Why Does Beef Turn Brown?

If you frequently prepare meals with ground beef, there’s a good chance that you’ve seen some color changes in the meat and chosen to throw it out. But do you need to do that?.

Ground beef frequently turns brown even before you get a chance to use it. However, despite the fact that it may be unsettling to see your meat appear a different shade from the bright pink you purchased it in, the U S. The Department of Agriculture (USDA) affirms that the food is typically still safe to eat, but it is always a good idea to smell it and look for other signs of spoilage. That’s because the meat’s exposure to oxygen, not the formation of bacteria, is what causes the color change.

According to the USDA, specifically, oxygen interacts with the meat’s oxymyoglobin pigment to produce that distinctive red color on the surface. The key word here is “surface,” as the remaining meat will be a gray-brown color since it hasn’t come into contact with oxygen. Now, there are some limitations to the color change rule. The likelihood that the meat in the package is actually going bad increases if all of it has turned gray or brown. Meat is no longer fresh if it has been exposed to oxygen for so long that it has turned completely brown.

After beef has been refrigerated for about five days, it may turn brown. This darkening is due to oxidation, the chemical changes in myoglobin due to the oxygen content. This is a normal change during refrigerator storage.

Is raw beef safe if it turns brown?

Many people believe that fresh meat is always bright red in color. That’s not exactly true.

When a cow is slaughtered its meat is actually purplish. The meat will keep its maroon color if vacuum-packed quickly. However, after just 15 minutes of exposure to air, the meat’s surface will turn a bright cherry red from the presence of oxygen. When the meat’s biochemical activity starts to wane, the cherry red will eventually turn brown.

According to Liz Boyle, a meat scientist at Kansas State University, it can begin discoloring in a matter of hours. Which is why meat is typically ground several times per day at grocery stores. They want consumers to see that bright red color. ”.

According to the USDA, raw cuts of beef keep for three to five days in a fridge that’s 40 degrees Fahrenheit or below; ground beef should be used within one or two days of purchase. So it’s entirely possible for meat still within its fresh window to develop a brown color.

How long is beef good after it turns brown?

While brown meat isn’t always bad and the color doesn’t necessarily mean the meat is bad, it might indicate that the meat is a little older.

So, investigate with your senses. Boyle informed me that even if you cook the meat, bad odors and slimy, sticky textures are signs that spoilage bacteria have been destroying the meat’s proteins and possibly ruining the flavor. (However, stickiness that you only notice after seasoning your meat is probably nothing to worry about. Myofibrillar proteins, which are tiny muscle threads, search for water when exposed to salt, which causes them to cling to your hands. ).

Pathogenic bacteria—that is, the type that make us sick—don’t typically impart any obvious odor, texture or color changes to the meat. Heating meat to 160 degrees Fahrenheit usually kills them (salmonella and certain strains of e. coli are the top concerns in undercooked beef). Use a food thermometer to check, and for more detailed temperature guidelines, head over to the Partnership for Food Safety Education.

Beef color behaves differently in vacuum packaging

Since vacuum-packaged beef hasn’t been exposed to oxygen, it appears purple on the left. After being exposed to oxygen, beef in trays covered in oxygen-permeable plastic, on the right, turns bright red.

Beef vacuum-packaged without oxygen exposure won’t ever turn bright red. Over time, it will eventually turn brown.

Janeal Yancey, a University of Arkansas meat scientist, emailed me and said, “It could take weeks.” However, she noted that a variety of factors, such as the age and type of the meat, its packaging, and the temperatures it is exposed to, would affect the actual rate of browning.

When meat is vacuum-packed, the package swells with gases released by bacteria. That is your clear indication that you should discard it.

Why exactly does raw beef turn brown? Give me the chemistry!

Myoglobin, a protein, is the star of the beef variety show.

“Its purpose is to be oxygen storage,” explained Yancey, who writes about meat at Mom At the Meat Counter. “It just holds onto the oxygen for other things to use.”

You may be familiar with how hemoglobin, which is found in blood, goes from dull, dark red to bright red depending on its oxygen status (our blood actually never turns blue–that’s an optical illusion). While hemoglobin courses through arteries and veins, myoglobin inhabits muscle tissue in animals (including us!). When hemoglobin stops by muscles, myoglobin steps up to accept its oxygen. Muscles then use the oxygen to contract and to conduct regular cellular business, like respiration. While muscles stop contracting after slaughter, cellular functions continue.

A long, tangly protein molecule bundle connected to a single iron atom makes up myoglobin. As it fuels the muscle, oxygen is constantly bursting on and off that iron. Depending on its oxygen status, myoglobin changes shape. It changes shape and reflects light differently with each change, producing hues of red, purple, or brown.

A protein called myoglobin changes color depending on the amount of oxygen it contains (oxygen switches on and off an iron atom within the protein molecule). Deoxymyoglobin is what it looks like when it lacks oxygen and is purple. It turns bright red and is known as oxymyoglobin when it is oxygenated. The meat oxidizes (which is different from oxygenation) in a low oxygen environment as the iron atom loses an electron and myoglobin transforms into metmyoglobin. Oxidized meat, like oxidized fruits and vegetables, turns brown. ( courtesy of Janeal Yancey. ).

Meat is in the no-oxygen, purplish state shortly after slaughter, which explains why vacuum-packaged meat appears maroon. Cellular processes are then almost completely halted and only moving extremely slowly. until oxygen in the air and the myoglobin on the surface of the meat combine.

According to Yancey, “it’s like the oxygen is the gun that starts the race.” “But it’s like it’s waiting at the starting line if you don’t have the oxygen to start that process, like in the vacuum package bag.” ”.

After oxygen sparks a surge of cellular activity, the cells of meat use their resources more quickly. It becomes more difficult for the meat to store oxygen in its myoglobin storage tanks as resources are depleted. The exposed iron on the myoglobin molecule may lose an electron as a result of insufficient oxygen availability or the presence of free radicals in the area (confusion ensues, especially given all the talk of oxygen; losing an electron is known as “oxidation,” but it need not always involve oxygen). When myoglobin loses that key electron, it turns brown. And that’s when you see your raw steak turning brown.

Why is beef brown underneath stickers and where it touches the tray?

According to Yancey, an environment with some oxygen but not much oxygen can actually cause browning to come on the fastest once oxygen has sparked a rush of biochemical activity. The oxygen starts a cascade of processes that quickly exhaust the limited supply of oxygen because they demand more oxygen. Myoglobin’s iron atoms eventually lose hope of finding oxygen, and each molecule’s exposed, vulnerable electron is quickly snatched up by other meat-related processes or roving free radicals. Myoglobin loses its shape, changes how it reflects light, and appears brown when that priceless electron is removed.

This is why brown areas beneath stickers are more likely to be visible. While air can pass through the plastic wrap used to seal trays of meat, some areas lose their oxygen supply as soon as stickers are applied.

Meat touched by the tray is similarly depleted of oxygen and more likely to brown. In addition, it goes without saying that if you stack several trays of meat in the refrigerator, the areas they touch will lose access to oxygen and are more likely to turn brown.

As a result, if you notice a brown area beneath a sticker and your meat has been properly stored in the refrigerator, has no strange smells or textures, and is still within its fresh window, it is likely safe and will taste great. And no, the butcher didn’t use the sticker to try to hide the brown!

Why does beef sometimes turn brown just under the surface?

Therefore, we are aware that the meat’s bright red color is a result of an oxygen-rich environment on its surface. While this is going on, the meat’s oxygen-free interior remains purplish and appears to be in a state of suspension; without oxygen, its cellular processes move very slowly.

But where the purplish, no-oxygen interior meets the red, oxygen-rich exterior of the meat, things become uncomfortable. The little oxygen that has percolated down from the surface there activates rapid-fire processes. But the meat quickly turns brown as the oxygen well quickly depletes.

Ground beef’s outer layer turns bright red as a result of oxygen absorption. Myoglobin, the meat’s primary pigment, loses electrons beneath it due to a low oxygen environment (oxidation is the loss of electrons), which results in the meat turning brown. However, the meat retains its deoxygenated purple color because there is no oxygen at all deeper inside the meat. ( courtesy of Janeal Yancey. ).

Although the speed of the reaction depends on the type of meat and how it is handled, Yancey said the brown line beneath the surface typically appears after the meat has been on display for a few days. Ground beef changes color the fastest.

You can make out a brown line if you look closely between the red surface and the purplish interior. In whole cuts of meat like this, the oxidized in-between area forms more gradually than it does in ground meat. ( courtesy of Janeal Yancey. ).

Why does frozen meat turn brown? Does thawed meat turn brown faster?

Here at EatOrToss we love our freezer. It keeps food safe for long periods of time and is a great way to reduce food waste. It’s also perfectly fine to stash your meat in the freezer until you’re ready to use it. According to the USDA, frozen raw whole cuts retain their quality for four to 12 months; frozen ground meat should be used in three to four months for peak quality. Here at EatOrToss headquarters we once prepared ground beef that had been in the back of the freezer for more than a year — it was fine.

However, freezing can alter raw meat in ways that increase the likelihood of browning. As an illustration, freezing weakens some myoglobin molecules, causing their iron atoms to fragment. The unbound iron can then grab electrons from myoglobin, which is the nerve! Meat that has been frozen may have fats that break down and release free radicals that are aggressive in their attempts to steal electrons from myoglobin. And as we all know, myoglobin turns brown when it loses a specific, valuable electron from its iron atom.

Due to all of these factors, the meat in the following photo from EatOrToss reader Jeff S , turned brown. Yancey guessed that it turned brown while it was thawing.

This meat likely turned brown during defrosting. Both freezing and thawing, particularly gradually thawing, can quicken chemical processes in meat that result in browning.

“I wouldn’t worry about eating or serving that,” Yancey said, adding that she would marinate or heavily season the meat just in case the thawing also resulted in some fat oxidation that produced an unpleasant flavor.

The best way to preserve meat, according to Yancey, is still to freeze it.

She said, “I don’t want people to be scared of freezing meat.” When compared to the amount of waste and shelf life that freezing can prevent, the effects on fat, flavor, and juiciness are relatively small. I just want them to be aware that meat that has previously been frozen might not have as attractive of a color. ”.

Just one more reminder before we move on from freezing: don’t keep your frozen steak, ground beef, or anything else in the freezer for an extended period of time. Meat that has been frozen too long can develop freezer burn, which can appear as white patches or discolored spots on its surface in addition to the color issues mentioned above. Those locations won’t be unsafe as long as the meat was handled properly, but they won’t taste good.

Is ground beef spoiled if it turns brown?

Like any red meat, raw ground beef browns over time. The meat hasn’t necessarily gone bad just because the color has changed.

But compared to a cut of meat, ground beef has a shorter shelf life. The process of grinding the meat accelerates its breakdown. The meat will turn brown as a result of oxidation, which is caused by free iron and broken-down fats. Therefore, ground beef typically turns brown more quickly than whole cuts of meat. The flavor is more susceptible to oxidation because the risk is higher for fats.

When ground beef turns brown, “I’m a little bit more leery than I am with whole muscle cuts,” Yancey said But if it still smells good, hasn’t been subjected to excessive heat, and is brown, it should be fine. ”.

For fear of off flavors, she claimed she wouldn’t purchase ground beef in this condition:

What other factors cause raw beef to turn brown?

As previously mentioned, thawing beef and ground beef are more likely to brown quickly. Salt also promotes the biochemical reactions that lead to browning.

The type of animal and its life experiences, such as diet, age, and stress level, can also affect the chemical balance in its tissues and the trajectory and intensity of meat color changes. Older cows, for example, produce more myoglobin. There are some parts of the animal that have more myoglobin than others, especially those used for prolonged movements like running or wing flapping. More myoglobin will mean darker meat. (Fun fact: Yancey noted that animals that fly high or dive deep typically have more myoglobin. So, whale muscle is very dark and has a high myoglobin content. ).

The speed at which meat consumes oxygen and, consequently, how its color changes over time, is affected by how it is packaged and the temperature at which it is kept. When temperatures are higher, cellular processes move more quickly and require more oxygen. Additionally, as previously mentioned, freezing and vacuum packaging can have a significant impact on the color of raw meat.

Although a beef’s color alone shouldn’t be taken as a sign of spoilage, occasionally bacteria will produce sulfides and peroxides that give the beef a brown appearance. But spoilage bacteria aren’t covert operators. You’ll be able to tell the meat is spoiled just by the smell of their work.

Can a meat’s color tell you if it’s done cooking?

Many people determine whether meat has fully cooked using color. Bad idea.

Boyle stated that “cooked meat color is not a reflection of doneness.” “Using a meat thermometer is the only reliable way to determine whether ground beef is cooked correctly.” ”.

Not surprisingly, our friend myoglobin also gives us the colors in cooked beef. Heat denatures it, which means that the tangled protein molecule unfolds and ceases biological functions. The molecule then reflects light differently and the meat looks duller, lighter and, in the case of beef, browner than it did when it was raw.

But here’s the thing: Myoglobin can denature below or above a temperature that is safe for food (160 degrees Fahrenheit). Therefore, relying solely on color could result in undercooked or overcooked meat.

Where a meat cut is on the myoglobin spectrum can affect how quickly it denatures, and consequently how quickly it takes on a “cooked” brown appearance. Cooking takes longer for myoglobin that is still purplish and not carrying oxygen to turn brown. After being fully cooked, myoglobin will remain red due to a high pH’s “protective” effects. Myoglobin that is already brown denatures and appears “cooked” more quickly in the oxidized “metmyoglobin” state. Ground beef is particularly problematic because pathogens may end up inside the meat, where they are exposed to less heat.

When meat browns too soon, it becomes more dangerous, according to Yancey. Premature browning is what we refer to when meat that hasn’t reached a safe temperature appears to be done. This is why I always use a meat thermometer. ”.


Pleased to meat you!

Why Does Steak Turn Brown?


Why is my beef brown but not expired?

When meat is grayish-brown inside, it is not always a sign of spoilage. That color actually denotes an absence of oxygen exposure, which is normal. Even though it is well within its shelf life, grocery stores frequently offer discounts on meat that has turned brown, such as ground beef.

Why does cooked beef turn brown?

However, as the meat’s internal temperature exceeds 140 degrees, myoglobin loses its stability and transforms into a new molecule known as hemichrome. The chemical known as hemichrome is what gives medium-cooked red meat its light browned appearance.

Why is my frozen beef turning brown?

Information. Foods that are frozen may change color, but they are still safe to eat. Meat that is initially bright red turns typically dark or light brown depending on its variety. This could be the result of an oxygen shortage, freezer burn, or unusually long storage.

Why is my beef GREY in the fridge?

However, if the meat’s exterior or the majority of the contents of the package has turned gray or brown, that’s a sign that the meat is starting to go bad and should be thrown out right away.

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