Cooking science is the engine that powers advancements in food creation, whether that be on a technical scale – to create some new fancy sauce in a Michelin star restaurant – or on a manufacturing scale – to create a new way to prolong Twinkie™ shelf life. We create new recipes and cooking practices with the science of cooking methods, but often what we hear about cooking science is misleading, or sometimes even flat out wrong. Although incorrectly understanding why a cooking method works doesn’t make the method invalid, if we correctly understand them, we can invent new recipes and techniques in our own home. In order to make this clear, let’s take a closer look at an average weeknight meal to see what cooking science we may be misunderstanding.
Your dinner tonight will consist of some grilled chicken, rice, pasta, and a salad:
Grilled chicken, one of the most recognizable base proteins of an American meal, is best prepared with a marinade. A marinade is a mixture of flavor enhancers like acids, enzymes, fruits, spices, etc. which you submerge your meat into, allowing the meat to “soak” in all the flavors and arrive at a tastier, juicer product.
But this definition is at least vaguely misleading.
In an interview with The Splendid Table, Doc Willaby, editorial director at America’s Test Kitchen, had this to say about an experiment he performed with marination:
“We left [the chicken] in [the marinade] for 18 hours. After that time, the marinade had penetrated less than between 1-3 millimeters, which is less than a tenth of an inch...and that's after 18 hours. We took the chicken breasts, shaved off the amount the marinade had gone in – the outer three milliliters – and roasted them along with other chicken breasts that had not been marinated. We had people taste them. No one could taste any difference at all.”
Although this contradicts the idea that the marinade soaks into chicken to make it juicier and more tender, his conclusion that “marination does nothing” is wrong.
In Discover’s article “Science of Marinades,” author Catherine Hu details marinade science when she spells out that “Acids, such as lemon juice or vinegar, work by denaturing proteins through disruption of hydrogen bonds in the collagen fibrils [...] Enzymes increase the rate at which cellular reactions occur, and certain enzymes help attack the protein networks of tough meat.” Enzymes and acids are both integral components in marinades because they "denature" or unravel proteins. This denaturation tenderizes the meat and allows the other flavors from the marinade to become locked in the protein network when the chicken is cooked. This makes the outside of the chicken explode with the flavors in the marinade, and it relaxes the meat inside, delivering a softer, juicier bite. I often eat the outside of my chicken with the rest of it, so marination is key in my chicken preparation. If you want to shave the outside off, I'll leave it up to you to marinade or not.
Nothing hits the spot better than some nice seasoned rice to give you a break from the intense flavors from your marinated chicken, but at the very first step, you face a dilemma: “should I wash my rice?”
The simple fact of the matter is if you live in a country with rigid sanitation procedures, like America, the rice you buy from the store doesn’t need to be washed from a sanitary perspective, but that doesn’t mean there aren’t reasons to wash your rice.
The decision to wash rice depends heavily on culture. For example, East Asian dishes almost always call for the washing of rice, but in dishes for other cultures, like risotto in Italy and paella in Spain, you are not supposed to wash the rice to maintain a cohesive texture.
Rice grains are often coated in a thin layer of starch as a result of the milling process, and washing rice effectively washes away the starch that coats the rice. As with cornstarch, wet starches create a gooey, kind of creamy smooth texture. This network of watery starch binds the rice grains together, creating clumpy, creamy, smooth rice. The lack of this network from washing the rice results in separate dryer grains of rice.
Washing rice is, if you live in a country with rigid sanitation procedures, a matter of preference. Do you want a smooth, gel-like consistency, or do you want clearly separated grains? It's up to you.
You are excited for the seemingly easiest part of the meal, but you’re running out of time. The pasta box says 6 minutes in boiling water, but “that’s a waste of time,” you say, “can’t I just put in the pasta now, before the water boils?” You know your Nonna would disown you if you even thought about it, but does that mean it's not valid?
In his book The Food Lab: Better Home Cooking Through Science, Kenji Lopez-Alt investigates this question: “Is it actually even necessary to boil the noodles the whole time? I covered a pot of penne with water by a couple inches [...] seasoned it with a bit of salt, and set it on a burner [...] When the timer finally went off [...] The pasta sure looked cooked, and tasting it revealed al dente perfection.”
According to Lopez-Altz, you don’t need to wait for the water to boil because of the inevitable diffusion of heat from the water to the pasta. But he caveats his findings to exclude fresh egg pasta, which needs the egg to cook in the boiling water. Besides that, he finds no difference. That being said, other sources do claim a gummier texture materializes in pasta cooked in non-boiling water. Both sides of the argument could just be tasting what they want to taste, but nonetheless, the answer isn’t as clear cut as some may think and is definitely worth individual investigation.
There’s only one more thing to make before you can sit everyone down for the meal: the salad. This is something you can whip up in one or two minutes, but it still requires consideration. You don't want your salad to arrive on the table terribly wilted and drenched in dressing, and you’ve always heard that it's the acid/vinegar in your dressing that causes the wilting. You consider making an oil-based dressing because it'll prevent wilting. But is this really true?
Leaves are coated in an oily layer on their exterior to protect them from rain/contaminated water, and breaches in this oily layer cause wilting. For the same reason the polar (unevenly charged) water molecules can’t dissolve in nonpolar (with an even/no charge) oil, nonpolar oil can dissolve into other nonpolar oil. Thus it is not acid/vinegar that causes wilting but the olive oil that penetrates through the leaf's oily barrier. Salad leaves coated in oil will wilt much faster than those coated in vinegar, but how do we get the flavor of the oil into the dressing without wilting the leaves?
The answer is emulsification. If we were to just combine the vinegar and oil, they would immediately separate as they went into the salad with the oil wilting the leaves and the vinegar falling to the bottom. We want to create an emulsification which is a semi-stable mixture of two substances. Since oil and vinegar repel each other, we need to find a common ground between polar and nonpolar, something that can attract both oil and vinegar to keep them together on the leaf.
Most effective salad dressings incorporate an emulsifier, like egg yolk, mustard, honey, or mayonnaise. These ingredients all have molecules that at are polar at one end and non polar at the other, which prevents the oil and vinegar from repelling each other, resulting in the viscous, luscious texture achieved in a well-crafted emulsified dressing. Since we know the cause of wilting, we can prevent our spring mix salads and green bowls from turning into an embarrassing, dressing-at-the-bottom, wilted mess.
If we maintain our misconceived notions about cooking science, we will probably still get good results by following methods and recipes. That being said, the doors that open to us when we understand the chemistry that goes into the most basic dish allow us to create our own recipes or modify existing recipes/techniques. For example, learning how acids denature proteins in chicken may lead us to consider what they do to proteins in egg, steak, or fish, prompting our next experiment. Cooking without understanding the chemistry behind it is a bit like reading the rules to Monopoly and then going home. Sure you can understand the step by step principles, but you haven’t yet played the game. Furthermore, there’s no right way to play the game. We all need to consider and experiment until we find what yields the best results for us.