Don’t judge cooked meat by its color.

Just… don’t.

Everyone, myself included, does it. We look at the color of the inside of a burger or chicken to determine if it’s cooked. Is it pink? Nope. Chomp chomp!

Here’s the problem: Color is not a good indicator of safe cooking temperatures. You have to use a meat thermometer to be sure meat is cooked to safe temperatures.

Meat turns from pink to brown because the protein that makes meat red (myoglobin) is denatured as it is cooked. The protein is damaged and doesn’t reflect light in the same manner anymore, so the meat appears brown.

Lots of factors can affect how quickly or slowly the protein is denatured as it is heated. Meat color changes can vary due to the pH (acidity) of the meat, the age and gender of the animal, how long it was stored, the way it was packaged, whether it was frozen, even the feed and water of the animals can affect cooked meat color.

Sometimes meat turns brown too soon!

Meat scientists call this phenomenon Premature Browning. It can be really dangerous because meat looks done, but it hasn't been cooked to a safe temperature.

This photo is from a great fact sheet about beef color from the National Cattlemen’s Beef Association. Both of these patties were cooked to an unsafe temperature (55°C or 131°F). Patty A looks very undercooked, but patty B looks done.

I have a previous blog post about fresh meat color. Remember that we talked about meat being oxygenated (red), deoxygenated (purple), or oxidized (brown)? Researchers at Kansas State found that when patties were cooked in the oxidized (brown) state, their cooked color was brown, even at temperatures that were too low to kill deadly bacteria like E. coli and Salmonella. Other research has found that the packaging can cause meat to brown faster, too.

Regardless of why the meat turns brown at too low of a temperature, sometimes it happens. The best way to insure that your meat is cooked properly is to use a meat thermometer.

Ground beef should be cooked to 160°F and poultry should be cooked to 165°F.

Sometimes meat stays pink too long!

Meat scientists call this phenomenon Persistent Pinking. It is not as much a food safety issue as it is a perception and eating quality issue. When meat looks pink, even if it’s been thoroughly cooked, people will think it’s undercooked and will keep cooking it until its way overcooked. When it’s overcooked, it tastes terrible.

I am conducting research on persistent pinking in ground beef this summer. 

These patties were all cooked to exactly 160°F.
You can see how some of them are still pink in the middle.

Research has shown that a high pH (more basic) can protect the proteins at greater temperatures and keep them from turning brown. They may also stay pink because of a higher concentration of the myoglobin protein. Right now our research is creating more questions than answers, but it sure is interesting.

Persistent pinking can also be caused by outside substances interacting with the meat and creating the pink color.

Nitrites are a good example of one of these outside substances. Sometimes we want this pink color to appear, like in the case of ham, sausages, or bacon. However, very small amounts of nitrites can get into the meat (especially poultry) and create a pink color that kind of looks like ham. If you don’t expect the meat to be pink and it is, you may think it’s undercooked.

These pictures were sent to me by Dr. Jim Claus at the University of Wisconsin. He is one of the leading researchers in persistent pinking in processed meats. These are a pair of turkey slices and some tuna chunks with persistent pinking problems. All of these were cooked to a safe temperature, but some clearly have some color issues.

This is a pork chop that was cooked wrapped in bacon. Looks like the nitrites in the bacon seeped into the pork chop and created a pink color.

Sometimes the ovens that cook the meat can introduce gasses that react with the muscle and cause it to turn pink. We like it when this happens in smoked meats, but when you don’t expect it, you may be concerned it hasn’t been cooked enough.

This is a smoked sausage from an awesome BBQ restaurant in south Texas. See how the smoke has created the ring of pink around the edge of the sausage?

When you see pink color in meat, look to see where the off-color is within the pieces. Undercooked meat will be pink in the middle, but persistent pinking issues are more likely to occur on the surface.

Even what the animals (especially birds) eat or drink can introduce substances that can change the cooked color of their meat. Nitrates and nitrites that occur naturally in the feed and water can remain in the birds and create some color problems, especially around the bone.

This is another picture of some cooked chicken pieces from Dr. Claus. You can see some really severe pinking problems in them.

If you are served something that you think looks underdone, it’s OK to ask what temperature it was cooked to. Sometimes meat is just stubbornly pink, but sometimes it may actually be underdone. When it comes to my kids, if I think a piece of meat they've been served may be underdone, you bet I'll ask the waiter about it. 

The best way to know is to use a meat thermometer.

Cook it to a temperature not a color.

The USDA has a great fact sheet about meat color that gives more detail about persistent pinking and premature browning.

Antibiotics in the meat supply: Residues vs. Resistance

There has been a lot of news coverage and proposed legislation lately calling for the banning of antibiotic use in farm animals. People can get very frightened when we talk about antibiotic resistant bacteria or antibiotics in the meat supply.

This has been an especially personal topic for me because our family recently had a scare with antibiotic-resistant bacteria. In May, my daughter had a little lump behind her ear. I found it over a weekend and by Sunday evening, she was running a low fever, so we went to the doctor on Monday morning. By 6pm, we were admitted to the hospital with a very high fever and a freshly-lanced abscess. It took 2 of days of testing, and she was diagnosed with MRSA (methicillin-resistant staphylococcus aureus). She spent three nights in the hospital on IV antibiotics. Now, she’s fine and back to her little rotten self.

MRSA - Antibiotic-resistant Staph

Experiences like ours are very scary, and I know there are a lot of parents with much worse stories to tell than mine. However, most people know very little about antibiotic-resistant bacteria like MRSA. When they hear about antibiotics in relation to our food supply, they don’t know what to think.

First, what exactly are we talking about?

Antibiotics administered to animals headed to the food supply.

  

Why are animals given antibiotics?

There are two main reasons why animals are given antibiotics.

1. The most obvious reason is that animals are given antibiotics when they are sick or injured to fight infection.

Most people agree that it would be inhumane to withhold a drug from a sick animal and allow it to suffer. Even organic farms and antibiotic-free farms have a protocol in place to treat a sick animal and remove it from their herd.

2. Sometimes animals are given antibiotics to prevent them from getting sick. 

Just like kids, young animals are prone to infection. In some farms, animals live very close to one another and they are not very clean creatures (you just can’t teach a piglet to wash his hooves), so if one gets sick, they could all get sick very quickly. That could spell disaster for a farmer, so some farms choose to feed a low level of antibiotics to prevent disease.

3. Some antibiotics are given to improve how fast and efficiently animals grow.

There are new rules about antibiotics from FDA as of June 2015. I'm doing some research on them to make sure I understand them before I share what they mean in this post. Thanks for bearing with me. 

  

You may have heard a statistic in a news story that said that 80% of the antibiotics sold in the US are given to livestock animals. That number is largely disputed. First, it is impossible to know how many antibiotics are sold in the US, for use in livestock or in humans. Second, a large percentage of drugs used by farmers are not useful in human medicine. Lastly, livestock represent a larger population of bodies than do humans. And, cows and pigs are a lot bigger than humans; pound for pound, they need more antibiotics. What is the real number? Who knows?

What about antibiotics in my meat?

When people in the food industry talk about antibiotics, there are two terms they use: antibiotic residues and antibiotic resistant bacteria.

‘Antibiotic residues’ refers to actual antibiotic chemicals that have been given to the animals, either fed or given as injections, remaining in the edible tissue (meat, fat, or even milk).

The Food and Drug Administration regulates the approval and use of antibiotics in animal medicine. Any antibiotic that is given to a food animal has a specified ‘withdrawal time’ which is the amount of time that the antibiotic has to be withdrawn from the animal before it is slaughtered. These times are based on how long it takes the animal to process the antibiotic so that it is eliminated from the body. Farmers must wait to slaughter an animal for that amount of time after giving the antibiotic to the animal or they will be breaking the law.

The Food Safety Inspection Service (part of USDA) monitors the meat supply and tests for antibiotic residues in the meat. The levels of antibiotic residues found in the meat supply are very low (below 1%), and tests are done on a worst-case scenario basis, which means FSIS tests the tissues that are most likely to contain antibiotic residues (liver and kidneys) and they test a larger percentage of suspect animals (old cows, animals with injection scars, etc.). Although the levels are not zero, I am not really worried about antibiotic residues in meat.

A group called the US Farmers Ranchers Alliance has a video of experts discussing antibiotic residues.

‘Antibiotic-resistant bacteria’ refers to bacteria that are not easily killed by common antibiotics, they are resistant.

How do bacteria become resistant to antibiotics?

Bacteria are everywhere, and there are millions of species, strains, and serotypes… all fancy ways of saying ‘different’ bacteria. Bacteria have a genetic code, just like humans, and they change and evolve with each generation. Unlike humans, they multiply at crazy-fast rates, so their genes can change at fast rates. When you introduce something to kill the bacteria like antibiotics, most of them die, but a few live. The ones that live may have had something in their genetic code that allowed them to survive the antibiotic treatment. All the other bacteria are gone, so that leaves more room and food for the left over bacteria to grow. When they grow, they pass their antibiotic-resistant genes to the next generations. Eventually, those antibiotic-resistant bacteria are spread around, and found all over the place. We have to learn to fight them in different ways.

A study from 2003-2004 found that MRSA (the bacteria my daughter fought) was in 1.5% of American noses. That was 8 years ago, and the bacteria have been spreading since then, so the numbers are probably larger now.

Are antibiotic-resistant bacteria in my food and how did they get there?

Yep. Antibiotic –resistant bacteria are in our food supply. They are everywhere.

Our food is handled by several different people and goes through several steps to get to our plates, and bacteria can be introduced at any of those steps. Some people want to blame the use of antibiotics in animal feed and that may be part of it, but it is likely that several actions contribute to the spread of antibiotic-resistant bacteria.

Can it make me and my family sick?

There are some forms of dangerous food borne pathogens like Salmonella and E.coli that have developed some resistance to antibiotics. That means that if you get one of these bacterial infections in your gut, it will be harder for doctors to help you fight them. But, even the non-resistant forms of these bacteria are very dangerous and can make you very, very sick.

What can I do?

Antibiotic resistant bacteria are susceptible to foodsafety measures such as cooking food thoroughly and keeping raw food away from cooked food. 

• Cooking kills antibiotic-resistant bacteria just like it kills antibiotic-susceptible bacteria. Use a meat thermometer to be sure you cookmeat thoroughly. 
• Hot soap and water wash antibiotic-resistant bacteria off of counter tops and utensils. 
• Antibiotic-resistant bacteria cannot grow as well in cold environments just like the antibiotic susceptible strains, so getting fresh food and leftovers chilled quickly is very important.
• Antibiotic-resistant bacteria can’t jump through the air from raw food to cooked food, so keep raw and ready-to-eat foods separate.

  

Anything else?

The main two bacteria species that we hear about when we talk about antibiotic resistance are Staphylococcus aureus (MRSA) and Clostridium difficile. Although they are huge issues in the medical industry, the CDC does not see them as a risk in the meat industry. Food safety practices should keep you from getting sick from these bacteria in your food.

However, you may have heard that MRSA has been found in 6.6% of pork samples in a US study. I emailed the author of that study for this post. She was really nice and said that the worry with MRSA in meat is not as much about getting sick from it being in your food as it is about the MRSA spreading from the raw meat to other surfaces and being introduced to a scratch or an open sore and causing severe skin infections, like the one my daughter had.

Lots of bacteria from raw meat can cause skin infections if they are introduced to an opening in the skin, and these antibiotic-resistant ones are very hard to fight. So, my advice is to be extra careful with raw meat, especially with children (face it, they are dirty little monsters. I’ve seen mine lick the bottom of her shoe.).

Keep raw meat separate from other food from the time to pick it out at the grocery store until you cook it.  

• Use a plastic bag to keep raw meat away from other food items and away from surfaces like the bottom of the grocery cart.
• Wash your hands after handling raw meat
• Wash down the countertop with warm soapy water after it came into contact with raw meat (even in the package)
• If you have a cut on your hands, wear gloves when handling raw meat (like when you make hamburger patties.)
• Don’t let very small children handle or be in contact with raw meat

My friend Karen sent me this picture of her grocery cart. Her roast is in its package away from the rest of her food. Looks like she put a piece of butcher paper under it. Way to go Karen!

There have been studies connecting antibiotic-resistant E. coli bacteria from chicken to urinary tract infections. If I have been handling raw meat, I wash my hands before AND after going to the restroom.

I called and asked the pediatrician if there was any way to know where the MRSA that infected my daughter came from, and there was not. The doctor told us that lots of people are infected with it and kids ‘pick their nose, then pick their wounds.’ Gross.

What about buying meat from animals that have not been given antibiotics?

There are companies and farms that offer meat from animals that have never been given antibiotics. I’ve talked about such programs in a previous blog post. If you choose to buy those products because you want to support the practice of never giving animals antibiotics, that’s fine, but you should know that meat from these farms are not guaranteed to be free from antibiotic-resistant bacteria. The meat is not any safer than the meat that does not make that claim. A recent study found that the levels of Staphylococcus aureus and MRSA in pork were the same regardless of it being from pig farms that did not use antibiotics.

Denmark has banned the use of sub-therapeutic antibiotics and the results have not been positive for their pork industry. Jeff Fowle, a rancher and blogger from California discusses the ramifications of Denmark's decision in his blog.

Like I said earlier, there is lots of info on the internet about antibiotics (residues and resistant bacteria) in meat and in general.

I don’t know all the answers. Here is a list of a few more resources if you are interested.

MeatMythCrusher Video with Dr. Keith Belk

National Residue Program Fact Sheet from AMI

AMI Fact Sheet about antibiotics


NCBA facts on antibiotics

CDC page on antibiotic resistance

Antimicrobial resistance learning site for vets

FAQ from AVMA (American Veterinary Medical Association)

How would you like that cooked?

You order steak or a burger at a restaurant and the waiter or waitress asks, “how would you like that cooked?” What is your response? Well, if you are ordering a steak, there is no wrong answer to that question. HOWEVER, you should ALWAYS order hamburgers or any other ground meat dish cooked to medium, medium well, or well done. I always order mine medium well.

Why should hamburgers be cooked to medium well, but steaks can be cooked to rare?

Today, I visited a Family and Consumer Science Class and demonstrated to them the answer to this question with play-doh. (I had to fight the little Daughter at the Meat Counter off the play doh.) I took some pictures to share on my blog.

When steaks are cut, there is a possibility that bacteria (disease-causing germs) could be on the surface of the steak. Steaks (and roasts, too) are whole-muscle cuts, meaning that they have been cut into serving- or cooking-size pieces, but the internal portion of the cut is still undisturbed. So, those bacteria are going to only be on the surface of the steak, and when you cook it, the surface will be the first to get hot and it will get the hottest. Any bacteria on the surface are going to be killed in the cooking process. The internal part of the meat does not have to get hot enough to kill any bacteria. So cooking steaks to rare or medium-rare is perfectly safe.

Do you like my little play-doh steaks? The green dots are the bacteria (only on the surface). The Daughter at the Meat Counter thought they were peas.

Ground beef is made from smaller cuts of beef that are trimmed away from the steaks and roasts. They are not lower quality or inferior in anyway other than they are too small or too tough to make good steaks are roasts. (Actually, which parts are cut into steaks and roasts and which parts are ground into hamburger is largely driven by ground beef demand. People like hamburgers.) These parts and pieces (trim) are kept in large containers and transported to the grinding room in the plant. All of these little pieces could have bacteria on their surfaces just like the steaks above. Several companies have researched different ways to treat the trim pieces to lower the bacterial count on the surface.

Here is my play-doh trim. It’s smaller and cut into irregular pieces. The bacteria are still only on the surface.

Here is where the difference is. The trim is ground. When meat is ground, it is pushed through a metal plate with small holes. Behind the plate, is a rotating knife that cuts the meat and allows it to be pushed through the plate.

This is not play-doh. I actually have pictures of real meat! Yay! You can see the round strands of ground beef coming through the plate.

Now, any of those bacteria that were on the surface of the meat are mixed up and spread all throughout the ground beef. When we make patties out of the ground beef, the bacteria could be on the surface or anywhere inside the patty.

These are some patties we made for a research project. Real bacteria don’t have color and you can’t see them on or in your patties.

It is easier to see the green, play-doh, bacteria mixed in with the red in my play-doh patty.

When I tore open my little play-doh patty, the students could see the green bacteria all throughout the patty.

So, when you cook patties, you should always cook them to 160 °F. USE A MEAT THERMOMETER. Make sure the thermometer is inserted into the middle of the patty.

When you order hamburgers at a restaurant, ALWAYS order them to medium or greater.

If you have other questions about food safety, I wrote a blog post about food safety in September.

A common conversation over steak dinners with meat scientists is how we order our steaks. I order my steaks cooked to medium-rare. Why, you ask? Well, there are two main types of protein in meat that affect tenderness, connective tissue (holds it all together) and myofibrillar (causes the muscle to contract). These two proteins react differently to exposure to heat. Connective tissue (collagen) protein dissolves to gelatin when it is heated, so it becomes more tender. The myofibrillar proteins harden as they are heated and become tougher. The optimum combination of collagen dissolving and myofibrillar hardening happens at about the temperature of medium-rare. Yum.

Some people don’t like the serumy (bloody) flavor associated with medium-rare and they want their steaks cooked longer (my mom). I guess that’s ok. If you like more well done steaks, I suggest you buy steaks with more marbling (USDA Choice, Prime, and Certified Angus Beef). The extra marbling protects the tenderness of those steaks when you cook them more.

Like I said, there is really no wrong answer to the question, “how would you like your steak cooked?”

However, you must cook hamburgers to medium (160°F) or greater.