Happy thanksgiving everybody! It’s my favorite holiday ever, because it’s a chance to celebrate food and family. We just eat, hang out, eat, hang out, eat, drink wine, and hang out. But, there’s also a lot of science to this celebration, so here are some highlights:
Does Turkey make us sleepy? I’m sure that you’ve heard the claim that the tryptophan in Turkey is what makes you feel lethargic after the meal. Tryptophan is an amino acid that we have to eat, because our bodies can’t produce it, and it functions in the production of niacin, vitamin B3. Niacin plays a role in serotonin production, and serotonin helps us feel happy and relaxed. However, do we feel happy and relaxed after Thanksgiving dinner from consuming all of that tryptophan? No. We feel happy and relaxed from over eating, having time off work, and enjoying the company of family and friends. Turkey only contains similar amounts of tryptophan as many other foods, like chicken, or milk, or fish, and we don’t get sleepy after eating chicken. While you are feeling fat and happy on the couch, considering a nap, the tryptophan is still in your stomach, trying to absorb into the bloodstream slowly, which means it can’t be affecting your serotonin levels just yet. Over course, none of this means that you shouldn’t take a nap after dinner.
Why do people brine their turkeys? Serious foodies are serious about this one, recipes for soaking the big bird overnight in a salt water and spice solution will supposedly enhance the moisture and flavor of the turkey. The meat cells absorb more water while in the brine, so that they can retain more moisture during baking. It’s a diffusion process on the cellular level, and it starts with the salt. The brine is much saltier than the meat. Remember back to text book diagram of more salt ions on the outside of the cell’s permeable membrane, and fewer inside? The salt ions will diffuse across the membrane into the cell to try to balance the solutions.
Then, the increased salt concentration in the turkey’s muscle cells causes the myofibrils, the main structural component of muscles, to swell. When these fibers swell, the amount of water that is held between the thick and thin filaments increases as well, through capillary action. Studies have shown that a turkey’s weight can increased 10 percent through water absorbed during brining, and that moisture holds on through the hot, drying oven conditions.
Why do onions make you cry? We slice and dice a lot of onions on thanksgiving morning for my Dad’s famous stuffing, and we always tear up in the process, even on this, most joyful day of the year. The onions’ tear-jerk tendencies begin to form when the onions absorb sulfur from the soil. The bulbs form amino acid sulfoxides. When you chop up the onion, the cut tissues release lachrymatory-factor synthase enzymes. These enzymes react with the sulfoxides to produce a series of reactions that result in sulfuric acid production. The sulfuric acid floats up to our eyes and produces a tear-response. We cry to rinse particles or acids out of our eyes. A protien, TRPA1, causes the initial pain and tear reactions to encourage you to move away from the dangerous acid exposure.
Obviously, questions remain. What makes stuffing a complete food source? What is the different between sweet potatoes and yams? Why is pumpkin pie better for breakfast? Can you actually employ a second stomach to make more room for second helpings? What temperature do you actually have to cook a turkey to to be safe from salmonella? Should the stuffing go in the bird or in a casserole? What are the physics of gravy? I’ll write more after I get cooking…onions need chopping for the stuffing 🙂 Happy Thanksgiving!!