Say it’s summer. The day is an azure blue, the dandelions donating their seeds to the breeze, catching rays of sun as they float along happily. On the back patio, the grill is heating up and the meat is marinating. As someone sets the picnic table, you tuck the T-bone steaks into bed on the coals, at a slight diagonal for the perfect grill marks. They sizzle and pop, giving off a rich and robust aroma into the air. It makes your stomach start to sing in a low octave. The thought of a perfect meal on a perfect summer’s day is all that your mind can wrap itself around. But at the basis of it all is that cunning and surprising branch of science called chemistry. It is deeply embedded in why grilling meat tastes so good and why the broccoli that goes along with the meat will go dull if you don’t shock it. Chemistry weaves itself into the many ways you can cook food and each of these methods work in a different way and influence the tastes of the vast array of food that we create and consume.
One of the most important reactions, one that you would be able to observe on said summers day, is a browning reaction called the Maillard reaction. This reaction, discovered and described by Louis Camille Maillard, a French physician, not only deepens flavors, but creates new ones that are fundamental to the dishes we love to eat. Some of the foods that go through this reaction when cooking are: meats (such as steak and roasts), vegetables, chocolate and potatoes. In these types of food, the reaction begins with a carbohydrate molecule and an amino acid. These two molecules form an unstable intermediate particle which then changes until the familiar brown color and increased flavor have been reached. This happens because during the reaction elements, such as nitrogen and sulfur, are added to the mixture of mostly carbon, hydrogen and oxygen molecules.
Unlike the other browning reaction, called caramelization (see Experiment Number One: Caramelization), the Maillard reactions happen at 250°F/120°C and above (caramelization takes place at 330°F/165°C and above). Also, the Maillard reaction only usually happens on the outside of food because that is where the food will reach the proper temperature to initiate the reaction, while the temperature on the inside of the food will only get about as hot as boiling water (212°F). That is why when you grill meat (or vegetables) the brown grill marks will only appear where the meat has actually touched the metal because the heat there was at a high enough temperature to induce the reaction.
Below, in an experiment to test the tastiness and effectiveness different cooking methods and to see the effects of the Maillard reaction, we cooked a cut of beef (shoulder cut) in seven different ways: grilling, baking, braising, searing, then baking and resting, searing then baking and not resting, brining, then searing and resting, and microwaving.
Grilling is the oldest idea of cooking over an open fire brought into modern form. It uses a heat source below the food being cooked and requires that the food be turned in order to heat it fully throughout so that it is done. Grilling uses mostly infrared radiation from the glowing coals. This method of cooking can be especially difficult because the coals make the bars in the grill so hot, that the surface of the meat can become overly done (burnt) while the inside remains undone and cold. The correct way to grill a piece of food is to keep it far enough away from the heat so that browning rate at the surface of the food is comparative to the conduction heat within. (See On Food and Cooking by Harold McGee, pg 783)
The piece of beef that we grilled clearly was cooked with these principals in mind. Both the outside of the steak and the inside were heated with the surface containing a striping of grill marks; an indication that the piece of meat had undergone a Maillard reaction. After it had rested (as with all meat, a rest period of 10-15 minutes is recommended so the juices can be redistributed throughout the meat) we cut the meat in order to taste it.
The surface of the meat was rich and savory and the texture was crunchy. The inner portion of the meat was flavorful and very moist, and indication that it was cooked just right. In the end, the grilled steak was at the top of the groups favorites.
This method is by far the most used throughout the world. It is done by placing a heat source all around the food and using the radiation from the walls of the enclosure, such as an oven, and the convection movement of the hot air within the space to cook it. It is because of this convection of hot air that the baking method is a very good way to dehydrate the surfaces of food. This means that the appearance of much browning will occur, given that the temperature of the enclosure is hot enough (McGee, pg 784).
To bake a portion of the beef, we placed it in a ceramic container and introduced it to an oven temperature of 325°F, uncovered with a small amount of olive oil and salt covering the surface, for about an hour. When taken out, it was clear that the surface of the meat was very dehydrated and had undergone a large amount of Maillard reactions because it was a very crispy texture with a dark brown coloration.
The taste of the meat was very gamey and was better done than the others, though not tough. The doneness of meat is determined by the development of a white opacity as the myosin protein denatures in the presence of heat and clumps together in large enough portions to scatter light. This is what turns meat from a red to a pink color. The surface of the meat was very succulent, owing to the fair amount of browning that occurred during baking.
This method of cooking is very slow and needs to be done with large cuts of meat. In order to do a proper braise, the meat is put into a pan deep enough to hold the entire amount of meat, along with a sufficient amount of liquid. Then the entire dish is covered and placed into and oven at temperatures from 200°F to 325°F. Because the dish is covered, it means that browning will not take place because water molecules are not being evaporated into the air, thus the surface is not becoming dehydrated. For a good tasting piece of meat that has been braised, it is important not to let the inside of the meat rise above water boiling temperatures.
For the portion of meat that we braised, we put it into a pot with about a half of a cup of chicken broth for the liquid. Then, after it was covered, we cooked it in a 325°F oven for about an hour. After the meat was done and removed from the pot, the surface revealed that a Maillard had not taken place. Also, the broth, when tasted was more flavorful than the meat itself. This is because the meat lost its juices to the broth during the cooking process and did not have the browning flavors to supplement its loss. This piece of meat when tasted was comparative to the piece of meat that had been cooked in the microwave.
This is a relatively new cooking method which was first used in Scandinavia (McGee, pg 155). To cook in this manner, a piece of meat is submerged for an amount of time, allotted for how thick the piece of meat is, and then cooked normally to give a more juicier result.
A brine is a solution made of salt and water, being about 3% to 6% salt by weight. It is important when making a brine to crush the salt into a fine powder to give it more surface area to become more easily dissolved, unlike Kosher salt which maintains its solid state in very large crystals. The way a brine works on a piece of meat that is submerged in it, is that it dissolves part of the protein structure and the interactions between the salt and proteins results in the ability of muscle cells to hold more water.
To brine our piece of meat, we made brine out of 2.0 grams of pulverized salt with 2 cups of water. We then let the meat sit in the brine, completely submerged, for about an hour. We then seared the meat in a pan and finished cooking it in the oven.
The meat was definitely juicier and was pinker, instead of redder, on the inside. The surface browning was the same as the other seared meats. As assumed, the meat was saltier than the rest, but this did not prevent the savory notes from being prominent in the overall taste.
For most cuts of meat, especially a filet mignon or even a tuna steak, it is important to sear the surface. It has long been a myth that searing meat will help to seal in its juices, but this has been falsified after it was originally stated by Justus von Liebig, although professional chefs will still say that this is why they sear their meat. However, the real reason why searing is so important is because it lends itself to inducing the highly desired Maillard reaction, creating a more rich and luscious piece of meat. What makes pieces of meat that have been seared juicier is the fact that the browning reactions make our mouths water, giving the appearance and feeling that the meat is indeed juicier. In all actuality, the meat has been dehydrated on the surface because of searing, the opposite of the old wives tale most chefs think is true.
The three pieces of meat that we seared (one brined, the other two with the difference being how long they were allowed to rest) developed a distinct brown coloration on their surface after about 3 minutes on each side in a cast iron pan. The steaks were then allowed to finish cooking in the oven for about 15 more minutes. After they had finished cooking, one of the steaks was cut right away, not allowing for a resting period, while the other rested for about 15 minutes.
The one that did not rest was rarer than the other and lost most of its juices when it was sliced. The one that rested was slightly better done and did not nearly lose as much juice, and was therefore tastier to eat. Both, however, were very developed in Maillard reactions and had an intense richness that added depth to their flavor.
Each of the cooking methods that we used on the cuts of meat demonstrated that highly sophisticated reactions, like the Maillard reaction, are what give some of our most highly prized foods their mouthwatering appeal. However, just as it is important not to serve just steak at a picnic without side dishes, it was important for us to try out other cooking methods as well. The next method that we tried was with vegetables (broccoli) and it is called shocking.
The method of shocking is what cooks do to vegetables in order to maintain their texture, taste and color. In order to shock vegetables, one must cook the vegetables (mostly foods such as leeks, green beans and escarole are shocked after they are cooked) until done and then immediately submerge them into an ice bath, long enough to cool them but not long enough to allow them to become waterlogged. This process stops the vegetables from continuing to cook and to develop an unwanted soggy texture, a dull olive green color and a fresh, new taste.
In class, we wanted to see how much of an effect shocking had on vegetables. In order to do this, we cooked broccoli in the microwave (ceramic bowl covered in saran wrap with a base layer of water) and shocked a portion of it in ice water half way through cooking, a portion after it was fully cooked and then we did not shock the last portion at all after it had finished cooking. What we noticed was that the shocked broccoli, that had been fully cooked, was fresher tasting but the difference in color was basically undetectable from the broccoli that had never been shocked. We then waited a couple of hours, to see if any other changes would develop between the samples of broccoli, and what we found was that altogether they were pretty much undistinguishable. We hypothesized that shocking broccoli might not be the best way to test how shocking works because broccoli is a more stable vegetable than leeks, which are a vegetable that chefs would most likely shock. Also, if the broccoli had been perfectly cooked, then there would have been no need to shock it.
Cooking Methods: All Wrapped Up
So it is the end of the summer’s day, and it is time to clean up from a culinary successful picnic. Off of the plates you scrape the remains of Maillard reacted scraps of steak and grassy green broccoli into the garbage, giving thanks to the power of chemistry that made your meal as perfect as a picnic.