Cheese: From her udder to your stomach
As the vets and vendors, the farmers and their champion cows head home from World Dairy Expo, held in Madison, Wis., The Why Files is still thinking about cheese. How is it made? Is cheesemaking a science, an art, or a mishmash of the two?
What is the cutting edge — in science, technology and marketing — of a product that could be older than written history?
In the Odyssey (800-ish BCE), Homer described the one-eyed monster Cyclops as a cheesemaker…
Cheesemaking was likely invented by people who stored milk in containers made from the stomachs of ruminant animals. These stomachs contain rennet, a mix of enzymes that coagulates solids and causes them to separate from the liquid portion of the milk.
Those solids form curd, the first stage of cheesemaking. Curds are naturally acidic, and hence slower to spoil than milk.
But what started out as a method to preserve milk has persisted and proliferated in the age of refrigeration, as many people find cheese irresistible.
We started Cheese-Quest, Why-Files edition, with a logical move: hoofing half a mile west to the dairyland within America’s Dairyland: the Center for Dairy Research at the University of Wisconsin-Madison.
We lucked out. The center, one of six funded by America’s dairy farmers, was holding its semi-annual cheese technology short course, and we sat in on a class on cheese flubups, a talk about pizza cheese, and a hands-on cheesemaking session in the University’s dairy pilot plant.
Cheese begins when fresh milk is acidified with chemicals or bacteria. Within hours, the milk solids coagulate into pellets called curd, and the liquid whey is drained off. The cheese may be finished within in days (fresh mozzarella), or months or even years later after a long period of ripening in a cooler (aged cheddar, for example).
The unique form and flavor of a cheese reflects the:
Choice of milk: from cow, goat or sheep
Geography: where the cow’s feed was grown
Bacteria: strains can be blended for a specific process and desired flavor
Salt: for flavor and preservation
Soaking in brine: to form a protective rind
Aging and mold (as in blue cheese): to enhance flavor
A biological product
Cheese resists the standardization of the assembly line. “Why doesn’t the cheese from a given factory taste the same week after week, year after year?” asks Dean Sommer, director of cheese technology at the Center for Dairy Research. “Why does cheddar from factory A taste so different from cheddar from factory B? It’s because cheesemaking is a biological process, and there are so many variables.”
Local weather and soil chemistry affect the feed, and feed affects the taste of the milk, so local conditions matter, says Sommer, and cheddar has a different taste on the East Coast, Midwest and West Coast. On the West Coast, cows eat a high ratio of vegetable scraps from large California farms. “In the Midwest, most dairies are feeding total mixed ration, a mix of three to six different types of food; it might be hay, corn silage, cottonseed, some brewer grains. It depends on which ingredients are cheap and available, every farmer does it differently, so the feed is different.”
All these variations are reflected in the flavor of the cheese. “It’s similar to the concept of terroir [local taste determined by local conditions] in winemaking,” Sommer says. “In Switzerland, cows eat mountain flowers in the meadows in the summer, and those flavors come through in their cheese.”
Viva la difference!
While local variations are a problem for big producers, they are stock-in-trade for artisan cheesemakers. “In the ’80s, the industry mentality favored standardization; it was like the Big Mac, which should taste the same everywhere,” says Sommer, who once worked for a giant cheesemaker. “Today people want the ability to create a unique flavor that is different from the cheese factory down the road.”
While large dairy farms still rely on total mixed ration, the danger of erosion in hilly regions forces farmers to use more grazing, and the result is more flavorful milk, and more distinctive cheese.
New cheesemakers and new flavors have helped to save the Wisconsin dairy industry, says Sommer. “Twenty years ago we were heading down the dead-end road of commodity cheese, now we’ve gone into specialties that leverage the craftsmanship and heritage of the people, and our terroir, and that is why the industry is healthy and optimistic. Twenty years ago, the attitude was, ‘Last one out of the dairy industry please turn out the lights. Today you don’t hear that.'”
Bold bacteria to the rescue?
Multiple recipes can be used to make cheese, with variations in temperature, chemistry or timing, says Sommer. “Even if you start with the same milk, and end up at the same place compositionally, from a flavor standpoint the result can be different.”
Cheese is a biological product, and the taste reflects its living ingredient: the bacteria that initiate acidification and then confer flavor. Thousands of strains of bacteria are on the market, “and they all make slightly different flavors,” Sommer says. And that’s not even counting the bacteria that arrive in the milk or sneak aboard in the cheese factory. “Without those other bacteria, cheese would be very mild,” says Mark Johnson, a scientists with the Center for Dairy Research.
By analyzing DNA, Johnson has identified bacteria in cheese, and found up to a dozen strains — most of them accidental. “Usually, up to three strains are added, and everything else is native to the environment, the plant, or the milk,” Sommer says.
Johnson is a microbiologist by training, and if he detect better strains of these hitchhiking bacteria, he will check if they can accelerate curing. “One goal is to get the desired flavor fast, so you could put out the cheese at three months and it would have a unique character without the expense of aging.”
On the flip side, finding funky strains that make off flavors could help in their elimination.
Going for flavor
Because cheese is a high-calorie food that normally contains considerable sodium, a factor in high blood pressure, the industry faces rising concerns about and obesity and hypertension.
Youth obesity is soaring, so the issue is germane to school lunches, but cheese has real benefits, Johnson says. “People forget the protein, and especially the calcium, phosphate and potassium. The balance of calcium and phosphate is perfect for growing bone. If you take cheese off the [school-lunch] menu, you are going to deprive kids of these needed nutrients.”
The challenge, he says, is to lose the negatives while keeping the benefits — and the flavor. “We want to provide what kids like, to give the nutrition without the downside. Kids like a buttery flavor, but when you remove fat and sodium, you remove butteriness, the sweet character.”
Johnson sees progress in the flavor quest. “I have a low-sodium cheese aged nine months. At three months, people could tell it was low sodium, but at nine months, they could not. Bacteria are doing something in the cheese to make it taste so you would never say it lacked salt.”
When good cheese goes bad
Pity the diligent cheesemaker. Johnson says plenty of problems arise after good cheese has left the dairy. Excess acidity in cheeses like cheddar and Colby turn it brittle, grainy and bitter.
Bad flavors in the milk, which can result when the cows eat a strong flavor like wild onion, can cause off-flavors, especially in raw milk cheese. A “barny” odor — uncomfortably close to cat urine — can result from protein degradation or wild strains of lactobacillus. (Unlike most bacteria, lactobacillus, the group of bacteria used to make cheese and yogurt, can survive in acidic milk.)
Exposure to display-case lighting is another problem, and is one cause of “temperature abuse,” failing to hold the cheese between 35° and 45°F. High temperatures can lead to oil separation, loss of flavor and bitterness. “50° and above is hot for cheese, and 70° will destroy it,” says Sommer, who has seen even hotter cheese in store displays. “It was warm to the touch.”
Teaching the wrong lesson?
High temperatures are a problem “throughout the distribution system and also for importers who bring cheese in from Europe,” says Sommer. At a cheese plant in Philadelphia, the cheese was unloaded 12 months a year on an asphalt parking lot, which may work fine in February…
Many problem strike after the cheese has left the factory, Sommer notes. “I feel bad for a lot of cheesemakers. They put their heart and soul into the cheese, but it can get abused and turn awful, and the consumer buys it and probably blames the cheesemaker. They put their label on it, but it was fine when it left their door.”
Sommer thinks such degradation has an insidious cost. “I’ve bought cheese and given it to friends. I can’t swallow it, but they say, ‘It’s okay.’ We are teaching people that cheese should taste like lard or wet cardboard. I don’t think anybody in the industry has a handle on how much cheese sales have declined because people get turned off and won’t return.”
— David J. Tenenbaum