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My last blog post answered a bunch of questions about why we do what we do in baking. But there is a whole other set of "why do we..." questions that pertain to cooking. This post will try to answer some of them for you!
Why do I have to brown meat like chicken or steak before putting it in the oven? And why do I have to do it in a cast iron pan?
What is it about the crispy, golden brown crust on meat that makes it taste so good? Or the golden brown of a perfectly-baked cookie or loaf of bread? It's due to something called the Maillard Reaction. The linked video is a more complete explanation, but the TL;DR version (or is it TL;DW when it's a video?) is that heat triggers a domino effect of chemical reactions within the meat resulting in that wonderful golden brown color, crisp crust, and tantalizing aroma. In foods with a high water content, like meat or fresh vegetables, the moisture makes it difficult for the surface of the food to get hot enough to trigger the reaction without also overcooking the interior of the food. This is why it's important to pat dry foods like meats and fresh vegetables before you sear or sauté them, and also why it's important to sear at a high temperature. Cast iron pans are best for searing, as they are especially good at retaining high heat and spreading it evenly across the pan, and they can also go directly from the stovetop into the oven.
In addition to increasing the heat, there are several other ways to speed up the Maillard Reaction. One is to raise the pH of the food, or make it more basic. For example, pretzels and bagels are dipped in a solution of baking soda and water before baking, resulting in a beautiful golden brown, slightly crispy crust and a chewy, tender interior. (Sourdough, on the other hand, has a naturally low, or acidic pH, which gives it its distinctive tangy flavor, but also keeps its crust paler than most other types of bread.) Another way to speed up the reaction is to add a little extra sugar and/or protein to kick-start the process. Some examples of this are the egg wash on breads such as challah and the yogurt or milk coating on chicken satay.
Fun Fact: The Maillard Reaction also happens at room temperature (just MUCH more slowly) and in non-food items. It is responsible for the rich brown color of things from self-tanners to aged balsamic vinegar to slow-roasted coffee beans.
Speaking of color, why does blanching keep vegetables a brighter color than other kinds of cooking?
Blanching is a quick cooking technique, used mostly with vegetables, in which a food is partially cooked by immersing it briefly (usually for a few minutes) in boiling water and then "shocked," or plunged into ice water to halt the cooking process. It can also be done with steam and cold air. Many fruits and vegetables contain enzymes which cause them to brown, change texture, and lose flavor and color during storage or cooking; blanching quickly deactivates those enzymes, which keeps more of the food's original flavor, texture, and color. In addition, blanching forces out air trapped within the plant's cells, which also helps maintain color and improve texture.
Blanching is sometimes followed by another cooking method, such as sauteeing or roasting, or it may be used as a prelude to freezing or canning.
Fun Fact: Fruits, including peaches and tomatoes (yes, they really are a fruit), are sometimes blanched, not to cook them, but to loosen their skins for easy peeling.
What is the difference between "herbs" and "spices"? Can I substitute fresh for dried herbs and vice versa? Do herbs and spices expire or go bad?
Herbs and spices all come from plants; the difference between the two categories is simply what part of the plant they come from. Herbs come from the leaves or occasionally the stems; spices come from the seeds, bark, roots, flowers, or fruit. Examples of herbs would be basil, oregano, rosemary, and thyme (all leaves). Examples of spices would be cinnamon (bark), nutmeg (seed), ginger (root), and cloves (flower).
When you dry herbs by removing the water, they generally lose about 2/3 of their volume. So, unless your dried herbs are old and have lost some flavor, you need about 3 times the volume of fresh herbs as dried ones. So if your recipe calls for 1 teaspoon of dried oregano, you'll need 1 tablespoon (i.e., 3 teaspoons) of fresh oregano. And if it calls for 2 tablespoons of chopped fresh parsley, you can use 2 teaspoons of dried parsley instead.
Herbs and spices don't expire, exactly - as long as they're stored properly and kept dry, they won't "go bad" or grow mold - but they do tend to lose their flavor, aroma, and color over the course of time. In general, whole spices (things like peppercorns, whole nutmeg, and cinnamon sticks) will retain close to their original potency for 2-4 years, whereas ground spices (things like cumin, coriander, and ginger) are good for 1-3 years. Dried herbs will also keep for about 1-3 years. If you're not sure, smell and taste before you use it, and smell and taste again after you've added it to your food. Most herbs and spices should be adjusted to taste anyway, so if you want more of the flavor, just add more herbs or spices!
How do I know when a piece of meat is rare, medium, medium-well, or well done without cutting into it? How can I tell when chicken, pork, or fish is done?
The easiest and surest way to know when a dish is at your preferred done-ness is to use a kitchen thermometer and a temperature chart. Poultry, pork, and seafood can carry diseases, bacteria, and parasites (salmonella, norovirus, and E. coli, for example) and need to be cooked to a safe temperature; red meats like beef and lamb are usually cooked to either the cook's or the diner's preference (within reason; many restaurants will refuse to prepare either a blood-rare or an overly well-done steak, as the latter will ruin the steak and the former could ruin the diner).
Fish is the easiest to tell when it's done: The flesh should be opaque rather than translucent, and it should flake easily with a fork. But you can also use a kitchen thermometer to be sure.
Why do I have to "let the meat rest" after it comes out of the oven? Shouldn't I serve it hot straight from the oven?
As meat cooks, the juices are drawn to the center (coolest part) of the meat. When it is removed from the heat, the muscle fibers relax, which allows the juices to redistribute evenly through the meat. The relaxation of the fibers also makes the meat more tender. In addition, the meat's own heat will continue the cooking somewhat, so slicing the meat before it has rested can result in underdone, dry, tough meat. You can cover meat and skinless poultry loosely with foil to keep it warm while it rests, but skin-on poultry should be left uncovered to retain the crispness of the skin.
Why is seafood often served with lemon?
There are a few reasons. Firstly, fish and shellfish tend to be high in fat, creating a richness that is nicely complemented by the acidity and brightness of lemon. Lemon also tends to mask the sometimes unpleasant "fishy" or "briny" (or simply "strong") aroma of certain kinds of fish and other seafood. Lemon juice also contains citric acid, which breaks down seafood proteins, enhancing the texture.
As mentioned in my previous entry, the four components of delicious food are salt, fat, acid, and heat. Lemon juice, being acidic, becomes the acid component of a seafood dish which usually already includes fat and salt from the fish, and heat from the oven or grill. In the case of ceviche, the acidity of the lemon even stands in for the "heat" component, by slowly denaturing the proteins in the same way that heat does.
Why do we salt the water for pasta? Do I have to start with cold water? Why do some people rinse pasta in cold water when it's done cooking?
Although some people claim that salting the water makes it boil faster, there's not really enough salt in the water to make a noticeable difference, and if there was, it would actually raise the boiling point, taking longer to boil but admittedly cooking the pasta at a slightly higher temperature. What it really does is add flavor. The pasta absorbs salt while it's cooking, which seasons it throughout each noodle, not just on the outside. It's best to wait to add the salt until the water is already boiling, which will help it dissolve completely and spread evenly through the water and therefore the pasta. When the pasta is done cooking, drain it thoroughly, saving a little of the water, but do not rinse it unless your pasta is destined for a cold dish like pasta salad! The cooking process releases starch from the noodles, leaving a thin coating of sticky starch on the cooked noodles. This stickiness will help sauces from marinara to alfredo to adhere to the warm noodles, but if the noodles will be chilled before dressing is added, they will stick to each other and clump together if not rinsed. If you are making sauce to go with your pasta, you can use a few tablespoons of the starchy, salty pasta water instead of plain water to thin or stretch the sauce.
As for starting with cold water, it doesn't matter if you start with cold or hot water if you wait until the water is boiling to add your pasta. But many chefs, including Alton Brown, prefer to cook dried (as opposed to fresh) pasta via the "cold start" method, which begins with the pasta in a pot with a smaller amount of cold, salted water which is then heated to boiling and allowed to simmer for only about half as long as the standard method. The resulting pasta water is starchier and therefore even better when added to a sauce, and this process takes a little less energy, water, and time than the standard method.
How can I chop an onion without crying? Do any of the old wives' tales work - holding a piece of bread in your mouth or leaving one next to the cutting board, cutting under running water, chewing gum?
None of those methods have been proven to be effective. There are a few helpful techniques that minimize tears, however. The most important thing is speed, and the most important component of speed in this case is a really sharp knife. With a very sharp chef's knife, you can use Julia Child's method: cut the peeled onion in half from root to tip, lay one half on the flat side, then make a series of thin, parallel slices that don't quite reach the tip, then make a series of slices parallel to the cutting board, and finally cut across the onion starting at the tip and moving towards - but not quite reaching - the root, then repeat with the other half. This technique is extremely difficult if your knife isn't very sharp, but a with a well-sharpened knife the whole process will take you about 2-1/2 minutes and your eyes won't even have a chance to water. In addition, since the root has the highest concentration of sulfuric compounds, the substances that irritate your eyes, leaving that section uncut (or at least cutting it last) will also minimize tearing.
Another method that I like is to cut the onion into chunks and use a food chopper (aka, Slap-Chop) to finish dicing. As long as you check through the chopped onions to make sure there aren't any big pieces left, it works quite well - and it's an extremely satisfying stress reliever, to boot.
What does marinating meats do? How do I know how long to leave the meat in the marinade?
Marinating meats serves two purposes: to tenderize, and to add flavor. Marinades usually contain an acid (like citrus juice or vinegar) which breaks down the meat proteins to make it more tender, seasonings like salt and herbs or spices, and an oil which helps transfer fat-soluble flavors from the seasonings onto the surface of the meat. The longer the meat is in the marinade, as well as the warmer the temperature, the more the marinade will break down the fibers in the meat. For this reason, more delicate meats like fish marinate for only 15-30 minutes so they don't become mushy, mid-range meats like chicken marinate for 2-4 hours, and denser meats like beef, pork, and lamb can marinate for several hours to overnight, although even shorter marinade times can make a major difference in flavor and tenderness. Meats of any kind should not marinate at room temperature for more than two hours, so most marinades should go in the fridge.
In addition, the marinade that remains on the surface when the meat goes into the pan, onto the grill, or into the oven forms a caramelized, flavorful crust.
Why do recipes like sauces and stews often start with melting butter and then stirring flour into it?
A mixture of equal parts of butter (or occasionally another fat, such as ghee, lard, or vegetable oil) and flour is called a roux (the French word "roux" can be roughly translated as "auburn;" i.e., a rich golden or reddish-brown color), and serves as a thickening agent for many sauces and soups, particularly creamy, dairy-based ones. The melted butter combines with the starch granules in the flour, which swell and burst, creating long amylose chains that act as thickening agents. In addition, the Maillard Reaction occurs, developing color, flavor, and aroma. The longer the roux cooks, the more intense the color, flavor, and aroma, although at a certain point the thickening ability begins to decrease as the amylose chains break down.
A so-called "light roux" (or "blond roux," which seems to be a distinction without a difference), which is removed from the heat when the roux is barely golden, serves as the base for the classic "mother sauces" béchamel, which adds milk or dairy to the roux; and velouté, which adds a clear stock such as chicken or vegetable. In addition, it serves as a base for many creamy soups, such as cream of broccoli, clam chowder, and vichyssoise, and in dishes like chicken pot pie and macaroni and cheese. A "dark roux," which is cooked for a significantly longer time, serves as the base for sauce espagnole (another "mother sauce"), which adds beef stock, tomato puree, and browned mirepoix (a mix of diced vegetables such as onions, carrots, and celery); as well as gumbo, gravies, beef stew, and shrimp étouffée.
Why do fancy chefs use a pizza stone when baking pizza and calzones? Can't I just use a baking sheet? And does it really matter whether I preheat it or not?
A pizza stone is a slab of ceramic or stone that your pizza sits on while it bakes. It serves to transfer heat directly onto the bottom of the crust for slower, more even baking. It's important to preheat the stone so the crust is immediately hit with high heat when it goes in the oven, creating a crisp base for the pizza. A good pizza stone is made of a porous material, which allows the steam from the moisture in the dough to be absorbed, further crisping the crust. A metal pizza stone or cookie sheet that has been preheated will have some effectiveness in creating a crispy crust, but not as much as a quality pizza stone.
Why are you supposed to use chilled, day-old rice to make fried rice? Why do some people rinse rice before they cook it? How do I know whether to use long-grain, short-grain, brown, jasmine, sushi, sticky, basmati, etc.?
Fresh rice is moist and somewhat sticky, two traits that are not ideal for making fried rice. You want the individual grains to separate and be coated with the sauce, and to fry to a nice, crisp texture, which cannot happen if the rice is clumped together or overly moist. When rice is chilled, the starch molecules degrade and harden, making it firmer and less sticky, and day-old rice dries out a bit, so the grains separate more easily when stirred.
Rinsing the rice before cooking, if done thoroughly until the rinse water runs clear, removes excess starch and also results in less sticky rice. For fried rice and most other Asian dishes, this is good. But if you're making a dish like risotto (which uses Arborio rice) or paella, you want that starch and its corresponding stickiness, so don't rinse.
As for what type of rice to use, here is a rundown of some common types of rice and their uses - and differences.
Long-grain: This is standard "white rice." It's light and fluffy, with a neutral flavor. It's good for fried rice, rice pilaf, casseroles, soups, and as a bed under Cincinnati chili, salmon, or Swedish meatballs.
Medium-grain: These grains are shorter and fatter than long-grain rice, and it is also somewhat stickier. It works well in risotto and paella.
Short-grain: This short, wide-grained rice is very sticky, making it suitable for dishes like sushi, rice balls (onegiri), and poke bowls, where the rice is meant to stick together and be malleable.
Brown: Brown rice retains the cereal and bran layer of the grain, which gives it a nutty taste and a chewy texture (which, unfortunately, is not to everyone's taste). It is often added to salads, stuffings, and casseroles.
Basmati: Basmati is an Indian rice that is slender-grained and aromatic, with notes of nuttiness and butter. It absorbs moisture well, which makes it an excellent base for rice pudding, as it absorbs the milk without getting mushy.
Jasmine: Originating in Thailand, jasmine rice is also very aromatic, but has an almost floral flavor that pairs well with spicy, strongly-flavored, and tomato-based dishes like curry and barbacoa.
Arborio: Arborio is a starchy rice from Italy that is most commonly used in risotto. Arborio rice should not be rinsed before cooking, so its starches can create the creamy texture of risotto.
I made a dish and it tastes kind of bland. Should I just add more salt? How can I know what to add to make it taste better?
First of all, make sure that the ingredients in the recipe are all there in the right proportions. Can you taste the chili powder? The lime juice? The cumin? If there's an ingredient that should be present that you can't taste, try adding a little more of that first. But if it still tastes like it needs a little....something, remember the four components of delicious food: salt, fat, acid, heat. Keep them balanced! But think creatively: if the dish needs more salt, does it need table salt, or does it need more of a salty ingredient like parmesan, Worcestershire sauce, or anchovy paste? If it tastes a little too rich, perhaps it needs more acid - but should the acid take the form of vinegar, lemon juice, or mustard? If it's a little tart, perhaps the acid needs to be balanced with a little more fat, like a splash of olive oil, a dab of mayonnaise, or a drizzle of melted butter. Think about similar dishes and the types of salty, fatty, and acid ingredients that create their delicious flavor profiles. If you're making an Asian stir fry and need more saltiness, think soy sauce rather than Worcestershire. If the tomatoes in your marinara are a little too acidic, add olive oil, not butter. If your tzatziki tastes a bit greasy, add a few drops of lemon juice, not white vinegar.
The best way to adjust the flavors in a dish is to take a small portion and experiment by adding things to it: a dash of freshly ground pepper, a drop of balsamic vinegar, a dab of butter. If it works with that small taste, then you can add it to the whole batch. And make sure you write down what you did for next time! There's no rule that says you have to make a recipe exactly as written. If you find a way to make it better - at least, according to your own palate and preferences - then do it that way again.
Does it really matter if I cook a dish for 30 minutes at 400 or for 45 minutes at 375? How do I know what temperature to cook at, and how long a dish needs to cook?
There are some general rules of thumb for cooking temperatures. If a dish needs to be caramelized, such as roasted vegetables or potatoes, you need a high temperature to get good browning (remember the Maillard Reaction?), so set your oven at 425-450 degrees. If you're cooking something that's already partially or fully cooked, like shepherd's pie, lasagna, chicken casserole, or macaroni and cheese, you need a lower temperature like 350 to avoid overcooking or causing a sauce to break.
Here is a list of temperatures for various types of dishes:
300-325 degrees - roasting large cuts of meat
350 degrees - soft cookies, cakes, casseroles, reheating already cooked dishes
375 degrees - crispy cookies, fish
400-425 degrees - roasted vegetables, chicken, lamb, beef, puff pastry, roasting smaller cuts of meat
450-500 degrees - pizza
There are also lots of great online charts that go into much greater detail (this one is a great example), so if you're not sure, Google it! Even better, if your grocery store has an actual butcher at the meat counter, ask him or her.
If you need to cook two dishes at the same time, and they're intended for different temperatures, choose the lower of the two temperatures and let the other dish cook for a longer time. You can even bump up the heat at the beginning or end of the cook time if the first dish cooks for a shorter time.
Other Resources to Check Out
How to Cook Meat Safely - Real Simple
Culinary School Lesson: Roux the Day - Foxes Love Lemons
The Chemistry of Flavor - US Department of Agriculture
5 Essential Roasting Tips Every Cook Should Know - Allrecipes
Happy cooking and Bon Appetit!
Such wonderful and valuable tips and information here. Thank you so much for sharing.
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