Today we’ll analyse the scientific interactions that goes on when cooking a beefsteak: looking first the chemical composition of the raw ingredients we work with, what happens during the cooking process, and why certain steps are followed when cooking a nice hunk of steak.
Such knowledge will stand you in good stead in the strive towards cooking the perfect steak, especially for the important dinner date.
When we talk about meatiness of a steak, we are referring to its muscle fibres, which are made up of proteins.
Proteins are long chains of amino acids, held together by something called a peptide bond, which forms its primary structure. It then curls to form a secondary structure and then folded again into a globule, creating a tertiary structure, and then multiples of that goes on to create the quarternary structure.
"The proportion of collagen in a steak plays a large part in determining how tender it is."
There are two classes of proteins, one that forms the muscle fibres, as stated, and the second is collagen. These are protein structures that line up and entangle each other like a rope, it’s hard to break apart and its function is to hold muscle fibres together. You can see why the proportion of collagen in a steak plays a large part in determining how tender it is. We'll come back to this in a bit.
The temperatures stated above have a range of 1-2˚C for 2 main reasons. One, different cuts of beef vary in their composition of collagen and muscle fibres. Collagen and muscle fibres have different structures, repeat: different structures equals different cooking temperatures! Two, fat dissolves at a higher temperature than protein and we already know that not every cut of beef have the same amount of fat. A ribeye for example, has considerably higher fat content than a sirloin.
Heat, along with reactive elements like acid, alkali, salt or alcohol, causes bonds structures (other than the primary peptide bond) to break. This process is called denaturation. With those original structures broken, new linkages between amino acids, unravelling into a new, random shape.
The higher the heat, the more the proteins transform and solidify. Overcooking occurs when muscle fibres, contract, shrink and firm up, while a high percentage (about 18%) of the juices in the meat are dried out. The result of which I’m sure we have all experienced: dry, chewy and bland meat. Yuck.
Overcooking is a real taboo in the land of steak-grilling. Most recipes require removing the steak from heat when it's internal temperature is lower than desired because of carry-over cooking, whereby the cooking process continues due to transfer of heat from the exterior to the cooler interior. This is actually quite significant as internal temperatures could rise up to 5˚C.
This is also why a thickness of 1-1.5 inches is usually recommended for a piece of steak to be grilled – so that the internal heat isn't surpassed during the process of cooking, as well a longer amount of time is allowed for carry-over heat to reach the interior, reducing the risk of overcooking.
As oppose to overcooking, we aim to achieve steak nirvana: meat packed full of flavourful juices and so tender it falls apart in a single bite.
Marinating helps tenderise meat as marinades usually have acidic components such as wine, vinegar, lemons or tomatoes, which breaks down the collagen. Seasoning with salt has the same effect.
What is important to note however, is that marinades and seasoning has to be left on the meat for at least 40 minutes. Through a process called osmosis, salt draws out moisture onto the surface of the meat and cooking at this point will evaporate off a large part of the meat’s juices. After 40 minutes however, the salty brine has had time to break down some of the tissues and be reabsorbed into the meat.
With sous-vide cooking however, a stable temperature is maintained throughout the cooking process, and thus there is much less need of timing, thickness and marinating considerations to achieve the same results.
#2. Kickstart The Complex Flavour Compound
Apart from added salt and marinades, the flavour of the steak comes from firstly, high heat and high speed, which is the reason why we sear our steaks.
Sugars in the meat interacts with protein under high temperatures (110˚C to 170˚C) to produce complex flavours as well as aromas while causing the meat to brown. This is known as the Maillard reaction. The same reason why we add egg yolk glaze to our buns, or sugars when roasting nuts.
#3. Fat Content
Secondly, fat adds another taste dimension to steaks. This is why we are told to look closely at how meat is marbled when choosing our chunk of meat. Marbling refers to how streaks of fat appear between the muscle fibres, which sometimes does make the meat look like a gorgeous marble-surface. The more evenly distributed the marble, the more buttery and moist the steak will be.
To attain that moist and juicy piece of steak, we want to retain water, to not overheat it and evaporate too much of its juices. This is why we are also told to rest our meat for about 5 minutes after cooking for the moisture loss to be reabsorbed into our steak before serving.
Get dry-aged beef if you can, as this process allows excess moisture (up to 30%) to be drained out, thus concentrating the flavour. Moreover, natural enzymes in the meat are reacting as well, breaking down some of the connective tissues, and therefore, as we've discussed, tenderising it further.
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