You’re not supposed to defrost meats in warm water due to harmful bacteria growth, you’re not supposed to leave food at room temperature for long without being refrigerated because of harmful growth but, when you go to a buffet, food can sit out for hours under heat lamps and be fine?
In: Biology
Microbial growth can be slowed either by keeping food cold or hot, but the range around 41-140 °F is generally considered unacceptable for controlling the growth of pathogens.
Also it should be noted, most health regulation not only requires you keep buffet food in a certain temperature range, But they also don’t let you take food “exposed to the public” back into the kitchen. Nor do they allow you to have food in display for longer than a set time (even in a good range) – at least that’s the rules we have in Canada.
Chefs are required to have a much better understanding of how food go bad and are therefore able to follow different rules then what you are advised to at home. The big difference in a buffet and whan thawing out meats at home is that in the buffet the meat is cooked beforehand. This kills all the bacteria so that it takes a lot longer for any new infections to populate the meat. However if you do it to raw meat it have already spent a lot of time at room temperature since the animal was butchered as a lot of the meat processing takes place above room temperature. So it already have a high population of bacteria and fungi on it, although not toxic levels. But leaving it out on the counter even longer may cause it to go bad.
The advice you get about how to avoid spoiling food is also erring on the side of causion. Meat will not go bad immediatly as you put it in warm water but you should try to avoid leaving it thawed for long periods of time. A lot of people might be tempted to get meat from the freezer in the morning and either put it in warm water or just leave it on the counter so that it will be thawed when they get home from work which is obviously a bad idea. They might also be tempted to thaw some meat and cut a portion off it before freezing it again and doing this multiple times. Do not think so much about the rules themselves but rather just try to avoid doing anything stupid.
The first one is kind of an old wives tale and isn’t backed up by science, except in the case of particularly thick cuts where it will take a very long time to thaw the inside with hot water, keeping the outside in the “danger zone” for long enough for notable bacteria growth to happen. Here’s [an actual study on the matter](https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1750-3841.2010.02037.x) and here’s [a more reader-friendly article.](https://www.nytimes.com/2011/06/08/dining/a-hot-water-bath-for-thawing-meats-the-curious-cook.html).
When you’re talking about food at home, you’d likely be perfectly fine if you cooked some food, left it out at room temperature for an hour or two and then finished eating it. That being said, the advice tends to take into account that you’re likely going to put it back in the fridge, warm it up again, and consume more later – potentially multiple times. This gives way more opportunity for bacteria growth later.
With a buffet, you cook the food which kills everything, set it out and keep it warm (some stuff like meat might be kept warm enough to slow down but not completely stop bacteria growth), and then either the entire thing is eaten over a few hours or it’s discarded.
There’s a concept in food safety called the “danger zone”. It extends from about 40 F / 5 C to about 140 F / 60 C. You can keep food below the lower end of that range, or above the upper end, for a while without it going bad. The reason is that this is approximately the range of temperatures that the bacteria that cause foodborne illness can tolerate well enough to grow. They can survive in lower temps, but they won’t grow or will grow very slowly, which is why you can store meat in the fridge for a few days without problems. (They’ll die at higher temps if they’re kept that hot for a while, as in sous vide cooking, but can survive brief exposure.)
The food at the buffet is (at least supposed to be) kept above 140 F / 60 C, so that whatever bacteria may be present can’t grow effectively. The trays at a buffet usually sit above a pool of very hot water in addition to the heat lamps, which keeps them hot. (This is if the food does stay out for hours. It may simply be changed out regularly, in which case it can be kept in the danger zone.)
You can take the “keep it above the upper end of the range” principle really far, because temps above 140 F / 60 C will kill almost all bacteria with prolonged exposure. This is the principle behind [perpetual stews](https://en.wikipedia.org/wiki/Perpetual_stew), foods which were effectively cooked for years or decades.
Okay five year old explanation.
Very cold: freeze and die like you would in Siberia in winter with no coat.
Very hot: overheat and die like a person left in a car on a sunny, summer day in Pheonix, AZ.
In between: live and prosper.
Bacteria are like you. Too hot: die; too cold: die.
Keep in mind that the salad bar is usually the biggest source of food borne illness at buffets.
A huge amount of this is people not properly understanding what food safety guidelines mean and are for, by the way. Food safety guidelines were not written for your house, they were written for restaurants. A restaurant kitchen is chaos and it’s filled with both people and food and all sorts of other stuff. They serve tons of people. You serve yourself and your family and maybe friends.
a restaurant sized cut of frozen meat is often 10+ pounds. You almost never have that much meat to thaw.
So if you take out a steak (even a big one) and put in on a safe place on your counter, it will mostly me fine to thaw there. It won’t take that long and anything that might grow on it will be killed by the fact that you’re cooking it (as things will only really grow on the outside). A restaurant can’t make those assumptions (for starters because they often have whole cuts of meat that might take many hours or even days to thaw even at room temperature. Think of how long it takes to really thaw a turkey).
in reality, bacterial growth on food is MORE dangerous after you’ve cooked it for most things. Because then you just eat it. Think of the heat maps at the buffet as the equivalent of keeping things warm in the oven at home. Also bear in mind that at a buffet (in theory, but not always in practice) the foot gets cycled out. Bad stuff like bacteria, fungus, etc takes a while to take root in meat. At home you rarely ever run into this (unless you’re in college and leave pizza out on the counter for days) but in a buffet tons of people are eating that food. If you watch you’ll likely see new food coming out regularly. Sometimes the old stuff just goes in back and gets repurposed (which SHOULD include making it safe by way of more cooking) or get tossed when it’s old, but in theory the food on a buffet should always be relatively fresh and safe because of the time as much as anything else.
You can defrost meat by placing it in warm water as long as the frozen meat brings the water temp down to below 40F quickly. I do it all the time with no issues. I also check the temperature and ensure it’s safe.
Ive always wondered as well, why does it matter if some bacteria grows when we thaw meat under water. If we cook it, does it not eliminate all the harmful bacteria?
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