Off or just ugly? Discoloured raw meat.

  |   Science   |   7 Comments

What makes meat bad? This is not an invitation to discuss the ethics of consuming animal protein.  Does brown discolouration on raw meat* mean you should not eat it?


I often see this kind of question posted on internet fora that concern the home cook “I defrosted some mince yesterday but didn’t get to use it, have come to use it now and it’s gone completely brown, looks disgusting but smells absolutely fine, what should I do?”

You may have noticed a brownish grey colour in minced meat bought pre-packaged from a supermarket, particularly the underside of the mass. You may not notice any off odours, it may be well within its use-by date, you may have looked after it lovingly and bought it from a reputable supplier, but you may still be wondering if it will harm you.


Firstly, let’s look at the difference between spoiled meat and meat that will give you a food borne illness. “Spoiled” is subjective term. It is up to the consumer. You may have been expecting a glossy, juicy, red morsel and now you have a flaccid grey brown lump. Your expectation of quality has been spoiled, that is all.

I say ” that is all” but the meat industry spends vast sums of cash employing food scientists and technologists to make sure the appearance of meat matches consumer expectations.


What consumers in Australia and similar countries expect and associate with quality is PSE meat. That stands for Pale, Soft and Exudative – (definition of which is the opposite of firm, that’s all I ‘m going to say for the non-meat industry technologists, trust me)

Contributors to Colour


This is the protein molecule myoglobin which contributes a great deal to the colour of meat.  Myoglobin stores oxygen in muscle cells. When the cell is holding myoglobin it is nice and red. When myoglobin is used up inside the cell it turns in to metmyaglobin which gives a meat purple tinge and when water comes in to the equation, as in the syneresis of defrosting, it goes brown.

Minced meat is highly susceptible to this as so much of the meat’s internal surface area is exposed during the mincing process so lots of oxygen diffusion can take place. The plastic film which covers supermarket mince is permeable to oxygen so it remain stay red, unlike the vacuum packed stuff which usually looks dark purple. Often the oxygen starved underside of the mince mass can be browny grey.  But you can take steps to change the colour back to a more acceptable red if the meat is fresh not frozen by taking it out of its packaging and leaving it exposed to the air for 15 minutes. Basically, the remaining myoglobin will attract the oxygen molecules the meat will return to a red colour, known as a bloom.

Meat colour and animal welfare

Of course, you really want as much myoglobin in the meat as possible to start off with. Reduced levels of myoglobin lead to DFD or Dark, Firm Meat. And the consumer does not like that one little bit.


In the meat processing industry great lengths are taken to avoid Dry Firm Dark meat, it looks dry, firm and dark has a rough texture. This is a result of a high ultimate pH level in the muscle (ultimate meaning at the point of slaughter) which is also a response to stress.

After slaughter the muscle cells consume the remaining glycogen (stored energy) and accumulate lactic acid to a pH level of around 5.0  – 5.5. This reduces enzyme activity and slows down microbial spoilage. Some moisture is released from the muscle and this diffuses oxygen at low pH but keeps the red colour.

Because consumers demand meat of a certain visual and textural quality, it is in best interest of the meat and livestock industry to ensure that the final hours of stock are calm and relaxed right up to the ……. off.

I’m not saying animals believe they are going for a day at the beach as they trot up that ramp,  but reducing their response to stress is important.  The flight or fight mechanism response to stress uses up glycogen in the process of anaerobic glycosis which results in low myoglobin levels and dark, dry, firm meat.

So can I eat the off coloured meat?

If you can be certain that the pre-requisites of hygiene, best practice, temperature monitoring and safe storage are in place in a meat supply chain then the risk of food borne illness via pathogenic micro organisms of raw meat is low. Plus, it is up to you as the consumer to store and handle the raw meat according to instructions. It is safe to eat brown coloured meat if you are going to cook it thoroughly, and even the NSW food authority website agrees.

How can meat make you sick?

The original questioner said the defrosted meat looked disgusting but smelled fine, so how good an indicator of safety is the look of meat? We cannot tell what kind of pathogenic microbial load is on a piece of meat just by looking at it. (disclaimer – I am talking about pathogenic bacteria and bacterial toxins NOT contamination from parasites, viruses or prions.) The surface and texture of meat does not alter in the presence of pathogenic bacteria such as E. coli 0157, Salmonella, Listeria moncytogenes or Campylobacter. Generally these microorganisms reach meat muscle during the trimming and cutting process; hides must be removed in one piece and the gastro intestinal tract must not be damaged. You need a meat packer with a steady hand and pride in his trade.


In a well regulated, well monitored and ethical meat and livestock system it is unlikely that these pathogens will find their way in to the raw meat on the shop shelf. A Dutch study1 found small traces of Salmonella, E. coli 0157, Campylobacter and Listeria moncytogenes in beef. Pork tested negative for Listeria moncytogenes but showed minute traces of the other pathogens. Lamb showed minute traces of Listeria moncytogenes  (0.6%of samples taken ) and some Campylobacter. Those results are pretty darn good.

It could be argued that you risk become infected with any of those pathogens if you eat meat, however you would have to be paying little or no attention to

  • the way you stored it
  • they way you cooked
  • and you probably  bought from the back of a lorry (England English for ” a very suspect source with low integrity and possibly criminal connections).

That Lorry (or truck) is a very important part of the supply chain. Given that the meat is in perfect condition when it leaves the processing plant on the way to the retail outlet there is no potential threat to public health unless the truck’s refrigeration unit is operating above 4°C. And once you buy your meat you really need to get it in to your fridge quickly.


Even if you eat your meat practically raw like blue steaks, pathogenic bacterial load to is low start off with deep inside muscles. The surface area of a steak is fairly small compared to processed meat products, and of course you have bought it from a reputable supplier and it was pretty expensive, right?  That’s why there are no recipes for hoof Carpaccio or tail tartare. These cuts are too near the business end of an animal and its muddy field to be sufficiently reduce the risk of pathogenic contamination.

Breaking Bad Beef-wise

However, during my research for this piece I came across the Paleo Foodists, or Primal Diet crowd. It is a relatively new dietary fadwhich argues that 21st Century humans have the digestive systems of pre-agricultural hunter-gatherers and should eat modern foods that mimic what was available way back then. More information here.


It looks fairly healthy, if a little fussy: High protein, low GI, high fibre, omega 3 and unsaturated fats and low sodium. I know a couple of men who try and stick to this way of eating and don’t look bad for their age. However, as with any system that marks the consumer out as special, one can go to extremes.

This is Aajonus Vonderplanitz (real and less catchier name Richard Swigart), and I am not going to make any comment on his motives or medical claims because this is a science page but you can read about him here if you like. He kept meat states of putrification (anaerobic decay) and rot (aerobic decay) for months and then ate it.

How did he do it and survive? The stomach’s acid is very strong, pH 2, and protects against many bacteria that could cause illness. The short intestinal transit times in healthy people would reduce the risk of food borne pathogens including toxins taking hold. He has been doing this for a while and is most likely used to it. In the state of putrification / rotting microorganisms such Lacto bacillus thrive. They beat down the growth of pathogens like E. Coli by lowering the pH, competing for food and producing anti microbial agents

It is a showy trick, makes good TV and good luck to those that can afford to choose the best cuts of meat from quality suppliers. My guess is that Aajonus is getting a) valuable probiotic flora and b) a kick of out being manly enough to eat something repulsive to most people. It may also contribute to the shine on his impressive mane.


Always choose meat from a reputable butcher with clean and fresh smelling premises and evidence of a good cleaning regimen to minimise risk of pathogen


* Meat in this case is beef, lamb, goat, pork or venison. Not poultry which is a whole other ball game altogether.

1. Epidemiological research, carried out in 2005 and 2006 by the Dutch Food and Consumer Product
Safety Authority, retrieved from‎




  • Fiona | Sep 25, 2013 at 19:25

    Thank you crackling for this very informative piece. I will try to bear it in mind when I am next faced with brown mince at the back of my refridgerator…………unfortunately I tend get a primeval urge ‘not’ to touch it with a barge pole, a bit like my reaction to many of the local men round here.

    From the blog, one can only assume that my local butcher’s superior tasting beef mince will have a shorter a shelf life than the vacuum packed/plastic packed variety which is found in the supermarket?

    • Crackling | Sep 25, 2013 at 19:32

      Hello, and thank you for your comment

      Yes you are right, butchers’ mince is generally preservative free, in fact my local butcher ( who is actually from Wokingham) has a sign on it saying “use within 24 hours”. I suspect that to keep it at an acceptable colour to the consumer rather than for issues of food safety.

      I am very pleased to read you are keeping yourself classy in your local area.

  • Suedonim | Sep 25, 2013 at 19:39

    A great piece! I did know brown mince was ok but I do feel as though there is a taste difference with it.

    I am interested in the part about stressed animals not making good meat. I have more than once heard the argument that hunting deer makes for good venison due to the adrenaline coursing through its veins. What’s your opinion on that?

    You might also be interested to know that in some cultures tender meat is not an asset. A, to western tastes, chewy piece of meat is perceived as better value by some peoples.

    • Crackling | Sep 25, 2013 at 19:56

      Yes, you are absolutely correct that tender meat is a Global North/First World/Western preferred attribute. I was wondering whether the acceptance of dry firm dark or chewy meat in cuisines that use a lot of marinades and spices to tenderise and mask strong flavours had anything to do with cultural and psychological conditions applied to the slaughter stage.

      I have never heard that about vension, I will research it and report back.


  • Jas@AbsolutelyJas | Sep 26, 2013 at 21:45

    Fabulous post – really interesting topic and very well written!

    • Crackling | Sep 27, 2013 at 09:08

      Hello Jas, thanks for the response and for commenting, the comments boxes can be a lonely place.

  • A Life Unlimited | Nov 2, 2013 at 23:01

    He died – Aajonus I mean. In August. Poor chap. Not from the food though, according to wiki his balcony in Thailand gave way.

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