Meat: cook fast or slow?

by Martin Zibauer

If slow, low-heat cooking makes for fork-tender ribs, why is a fine sirloin steak grilled quickly over an open flame? Wouldn’t braising be better? The answer—a very firm, leathery no—lies in how proteins react to heat.

Let’s start cooking. As the meat’s internal temperature reaches 120°F–130°F (49°C–54°C), one protein, myosin, starts to change. As it heats, the meat begins to firm up a bit, though it’s still juicy. Natural enzymes become very active, breaking down big, boring molecules (proteins, glycogen, fats) into smaller, tastier, more aromatic, and more tender ones. Your steak is rare.

From 130°F– 140°F (54°C–60°C), or medium-rare, heat starts to impede enzyme action, and more muscle proteins start coagulating. Though the steak is getting chewier, for many of us it’s a worthwhile trade-off for an extra-tasty, well-browned surface.

From this point on, surface browning (Maillard) reactions continue. Connective tissue, mostly collagen, surrounding the muscle fibres starts to shrink, wringing out moisture, while -muscle proteins get tough, dry, and compact. A steak will first be well done, then leather.

But with ribs, keep cooking, because around 160°F (71°C) another process kicks in. Though
the collagen is still shrinking, it’s also converting slowly to gelatin. In time, muscle fibres separate, so they feel tender (though in fact they’re not), and now-melted gelatin bathes each fibre strand in rich, velvety liquid. Mmm—pull-apart, juicy ribs (or shank, shoulder, brisket, osso bucco, pork hocks, or pot roast).

Still, why not cook a steak until its collagen dissolves too? Problem is, tender cuts have little connective tissue, so long, slow cooking will only make them chewy. Young animals also tend to have less of the tough connective tissue found in the old. On the other hand, slow cooking suits less-tender cuts and older animals by giving collagen lots of time to melt.

Published in the June 2009 issue of Cottage Life magazine.

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