Cheese -- usually cheddar and jack, but sometimes more exotic combinations -- sold in plastic bags, already shredded (or grated) for your convenience. While "convenience" cheez products such as Velveeta have been around for quite some time, pre-shredded cheese appears to have emerged relatively recently. Thankfully, it is of rather higher quality than the former, and seems to contain a minimum of petroleum distillates.

Pre-shredded cheese, like many convenience foodstuffs, involves a tradeoff of price for ease of use. It costs more than the same quantity of cheese in a block or wedge -- but you don't have to use (and then wash) a cheese grater in order to have grated cheese on your salad, soup, or pizza. You also don't have to buy and mix several kinds of cheese in order to achieve taco cheese, pizza cheese, or any number of other combinations.

All this is well and good. However, pre-shredded cheese also involves another tradeoff, one that in my mind greatly imperils its value. The fate of all cheese is the fate of all flesh -- decay. When a block of Cheddar grows a small green spot or two, you can easily cut off the contaminated area -- or even trim all six edges if you're squeamish. But when a bag of pre-shredded cheese turns green, there's no "cutting some off" to save the rest; you have to chuck the whole bag. What a waste. (Moreover, pre-shredded cheese goes bad much faster than un-handled block cheese.)

Hence, my advice regarding pre-shredded cheese is to avoid it unless you are sure you're sure you'll use the whole bag within a few days. Stick to block cheese and the grater, or the food processor -- and avoid inadvertently contributing to the green-fuzz population.