Pork, another red meat.

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In the eighties fat was public enemy number one.

Today, sugar, seed oils, nitrites and ultra-processed foods also make us contemplate our mortality every time we eat, but back then it was all about fat. Especially saturated fat.

Back then, trusted sources of scientific information like the National Heart Association, the National Institutes of Health and Oprah Winfrey all beat the war drums.

Fat is bad. Fat will make you fat and unlovable. Fat will wrap its chubby fingers around your heart and squeeze till you are dead.

In this environment the pork industry started to get a little worried.

Let’s face it, the poster for saturated fats has the rosy face of a pig staring out at you like a porcine Uncle Sam. It is very, very hard to talk around the fat content of pork belly.

But those Madison Avenue geniuses found a way.

Terrified of saturated fat, consumers had rushed into the arms of big poultry. Turkey and, especially, chicken, perceived as lower in fat, had gotten a big boost in sales.

Well, the advertising gurus mused, chicken is white meat, pork is white when it is cooked. Ergo, pork is a white meat, just like chicken.

And just like that one of the most successful advertising campaigns of all time was created: pork the other white meat.

Was it true? Did it matter? It worked, and it worked well. Donald Draper eat your heart out.

Just for the record, though, pork is not a white meat it is a red meat. Always has been, always will be.

And there is an irony here somewhere. Some cuts of pork are actually quite lean. Not the good ones like pork belly and ribs unfortunately, but pork tenderloin is almost as lean as chicken breast.

What we are really worried about these days with red meat is haem, not fat, and in this pork, no matter how white it looks when cooked, is most definitely a red meat.

What Actually Determines Meat Colour?

This is simple. A meat is red because it contains myoglobin. The more myoglobin a muscle has the redder it is.

Myoglobin, like it’s cousin haemoglobin that transports oxygen around the circulatory system, is a protein that contains a small molecule called haem (which we met in the bacon post).

Haem is a small molecule that contains iron. In the body haem is almost always associated with a protein and in muscles this protein is myoglobin. Together haem and myoglobin are able to bind a single oxygen molecule.

When the myoglobin is bound to oxygen it is bright red, but when no oxygen is bound it is a darker, purplish red.

Why Different Muscles Have Different Levels of Myoglobin

Because myoglobin is what gives red meat its colour, the question is really why do some muscles have more myoglobin than others? One muscle is much like another, isn’t it?

Well, no muscles can differ. In broad terms some muscles are built for speed and others are built for endurance. This, as it usually is when talking about muscles, is all because of anatomy.

We’ve seen in previous posts that muscles are bundles of long cells, or fibres, called fascicles that are, in turn, bundled into muscles.

I didn’t mention it at the time, but muscle fibres can be grouped into slow twitch or fast twitch fibres. Every muscle has varying proportions of each of these muscle fibre types.

The difference between slow twitch and fast twitch fibres, as their names suggest, is the speed at which they can contract.

Energy Metabolism and Speed

Fast twitch fibres are larger and have more contractile machinery but the major reason for the difference in speed is how the different fibres get the energy for contraction.

If you remember the post on beer, we learned that energy, in the form of ATP, can be generated, usually from glucose, in the presence or absence of oxygen.

When anaerobic respiration, energy production in the absence of oxygen, takes place there are by-products of the process apart from ATP.

Yeast, for example, produces the bubbles, and the alcohol, in our beer as by prodycts of anaerobic respiration.

Human muscle cells can also produce energy, for a short while, in the absence of oxygen. In a giant missed opportunity, though, they produce lactic acid as a by-product, not alcohol like yeast.

Nonetheless, lactic acid respiration is useful when muscles are working hard, and the blood system can’t get sufficient oxygen to the cells to regenerate ATP aerobically. Like when you are sprinting for example.

The muscle fibres that are setup to respire anaerobically like this are the fast twitch muscles. Fast twitch fibres provide fast explosive movement, contracting extremely quickly and regenerating ATP without oxygen.

Fast twitch fibres can only keep this up for a short time though. They quickly burn through their available energy and become fatigued.

Slow twitch muscle fibres, on the other hand, are the ones you use when you go for a jog. They provide slower, but steadier and longer lasting movement but they rely on a steady stream of oxygen and glucose, from the bloodstream, to keep things ticking over.

Myoglobin Is a Muscular Store of Oxygen

Slow twitch muscles, that need a constant supply of oxygen and glucose, are surrounded by plenty of blood vessels and they are rich in mitochondria, the place in the cell that aerobic respiration takes place.

They also contain a lot of myoglobin. As I said above, myoglobin can bind oxygen and oxygenated myoglobin, in slow twitch fibres, provides a store of easily accessible oxygen in the cell.

As you’d expect this makes slow twitch fibres red.

Fast twitch fibres don’t need all this help and they don’t need a cellular store of myoglobin. So, fast twitch fibres are not red.

An that’s basically it, a muscle that has a lot of slow-twitch fibres will be red, or darker, and a muscle that has a lot of fast twitch muscles will be a lot lighter in colour.

Comparing Myoglobin Levels Across Common Meats: Why Pork is a Red Meat

With all this science under our belt we can now see that we don’t really need to talk about red meat or white meat anymore. We can just measure the myoglobin in our favourite meats.

If we do that we see pretty much what we might expect to see.

Aged beef has the highest amount of myoglobin (1.5-2.0\% ), followed by normal beef (0.4-1.0%), lamb (0.2-1.3%), pork (0.10-0.30%) and veal (0.10-0.30%).

The classic white meat, chicken breast, has a much, much lower myoglobin level, containing only 0.005% by percentage of mass.

We can see now why pork is considered a red meat. Although it has way less myoglobin than beef and lamb it also has way more myoglobin than chicken breast.

In fact, mammalian meat in general is considered a red meat, mammals just seem to have more myoglobin in their muscles. Rabbit being a bit of a borderline case.

Even a cheetah, which you’d think has heaps of fast twitch muscles, still has significant amounts of myoglobin in their muscles (see the graph above).

So comparing mammal to mammal can get a bit confusing. Where you can really see the difference between fast twitch and slow twitch muscles is in non-mammalian species.

Chicken breasts, which are used for short bursts of flapping, are almost a hundred percent fast twitch muscles and have virtually no myoglobin. Chicken thighs, on the other hand, can rival mammalian muscle for myoglobin content because they have much more slow twitch muscles.

Likewise, fish like cod, flathead, snapper, and barramundi are mostly stationary except for short bursts of explosive speed. These fish have almost no slow twitch muscles and have white flesh. Endurance swimmers like tuna and mackerel have more slow twitch muscles and hence darker flesh.

Meat Type	Typical Myoglobin Content (% of Muscle Mass)	Meat Classification
Aged Beef	1.5% – 2.0%	Red Meat
Normal Beef	0.4% – 1.0%	Red Meat
Lamb	0.2% – 1.3%	Red Meat
Pork	0.10% – 0.30%	Red Meat
Veal	0.10% – 0.30%	Red Meat (Young Bovine)
Chicken Breast	0.005%	White Meat
Turkey Breast	0.008%	White Meat

A Short Digression: Mammalian Myoglobin Levels

If you have a look at myoglobin levels in mammals, like in the graph below, you can see that the myoglobin in land mammals is all over the place. Just looking at it I’d guess, if anything, it looks to be correlated with size.

The real difference seems to be between land animals and sea mammals. Sea mammals appear to have a preference for lots of myoglobin in their muscles.

This makes sense if you consider that storing large amounts of oxygen in muscles would be good if you want to spend a lot of time underwater. You don’t need to come up for air every two minutes.

It’s been calculated in humans, for comparison, that there is about 7-10 seconds worth of metabolic activity stored in skeletal muscle oxygen stores whereas a sea lion has 47% of total oxygen stored in myoglobin.

An interesting question that this raises is do land mammals need myoglobin at all? Mice genetically engineered to have no myoglobin seemed to survive quite well.

This is just speculation but if it turns out the haem is the problem molecule in red meat (which may well be the case) could we engineer cows without myoglobin?

Would you want to eat a steak that looked like a chicken breast though? Maybe not.

Why Does Cooked Pork Look White?

This talk of myoglobin is all well and good, but the reason why the advertising campaign worked so well is that pork looks white when it is cooked. Why is that?

When we cook food we denature proteins. Myoglobin is a protein, and as we cook a piece of meat it will unwind and lose its ability to bind oxygen. When this happens it also loses its colour.

This happens in beef just as much as pork but we tend to eat beef rarer than pork. A rare steak is red on the inside because it has more intact myoglobin.

A rare pork steak isn’t as red as a beef steak, it’s more a pink colour because it has a smaller amount of myoglobin. But traditionally we’ve eaten well done pork which means all the myoglobin is denatured and the flesh looks white.

Veal, the meat of young calves, is also much paler when cooked, and again it has a smaller amount of myoglobin. So much so that in some older culinary traditions veal, pork and rabbit were considered white meats. The viandes blanches of traditional French cuisine.

Conclusion

Ultimately all this ‘is it a red meat or a white meat?’ is beside the point. Leaving fat content aside, current thought is that high levels of haem are thought to be carcinogenic because of its role in the production of carcinogenic N-nitroso compounds.

The other source of carcinogens in our meat are the heterocyclic amines and polycyclic aromatic hydrocarbons that can form when meat is cooked at high temperatures (such as grilling or BBQing) but this happens regardless of the meat’s putative colour.

So we should really forget about the red/white meat thing and just think about haem.

In this scenario pork has less haem than beef but still a whole lot more than chicken.

So if you are worried about red meat, pork might be better than beef but it’s not as good as chicken breast. And eating cheetahs, if you can catch them, wont help either.