White striping in chicken

Dr. Christine Alvarado and Dr. Casey Owens
the Moms at the Poultry Counter

I have recently seen a few social media posts and had a few questions about white striping in chicken breasts. And honestly, I don’t know as much about chicken as I would like to, so I didn’t have very thorough answers to people’s questions.

So, as a scientist, what do I do when I don’t know something? I ask questions and do a little research.

As a mom, when I don’t know something? I ask my friends. Luckily, I have some really smart friends in Poultry Science who know more about chicken than I know about beef.

Dr. Casey Owens and Dr. Christine Alvarado (pics and bios below) are moms and Poultry Scientists who have been conducting research on the white striping that we sometimes see in chicken breasts. I asked them to write a few words for my blog about it.

So today we hear from The Moms at the Poultry Counter! 

White striping in chicken? What is that and is it harmful? What you need to know from Scientist Moms…..

Recently, I am sure many of you have been hearing about white striping in chicken breast meat – everything from ‘its fine’ to ‘don’t eat the chicken’.  So, we just thought we should clarify some information.  We have conducted scientific research in this particular area and this research may be misrepresented and/or misinterpreted in some cases by the general public. Many of our studies have been written for an audience consisting of scientists and industry in efforts to identify these quality conditions and improve them.

We as moms and scientists want to clarify that white striping in chicken breast meat is absolutely safe to eat – there is no food safety concern. We also wanted to make sure that as moms and scientists, everyone knows we feed chicken breast meat to our own children knowing we have the highest safety and quality standards in the USA. 

Now on to the science….. White striping is a quality factor in chicken breast meat caused by deposits of fat in the muscle during the bird’s growth and development (i.e., the bird’s life). In fact, it is similar to marbling in red meat.  Consequently, protein levels decrease slightly as fat increases.  However, white striping can occur in meat in varying quantities (also observed visually).  Meat that we consider to be mild or moderate may have striping that appears as very fines lines.  It isn’t always noticeable or necessarily detracting from its appearance. This level has been observed in chickens for many years; it just isn’t always noticeable.

Normal chicken breast (left) vs. a breast with white striping (right)

The striping we refer to as severe can be more abundant and prominent.  In more recent years, there has been more meat with increased severity of white striping and this is the potential quality issue. With that said, fat is present in any chicken breast meat in low amounts anyway so while there may be a slightly higher fat content in white striped breast fillets when compared to those that aren’t white striped, the overall fat content is still low.  Some references in social media are citing that white striping can increase fat by 224% and we know that sound like a lot, but when starting fat content is only 0.5%, that doesn’t result in much of an increase at all. Other studies state a much lower increase in fat (224% vs 84%); regardless, even a 100% increase would only double the amount (e.g., 0.5 to 1%), still resulting in low fat content.  The same is true for protein though the protein levels generally decrease as white striping increases, but again in very small quantities (2-3% decrease).

So what has changed? Why are we seeing more white striping in chicken meat? Chickens used in the meat industry are young, but they are now generally growing faster and bigger due to better management, nutrition, animal welfare, and genetics. Therefore, their growth and development is also changing and this can lead to more fat deposits in the meat.  By raising bigger birds, it means that fewer birds can be raised for the same amount of meat and at the same costs, thereby a relatively inexpensive, quality protein can be provided for people to eat.   

Another question from consumers is why don’t we just slow the growth down? Slower growing birds are less sustainable and will result in more birds being raised to produce the same amount of meat.  Also slow growing birds and organic birds have white striping as well.  So researchers are working on ways to reduce white striping through different feeds and ways of breeding the chickens. 

Our research studies use models to create white striping in the chickens, so we can study it better.  These studies are published to help the industry with improving quality and not to be misinterpreted that this meat is not safe or wholesome.  So, when you read information about white striping in chicken, don’t forget that we are moms and we have confidence that our industry produces a safe and high quality product for consumers. 

 Christine Z. Alvarado, Ph.D. and Casey M. Owens, Ph.D.

Dr. Christine Alvarado earned her B.S. in Biomedical Science ('93) and MS and Ph.D. (2001) in Food Science from Texas A&M University. She has been on faculty at Virginia Tech, Texas Tech and is now an Associate Professor in the Department of Poultry Science at Texas A&M University. Dr. Alvarado’s applied national and international research program primarily focuses on improving meat quality and process efficiency for poultry processors and determining functionality of non-meat ingredients used in further processed poultry. Dr. Alvarado also conducts research in food safety with an emphasis on working with processors to evaluate current and new innovative antimicrobial applications for efficacy and cost effectiveness.  

Dr. Alvarado is a Novus International Teaching award recipient and currently teaches graduate and undergraduate courses in poultry processing, poultry further processing, an undergraduate capstone poultry science systems course, and a graduate seminar. Dr Alvarado has 5 children, loves to teach students to be agricultural advocates, and loves to help empower students to be better leaders in society. 

Dr. Casey Owens received her B.S. degree in Poultry Science and her M.S. and Ph.D. degrees in Food Science and Technology from Texas A&M University in 1994, 1996, and 1999, respectively.  She joined the faculty of the Department of Poultry Science at the University of Arkansas in 2000 and she is currently an Associate Professor and holds the Novus International Professorship of Poultry Science.  She is also an Adjunct Associate Professor in the Department of Food Science.  Her research has a strong emphasis on evaluating production and processing factors affecting poultry meat quality including tenderness, water holding capacity, color and sensory attributes.  Her recent research has focused on quality of meat from broilers in big bird market programs including muscle myopathies such as white striping and woody breast, and issues with meat texture.  Past research has included meat tenderness and methods for assessing meat tenderness with the development of the Meullenet Owens Razor Shear, pale, soft, exudative poultry meat, and the use of marination in poultry meat for improved meat quality.  She has published over 100 peer-reviewed articles, book chapters, and popular press articles as well as over 100 research abstracts. She has given over 45 invited presentations nationally and internationally. She is a Subject Editor for Poultry Science in the Processing and Products section. In addition to her research, Dr. Owens teaches Egg and Meat Technology and Value Added Muscle Foods at the undergraduate and graduate levels for students in Poultry Science, Food Science, and Animal Science. She also teaches industry workshops related meat and egg processing and further processing. She serves as an undergraduate academic advisor, and Dr. Owens has directed the research of numerous Ph.D. and M.S. graduate students in addition to undergraduate research. Dr. Owens has two children.

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.

Packaging questions: Purge

It’s one of my most commonly-asked questions.

What is the deal with that blood or water in my package of meat?

Beef steaks and purge
Photo courtesy Macc Rigdon

When you take your tasty cut of meat out of the package, there is a pinkish liquid that is left behind. Most of the time, there is even a little soaker pad in the package to soak it up.

What is that stuff?

Short answer:



It’s a combination of water, lactic acid, and meat pigments that seeped out of the meat.

Longer answer:



Soaker pad in a chicken tray

In science class, we all learned that our bodies are largely made up of water. The same is true for animals, and a high percentage of that water is held in the muscles and stays in the muscle when it’s converted to meat.

Water in the meat is what creates the juiciness we experience when we eat a juicy steak, a tender ham, or a succulent turkey (#tokenthanksgivingreference). Water helps give meat the texture and flavor we expect. Meat without water is jerky, dry and tough.

Think of the proteins in meat as a sponge. As the meat ages and the more it is handled (cut, shipped, packaged, etc.), the protein sponge loses its ability to hold onto water. So, the water seeps out of the meat over time.

When the water seeps out, the protein that gives meat its color (myoglobin) flows out with the water. That protein gives the purge its color. Although it’s similar to the protein that gives blood its color (hemoglobin), it is not blood.



Pork chops in a purge loss study
Meat scientists have lots of
creative ways to measure purge
Photo courtesy Macc Rigdon

The ability of the meat to hang on the water is dependent on several different things, including the species and age of the animal, the fatness and grade of the meat, the length of time since the animal was harvested, which muscle the cut of meat was from, and how the meat has been handled and processed. Meat scientists spend hours and hours trying to figure out purge and what causes it.

Sometimes meat processors will add a solution to meat cuts to make them more tender, flavorful and juicy. That solution can change the amount of purge in a package, but the presence of purge does not automatically mean that water or anything has been added to the meat. Most of the time, purge is just a natural result of water leaving the muscle.

Some of the water in meat will evaporate out when it’s cooked. That’s why cooked meat is lighter in weight than raw. As the meat is cooked, the myoglobin will denature and lose its red color. So the juice that runs out of a rare steak may still be pink or red, but the juice from a cooked steak is colorless.

So, the water in meat packages is just purge, water and a little myoglobin. Maybe we should give it a better name.

Vacuum packaged pork with purge
Photo courtesy Macc Rigdon 

 

Something I learned from writing this blog: When you ask your meat-scientist friends to send you pictures of purge, be prepared to get a whole lot of them! I wasn’t pleased with my own photos, and a whole community of meat scientists responded when I sent out a request for pictures on facebook. Thanks, friends!

What’s in a food label? Raised without hormones

I’ve been writing a series of posts about food labeling. My previous posts have been about labels that involve the whole system of raising animals, like Organic, Naturally-raised or Grass-fed. Some labels are more specific and address one particular technology used for raising animals like hormones or antibiotics. Today I’m going to address the labels concerning hormones in meat.

First let me address “Hormone Free”

A big joke in the livestock industry is when we see a food, especially meat milk or eggs, advertised as “Hormone Free.”

All animals have hormones and need them to grow and produce meat, milk, eggs, babies, or whatever. All food has hormones. Nothing can actually be ‘hormone-free.’ Saying that beef is “hormone free” is about as pointless as talking about a boneless chicken ranch (you know, all the chickens just lay there.)

But, we all know that they really mean that the animals were raised without the use of added hormones.

Technically, you cannot label a meat product as hormone free. You see it on signs and menus, but it shouldn’t be on a label.

You CAN label a meat product as “Raised without hormones” to let the consumer know that no extra hormones were administered to the animal. Now, that means different things depending on which species the label is on.

What does that mean for Pork and Poultry?

In the US, it is against federal regulations to use hormones to raise pork and poultry.

Yep, its true.

 

Wait… what?

That’s right, no pork or poultry in the US is raised with hormones (other than the ones they make in their own bodies).

But you see it on pork and poultry labels?

Yep, meat companies are allowed to label their pork and poultry with a “No hormones administered” label. All pork and poultry in the US is eligible for the label. When they choose to use that label, they have to also write that “Federal Regulations prohibit the use of hormones in pork/ poultry.”



Some examples of pork and poultry labels that say that hormones are not allowed to be used.

 

So, what about beef?

In beef, it is legal to administer hormones to the cattle. They are similar to the hormones the cattle produce naturally and they allow them to grow larger, leaner, and more efficiently. They help the cattle grow more beef using fewer natural resources.

These hormones are actually administered in what we call an ‘Implant’ in their ear, not usually fed to them. There are several different options available, and they are usually applied in the feedlot or finishing phase of the animal’s life (the last few months) before harvest.

Just like anything given to the cattle, the FDA and USDA have rules and regulations that the farmers must follow concerning the implants. These rules will involve how long they can be administered and how long before harvest.

Back to the label. When the implants are not used, the beef company may say so on the label.  

Big Island Beef was really popular in Hawaii
It is raised without the use of hormones.

Very often the ‘raised without the use of hormones’ label will accompany another claim like Natural, Grass-fed, or Organic.

How much does it really matter?  

When beef raised without hormones was compared to that from cattle that was given hormones, the level of hormones in the beef was slightly different. In an 8-oz steak, the amount of estrogen found in steak from the implanted steer was 5.1 nanograms and that found in a non-implanted calf was 3.5 nanograms.

How big is a nanogram? One nanogram is one billionth of a gram. That 8 oz steak is a little over 226 grams.

 
This has been an awfully long post to answer a simple question, but people that know me expect that. I hope this helps to understand another meat label. Please let me know if you have any more questions.