Every barbecue chef knows, in practice, what a perfect barbecue is. But what about the theory? Here’s how science explains why barbecued meat is good (or bad).
If you’ve ever barbecued meat, you know that everyone has their own grilling technique. Some are purists (salt it, put it on one side, turn it over, and that’s it), others invent tricks. But what is the best way? Perhaps the science of the perfect barbecue has the answer.
Yes, it exists. Several meat scientists (many of them from Texas, USA) have dedicated their careers to studying what, scientifically speaking, makes the most tender and flavorful meat possible. And some of their findings may help barbecue fans to understand how and why, according to science, a meat turns out good or bad.
A matter of fat and acids
Let’s start with the choice of meat. Every experienced barbecue chef knows that the less used muscles of the tenderloin, along the backbone, have less connective tissue and therefore produce more tender results than the hard working leg muscles. And you also know how to find the parts with the most marbling (the fat between the muscle fibers that signals high-quality meat).
So the first thing to understand is that, from a taste point of view, the differences between one meat and another are mainly a matter of fat content: the level of marbling and the composition of the fatty acid subunits of the fat molecules. Premium cuts, such as the rib eye, have more marbling and are also richer in oleic acid, an especially tasty fatty acid. On the other hand, a tenderloin has less oleic acid and more types of fatty acids that can produce a less attractive flavor when roasted.
This difference also comes from the animal’s diet. Those raised on a diet rich in corn and soy have meat with a high oleic acid content. Whereas animals that spend their entire lives grazing have a higher proportion of omega-3 fatty acids, polyunsaturated fatty acids that break down into smaller molecules with flavors that can be reminiscent of fish. Despite this, many consumers prefer to buy naturally fed beef, either to avoid the ethical issues (animals raised on feed live in confinement) or because they like that leaner beef flavor.
Heat and molecules
The biggest influence on the final flavor of the meat, however, comes from how you roast it. In terms of flavor, roasting meat does two things. First, the heat from the grill breaks down the fatty acids in the meat into smaller molecules that are more volatile – that is, more likely to spread through the air. This is what gives the good barbecue smell: molecules called aldehydes, ketones, and alcohols mixed together and released into the air.
Secondly, when roasting meat you “brown” it, in a process that chemists call the Maillard reaction. It is a fantastically complex process in which amino acids and trace sugars in the meat react at high temperatures to initiate a cascade of chemical changes that result in many products. The most important of these are molecules called pyrazines and furans, which contribute the toasty, almond-like flavors that fans of perfect barbecue seek.
So the longer and hotter the roast, the deeper you go into the Maillard reaction and the more of these end products you will get. If you overdo it, however, the meat will start to char, producing undesirable bitter and burnt flavors.
The one-third trick
The challenge for the barbecue chef, then, is to achieve the optimal level of Maillard effects at the moment when the meat reaches the desired degree of cooking. How? By controlling three variables: temperature, time, and thickness of the steak.
Thin steaks cook faster, so they need a very hot grill to brown enough in the short time available. Thin steaks (up to 2 cm) seared at relatively low temperatures achieve the “barbecue” flavors characteristic of fatty acid breakdown, while higher temperatures produce many of the “toasty” pyrazines that result from the Maillard reaction. Translation: if your steak is thin, raise the grill so that the meat cooks a little slower. This gives it the time it needs to build up a complex roasted meat flavor.
And here comes some new information – and proven by the science of the perfect barbecue: to get the best seal on both sides, flip the meat about a third of the way through the planned roasting time, not halfway through. The explanation: while the first side is roasting, the contracting muscle fibers send water to the raw side. After turning, the water cools this raw side, taking longer to brown.
The thicker the piece, the better
In thicker steaks and pieces of meat (from 5 cm upwards) the opposite happens: the outside burns unpleasantly before the middle is finished cooking. In such cases, a moderate temperature on the grill provides the best mixture of volatiles.
In other words, that thick, showy piece of prime beef you see at the steakhouse was not done on a grill on the stalk. Normally, steakhouses do a two-step roasting process: first they seal the meat on the hot grill, and then they finish cooking it in a medium oven. Imagine doing that at your barbecue, what an offense that would be to those present.
What science says about the question of the well-done vs. the badly-done
The point of the meat is a matter of personal preference. But science also has something to say about this barbecue controversy. Medium-rare meat doesn’t get enough heat to break down its fatty acids and generate “meaty” flavors. In contrast, when you overcook it you lose some of the “bloody” flavors that come with lightly cooked meat.
So the best combination of “bloody” notes and pyrazines and Maillard compounds released to the extent would be meats done between “over done” and “under done”. If you grill more or less than that you can bet that you will lose one of the flavors.
The advice for fans of perfect barbecue (and science), then, is: watch the meat carefully while it is on the grill. At these temperatures, many chemical reactions happen very quickly. And science reinforces what every experienced barbecue chef knows: it’s easy to burn meat if you’re not paying attention.