Gleanings for Thanksgiving: turkeys and sweet potatoes

From a quick survey of recent advances in turkey science, it looks as though producers still have a lot to learn about processing their birds to give them the best cooking qualities--so that cooks have at least a fighting chance of making a tender, succulent roast.
After being slaughtered, eviscerated, and plucked, turkeys are generally immersed in chilled water to bring down their temperature rapidly and limit the growth of bacteria. The wet chill certainly improves the bird's shelf life. And by slowing down the enzymes that consume glucose for energy, it prevents the muscle cells from accumulating lactic acid and releasing fluid, a defect known as "soft exudative" meat.
But it also adds a substantial amount of water to the carcass, which makes it harder to crisp and brown the skin. And it also appears to eliminate the chance for the turkey's own muscle enzymes to tenderize and flavor the meat, as happens in the aging of beef. Scientists at Lincoln University in Canterbury, New Zealand found that rapid and prolonged chilling doesn't just slow down the tenderizing enzymes: it prevents them from acting at all. The result is "significantly tougher meat" than would be obtained if the enzymes retained some activity.
In the case of beef, cooks can compensate for inadequate aging by holding the meat for an hour or so at body temperature and giving the enzymes a chance to work much more rapidly than they can in a cold meat locker. This is one of the several benefits of cooking roasts slowly. But this kind of accelerated aging would be risky with chickens and turkeys, which have higher loads of bacteria both on the skin and in the body cavity: a temperature that encourages bird enzymes also encourages microbes. And it's not clear that the bird enzymes survive rapid and prolonged chilling.

So it's great to have more flavorful "heritage" turkeys making a comeback. Let's also figure out how to make them, and the rest of our birds, as tender and tasty as they can be.

F. Obanor et al. Effect of processing on turkey meat quality and proteolysis. Poultry Science 2005: 84, no.7, p.1123-1128.


Now a side dish. It may be that the sweetness which gives sweet potatoes their name involves more than just ordinary sugars. Chemists at the University of Naples have found that, in addition to being rich in maltose--a sugar made up of two glucose molecules--sweet potatoes contain unusual "aminoacyl sugars." These are molecules that combine a sugar (here sucrose, or table sugar) with an amino acid. In the past, chemists have synthesized similar molecules in the laboratory and found that some had a sweet taste. If the sweet-potato types do as well, then they may find use as natural and probably low-calorie alternatives to the sweeteners we now extract from cane, beets, and corn.

I. Dini et al., J Agric. Food Chem. 2006: 54, 16: 6089-93.