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After 14 seasons on the Food Network, Alton Brown announced the end of his Good Eats series in May. While I am disappointed that there will be no more new shows to look forward to, the nearly 250 episodes already produced will keep me going for some time. (The last two seasons are available on iTunes, earlier episodes are on DVD, and the Food Network airs reruns every day.)
As a science educator and food enthusiast, I appreciate Alton Brown's approach to cooking and cooking shows. He explains the science behind the recipes and cooking techniques, rather than just telling viewers to follow the steps he prescribes. I find knowing the context and reasoning behind a recipe helps me remember it better, and gives me the flexibility to improvise in the kitchen (either when something goes wrong, or when I am missing an ingredient). His goofy sense of humor and silly props are just the sort of thing physics teachers like me find irresistible. Though sometimes a bit oversimplified, his science is generally strong. Brown has covered everything from grilling to making biscuits, from ginger to cinnamon, and has produced several episodes devoted to chocolate.
I will look closely at an episode from season 13, The Ballad of Salty and Sweet, during which Brown explains some of the chemistry behind adding salt to foods as a flavor enhancer. (In two earlier episodes, he explained the use of salt as a preservative in pickling, which is another very important part of the history of food science.) I must point out that a chef's definition of "salt" is not the same as a chemist's. For cooking purposes, "salt" generally refers to sodium chloride, while a chemist uses the term for an ionic compound formed when an acid and base neutralize each other. Sodium chloride is just one of many compounds chemists call "salt." Potassium chloride (a salt substitute prescribed for people on a low-sodium diet) is just one such chemical salt.
The set of Good Eats on the Food Network.
Brown explains salt is more effective at counteracting bitter flavors than sugar for a very good scientific reason. The chemical receptors on our tongue that sense flavor (sweet, bitter, sour, and salty) have some surprising chemistry. Receptors for sugar are entirely independent from those that sense bitter compounds, so your tongue and brain can sense both at the same time. If you want to mask a bitter flavor with sugar, you have to use a lot so the sweet signal overwhelms the bitter signal. When you ingest salt, the sodium and chloride ions dissociate in your saliva, and your tongue recognizes the sodium ions as tasting salty. The receptors for bitter can be blocked by sodium ions, meaning that you will detect fewer bitter compounds in the food if you have also eaten some salt. Sodium also appears to enhance sweet and sour signals, so the intensity of those flavors is increased by adding salt. Brown demonstrates this application of chemistry in a recipe for grapefruit with melted sugar and salt topping. I haven't tried it yet, but it sounds great.
Candy making is another exacting science in the kitchen. The temperature of a sugar solution needs to be carefully controlled to determine the final product you will achieve. Dissolve a sugar such as sucrose in hot water, and it will form crystals as the water in it evaporates. (Rock candy is an example of really big sugar crystals.) A cook often does not want crystals, though, so something must be done to disrupt the crystal lattice when the sugar cools. Introducing impurities is one easy way to inhibit crystal formation. This explains why many candy recipes call for a combination of table sugar (sucrose) and corn syrup (mostly glucose and maltose). With three different sugar molecules in the solution, it is unlikely that any large crystals will form. Many recipes also call for cream of tartar (potassium bitartarate), which also helps to inhibit crystal formation. In this episode, Brown takes advantage of both techniques in his recipe for salted caramels at home, which is a good way to save $2 per piece for artisanal candy.
Many episodes of Good Eats feature guest appearances by food experts, including Shirley Corriher, a biochemist who has written a book about the science of cooking called CookWise: The Hows and Whys of Successful Cooking. Click here to watch Corriher discuss a few examples of how knowledge of chemistry will make dinner both look and taste good.
For middle school physical science teachers and high school chemistry teachers, Good Eats provides an excellent way to connect science to students' everyday lives in the kitchen.
Jacob Clark Blickenstaff is teacher education programs manager for the American Physical Society. He can be reached at firstname.lastname@example.org.
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