What happens when you cook?
Hot air cooks the surface of meat, but it cannot penetrate, so the energy built up on the outside of the meat moves slowly towards the center, eventually cooking the meat throughout. As the internal temp of your meat rises, its color is not the only thing that changes. A number of chemical and physical reactions take place, as the molecular structure of proteins and fats are altered by heat. Different reactions kick in at different temperatures.
Here’s a general guide to temperatures organized from cold to hot. The meat temps shown here are approximate because other variables come into play such as the age of the animal, acidity, salt content, type of heat, humidity, etc. This info has been gathered from multiple sources, including meat science research papers, textbooks, and Harold McGee’s important book, On Food And Cooking. Click here for a complete guide to target cooking temperatures.
0°F (-18°C). Ideal freezer temperature.
25°F (-4°C). Meat freezes. Meat starts to freeze at a lower temperature than water because water in meat is combined with proteins. Water expands as it freezes and sharp-edged crystals form that can rupture cell walls, creating “purge” when the meat is thawed, which is a spilling of liquid, mostly the pink fluid protein called myoglobin. Faster freezing makes smaller crystals, resulting in less purge.
32°F (0°C). Water freezes.
34-39°F (1-4°C). Ideal refrigerator temperature. Water is not frozen, and microbial growth is minimized. You do have a good refrigerator thermometer don’t you?
41-135°F (5-57°C). The “USDA Danger Zone,” in which many pathogenic bacteria grow, sometimes doubling in number in as little as 20 minutes. According to the USDA, cold foods must be stored below 41°F (5°C), and hot foods above 135°F (57°C). That’s why we don’t leave meats sitting around to come to room temp.
60°F (15°C). When chilling cooked meat, liquid gelatin forms a solid gel called aspic. Gelatin happens when connective tissues that wrap muscle fibers and connect them to bones, called collagen, melt. Yep, it’s the same stuff they inject under your skin to hide wrinkles.
95-130°F (35-54°C). Animal fats start to soften and melt.
114°F (46°C). Myofibrillar proteins begin to gel, changing meat texture.
120°F (49°C). Myosin, a protein involved in muscle contraction within fibers, begins to lose its natural structure. It unwinds or unfolds, a process called denaturing. It starts to clump, gets milky, and begins firming up the muscle fibers. Purple meats, called “rare,” start turning red. Fish begins to flake, and parasites begin to die.
130°F (54°C). Many pathogenic bacteria begin to die, slowly at first, but as the temp rises, they croak more rapidly. At this temp, it takes more than two hours to pasteurize meat. At 165°F (74°C), it takes just seconds.
130-135°F (54-57°C). Medium rare. Most mammal meats are at optimum tenderness, flavor, juiciness. If you eat your meat well-done, you need to snap out of it.
130-140°F (54-60°C). Fats begin to liquefy, a process called rendering. This is a slow process and can take hours if meat is held at this temp.
140°F (60°C). Connective tissues called collagens begin to contract and squeeze out pink juice from within muscle fibers into the spaces between the fibers and out to the surface. Meat begins to get dry. Myoglobin, the pink protein liquid within muscle cells, denatures rapidly and red or pink juices begin to turn clear or tan and bead up on the surface. It is not blood!
150°F (66°C). Actin, another protein important to muscle contraction in live animals, begins to denature, making meat tougher and drier still.
150-165°F (66-74°C). This is “the stall zone,” in which large cuts such as pork butt and beef brisket seem to get stuck for hours when cooked at low temperatures like 225°F (107°C). In this range, moisture evaporates and cools the meat like sweat on an athlete. Inexperienced cooks panic. Eventually, temps start rising again. Whew!
155°F (68°C). Known as “well done,” meats are overcooked at this internal temperature. Much moisture has been squeezed out, and fibers have become tough. Bacteria are killed in less than 30 seconds, but spores can survive to much higher temps.
160-165°F (71-74°C). The “instant kill zone.” Normal cooking temps kill microbes on the outside of meats rapidly, so solid muscle meats are not likely dangerous since contamination is almost always on the surface. But ground meats and poultry often have bad guys beyond the surface, so you must cook these meats beyond the instant kill zone. That’s why the recommended internal temp for ground meats is 160°F (71°C) and for poultry is 165°F (74°C). When you reheat foods, you should take them up to 165°F 75°C).
160-205°F (71-96°C). Tough collagens melt and form luscious gelatin. The process can take hours, so low and slow cooking creates the most gelatin. Dehydrated muscle fibers begin to fall apart and release from the bones. Meat becomes easy to shred. Even though the fibers have lost a lot of water, melted collagen and fat make the meat succulent.
212°F (100°C). Water boils at sea level. Boiling point declines about 2°F for every 1000′ above sea level.
225°F (107°C). Ideal air temperature for “low & slow” cooking of meats high in connective tissue. It is high enough so water evaporates from the surface to help form the desired crust called “bark,” but low enough to get the most out of enzymes, collagen melting, and fat rendering.
230-234°F (110-112°C). Table sugar melts and pulls into a thread but will not form a ball (thread stage).
300°F (149°C). Butter starts to smoke.
310°F (154°C). The Maillard reaction accelerates surface browning, which is caused by chemical changes in proteins and sugars and results in thousands of delicious new molecules. The Maillard reaction begins at lower temps, but really takes off at 310°F (154°C).
320°F (160°C). Table sugar liquefies, starts to caramelize, turns light amber in color (clear liquid stage).
325°F (163°C). Ideal air temperature for cooking chicken and turkey so skin browns and fat renders.
350°F (177°C). Table sugar and brown sugar begin to burn (burnt sugar stage).
361°F (183°C). Some animal fats begins to smoke.
375°F (191°C). Extra virgin olive oil begins to smoke.
400°F (204°C). Canola oil begins to smoke.
425°F (218°C). Teflon thermometer cables can begin to melt.
440°F (227°C). Inexpensive olive oil begins to smoke.
450°F (232°C). Peanut oil begins to smoke.
450°F (232°C). Some nonstick surfaces begin to emit toxic gases.
570-750°F (299-399°C). Primary combustion temperature of hardwood, wherein it smolders and releases large quantities of unburned gases, including microscopic particles called smoke.
600-700°F (316-371°C). Flash point or fire point, the temperature at which smoke from burning fat can burst into flame. Never use water to extinguish burning fat. Smothering it works better.
1110°F (599°C). Secondary combustion of wood when gases, cellulose, and lignin burn rapidly.
What causes properly cooked pork and poultry to be pink, even if it is not smoked?
Several factors: Gases in the atmosphere of an oven, particularly carbon monoxide, can react with myoglobin in meat and turn it pink, especially on the outer edges. These gases occur in all ovens, especially those that heat by combustion such as gas, charcoal, or wood. They are also present in electric ovens, but to a much lesser degree. When grilling or smoking, there are more of these gases. They more easily penetrate the thinner skin and fat layers of younger animals, so age of the animal is also a factor.
Also, meats with high levels of naturally occurring compounds such as myoglobin are more likely to turn pink. Nitrites in meat can also cause pinking. Nitrites are converted from nitrates in feed and water by microorganisms within the animal. Nitrates naturally occur in many leafy vegetables and can transfer to the meat during cooking, say, from a rub or braise. In fact, grocery store meat trays are occasionally packed with carbon monoxide or nitrogen to keep the meat in the pink.
Why is raw red meat sometimes bright red on the outside and dull gray on the inside?
Fresh cut or ground beef is purplish-red in color. Oxygen reacts with the pigments in red meat to form the bright red color in the grocery store. The interior of the meat may be gray or brown because oxygen has not penetrated into the muscle. This is normal. If, however, all the meat in the package has turned gray or brown, it may be spoiling.
What is spoilage?
There are two types. Oxidation is caused by compounds in meat combining with oxygen and changing the meat’s smell, flavor, and color. Badly oxidized meat is called rancid. But oxidized meat is usually not dangerous. The other type of spoilage is bacterial or viral spoilage, and it is very dangerous. There are several commonly occurring bacteria in food that can spoil it, such as are Bacillus cereus, Campylobacter jejuni, Clostridium botulinum, Listeria monocytogenes, Salmonella, Shigella, Staphylococcus aureus, and STECs (Shiga toxin producing E-coli). Some of these bacteria will merely have you kneeling before the porcelain god, but others can maim or kill you. You can begin killing bacteria by cooking food to a safe temperature of 131°F or higher. At 165°F, bacteria are killed instantly. At 131°F, it can take hours. For more on bacterial kill temps, click here and scroll down.
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