Cooking kills bacteria. How about toxins excreted by bacteria?

[Lush]

Hi all,

Of course cooking can make unsafe food safe to eat. But not always. Bacteria can excrete toxins (poison) that can't be "cooked to death".

I like to start a topic about bacteria and their toxins; just to understand the difference between food that can be made safe to eat/drink by boiling and food that can't.

Let's throw in a few stupid examples to get, hopefully, a discussion going:
- Is it safe to cook and eat a fish that is floating in the water for some time?
- Can rotting(maggot infested) deer meat be eaten after cooking?
These are just extreme examples. I have seen ppl. eating maggots from rotting meat on TV. What about the bacteria (with their toxins) those maggots are crawling in? Maggots seem a strange thing to eat. Especially raw maggots, without cooking?!

Many of us know that mussels, shrimps (and some other foods) can be extremely dangerous if they go bad. Is this because of their bacteria, or because of their toxins? I don't think dead mussles, gone bad, can be eaten after cooking.

Lets be careful in the things we say or recommend in this topic

Any input would be greatly appreciated!
Lush

 

[crazydave]

I've never understood nor like the taste of game meat left to hang and that is basically half rotten. my favourite tale was of the ddiner who complimented the chef on the rice used to stuff the pheasant

saying that though the spice trade came about because of the need for strong flavours to hide the taste of bad meat so I guess it depends on the meat in question. I definately wouldn't eat dead fish or shellfish as you dont know what killed it and they can be pretty toxic. they might make good bait though.

 

[Wayland]

I'm not so sure about the spice / bad meat story.

If you look at the periods in question, spice cost far more than meat so why would you try to rescue bad meat with fantastically expensive spices?

If you could afford spices you could also afford good meat.

Sorry to go off topic, this one could be interesting but I don't know the answers myself.

Watching with interest.

 

[crazydave]

well thats whats been drummed into me over the years at school anyway, not sure about off topic as it was meant to demonstrate that cooking could possibly do something in the same way that game meat is still edible when its been hanging so long the feathers drop off in the manner of hanging pheasant or it glows in the dark which was a description from clarrissa dickson wright about when venison was supposed to be ready when it was hung in a cellar. sailors used to salt beef and pork in barrels and still ate it when it was off as they had no choice. they probably became aclimatised to the bugs and toxins in the same way the locals are to the water when we go on holiday.

I've been reading up and there doesn't seem to be much on the subject of destroying the toxins but loads on how they get in and cause foot and mouth, gangrene etc... or produce nerve poisons like the stuff they make botox from so I think I'd be pretty desperate. a lot of herbs have anti bacterial effects so I wonder if they would make a difference. the toxins are all listed as insoluable though so I assume that makes them difficult to get rid of and why we get delhi belly or pharohs revenge.

 

[Wayland]

Sorry, I meant to say it was me taking it off topic by being pedantic.

It's a common misconception, perpetuated by many books I must say. Often one writer makes something up and everybody else copies it thinking it must be right.

History is full of such problems, just think of horned helmets as a good example.

 

[chickenofthewoods]

On the subjet of spices, I think it's far more likely to have been that those who could afford them (and remember we're really only talking about the upper end of society here) would almost certainly want their guests to know they could, and that meant being very, very liberal with their use.

It would certainly help to explain some of the bizzarre taste combinations you find in medieval cookery. The average joe in his hovel only had recourse to basic seasonings that he could grow, barter for or forage.

With bacteria and toxins I think it'll be hard to discuss in anything but very general terms unless there's someone here who has specialised knowledge of the processes and the definitions for each.

However, it's worth remembering that 'toxins' can be present in fresh foods too, it's not just rotting that produces them. A good example is saponin, a toxin which our bodies doesn't really absorb very well and so much of it is also usually excreted - yet it's highly toxic to fish and can be used to stun them. Fortunately for us, Saponin can be broken down by cooking, further reducing the risk. But you can see the potential differences to your health that could be made between say, eating a Fat Hen* leaf raw, and cooking it.

*Which contains saponins and oxalic acid, both of which are mitigated by cooking.

 

[DoctorSpoon]

I did advanced food hygiene certification when I used to run a cafe for the National Trust and it was very useful info...

You have two types of bacteria - food spoilage and food poisoning. The ones that cause food spoilage do not cause food poisoning and the other way around. Meat that has sat around for two weeks and is green on the outside might taste funny (or you might like the taste) but as long as it is cooked properly (I'll get to that later) it will not give you food poisoning. Meat that is fresh from the supermarket and looks lovely, might also taste lovely, but might well kill you if you don't cook it properly because it contains food poisoning bacteria.

So cooking can't kill the food spoilage bacteria - spoiled food is spoiled food - but it won't kill you and you might like the flavour or you can put in loadsa spice to hide it! However, cooking will kill food poisoning bacteria if you do it right.

Basically the bacteria will die if you get it hot enough (I can't remember how hot now, sorry). It is only on the surface of the meat, so even if your steak is covered in salmonella bacteria by searing the outside you'll kill the bacteria and it's fine to leave it pink inside as there's no bacteria there. However if you do the same with a burger, the mince has lots of cut surfaces which might be covered in food poisoning bacteria right inside and if you don't cook them through you won't kill them, so they might kill you.

This is why roast chicken is so problematic. The salmonella is spread from one carcass to the next by the machine that scoops their guts out, so it is inside the cavity of the bird. This is the last place to get hot, so the meat might look cooked but you have to be sure it has got hot enough right the way through.

Feeling queasy?
Nicola

 

[chickenofthewoods]

Not yet!

That's pretty informative and explains a lot. I guess that's another reason why you need to keep your raw and cooked meats well apart during processing, handling and storage?

 

[robin wood]

One more point. The most common causes of food poisoning is not undercooked meat but "cross contamination". This happens frequently at Barbies, you are outside, the raw chicken (coated with salmonella on the outside because of our industrial food processing) is on a cutting board and then goes onto the barbie. The board is now coated with salmonella, someone else cuts up the salad on the board and then leaves it somewhere warm for the bacteria to multiply up to harmful levels. Everyone gets ill and blames the chicken even though it was seared to death.

I remember seeing exactly this on one of those dreadful reality TV shows where folk were living sort of iron age style years ago. One family came onto site with a bad gastroenteritis bug ( the squits) the chap proceeded to cook for everyone else in the community and they all became ill, so ill that a doctor was brought onto site and the program nearly had to be stopped. Doc said yes they all have gastroenteritis. Commentator said they were all taken down by undercooked chicken.

Basic food hygiene is very important in camping, don't cook for others if you have the squits and be careful about cross contamination.

 

[firecrest]

Just on a side note to cross contamination. When I went to honduras we all ended up with "montezumas revenge" we were all fine until one person got it, the everyone did. It was blamed on `sharing food and cups` but I don't think that was the case. There was millions and millions of flies. When you put a cup down, or it even left your lips, they would all land on the rim, then fly a couple of yards to the next person and onto their cups. The same flies landed on the sewage pipes and on peoples food. Perhaps a problem with rotting meat therefor,especially in a hot country, is that you risk contamination from the flies and insects surrounding the meat which will most likely land on you.

 

[Lush]

With bacteria and toxins I think it'll be hard to discuss in anything but very general terms unless there's someone here who has specialised knowledge of the processes and the definitions for each.

I think you are right. I did some reading on the subject, but stopped http://aggie-horticulture.tamu.edu/extension/poison.html

Fish and clamps seem more dangerous then meat. Basically it is hard to tell which food can contain which bacteria. Even if you do know, the next question is; do they produce toxins that can be broken down by heat or not! Botulism for example can be broken down by heat (don't try this at home, it is just a stupid example). Most other toxins can not.
On the other hand, there are bacteria that can not even be killed by heat, hahaha, help!

Then you have all the variables, like "do you store the food after cooking" ect. ect. No..., this is a hard subject to really understand. Although some very useful things are already pointed out in this topic.
It would need one to specialize and study quite a bit before being able to tell which foods can be made safe (after they have gone bad) by cooking and which not!

Lucky me I was just wondering and have no plans eating things that are spoiled

Does anyone know what to look for when collecting clamps? Some clamps can have a built up of very dangerous toxins isn't it? What circumstances are more likely to produce healthy mussels? Or is it just a lot in the lottery?

 

[crazydave]

near were I grew up in scarborough we had a bay which contained the sewage outflow for the mcains food factory. it was only a small bay which at low tide had no other visible life except huge mussel beds. while we used to collect them for bait as did the local fishing shops but we never touched them foodwise and were advised to look for the growth patterns on the shell rings and the life around them as if it was down to rich natural feeding then all the seashore would have benefitted. Instead we picked the ones closer to home that were about 5-7cm or thumb sized and buried in seaweed as they were generally the tastiest.

mind you scarborough did have the odd sewage issue when the currents were bad - they did extent the pipes though and add a pumping station which was better than filey which pumped it out right next to the beach

I tend to be overly carefull when I cook or eat so err on the side of over cook it if unsure. you cant get everything right though and have spend the past day fighting off some egg custards I found at the back of the fridge. off to egypt in two weeks so I imagine I'll be on the porcelain for bit after I slip up.

 

[Lush]

wish you good luck on the porcelain! Those damn egg custards. It's alway's the same

What do you mean with: "...we were advised to look for the growth patterns on the shell rings..."

 

[Stupot]

Basically the bacteria will die if you get it hot enough (I can't remember how hot now, sorry

I think its 83 degress celsius or something. Dont quote me on it but I'm a kitchen assistant and thats what I have to re-heat all foods back up to to be served.

Stu.

 

[crazydave]

wish you good luck on the porcelain! Those damn egg custards. It's alway's the same

What do you mean with: "...we were advised to look for the growth patterns on the shell rings..."

okay like trees shellfish have growth rings on their shells and they should be reasonably close together ie a mm or so like the grooves on a record. have a look next time you're paddling.

 

[crazydave]

I think its 83 degress celsius or something. Dont quote me on it but I'm a kitchen assistant and thats what I have to re-heat all foods back up to to be served.

Stu.

thats reheat though assuming the original cooking killed everything off to start with. we are advised a rolling boil for 5 mins to clean water.

 

[Stupot]

Ahhhhh an extremely good point.

Thanks for the help.

My bad, sorry about that.

Stu

 

[Lush]

okay like trees shellfish have growth rings on their shells and they should be reasonably close together ie a mm or so like the grooves on a record. have a look next time you're paddling.

Wow, that's a good thing to keep in mind. Thanks!

 

[hedgepig]

Right, first up Lush is correct ...

Of course cooking can make unsafe food safe to eat. But not always. Bacteria can excrete toxins (poison) that can't be "cooked to death".

Cooking will kill most bacteria that cause food "poisoning" (food "poisoning" is a slight mis-description, but more of that in a minute.). However, some bacteria will cause food poisoning even after they have been killed by cooking because of the toxins they produce.

An example of this are the superantigens produced by Staphylococcus aureus. Staphylococcus aureus is part of the normal microbial flora that exists on everyone's skin and is one reason why hands should be washed before food prep (not the only reason though!). The symptoms of Staph aureus poisoning are nausea, vomiting and diarrhoea in 4 to 6 hours and without a fever. It is so quick because the body is reacting to the ingested toxins. In contrast ingesting live Salmonella bacteria in food produces and intestinal infection (the bugs are growing inside the gut) and so the time to the onset of symptom is much longer - maybe 12 to 24 hours depending on the number of bacteria ingested. Here the symptoms include nausea, vomiting, diarrhoea and a fever.

Cooking would prevent Salmonella infection but not Staphylococcus aureus poisoning.

There are plenty of other bacteria (and some viruses, fungi, protozoans and algae) that will cause food borne disease, but the best thing to do is to practice good food hygiene at all times. If you remember that bacteria are living organisms and they will grow given the chance then you are halfway to understanding the problem. Cooking them to death is fixing a problem that could have been avoided in the first place ... and in the case of the heat stable toxins doesn't work anyway. Don't cross contaminate your food and don't let the bugs grow in the first place and you will be much safer on the occasions when you do accidentally undercook your food.

 

[dommyracer]

Regarding the spice debate:-

As we all know, salt has been used to prevent meat from spoiling since waaay back.

Spices are/were considered expensive to us due to the fact that they didn't grow on these shores and so had to be shipped over - hence the increased cost.

For areas where the spices are/were plentiful, it's likely that they used the spices as other used salt - not to hide the taste of bad meat, but to preserve it in the first place.

If you look at areas where they use spice marinades / rubs, they don't tend to use a lot of salt....