• Friday, October 28, 2011

    What is Nitrate?

    I recently had a discussion with another mom about nitrates and nitrites in meat and their safety. She said that she buys nitrate-free products for her kids. She is a smart lady and wants to do the best for her family’s health, but she didn’t even understand what nitrate or nitrites are and sure didn’t know why they were added to meats.
    I touched on nitrite a little bit in my processed meats post, but I thought a whole post about them might clear things up.
    Question one. What is nitrate/nitrite?  

    Nitrates and nitrites are chemical groups, part of lots of compounds, both natural and man-made. They are a combination of a nitrogen atom and either two (nitrite; NO2) or three (nitrate; NO3) oxygen atoms. When it’s added in processed meats it is usually combined with sodium or potassium (you would see it as Sodium Nitrite on the ingredient statement). Nitrite (the one with 2 oxygens) is most commonly used in meats.
    I mentioned in a previous post the benefits of nitrite in the diet and linked to the video by Dr. Nathan Bryan.
    Question two. Why is nitrite added to meats?
    Good question. Have you ever heard of cured meats of meat curing? Curing meat requires nitrite. Some good examples of cured meats are ham, bacon, hotdogs, and pepperoni.
    The nitrite in cured meats serves several purposes.

    1. It gives cured meats that pretty pink color and the color that lasts a long time (unlike fresh meat color).
    2. It gives cured meats their distinct flavor.  (Think about how a ham tastes so different from a pork roast.)
    3. It protects the meat from organisms that cause spoilage and disease. Cured meats have a longer shelf life than most uncured meats. Nitrite directly prevents the growth of that nasty ol’ Clostridium botulinum, which is the bacteria that causes botulism (it’s also the organism used to make Botox, but that doesn’t mean we want it in our meat).
    4. It prevents the meat from going rancid and protects the flavor of the meat.

    Many historians think that meat curing was discovered by accident when salt contaminated with nitrite was rubbed on meat. (Salt was one of the first ingredients added to meat).

    Question three. Why do we have uncured or no nitrite/nitrate added products?

    Natural and organic products have become very popular in the last few years.  I covered this in one of my first blog posts. The definitions of Natural and Organic are regulated by USDA, and nitrates and nitrites are not permitted as an ingredient in products with those labels. If you try to make cured meat products like ham, bacon, or hotdogs without nitrite, the meat turns out a gray color and won’t have the typical cured flavor. Not so good.

    Why don’t people want it?

    When consumed in large quantities, nitrite can be toxic. Also, nitrite can combine with protein in meat at high temperatures and form nitrosamines, which are cancer-causing agents. Now, the amount of nitrite added in processed meats is very small and most processed meats are not cooked at those very high temperatures, so the level of nitrosamines formed is almost none. Processors also started adding the antioxidants, ascorbate (vitamin C) and erythorbate (structurally related to vitamin C), to cured meats to block the formation of nitrosamines. There has also been some scary stuff published that attempted to link hot dogs with cancer, but those studies have since been disproven.

    So how do we get uncured ham and hotdogs that still look and taste like ham and hotdogs?

    Remember in the processed meats post, I mentioned the video of the interview my friend Dr. Jeff Sindelar? He told us that people ingest most dietary nitrite from green leafy vegetables and not from processed meats. Technically, it’s nitrate (NO3) that is found in most vegetables, but it’s is converted to nitrite in when it comes into contact with the saliva in your mouth. These same vegetables and/or their juices can be added to Natural meats as a source of nitrite. Processors may also add harmless bacteria, called a starter culture, to convert the nitrate in the vegetables into nitrite.

    But, why does it say “no nitrite or nitrate added” and “uncured”?

    Because nitrate or nitrite is not added directly, the process of the traditional cured meats is altered, so the manufacturers are required to say that it is “no nitrate or nitrite added” or that it is “uncured”. A more accurate term would probably be “indirectly cured” or “naturally cured”.

    So, is it better or worse than conventional cured meats?

    The answer to that question is, “Yes.” If you feel very strongly about eating natural or organic products and don’t want to consume artificial ingredients, or if there are other claims that accompany the natural claim, like grass-fed or antibiotic free, that are important to you, then these products will allow you to still enjoy hot dogs and ham and other cured meats. Realize that the nitrite is still in the meat product. It just comes from a natural source. 
    One concern I have is that other ingredients, such as lactates, that help inhibit spoilage and fight off pathogenic organisms are not allowed in natural and organic meats, so they may be more susceptible to spoilage and are more dependent on processing techniques to guard against pathogens. You should be very careful to observe the use by dates and store them correctly. See my lunch box safety post for that info.
    Natural and organic meats products are more expensive than traditionally-processed products, so the benefit of low cost protein is somewhat lost when you choose natural or especially organic.

    Thursday, October 13, 2011

    Meat color is a-changin’!

    Let’s say you bought some steaks or a roast at the grocery store, brought it home and stuck it in the fridge. (Hopefully, stored on a plate on the bottom shelf.) You don’t get around to fixing it (that’s Texan for preparing it) for supper for a day or two. You take it out of the fridge and it has a brownish color. Maybe a few brown spots or maybe the whole thing is just a little browner than it was when you bought it. Has it gone bad? Should you throw it out? It wasn’t cheap, so you hate to throw it out. What to do?
    Check the use-by date. Smell it. Does it smell bad? If it doesn’t smell bad and if you haven’t passed the use-by date, it’s probably ok.

    Why is it brown in my fridge when it was red in the store?
    Short answer. It oxidized. Muscle has an ability to prevent (really slow down) oxidation, but that ability runs out with time. Oxidized muscle is brown.
    Long answer. Well, to understand why meat is brown, we need to understand why it was red, first.
    Meat contains lots of proteins. Some are structural (they hold the meat together). Some are for contraction (remember that the meat was originally for moving an animal around). Some proteins hold onto oxygen to help provide the muscle with energy.
    These oxygen-holding proteins are largely responsible for meat color. The main one is called myoglobin. Myoglobin is closely related to the hemoglobin that holds oxygen as it is transported through our blood. Just like we learned in sixth grade science class that blood comes in two colors (red when it is exposed to oxygen in the arteries and blue when the oxygen is gone in the veins), meat pigment comes in those two colors, too. When it is not exposed to oxygen, meat has a purple color. You can see this color right after it is cut. Meat scientists call this ‘deoxymyoglobin’ because the myoglobin doesn’t have any oxygen. If you buy meat that has been vacuum packaged, it will be purplish in color.
    The meat will slowly take up oxygen from the air and turn red. In the meat business, we refer to the time it takes go from purple to red as ‘bloom time’. Most of the meat you buy in the store has been packaged so that the oxygen in the air is available to combine with the myoglobin in the meat. That’s why it is a pretty red color in the store.
    We recently did a research project studying bloom time. This is a picture of some steaks from that study. The ones in the front had just been removed from a vacuum package and were the purplish deoxymyoglobin. The ones in the back had been setting out for an hour, and you can see the bright red color.
    Purple to red… what about brown?
    Ok. So, even though the animal is no longer living, the enzymes in the muscle are still somewhat functional. The enzymes in charge of using oxygen to produce energy will take the oxygen and metabolize it. To do this, the pigment (actually, the iron in the pigment) is oxidized (it loses electrons). When the iron is oxidized, the meat will turn brown.
     In fresh meat, other enzymes can fix the problem by reducing the iron (give it electrons back) and it will turn back to purple. Then, it can grab some more oxygen and produce more energy and the cycle begins again. This really only happens on the surface of the meat where it is exposed to oxygen, so at first, you have a red layer with the purple underneath (everywhere on the meat that is exposed to air will be red. You won’t see the purple unless you cut it). At first, the brown coloring is not around long enough to see. As the process slows with time, a brown layer of pigment will form between the red and purple.

    Eventually, the enzymes will run out completely and the muscle will not be able to fix the oxidized, brown pigment and it will turn completely brown on the surface. That is the brown coloring you see. If you leave it long enough, the oxidation could spread to the fat and cause some off-flavors, but the paying attention to the use-by date should prevent that.
    Here is a picture from a study we conducted. Some steaks were left in retail cases (in our lab) for a week and allowed to turn brown. Then we cut them into little cubes. You can see the completely oxidized brown coloring on the surface and the purple coloring in the middle.

    Just remember to pay attention to the use-by dates on the package and if you don’t cook it by then, freeze it by then.  Use your nose and feel if the meat is slimy. If it’s smelly or slimy, cut your losses and throw it out.

    I also have a video blog about why meat is red.

    Wednesday, October 5, 2011


    Nothing is more frightening than seeing a food recall or a food poisoning outbreak on the news or online. Especially when it is a very common product that you use all the time, like ground beef or cantaloupe.

    A recall means that a problem has been found with a food, and the company that produced it is removing it from the food supply. This can be for a variety of reasons from undeclared allergens (ingredients that people may be allergic to that are not on the label) to contamination with bacteria or a virus.

    One recent recall was due to people getting sick from E. coli O157:H7 infection in Ohio (not all recalls are associated with sicknesses). Scientists tested the ground beef in the people’s homes and found that it was contaminated with that strain of E. coli. Meat companies print codes on their packages that allow them to trace any package back to the plant where the meat was produced, the day, sometimes even the production line and the time of day. They can use that information and look at their records to know exactly what other packages may be contaminated with the same bacteria and where they were sold.

    How do I find out about recalls?
    Recalls of retail products are usually on the local news. If you see something being recalled on the news, you can usually find out more information by going to the news website or to the website of the company that is issuing the recall. Sometimes you may have to search ‘recall’ when you get to their site.

    I know that not everyone watches the news, so I have been thinking of some other ways to find out about recalls. Because I’m a meat scientist, the first thing I thought of was FSIS. The Food Safety Inspection Service of the USDA has a recall page on their website that you could check, but this will only cover products under the jurisdiction of USDA (meat, poultry and eggs). The FDA also has a recall page, for FDA-regulated products (all food except meat, poultry, and eggs). Both of these pages offer an option to sign up for email alerts. The webpage http://www.foodsafety.gov/ combines the food safety information from FSIS and FDA and has US food recall information on one page where you can sign up for email alerts, follow them on facebook, twitter or as an RSS feed.

    How do I know if recalls apply to me?
    The recall information should give where the product was produced and the establishment number of the processing plant associated with the recall.

    What is an Establishment number?

    Every meat processing plant is given a specific number by the USDA. Any product that exits that plant has to have the Establishment number on its label.

    If the meat being recalled is red meat and is processed (most of it will be processed), it will have an inspection mark like the one in the middle of the picture above. If it is poultry (chicken, turkey) it will be like the one on the right.

    The recall will also tell you what states the recalled product was sold into. For meat and poultry recalls, they will tell you the ‘Best-by’ or ‘Freeze-by’ dates printed on the package. When meat is packaged in a plant, the processor prints a ‘Best-by’ or ‘Freeze-by’ date on the package that allow the consumer to know when to eat or freeze the product and to allow the processor to know when the product was made (simple subtraction).

    Sometimes these dates are hard to find. They are printed on the package as the meat goes down the production line, so they are simple, one-line, almost stamp-like. Sometimes they are on the bottom of a can or on the side of the package.

    Here are some pictures of some ham I had in the fridge. Notice the inspection mark with the establishment number on the bottom and the ‘best-by’ date at the top.
    See the establishment number
    in the little circle at the bottom?
    The use-by date

    Many times when a recall is issued, people will throw out things in their fridge or freezer just because it is the same type of product as what is being recalled. I think that is wasteful. 

    Here is an example: According to the Tyson website, a product recently recalled was 73% lean ground beef sold in 3- and 5-pound packages. The chubs had an Establishment Number of EST 245D and a Best-by or Freeze-by date of September 12. The product was produced on August 23. That means if you bought some 3- or 5-pound chubs of 73% ground beef between August 24 and September 12, you should go check your freezer and look to see if your ground beef has the EST 245D and a Best-by date or Freeze-by date of September 12.
    Chances are you didn’t buy 3 and 5-pound packages of 73% ground beef. Those are really big packages and it’s the fattiest ground beef available. If you buy leaner ground beef, it is not part of this recall. Don’t just throw out any ground beef you find.

    What about buying meat at the store?

    If a recall has been issued, you shouldn’t have to worry about that product still being on the shelf at a store. Stores are very diligent at getting recalled product removed from their shelves. Stores that have had recalled product will also have information about it on their website.

    What if I find recalled product in my fridge or freezer?

    If you find product in your house that has been recalled for any reason, you can take it back to the store. I would call the store first and ask about taking it back. You don’t want to show up with it and no one knows about the recall or what to do. I say this because after my year working in a grocery store, I realized that not everyone is always on the same page.

    If the recall was for some type of bacterial contamination (E. coli, salmonella, and Listeria have been the ones in the news lately), remember to treat the recalled product with care. If you find it in the fridge or the freezer, I would take it out, put it in a big, zip-lock-type freezer bag, make sure it sealed, and put it in the freezer. That will lessen the chances of it contaminating something else. Wash your hands thoroughly after you’ve handled it. Be sure to clean any surfaces it touched (plates for thawing, refrigerator shelves, counter top) with warm soapy water. When you do take it to the store, go directly there. Don’t leave it in your car for very long.

    If you have a question about a recall, you can always just ask me. If I don’t know the answer, I will find someone who does.