Thanksgiving Part 3 — Turkey

A while back, before I retired from the Division of Nutritional Sciences at Cornell University, I helped write answer for a nutrition Q&A website that we called Nutriquest. Was looking over my files and found a four-part series I wrote for Thanksgiving. Here is the third part, lightly edited.  The final part will be posted tomorrow.

  The turkey—shown here shoving the bald eagle off our national shield—is truly the US national bird for at least one day a year—Thanksgiving Day. We take the opportunity to pass on some information about turkeys, both historical and nutritional, and tell you about our (rather complicated) way of ensuring that you don't hear anyone say at your Thanksgiving feast: "The turkey is good, but it's a bit dry."

The turkey, our national bird?

Ben Franklin proposed that the wild turkey become our national bird, but the bald eagle (the only eagle native to North America) was chosen instead. People of European descent, as well as Native Americans, were used to considering eagles symbols of bravery—the wild turkey was ungainly and far too secretive. In fact, the wild turkey is a very clever bird, with extraordinary eyesight and the ability to run very fast for short spurts, and to take off into flight in an almost vertical rise—an amazing sight! That's why Native Americans considered he turkey one of the hardest game to catch.

But catch turkeys we did in North America, to the extent that the population dwindled from 10 million when Europeans first arrived on these shores, to 30,000 at the dawn of the 1900's. Hunting bans and efforts at growing and releasing wild turkeys have yielded one of the few bird conservation success stories—along with the success story of the official bird, the bald eagle!

To learn more about wild turkeys, the page on wild turkeys in Matt Miller's blog on nature (written for the Nature Conservancy) called Cool Green Science will give you amazing information.

And to learn more about the wildlife conservation measures to rescue the turkey, visit http://www.nwtf.org/conservation — the National Wild Turkey Conservation Federation site.

By the way, take a look at the face of a wild turkey: its neck and head are red, white, and blue, the colors of the American flag—perhaps Ben Franklin was right!

Turkey portrait. Photo by Peter Lloyd on Unsplash

Where does our domestic turkey come from?

Surprisingly, North American domestic turkeys are not descendants of the wild turkeys that once wandered the plains and wood edges in such vast numbers...and are doing so again. Instead they are descendants of the domestic turkeys of the Aztecs in Mexico.

These domesticated turkeys were brought to Europe in the 16th Century, well before the Pilgrims came to North America in 1620. The turkeys made their way from Spain to France and then to England, where they were gained the name "turkey" for reasons that are not clear. Some say the name came from the "tuke-tuke" sounds that the turkey can make. Others claim that it was the bird's exotic look, coupled with the fact that it was newly arrived from far away—Turkey was thought to be the source of all things rich and strange, and especially anything extravagant in appearance. The French, who passed the bird on to the English, called the bird "dinde" or "dindon" which means "from the Indies"—where people thought Columbus had gone.

The first domestic turkeys were brought to North America in 1607 by the English colonists in Jamestown. I was not able to determine whether the Pilgrims brought turkeys with them from England—if any of you knows the answer, please let us know!).

Domestic turkeys have been subject to extensive breeding and inbreeding, so they have lost the wiliness that enables their wild cousins avoid capture—the idea that a turkey is dim-witted comes from observations of the domestic version; as you can imagine, dim-witted turkeys are much easier to raise...they don't cause any fuss.

Does turkey meat have nutritional value?

Like all meat, turkey meat has the appropriate complement of amino acids to maintain you in good amino acid balance (a topic we discussed yesterday in connection with succotash).

Turkey has less fat than chicken, and less cholesterol, but also less vitamin A. Dark meat turkey has double the amount of iron of dark meat chicken -- which is why dark turkey meat is much darker than dark chicken meat. Light meat turkey, by contrast, has less iron than light meat chicken.*

All in all turkey is a good substitute for chicken, and is a particularly good meat to eat when you want to keep your fat and cholesterol intakes down. You may have noticed that many of the low-fat varieties of sausages and luncheon meats are made with turkey instead of pork or beef. It's not just a question of price.

Are there other important properties of turkey?

Do you fall into a pleasant stupor after Thanksgiving dinner? There is reason to believe that this stupor may be due to the tryptophan content of the turkey, coupled with the high carbohydrate content of the rest of the meal.

In the brain, tryptophan is converted to an important chemical, serotonin, which together with other chemicals is responsible for mellow feelings and sleepiness. But to get into your brain from your food, tryptophan has to cross the blood-brain barrier, which limits the transfer for nutrients from the bloodstream to the brain. There are only a limited number of channels through which tryptophan can be transported across this barrier. Other amino acids compete for passage through these channels, so if other amino acids are present in large quantity in the blood, not as much tryptophan will get into the brain.

If you eat carbohydrates and protein, however, you may get more tryptophan across. The carbohydrates and proteins cause you to secrete insulin into your blood stream. Insulin moves both sugar (glucose) and most amino acids into the body's cells, leaving tryptophan behind. So after Thanksgiving dinner, the levels of tryptophan in your blood are high relative to the levels of the other amino acids, and tryptophan moves more readily into the brain. Thanks to the tryptophan, and most likely to other chemicals and hormones that make their way to the brain as well, we feel full, content and sleepy...and we don't want to eat any more!

This effect is probably not unique to turkey -- chicken has as much tryptophan as turkey, and so do beef and pork, but vegetables or fruits do not have nearly as much tryptophan. So these feelings are probably an effect of meat in general, coupled with a large carbohydrate-containing meal.

So turkey is good for me -- now how do I cook the turkey?

There are as many recipes for turkey and ways of cooking turkey as there are cooks on Thanksgiving! There are dozens and dozens of websites with recipes for turkey, which you can find using your favorite search engine.

If you roast a turkey this Thanksgiving, we would like to remind you of a few food safety precautions, and then tell you how we roast our bird. First the safety precautions:

• Turkey, and all poultry and eggs, are potentially contaminated with Salmonella and Campylobacter, bacteria that can give you severe gastrointestinal problems with nausea, vomiting, diarrhea, and fever. For the very young, the old, and people with weakened immune systems, these bacteria can be deadly. So please:
• Handle raw poultry with care, and make sure that it only touches surfaces which you can clean easily, for example cutting boards which you can clean with salt and bleach or in the dish washer.
• Make sure that you do not use utensils that have touched poultry for any other purpose until you have thoroughly washed them.
• If you touch poultry with your bare hands, do not touch anything else (not even the faucet) before you have thoroughly washed your hands; if necessary, have someone else turn on the water for you.
• Be sure to clean all your work surfaces thoroughly after preparing poultry,
• ...and last but not least, make sure that the turkey or other poultry is thoroughly cooked before eating it.
• Stuffing, if warmed but not thoroughly cooked, can also be a health hazard due to overgrowth of bacteria in the warm moist environment, so please cook the stuffing outside the turkey. Your turkey will be better cooked as well. Instead, place herbs such as rosemary and sage, as well as a boiling onion or two, in the turkey cavity. 

And now for our roasting method, which we think results in a much juicier breast than traditional methods:

• First, with a baster, squirt a mixture of olive oil, salt and pepper (and if you like, crushed garlic and juniper berries) under the breast skin of the turkey, followed by a couple of sprigs of rosemary. Rub the surface of the turkey with the same mixture. Then place the turkey breast-up in a roasting pan and cook it in a pre-heated hot (425º F) oven for about 20 minutes. This heat starts to cross link the skin proteins and to form delicious Maillard browning products, made by the joining of sugars and proteins in the skin. Turn the heat down to 325ºF, and take the turkey (which should be starting to become a golden brown) out of the oven, and turn it so that it is breast-down. 
• Note: if you have some string netting or a turkey rack under the turkey, it will make turning the turkey easier—I use both. Also, always take the turkey out of the oven to turn it and be VERY careful!—this decreases your chances of burning yourself. The fact that the cavity is empty also helps because I can stick a large item such as a barbecue fork inside to help steady the turkey. I usually enlist a helper to hold down the pan and one to help turn the turkey—a process accompanied by much laughter as it isn't easy with a large turkey!
• Also a non-stick pot or rack will make life a lot easier; if you don't have one of these, be sure that the pot or rack has been treated with fat spray or olive oil (our preference for health reasons), or is spread with a thin layer of butter. But even if the skin sticks, the turkey may not be so beautiful but it will still taste superb!  
• Put oil or butter in the pan and place the turkey back in the oven and cook until very nearly done. If I am using a rack (recommended), I also add some broth to the pan. Because the breast is down, the juices will run into the breast, so the breast will taste very moist. Be sure to baste the turkey regularly—at the risk of prolonging the cooking time I baste every 15-20 minutes. If you have omitted stuffing the inside of the turkey, the upside-down position will allow you to baste the body cavity easily as well. 
• Another thing: about 1.5 hours before the end of cooking, I place carrots, halved boiling onions and halved boiling potatoes in the pan around the turkey, and add some more broth, and (I'll admit it here) some butter. Not only do the veggies taste great on their own, but they also add flavor to the basting juices.
• If you like (and we do) you can put cheesecloth on top of the turkey instead of the tin foil most people recommend. We dribble a generous amount of olive oil on top, but you can use pats of butter which will melt—just make sure the cheesecloth is soaked with oil/butter and turkey juice and baste this too. That way the cheesecloth also helps keep the bird moist.
• When it looks like the turkey is almost done, take it out of the oven, remove the cheesecloth, and very carefully place the turkey back in the standard breast-up position—again, helpers usually needed.
• Cook the turkey in this position until it is throughly done, basting regularly, and most of all...

...Enjoy!

And before we leave the topic of turkeys, you might want to learn how the turkey may (or may not) have saved the tambalacoque tree.

More tomorrow!

Please note: the information contained in this blog is for interest only, and does not constitute recommendations for health or any other purpose.

* For those of you curious as to why this might be the case, the reason lies in what the turkey and the chicken do in a day. The darkness and redness of any meat comes from the presence of myoglobin, a protein that contains iron. Myoglobin catches oxygen from the blood stream, and releases it to the muscle as needed for use by its contractile machinery.

Muscles that are used for posture, for example for standing and walking around for long periods of time, need to contract constantly and therefore need a large and steady supply of oxygen. Turkeys are much heavier than chickens and they stand and walk around most of their waking hours, so their leg muscles are well endowed with myoglobin. By contrast our commercial chickens don't stand and  don't walk around, so their muscles don't need much myoglobin.

Our domestic turkeys may stand and strut, but they don't fly around, so they don't need much myoglobin in their breast muscles. In fact they have been bred to have large breasts with very low myoglobin content, because people expect turkey breasts to be white, not pink. Furthermore, the older the bird, the darker the breast meat, so turkeys are bred and fed to grow quickly, before their muscles can accumulate much myoglobin.