s director and a professor of food science at Wisconsin.

One facet of the center’s work is recipe development. “People will come to us and say, ‘I’d love to make a blue cheese, but I don’t know anything about blue cheese. Guys, do you know how to make a blue cheese?’ … We’ve been doing that for over 30 years, in all kinds of cheeses,” Lucey says.

Another facet is sensory testing. People want to eat — and therefore food brands want to sell — products that taste the best. So the research center works with companies that want to know if, for example, an eggnog recipe pleases the taste buds of potential buyers. The center has a database of more than 2,000 people in the Madison area who’ve agreed to be part of a consumer sensory panel and occasionally try out different products and share their thoughts. Once, Prochaska recruited preteens and teenagers to drink several chocolate milks for a client seeking a formulation that would appeal to both kids and adults.

But the descriptive sensory panel eschews questions of preference. As opposed to the consumer panel, its members are all trained for months to use a uniform lexicon and scoring system. That uniformity allows the descriptive panel to be a tool for scientific research seeking to improve cheese production and performance. Its feedback appears in peer-reviewed papers with titles like Use of high-pressure processing and low-temperature storage to extend the performance shelf life of 2 types of string cheese. (That study not only examined “stringiness” but also “firmness,” noting that the latter is an “important performance attribute for consumers who just bite into the string cheese without peeling off strings” — a.k.a. monsters.)

If working properly, the panel should operate “like a machine,” Lucey says. So why not use an actual machine? Prochaska says the center owns an electronic nose — a device that uses sensors to mimic the human olfactory system — but that it fell short when “smelling” cheddar samples. “Things that we thought were really different, it wasn’t detecting differences in,” he says. In Prochaska’s experience, “it was not even close to matching the performance of the human nose.”

Anyone interested can apply for the center’s part-time panelist position, if applications are open. (It keeps a roster of 20 to 25.) Candidates undergo a general “sensory acuity” screening, mostly to make sure their sense of taste isn’t grossly deficient. Rarely is someone turned away for that reason, Prochaska says. “I’m a firm believer that whatever variability there is in natural genetic predisposition,” with sustained instruction, “you can easily overcome that.”

During his screening, Russ Tilsner, a 60-year-old retired manufacturing executive, says he remembers thinking, “Oh my gosh. What did I get myself into?” The test was more technical than Tilsner expected. He says Prochaska lined up vials of liquid that he had to arrange from least to most salty, sweet, acidic, bitter, and umami. After they were through, “I think my exact words to Brandon were, ‘Thank you for your time. I don’t think I’m the right person for this job.’ And Brandon looked back at me and said, ‘Now don’t write yourself off just yet.’”

Once hired — at around $16 an hour — trainees meet with Prochaska once a week for a few months. Under his tutelage, they learn to pinpoint the presence and intensity of the flavors, textures, and visual attributes of cheese and other dairy products. They start with the five basic tastes, then take on more sophisticated fare. Concepts like “adhesiveness” (the degree to which a “chewed mass” sticks to your teeth and mouth) and flavors like “brothy” (the aromatics associated with boiled meat or vegetable stock) are all rated on 15-point scales.

Those scales frequently have “anchors,” or common points of reference, that help the panelists compare and contrast. For example, cream cheese, at a 1.0 rating, is the lowest anchor for “chewiness,” which Prochaska defines for his panelists as “the total amount of energy required to masticate the sample to a state pending swallowing.” (Haribo-brand gummy bears are the highest anchor, at 13.0.)

Panelists also must unlearn certain ways of talking about taste. Take the word “creamy,” which is popularly used to describe both texture and flavor and is thus unhelpful in pursuing specificity. Then there are the biases that could affect their scoring, like expecting a cheese to taste more intense because of its vivid color. (Annatto, a plant extract, is added to many cheeses for color but typically does not correlate with flavor.) Barbara Wright, a recent addition to the panel and a former restaurant owner and chef, says she stopped drinking coffee in the mornings on work days because it can warp her ability to assess bitterness.

Ultimately, Prochaska says, “You’re trying to take what’s really subjective, what’s really kind of touchy-feely, and make it something that is more concrete, more anchored, more repeatable. That’s kind of the heart and soul of what sensory is trying to do, as a discipline.”

Certain tools help with this. Before the day’s evaluation gets going, Prochaska shows me some of them. On a tray are dark glass medicine bottles with labels like “waxy/crayon,” “mushroomy,” and “sulfur.” Prochaska screws the top off of “grassy,” and the liquid inside makes it smell like we’re outdoors watching a children’s rec soccer game. When he does the same for “cowy/barny,” I’m transported to the feedlots adjacent to my hometown in Colorado.

Prochaska tells panelists to latch onto memories they associate with aromatics. He’s been in this field for more than a decade, but despite his experience, it can still be tricky to put words to what he’s tasting.

“There’s so many times where it’s on the tip of my tongue of what this is, but I can’t articulate it,” Prochaska says. “I had that the other day. I’m like, what is it? What is it? And eventually I got it. Oh! It’s black olives,” he says, adding that he hasn’t eaten black olives “since I’ve been, like, eight.”

Another helpful tool at the panelists’ disposal are jugs filled with solutions that isolate the basic tastes, ranging from weak to strong. They can sip them between bites to calibrate their scores.

I ask to try a few, including the bottle labeled “Salt 13.5.”

“I don’t know if I’ve ever actually tasted this reference or not, because the extremes of the scale are extreme for a reason,” Prochaska tells me, pouring the solution into two miniature plastic cups, one for him and one for me. For saltiness, he says, an average cheese is in the six to eight range.

My tongue recoils. It tastes like the ocean. I follow Prochaska’s lead and spit the liquid into a large trash can in the center of the evaluation area, which will only become more waterlogged throughout the afternoon.

Though a panelist’s job is to render judgments in a controlled and uniform manner, sometimes one can’t help but react like a human.

“When I first started, I had a problem with retching,” says Carolyn Haswell, a laid back 27-year-old who fits in panelist work around her day job as an electron-microscope technician. Haswell sits at a lab table conducting a solo evaluation before the afternoon’s group analysis. Arrayed in front of her are brightly colored putties varying in stiffness. She’d been compressing a cube of Manchego cheese “by approximately 30 percent,” per the instructions, then comparing that feeling to the putties to score the cheese’s “hand firmness.”

When Haswell applied for the job, she thought she’d be eating pizzas made by companies like DiGiorno, not what she calls “experimental cheeses” concocted by students testing their theories. Of everything she’s tasted since joining the panel a year-and-a-half ago, Haswell reckons she’s only enjoyed about 10 percent of it. “I’ve learned how much I don’t like cheese,” she says, dryly. (She’s still a fan of pepper jack.) When I asked if she’d worked through her retching problem, she replied, “I retched last week.”

Still, Haswell likes the job. It’s a fun way to break up the work week and she’s noticed that she uses her nose more while cooking. Wright, the former restaurant owner, fits in panel work amid her hobbies, including working on her trio of science-fiction fantasy books. She says she likes feeling as if she’s “part of something bigger, like I’m helping advance dairy science.” Tilsner, the retiree, recently got a puppy that he and his wife named Kolbie Cheddar Jack. He says it’s been rewarding to try something totally novel and find success, especially now that he can offer guidance to new trainees. “If they’re struggling with something, I can say, you know what? I was right there with you six months ago,” he says. “But you’ll get it.”

Still, everyone agrees that bad cheese is an occupational hazard of sensory testing. Says Grace Cassidy, a master’s student in food science: “We’ve had pizzas that somehow tasted like glue. We’ve had pizzas that were so sour. We’ve had ones where the texture, when you chew it, somehow feels like oatmeal.”

That’s because student researchers are not attempting to bring a product to market. Rather, “we change things,” Cassidy says, “and see what happens.” And occasionally, she says, “we get cheese and we’re like, ‘I can’t believe that one was actually good. We did so much weird stuff to it, and it was still good.’”

Cassidy’s mozzarella is what the panel is testing on the Tuesday and Wednesday I visited. It was made on-site at the research center, which has an operating dairy plant. The “weird stuff” done to it involves its protein content. Cassidy upped the milk’s concentration of casein protein dramatically. “We’re not aware of any company that’s ever gone to the range that she’s going to” and still use traditional cheese vats, says Lucey, the center’s director.

Concentrating milk increases the amount of cheese that can be produced from that milk, thus boosting efficiency and lowering costs in the dairy-industry pipeline, but it can complicate the cheese-making process. Cassidy’s research focuses on those complications. With the dairy plant’s assistance, she made eight different recipes of mozzarella and was putting them “head-to-head” to see how they perform. The panel’s feedback will inform her thesis.

On both days, panelists observe Cassidy’s cheeses in two forms: shredded and melted. For shred performance, they judge characteristics like “straightness” and “fusion.” On the wall to guide panelists is a straightness scale — close-up photographs of cheese ranging from pin-like to squiggly to globule.

For fusion, Prochaska grabs shredded cheese between his fingertips and sprinkles it about eight inches in the air while panelists watch, deciding to what degree the shreds have melded together. Some bits of cheese rain down freely. Others form a stubborn clump in Prochaska’s hand.

Then, handfuls of yellowish-whitish cheese are passed out to panelists. Sitting at his lab table, Jim DiUlio, a retiree in boat shoes and a polo, plucks individual shreds off his plate and measures them against a ruler, recording their lengths in centimeters. When gauging the shreds’ “surface oil” — not to be confused with “free moisture,” another criterion — DiUlio and other panelists are taught to manipulate the cheese with a light touch, so as not to deform it. The goal of such specific instructions is to control variables as much as possible. Between each tactile benchmark, they wipe their hands on paper towels, another method of control.

Cassidy’s melted cheese is assessed in the form of 16 pizzas over the two days. Each one is cooked for four and a half minutes at 475 degrees Fahrenheit, photographed, poked with a thermometer, visually assessed for things like “free oil” (known to laypeople as greasiness), then stretched with a fork, sliced, chewed, and spat out. Both days I try a few samples for myself, to see if I can taste what the panel tastes. I can’t — I barely have time to write down a couple of obtuse observations, like “medium good,” or “gummy,” in the time it takes the panelists to do their work.

However, we all agree that Tuesday’s pizzas tasted superior to Wednesday’s. Prochaska asks the group if the latter batch is the worst they’ve ever had. No, they answer. Prochaska thinks it’s in the bottom half. “There was maybe one of these that I’d eat if it was given to me for free,” he says, while dumping a post-evaluation pizza carcass into the large trash can.

Wednesday marked the end of the panel’s Pizza Era. For the past couple of years, they evaluated mozzarella more than any other cheese. But soon, they’ll be moving into new territory: A graduate student is studying Swiss cheese, which means there’s a novel set of holey criteria on which the panel must be trained.

Before being dismissed for the day, Prochaska gathers everyone to examine 10 slices of Swiss cheese arrayed on white pieces of paper. The group hovers over the slices, and begins assessing characteristics of the holes, like how round they are. On the table is a cue card with plastic imitations of cheese that features different hole-types, labeled with words like “pinny,” “slitty,” and “open.”

As the lesson wraps up, one of the panelists makes a suggestion to Prochaska. To see the intricacies of the cheese even better, should the slices be offset against a black background, as opposed to a white one?

That’s something to consider for the future, Prochaska replies. He wants “whatever is closest to accurate.”