But there are countless variations in the process, which account for the hundreds of cheese varieties made around the world: the source of the milk (cow, sheep, goat and even more exotic animals, including reindeer), its fat content, whether it is pasteurized, the strain of starter bacteria used, when and how the salt is added, whether the curds are “cheddared” (cut up, allowed to set, then cut and stacked several times, a process that was developed in Cheddar, England), whether the block is pressed or molded, how long and where it is ripened — the permutations are almost infinite.

“Cheese is just this big biochemistry experiment,” said Tonya C. Schoenfuss, a professor of food science and nutrition at the University of Minnesota.

It’s an experiment in which salt plays a large role, and cheese makers “really haven’t found a magic approach” to reducing sodium, said Dr. Miller of the Dairy Research Institute. “It’s a real technical challenge.”

Most efforts focus on young, mild cheeses, because even though the reduction of salt may make it more difficult to control bacterial activity, the cheeses are not aged long enough for this to affect flavor, Dr. Metzger said. But no cheese maker is going to spend the time and money to age a Cheddar for several years, for example, and risk that it may develop off flavors.

A common salt-reduction technique is to replace a portion of the sodium chloride with potassium chloride, which has a similar ability to control bacteria and provides a similar salty taste. But that chemical presents other problems.

“Potassium salt by itself also gives a bitter note,” Dr. Johnson said. “If you get it too high, then you taste that as an off flavor.” So some cheese manufacturers add compounds that bind with the taste buds so the potassium salt does not. “They’re natural ingredients, not any weird chemical,” he continued. “It masks the unpleasantness.”

David McCoy, vice president for product research at the Dairy Research Institute, said one avenue of study was to look for bacterial strains that are more sensitive to sodium — so less salt would have to be added to control them — but still produce the right flavors. “But that’s a long-term process,” he said.