Better cheddar: UW scientist finds enzyme to cut bitter taste

Discovery could save makers millions in production fees, sales Bitterness has plagued the international cheese community for thousands of years. But the efforts of a Wisconsin scientist may soon put that acrimony to rest - forever. Jim Steele, professor of food science at the University of Wisconsin-Madison, has discovered an enzyme that reduces the bitterness that afflicts low-grade cheddar cheeses, potentially saving cheesemakers millions of dollars in lost or reduced sales. "This find could be a real boon to cheesemakers," said John Umhoefer, executive director of the Wisconsin Cheese Makers Association. "It has the potential to give consistency to the quality of cheese that we produce, and save us a whole lot of money." The costs of making cheese are manifold. From buying starter and adjunct cultures, to storage and aging, the production of cheese can be costly and time-consuming, especially if the end product is uncertain. "A lot of it just becomes fish food," said Umhoefer, describing the fate of bad-tasting cheddar. Steele's discovery could wipe out the unpredictability of cheesemaking, guaranteeing an edible product in the end. A medley of cultures When cheese is made, a medley of bacteria, called a starter culture, is stirred in with warm milk. Starter cultures are specific to the cheeses that are desired. Sometimes, a second batch of bacteria is added, called an adjunct culture. In cheddar production, an organism called Lactobacillus helveticus is mixed in. This bacterial strain smooths out the taste of the cheese and reduces bitterness. Steele wanted to identify what it was about this strain of Lactobacillus that produced this desirable effect. "People have been adding these (adjunct) cultures for hundreds of years," said Steele, "not knowing what they were doing scientifically, but knowing that it did something." Twelve years ago, Steele and some of his colleagues at UW started their search. If they could find the secret behind Lactobacillus helveticus and incorporate it into the starter culture, not only would they drop the added cost of the adjunctcultures, they also could improve the predictability of good quality cheddar cheese. They started their search by examining 11 enzymes they suspected might play a role in Lactobacillus' smoothing effect. And for the next decade, they "knocked out" - or deleted - genes from the Lactobacillus DNA that they believed were associated with their target enzymes. They'd then test each genetically altered strain by making cheddar with it - a slow process requiring six months of aging for each cheese. If the smooth enzyme was knocked out, the cheese would taste bitter, meaning the key enzyme was not present in the test strain. If this occurred, they would have known they had pinpointed the right gene. But for 10 years they kept churning out smooth cheeses, identification of the enzyme eluding them. It took the advent of cheap genetic testing techniques to really get things moving. In 2001, they were able to sequence all of the 2,400 genes in Lactobacillus. And within six months, Steele's team identified the gene it was looking for - the one that produced the bitter-reducing enzyme. That gene can now be added to starter cultures, reducing the unpredictability of the end product, and eliminating the need for an adjunct culture. Steele and his colleagues have applied for a patent and expect that the engineered starter culture will be available within the next couple of years. Art vs. results Cheesemakers and tasting judges at the 2003 U.S. Championship Cheese Contest, being held in Milwaukee this week, had mixed opinions about Steele's find. Paul McShane, sales manager for Roth Kase, a small family-owned cheese production company in Brookfield, sees Steele's enzyme as little more than a tool to take the art and mystique out of cheese production. "I say, don't screw with mother nature," he said. "Cheesemaking is an art, and you lose something - a quality - when you try to take shortcuts," he said. But Bill Schlinsog, chief judge of the contest, thinks the identification of this enzyme is "wonderful." Bitterness is a taste that can kill a cheddar, he said. "It's undesirable. And if it can be avoided, then that's great," he said. Indeed, even the top cheeses are susceptible to bitterness. The winner of the 2003 non-aged cheddar cheese class, Land O Lakes, received demerits for hints of bitterness. "Mind you, most people wouldn't notice it," said Schlinsog. "But they're (cheese judges) trained to make those kinds of distinctions."