In the case of string cheese the curds are “Cheddared."
Dear Matt: How do they get the string in string cheese? — Mike, El Cajon
Dear Matthew Alice: How come milk goes bad in so many different ways? Cheese is pretty much just soured milk, but how come it can turn into Cheddar or Roquefort or Swiss or so many different-tasting cheeses? And mild Cheddar is cheaper than sharp Cheddar because sharp Cheddar is aged longer. Could I save some money by buying mild Cheddar and aging it myself? — Roberto, downtown
A provisional yes to that second question, Roberto, assuming you don’t charge yourself time and materials for digging a root cellar and installing the climate-control system. You probably can’t just clean the skateboards and snow tires out of the hall closet and roll in that wheel of Cheddar to ripen.
Cheese is basically spoiled milk (like wine is just spoiled grape juice). But it’s very carefully spoiled — virtually pampered — with specially cultured bacteria or fungus to create its unique taste. The type of milk (cow, yak, sheep, goat, reindeer, even ape milk has been used) also affects the taste. Once upon a time, the bacteria entered cheese naturally as the fermenting milk curds sat around in a cave somewhere. Different bacteria thrive in different environments, so each geographical area produced a different-tasting cheese. Today the bacteria on the hoof have been replaced by cultured strains that are careftilly introduced into the milk or milk curd.
Cheese starts out like yogurt, with bacteria and enzymes added to milk. But with yogurt, the fermentation stops after the bacteria have turned the milk sugar into lactic acid. This results in a product that is soft and unsmelly. Left to their own devices, the bacteria then start fermenting the milk proteins and fats, and here's where cheese’s distinctive smell comes from. Among the byproducts of the fat breakdown are the same molecules released by bacteria living on human skin, which explains why the smell of cheese often reminds people of the smell of grubby feet. One out-of-control poet actually dubbed Camembert les pieds de Dieu, the feet of God. Apparently the ultimate compliment to the reeking French fromage.
Once the starter bacteria have clumped together the molecules of casein, protein, and fats into a soft, lumpy substance called curds, the watery liquid (whey) is drained off and the curds are handled in different ways, depending on the kind of cheese being made. In the case of string cheese and many other semi-hard and hard cheeses, the curds are “Cheddared,” that is, they are cubed and piled together to force out more whey. The casein molecules, which have clotted together, form chains that fuse into thick, smooth fibers, all running perpendicular to the pressure exerted on them. If you stop the manufacturing process at this stage, you have string cheese.
Most other cheeses are milled after cheddaring to break up the casein chains and make a finer-grained product. The milled curds have ripening bacteria added, the curds are put into molds, and they’re stored away to develop their characteristic texture and flavor. The longer they’re aged, the more the bacteria can work on the protein and fats, and the sharper, harder, and drier the cheese.
But like wines, cheeses have optimum aging times — anywhere from a few months to several years. Store them too long and they’re inedible. And the odds are that even the natural cheese you buy in the market has preservatives added to slow the bacterial growth (ripening) to a crawl and extend the shelf life. Only the most natural of natural cheeses will age gracefully once you bring them home, but those have probably been aged to their optimum point anyway, so you wouldn’t want the product to sit around for too long. And ripening takes place under very specific temperature and humidity conditions. Your refrigerator or kitchen counter probably wouldn’t do. So I say spend the few extra pennies for sharp Cheddar and make sure you get what you want.
The one product that won’t do anything but lie there is any kind of processed cheese or imitation processed cheese. Both of these products are made from ground natural cheese mixed with other ingredients, then rendered as sterile as a Band-Aid to last on the shelf nearly indefinitely. Kept long enough, they probably become one with the little plastic envelopes each slice is wrapped in and become even more inedible than they were originally.