"Danger zone" for food and beverages left at room temperature

[ScienceNostalgia101]

So I'm hearing that the danger zone for food and beverages left at room temperature is 1 to 2 hours; 1 if the room is warm enough, 2 if the room is reasonably cool. But does this depend on the food item?

 

Suppose I had a cup of tea, and left the teabag in the cup for reuse later. Do I need to pour boiling water in within 2 hours or otherwise discard the teabag? If so, does the boiling hot water reset the cycle for another 2 hours, or does the fact that the teabag was at room temperature somewhat reduce it?

[exchemist]

23 minutes ago, ScienceNostalgia101 said:

So I'm hearing that the danger zone for food and beverages left at room temperature is 1 to 2 hours; 1 if the room is warm enough, 2 if the room is reasonably cool. But does this depend on the food item?

 

Suppose I had a cup of tea, and left the teabag in the cup for reuse later. Do I need to pour boiling water in within 2 hours or otherwise discard the teabag? If so, does the boiling hot water reset the cycle for another 2 hours, or does the fact that the teabag was at room temperature somewhat reduce it?

This seems a bit of a strange question. Of course it depends on the food item. Think about it. You probably have a whole cupboard full of dry groceries that keep almost indefinitely at room temperature. You can leave a freshly cooked stew overnight, if you keep the lid on so it stays sterile.

It all depends on, first, whether the item is a good medium for growing bacteria, yeasts etc., and second, whether or not it already has some on it or starts from a sterile position and picks them up from the air.  So fresh meat and fish goes off fast, as it is an excellent medium and already has plenty of micro-organisms on it. Fresh fruit and vegetables are a less good medium (having a natural protective layer on them, i.e. skin) and will last for several days, usually.  Your teabag is quite a good growth medium but starts off sterile. So that's like the stew. If you leave it exposed it will pick up spores and go mouldy after a bit but you have some time in hand before it does that - and you will re-sterilise it when you re-use it.  I should have thought a teabag would be still OK after leaving overnight. (But I must say reusing teabags is not something I would do as the tea will taste pretty awful.)

What is definitely a bad idea is leaving food and drink at a temperature close to blood temperature (say 30-40C) for any protracted length of time, as that is the perfect temperature for micro-organisms to multiply rapidly.   

Edited February 1, 2022 by exchemist

[swansont]

35 minutes ago, ScienceNostalgia101 said:

I'm hearing that the danger zone for food and beverages left at room temperature is 1 to 2 hours

Where are you hearing this?

[mistermack]

Just like exchemist says, it depends on the item. Certain foods can be dangerous, and others are no problem. I can't imagine your teabag ever being a hazard, unless you leave it long enough to go mouldy. 

I would do a search on what are the most dangerous foods, and learn how to avoid those particular hazards, there is no general rule. 

Sometimes it's a combination of things that causes food poisoning. Handling raw chicken, followed by handling raw beef, for example, is highly dangerous, because the chicken has salmonella, and the beef is an excellent growth medium, and is often eaten rare. Thorough cooking of the beef would have destroyed the live salmonella, so it's the combination of things that leads to danger. One to two hours would be risky under those circumstances.

Obviously, chicken itself is hazardous for salmonella, but most people make sure that it's cooked thoroughly as it's not pleasant cooked rare.

One thing to be very wary of is rice. Eat rice straight away, and throw away any left over, it can be very dangerous. You can make it safe by cooking it for a long time, or pressure cooking it. Or freezing it directly after you cook it. But it should never be left at room temperature, it's even risky keeping it in a fridge.

[exchemist]

1 hour ago, mistermack said:

Just like exchemist says, it depends on the item. Certain foods can be dangerous, and others are no problem. I can't imagine your teabag ever being a hazard, unless you leave it long enough to go mouldy. 

I would do a search on what are the most dangerous foods, and learn how to avoid those particular hazards, there is no general rule. 

Sometimes it's a combination of things that causes food poisoning. Handling raw chicken, followed by handling raw beef, for example, is highly dangerous, because the chicken has salmonella, and the beef is an excellent growth medium, and is often eaten rare. Thorough cooking of the beef would have destroyed the live salmonella, so it's the combination of things that leads to danger. One to two hours would be risky under those circumstances.

Obviously, chicken itself is hazardous for salmonella, but most people make sure that it's cooked thoroughly as it's not pleasant cooked rare.

One thing to be very wary of is rice. Eat rice straight away, and throw away any left over, it can be very dangerous. You can make it safe by cooking it for a long time, or pressure cooking it. Or freezing it directly after you cook it. But it should never be left at room temperature, it's even risky keeping it in a fridge.

That's interesting. What's the issue with rice? 

[StringJunky]

17 minutes ago, exchemist said:

That's interesting. What's the issue with rice? 

It seems cooked rice left for too long is an ideal environment for any Bacillus cereus spores that are floating around to germinate into bacteria, and poison you - from the NHS site.

Edited February 1, 2022 by StringJunky

[mistermack]

I remember it rather differently. Rice in the field gets a wild mould growing on it, (can't give the name without looking it up). The spores get dried with the rice, and are actually activated by the cooking, rather than sterilised, so that once you have boiled your rice, the clock is ticking. If it's left at room temperature, or kept warm even, it quickly grows and produces a pretty deadly toxin. 

It can be killed with prolonged boiling, or shorter cooking in a pressure cooker, which raises the temperature. There have been cases where several people have died as a result of rice poisoning, at functions like wedding receptions etc, where the rice was kept too long in warm conditions.

[studiot]

1 hour ago, StringJunky said:

It seems cooked rice left for too long is an ideal environment for any Bacillus cereus spores that are floating around to germinate into bacteria, and poison you - from the NHS site.

Am I really in danger of poisoning from the NHS website as well as the Russian embassy ?

 

More seriously, sorry to be a sourpuss, especially when my comment is sweet.

One thing I discovered when island hopping in the Greek Isles some years ago.

That was how much better cold rice pudding keeps than ice cream in warm weather or cold.

 

A note to the OP,

If you ever read manufacturer's instructions you will have noted that you are not supposed to put hot or even warm food straight into a fridge or (perish the thought) the freezer.

So it is clearly OK to cool it off somewhere else.

Of course the food concerned should be covered. The old fashioned practice of serving food in containers with lids and keeping them lidded after serving, bear witness to this.
I find a good place to allow things to coolis in the oven they were cooked in.
This will be a sterile cooling environment.

Edited February 1, 2022 by studiot

[TheVat]

The rice mold toxin is one to add to my list of rice negatives.  Others are (for white rice, the most commonly eaten form): very high glycemic, very constipating, potential arsenic residues, and nutritionally meager.   I tried a gluten free diet for six months, which tends to lead to lots of rice consumption (most GF breads are mainly rice flour) and felt so better when I returned to wheat.  

Tea bags?  Let me sing the praises of loose tea.  Better flavor, better control of brew strength, and no plastic nanoparticles from the bag moving through your gut villi.  You can now find bags made with plant fibers, but it's usually more expensive.  

[Peterkin]

3 hours ago, ScienceNostalgia101 said:

So I'm hearing that the danger zone for food and beverages left at room temperature is 1 to 2 hours;
1 if the room is warm enough, 2 if the room is reasonably cool.

In two hours, pop will lose its fizz, and ice cream will melt, cookies may harden and whipped cream will collapse; they may become unpalatable, but not unsafe. Even a glass of wine won't go sour in any room where the temperature is bearable for humans. Any hotter, and food might denature, but not spoil in that time. 

Quote

But does this depend on the food item?

Of course. And method of preparation, and container.

 

Quote

Suppose I had a cup of tea, and left the teabag in the cup for reuse later. Do I need to pour boiling water in within 2 hours or otherwise discard the teabag? If so, does the boiling hot water reset the cycle for another 2 hours, or does the fact that the teabag was at room temperature somewhat reduce it?

   If you leave a teabag in a dry cup without water, the leaves inside will dry and you can reuse it hours later. Nothing can 'restart the cycle', because every time you pour water on it, more of the chemicals dissolve out and the tea is depleted of its tea-ness, so you're drinking warm paper-water. 

19 minutes ago, studiot said:

If you ever read manufacturer's instructions you will have noted that you are not supposed to put hot or even warm food straight into a fridge or (perish the thought) the freezer.

That's to prevent steaming/icing up the freezer, and trapping condensation in the food container. It's also a waste of cooling energy, like opening the door to stare inside.   

3 minutes ago, TheVat said:

very high glycemic, very constipating,

...and thus ideal for someone suffering from that hard-to-spell word. They used to give rice-water to sick babies who lost too much fluid through vomiting and diarrhea and couldn't get enough nutrients into their system. 

[Peterkin]

BTW - Not all 'spoiled' food is necessarily harmful. One way fruits, grains and legumes go 'bad' in a warm environment is through fermentation. Soured milk can become cheese or yogurt; bad barley might eventually turn into good scotch.     

[CharonY]

1 hour ago, TheVat said:

The rice mold toxin is one to add to my list of rice negatives.  Others are (for white rice, the most commonly eaten form): very high glycemic, very constipating, potential arsenic residues, and nutritionally meager.   I tried a gluten free diet for six months, which tends to lead to lots of rice consumption (most GF breads are mainly rice flour) and felt so better when I returned to wheat.  

Tea bags?  Let me sing the praises of loose tea.  Better flavor, better control of brew strength, and no plastic nanoparticles from the bag moving through your gut villi.  You can now find bags made with plant fibers, but it's usually more expensive.  

It is likely Bacillus cereus as StringJunky mentioned and not a mold. Bacillus is able to sporulate. However symptoms are mostly somewhat mild to moderate food poisoning. That being said, the same bacterium can also be found in pasta and wheat products. In either case, deaths are exceedingly rare (and I believe some of the prominent reports were traced back to pasta). Either product should not be kept at room temperature for prolonged time, but it is not quite as dramatic as some might believe (considering how common it is as a food staple). With regard to risk, Bacilllus growth moderately fast (a bit slower than E. coli) with an ideal temperature of around 37C. However, after cooking most bacteria would be dead and it takes a while until spores germinate and they start to replicate. Growth ceases once you hit ~10C, however they can produce two types of toxins even at suboptimal temps (as low as 10C, but at very low rate).

With regard to outbreak frequency, it is one of the rare food-borne illnesses (E. coli and Salmonella are far more frequent) and it seems that at least major outbreaks were mostly associated with things like spaghetti with tomato sauce stored for a week (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3232990/), vegetable sauces and couple of others. So rice-related illnesses are potentially more common but too small-scale to be noticeable.

There have been reports of contaminated rice with certain  molds that produce aflatoxins (which are carcinogenic) but that is also rather rare (and resulted in recalls). 

[ScienceNostalgia101]

5 hours ago, swansont said:

Where are you hearing this?

https://ask.usda.gov/s/article/What-is-the-2-Hour-Rule-with-leaving-food-out

 

As for tea... I'll look into making sure I find tea with paper instead of plastic bags. (Some of those teabags made strong enough tea to fill a teapot with enough strong tea for 3 cups, so it feels like a little bit of a waste to throw it out after only one use. Besides, a weaker second cup of tea means a gradually diminishing caffeine dose...)

[mistermack]

Yes, it's a bacillus, I was going from memory. Pretty nasty though. It's rare for a food pathogen to survive cooking in that way. I always assumed that rice would be sterile once cooked, till I heard about those spores. 

https://www.bbc.co.uk/news/world-asia-india-46573273   

https://www.sciencealert.com/5-day-old-pasta-or-rice-can-be-deadly-here-s-how  

I was remembering a case in the UK where several people died after eating rice at a wedding, but I couldn't find it on google. It was about ten years ago I think.

 

1 hour ago, Peterkin said:

BTW - Not all 'spoiled' food is necessarily harmful. One way fruits, grains and legumes go 'bad' in a warm environment is through fermentation. Soured milk can become cheese or yogurt; bad barley might eventually turn into good scotch. 

Fermentation can have it's dangers too. There's another bug, Burkholderia cocovenenans, that can produce toxins during fermentation and can kill a lot of people in one go :  https://www.foodsafetynews.com/2020/10/nine-dead-in-china-from-contaminated-corn-noodles/   

Edited February 1, 2022 by mistermack

[CharonY]

36 minutes ago, mistermack said:

I was remembering a case in the UK where several people died after eating rice at a wedding, but I couldn't find it on google. It was about ten years ago I think.

I do not see studies associated with it, but there is an article from 2013 that a catering company was sued after several hundred folks got food poisoning. E. coli and Bacillus cereus were implicated, but no deaths reported. But B. cereus associated deaths are very rare. Similar to Shigella and STEC, the toxins are also heat stable, but tend to be less lethal (if memory serves).

I was curious and wanted to see whether there are statistics on B. cereus but it seems that they are likely underreported because they are so commonly mild and folks often confuse them with other infections. Estimates for the US are around 25-60k annual cases (and estimates of ~20 hospitalizations and 0 deaths). Salmonella in comparison causes about 1.4 mio infections, 25k hospitalizations and about 400 deaths per year. Camplylobacter hovers around similar values in terms of infections, but around half the deaths. 

That is not to say that one should not keep an eye on B. cereus infections but it pales quite a bit to other common food-borne pathogens. 

[swansont]

2 hours ago, ScienceNostalgia101 said:

https://ask.usda.gov/s/article/What-is-the-2-Hour-Rule-with-leaving-food-out

Did you notice that this refers to food that was being refrigerated?

[Peterkin]

3 hours ago, ScienceNostalgia101 said:

Some of those teabags made strong enough tea to fill a teapot with enough strong tea for 3 cups, so it feels like a little bit of a waste to throw it out after only one use.

I make a pot from one bag at lunch and keep the rest in a thermos for whenever.

[StringJunky]

3 hours ago, CharonY said:

IThere have been reports of contaminated rice with certain  molds that produce aflatoxins (which are carcinogenic) but that is also rather rare (and resulted in recalls). 

If one caught cancer induced by an aflatoxin, could someones malignancy be directly traced back to it as cause, or has it just been isolated in research experiments as a potential cause? As an example, Koposi's sarcoma is directly attributed to HIV and HHV-8 infection, aren't they?

[CharonY]

1 hour ago, StringJunky said:

If one caught cancer induced by an aflatoxin, could someones malignancy be directly traced back to it as cause, or has it just been isolated in research experiments as a potential cause? As an example, Koposi's sarcoma is directly attributed to HIV and HHV-8 infection, aren't they?

Yes, so individually it is highly unlikely to be traced back to a specific source in this case. Exposure-related cancer is generally based on larger association studies, i.e. looking at groups that for whatever reasons have higher than normal exposure to the agent in question (an outbreak in Kenya was one of those studies providing much evidence for liver cancer) and/or in vitro or animal studies. Even with viral causes the discovery is often (at least intiially) based on associations (e.g. rate of a given form of cancer among infected vs non-infected folks), rather than tracking back the cause within a given individual.

[StringJunky]

45 minutes ago, CharonY said:

Yes, so individually it is highly unlikely to be traced back to a specific source in this case. Exposure-related cancer is generally based on larger association studies, i.e. looking at groups that for whatever reasons have higher than normal exposure to the agent in question (an outbreak in Kenya was one of those studies providing much evidence for liver cancer) and/or in vitro or animal studies. Even with viral causes the discovery is often (at least intiially) based on associations (e.g. rate of a given form of cancer among infected vs non-infected folks), rather than tracking back the cause within a given individual.

Right, cheers.

[mistermack]

The reason that the rice poisoning stands apart for me, is that you can get poisoned by it, even if you follow the usual rules. Most people would assume that boiling something like rice or pasta would render it safe for a reasonable period, and not actually activate the pathogen within the food. So it has the potential to catch out people who are otherwise pretty careful about food poisoning. I don't think it's particularly common. I have many times eaten leftover rice that's been kept at room temperature. I don't remember ever getting ill from it, but then, if I did, I probably wouldn't have made the connection. 

I've eaten undercooked chicken on occasions as well, and not got sick. It's probably the luck of the draw. It pays to know the hazards though, to tip the odds in your favour. 

You would think that the practice of hanging game until it's "high" would be risky, but apparently it's not too bad, if you cook it thoroughly. 

Our ancestors are supposed to have made a living scavenging kills off predators millions of years ago. They would have eaten some pretty high meat. Maybe the invention of cooking on a fire was more to do with making food safe, rather than more digestible. 

I watched one of those survivalist tv programs the other day, and the guy found a dead sheep carcase, that was stinking pretty badly, and he cut out the best bits, and cooked and ate some of it, and smoked and dried the rest to eat as biltong. He didn't get sick. 

[CharonY]

Just for clarification, boiling does not activate spores, they are just not killed. They germinate once they are in favourable conditions. It is actually also not that straightforward with other pathogens, easier. We found that some Salmonella survive heating as done in certain food processing protocols.  Many toxins are heat resistant, so once the bacteria start producing it, heating might not render it safe.

But you are also right that individual risks vary and these rules are to minimise risk.

[exchemist]

14 hours ago, Peterkin said:

In two hours, pop will lose its fizz, and ice cream will melt, cookies may harden and whipped cream will collapse; they may become unpalatable, but not unsafe. Even a glass of wine won't go sour in any room where the temperature is bearable for humans. Any hotter, and food might denature, but not spoil in that time. 

Of course. And method of preparation, and container.

 

   If you leave a teabag in a dry cup without water, the leaves inside will dry and you can reuse it hours later. Nothing can 'restart the cycle', because every time you pour water on it, more of the chemicals dissolve out and the tea is depleted of its tea-ness, so you're drinking warm paper-water. 

That's to prevent steaming/icing up the freezer, and trapping condensation in the food container. It's also a waste of cooling energy, like opening the door to stare inside.   

...and thus ideal for someone suffering from that hard-to-spell word. They used to give rice-water to sick babies who lost too much fluid through vomiting and diarrhea and couldn't get enough nutrients into their system. 

On the point about fizzy drinks, a half drunk bottle of champagne still has enough fizz to be enjoyable 24hrs later, if kept refrigerated. But that has a very smooth glass bottle with few nuclei on which bubbles can form. 

(Champagne is on my mind as it seems possible Boris Johnson may be thrown out.)

[Peterkin]

8 minutes ago, exchemist said:

On the point about fizzy drinks, a half drunk bottle of champagne still has enough fizz to be enjoyable 24hrs later,

If you have a very tight cork and you bung it in right away. Not if you leave it sitting in a glass. I put the screw-cap tightly back on the bottle when I pour ginger ale, and it lasts, with a little less energy each time, for three or four more pourings. Containment makes a difference.

8 minutes ago, exchemist said:

(Champagne is on my mind as it seems possible Boris Johnson may be thrown out

I'll toast you with whatever British beer I can get quickly. Never could stand the poser! 

Edited February 2, 2022 by Peterkin

[exchemist]

1 hour ago, Peterkin said:

If you have a very tight cork and you bung it in right away. Not if you leave it sitting in a glass. I put the screw-cap tightly back on the bottle when I pour ginger ale, and it lasts, with a little less energy each time, for three or four more pourings. Containment makes a difference.

I'll toast you with whatever British beer I can get quickly. Never could stand the poser! 

I meant leaving half of an opened bottle, not a glass, in the fridge. It's still good 24hrs later, although the fizz has subsided to more of a crémant. But still perfectly pleasant.

I presume it's all to do with, firstly, the absence of surface roughness in the glass of the bottle, so few nuclei to initiate bubbles, and secondly, the low temperature of the fridge, which will increase the solubility of CO2. 

(There are silly old wives's tales about putting a silver teaspoon in the top, but in fact it's just that it holds its fizz quite well by itself.) 

Full disclosure: having something of a "dicky ticker" (a tendency to atrial fibrillation), I have to watch my alcohol intake. So I've explored a number of ways of keeping  opened part-bottles of wine, to last over 2 or more days. 

Edited February 2, 2022 by exchemist