Cheese Myth #957: "If there is only a small amount of visible mold on a cheese, it can always be scraped off and the remaining cheese salvaged."
Some supporters of this myth think that cheese cannot be ruined by mold because in some sense cheese is mold or at least is derived from mold. While it is true that molds are often used in cheesemaking, it is not a necessary ingredient.
Cheese is simply what you get by isolating the solid material in milk. Separating the curds (the solid part of milk) from the whey (the liquid part) most often begins with the addition of a starter culture to fresh milk. Starter culture is always a kind of bacteria, whereas mold is a kind of fungus. I think Myth #957 gains some of its support from the conflation of mold with bacteria.
In any case, starter bacteria is not even strictly necessary to cheesemaking. Its primary role is to increase the acidity of milk, so that the separation of curds and whey happens more quickly. Some quick and easy cheesemaking recipes bypass the starter culture and call for adding lemon juice to fresh milk to increase its acidity. This doesn't result in the best cheese, but it illustrates how starter bacteria is not absolutely essential to the process.
After curds are isolated from the milk, you've got cheese. The curds they can be cut, pressed or enriched with various additional flavors without molds ever entering the picture.
Molds do play an important role in the production of blue cheeses and soft-ripened cheeses like Brie and Camembert. Penicillium roqueforti, for example, is used in the production of Roquefort and other blue cheeses, and Penicillium camemberti and Penicillium candida are used in Brie and Camembert. (A different variety of Penicillium is used to produce penicillin.) Most types of cheese, however, do not require the action of any kind of mold.
In my early days as a cheese taster, I made the mistake of buying some blue cheese from an ordinary grocery store instead of from a specialty cheese retailer or an upscale grocer. Unsurprisingly, the cheese was nasty. Who knows how long it had been languishing in the display case. When I returned the cheese to the store, one of the workers was reluctant to give me my money back for the following reason: I complained that a blue cheese smelled and appeared nasty, but blue cheese is supposed to smell and appear nasty.
The grocery clerk's mistake lies in thinking that any kind of nastiness is appropriate in a blue cheese because allowing the cheese to mold is an essential part of its production. The fact is, however, that only a carefully selected strand of mold was introduced into the cheese--and this under closely monitored conditions. It is not the case that any old mold will do.
Some think of the growth of mold on cheese as a kind of controlled spoilage. One should not forget, however, that it is controlled rather than indiscriminate spoilage. Cheese Myth #957 fails to separate controlled spoilage from spoilage due to incorrect storage, refrigerator mold, bacteria or other foreign pathogens.
I don't think the 'controlled spoilage' motif is a very good one because 'spoilage' wrongly suggests destruction. The biochemical processes involved in mold growth on cheese, however, are productive. Baker's yeast (another kind of fungus) doesn't spoil flour and oil. It makes certain kinds of bread possible. Do the yeasts that turn grape juice into wine "spoil" the grape juice? Not if your intent is to make wine. In that case, it's an important part of the production process.
If you find a small amount of mold growing on a hard cheese (e.g., Cheddar, Parmesan), you can generally scrape it off and the cheese will be OK to eat. To some extent, then, there is a grain of truth in Myth #957. Unwanted mold on soft cheeses, however, is more of a problem. One reason is that the molds can more easily penetrate into the heart of soft cheeses than they can into harder cheeses. This causes spoilage from within that cannot be scraped away.
When buying soft or blue cheeses, there are several things you should look for. First, look for grey or pink discoloration around the edges. Fresh, unspoiled cheeses never display these colors. Also, look to see how many wedges of the cheese you want to buy are in the display case. Never buy one of the last wedges of a cheese round. In ordinary grocery stores, blue cheeses do not sell quickly. In fact, even at Premier Gourmet, where I buy most of my cheeses, the blue cheeses move rather slowly. In such a store, the last wedge of a blue cheese will likely be spoiled before anyone buys it. One nice feature of Wegman's grocery stores is that they put the date a wedge is cut on the label of the cheese.
Don't be afraid to ask the person behind the cheese counter to cut you a new wedge of cheese, even if several can be found in the display case. Also, feel free to ask them to remove an unwanted outside portion of a cheese round if it doesn't look like something you want to eat.
Finally, if you didn't already think America had enough pointless holidays, here is one more: October 9th is officially Moldy Cheese Day.