Any way you slice it, Americans are obsessed with pizza. One in eight of us are noshing it on any given day, according to the U.S. Department of Agriculture. And the average American consumes pizza about 39 times a year, according to the NPD Group, a market research firm. The signature of a great American-style pizza is not the toppings du jour but the cheese: hot, gooey mozzarella, with big, dark splotches of caramelization. Pizzerias didn't happen upon that winning recipe by coincidence. Food scientists have been studying and finessing the low-moisture part-skim mozzarella we now put on most of...