I work in a restaurant which uses a lot of Parmesan cheese. We get the good stuff, the kind which costs a lot in the grocery store or cheese shop. Our line cooks shred pounds of Parmesan cheese every week, and about once a week, I beg for the Parmesan rinds, or "Parm butts," as we lovingly refer to them at work. People are always asking me why.
There are a few reasons. As we all know, wholesale beats out Whole Foods anyday, so I try to be as enterprising (read: cheap) as possible when it comes to this precious comodity. Our cooks use a coarse grater, and are on a time constraint. At home, I use a fine grater for light, fluffy shreds, and have more time to devote to my grating. As a result, I can get a lot of mileage from the cheese they leave behind.
But more than that, Parmesan rinds make a delicious addition to any number of things after all usable cheese has been grated from within: they are wonderful added to soups and stocks, they in fact make their own delicious stock when poached slowly, and they are also a great enhancer to all sorts of tomato sauces. Just throw the rind in and pluck it out before serving or canning. The flavor is subtle yet wonderful - it isn't overtly cheesy, just as Parmesan itself isn't overtly cheesy - it's rich, salty, savory and satisfying. Some might call this Umami.
Which brings me to my finer point: using typical Lisa logic with no concrete scientific evidence to support my theory, I believe Parmesan makes everything taste so wonderful because it contains large quantities of naturally occuring MSG - the largest occuring naturally, I believe. Now, don't freak out on me, folks. Your body loves MSG so much it creates it on its own - it also occurs in large quantities in breast milk.
So what have we learned today? Don't throw away those Parmesan rinds! They are very useful. You can acutally purchase them at Whole Foods, by the way, just in case you don't have unlimited access to them as I do - not in the regular cheese section but in the cheese cooler where they have the "lesser" pre-packaged cheeses. Happy eating!