# If I boiled spoiled milk, could I safely drink it? **URL:** \ **Category:** Factual Questions\ **Created:** [June 11, 2009, 4:46am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419 "2009-06-11T04:46:54Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [June 11, 2009, 6:24pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/21 "2009-06-11T18:24:26Z")
Mongols conquered much of the [world with it.](http://www.fsmitha.com/h3/h11mon.htm) ---
**Author:** ![bordelond](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bordelond/32/150_2.png) [@bordelond](https://boards.straightdope.com/u/bordelond)\ **Post date:** [June 11, 2009, 6:26pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/22 "2009-06-11T18:26:03Z")
> [@lazybratsche](#): > > These [toxins]happen to be structural components for the bacteria, not used to infect or harm us, but they’re compounds that are recognized by our immune system as foreign. Is that what bacterial toxins typically are? I’ve been thinking that some bacteria are actively excreting a discrete substance that’s poisonous to humans. If the toxins are instead the structural components of the bacteria … why does heat not denature them the way protein structures are typically denatured by cooking? Or is just a case of not enough heat – they can take 300 degrees, but not the surface of the sun? ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [June 11, 2009, 7:17pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/23 "2009-06-11T19:17:48Z")
> [@bordelond](#): > > Is that what bacterial toxins typically are? I’ve been thinking that some bacteria are actively excreting a discrete substance that’s poisonous to humans. Some types of toxin are specifically created by bacteria to poison us. That class of toxins is more specifically referred to as an exotoxin. The really nasty toxins are all exotoxins, and they’ll do things like punch holes in cell membranes or block signals in the nervous system. Confusingly, enterotoxins are a subset of exotoxins, and neither are the same thing as endotoxins. > [@](#): > > If the toxins are instead the structural components of the bacteria … why does heat not denature them the way protein structures are typically denatured by cooking? Or is just a case of not enough heat – they can take 300 degrees, but not the surface of the sun? Not all proteins are easily denatured. Some are very sturdy and won’t unfold even at very high heat, others will readily fold back up at lower temperatures. For toxins, some are heat-stable, others are not. Obviously, hot enough will destroy anything, but some proteins will stand anything up to incineration. In the case of common bacterial endotoxins, they’re not actually proteins, but complex arrangements of lipids and branching polysaccharides. These form part of the cell wall of gram-negative bacteria, so they’re built to be sturdy. ---
**Author:** ![chique](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@chique](https://boards.straightdope.com/u/chique)\ **Post date:** [June 11, 2009, 9:34pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/24 "2009-06-11T21:34:56Z")
> [@muchmark](#): > > As a kid my grandmother would make an Indian desert similar to rasmalai with spoiled milk. And my German great-grandmother would cover a bucket of milk with cheesecloth (to keep out the dust), set it someplace warm for a few days, and serve cottage cheese with dinner. This was with raw milk. I’m not actually typing this; my grandfather was killed off by microbes 80 years ago. ---
**Author:** ![FoieGrasIsEvil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foiegrasisevil/32/16638_2.png) [@FoieGrasIsEvil](https://boards.straightdope.com/u/FoieGrasIsEvil)\ **Post date:** [June 11, 2009, 9:38pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/25 "2009-06-11T21:38:24Z")
> [@bordelond](#): > > Anecdote – I am a cheap SOB, and I use just-past-the-date milk in cereal fairly regularly (maybe once or twice a month). Been doing this for several years. Haven’t noticed any ill effects. Slightly past the date milk doesn’t necessarily imply it’s spoiled, especially if properly refrigerated. ---
**Author:** ![phreesh](https://avatars.discourse-cdn.com/v4/letter/p/9fc29f/32.png) [@phreesh](https://boards.straightdope.com/u/phreesh)\ **Post date:** [June 11, 2009, 9:46pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/26 "2009-06-11T21:46:04Z")
Awesome thread full of great answers. Well done, Straight Dope! ---
**Author:** ![bordelond](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bordelond/32/150_2.png) [@bordelond](https://boards.straightdope.com/u/bordelond)\ **Post date:** [June 11, 2009, 9:47pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/27 "2009-06-11T21:47:30Z")
> [@FoieGrasIsEvil](#): > > Slightly past the date milk doesn’t necessarily imply it’s spoiled, especially if properly refrigerated. Correct. I am talking about instances in which the sour smell has kicked in, however. It’s milk my wife summarily throws out if she gets to it first. ---
**Author:** ![Teacake](https://avatars.discourse-cdn.com/v4/letter/t/e9bcb4/32.png) [@Teacake](https://boards.straightdope.com/u/Teacake)\ **Post date:** [June 12, 2009, 6:31pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/28 "2009-06-12T18:31:39Z")
My little old Irish granny used to leave a bottle of ordinary milk in the fridge until it went bad enough to separate, then strained it and used the thin part to make the most delicious soda bread. She lived to be 93, I think. All her children, grandchildren and great-grandchildren are doing well so far. ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [June 12, 2009, 6:38pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/29 "2009-06-12T18:38:14Z")
Perhaps there’s some value in specifying “illness” – pathogenic infection or short-term vomiting/diarhhoea? ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [June 12, 2009, 7:15pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/30 "2009-06-12T19:15:00Z")
> [@MOIDALIZE](#): > > Are you saying spoiled milk never contains harmful bacteria? Spoiled milk may contain harmful bacteria, but that would be due to contamination of the milk, not growth of the bacteria causing the “spoilage”. For what it’s worth, American milk is the next best thing to sterile. It’s so clean that my Microbiology teacher had to inoculate it with bacteria from our lab so that we could get any positive bacterial counts on it at all. Even leaving the milk out for several nights didn’t get the bacterial counts high enough to count with a 48 hour culture on agar. > [@phreesh](#): > > Yeah. This is against everything my mom ever told me. Now, I realize that not all spoiled milk will kill/sicken people, but the stories I’ve been told equate spoiled milk with hamburger disease - sure, you may not get sick if you don’t properly cook your burgers, but do it enough and you’ll get sick. If you drink spoiled milk enough, it will make you sick. > > This is really interesting and I eagerly await the straight dope - is there nothing dangerous in spoiled milk? The bacteria in hamburger that makes you ill is e. coli. While there’s theoretically a danger of e. coli getting into the milk supply, it’s one that’s specifically tested for by the USDA. And, like I said, our teacher had to \*add \*it to our milk samples so we could learn how to test for it. > [@MOIDALIZE](#): > > I get that. I’m asking if there can ever be a point where bacteria have so thoroughly taken over that even if you boiled it and killed all the bacteria it still wouldn’t be safe to drink. If it was contaminated by e.coli or clostridium, sure. I probably wouldn’t try it if it was visibly contaminated with mold colonies, either. Regular “spoiled” milk (sour smell, clots or chunks) is safe to consume. > [@acsenray](#): > > Which makes me wonder – What would a loaf of pure, dead bacteria look like? Most of the bacteria we can culture in large enough quantities to make a “loaf” of form [white](http://en.isernhaeger.de/picts/60ee623150ca2d39c406db58faa41dbd/th3/Petrischaleb.JPG), [ivory,](http://www.allbacteria.com/images/bacteria-colonies.jpg) or [yellow](http://www.geneticarchaeology.com/Images/BacteriaColonies.jpg)colonies. Serratia marcenscens makes awesome [red colonies](http://image.blog.livedoor.jp/kiyosawaganka/imgs/b/9/b9b673bd.jpg). But why stop there? [Fluorescent bacterial colony art](http://www.tsienlab.ucsd.edu/HTML/Images/IMAGE%20-%20PLATE%20-%20Beach.jpg), anyone? ---
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [June 12, 2009, 7:21pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/31 "2009-06-12T19:21:12Z")
This could cause the total collapse of the yogurt and cheese industries! Seriously, different types of cheese are simply milk allowed to spoil in different ways. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [June 12, 2009, 7:26pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/32 "2009-06-12T19:26:27Z")
> [@bordelond](#): > > Correct. I am talking about instances in which the sour smell has kicked in, however. It’s milk my wife summarily throws out if she gets to it first. A question to your wife: Does she drink yoghurt, use sour cream or eat Quark? Because all those contain the same lactibacilli as sour milk. Secondly, if you “started” sour milk by adding the right bacteria (this is how yoghurt is made, btw: you heat the milk to kill the unwanted bacteria, add the “good” lactobacteria, and let them start the fermentation process.) to be sure it’s safe - would she at least try it? I can understand not liking the taste, because taste differs, although many people like the refreshing part of the sour milk esp. in summer. You can also eat the thick parts in your cereal or as a dessert - the Greeks add honey to yoghurt in summer, and drink yoghurt and sour milk drinks for refreshment, instead of Cola. If she throws away a lot of milk without tasting it because of exaggerated fear, and if you don’t like the taste either, then I would suggest you change your shopping habits to buy less milk in the first place to reduce spoilage. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [June 12, 2009, 7:35pm UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/33 "2009-06-12T19:35:31Z")
> [@DrFidelius](#): > > Seriously, different types of cheese are simply milk allowed to spoil in different ways. Well, no technically. Joghurt and all based on it is made with bacteria (the same fermentation process that turns white cabbage into Sauerkraut and wet grass into Silage, btw, which is why we call it lactic acid fermentation). But normal cheese (I don’t know what chemical ingredients are used for aberrations like Kraft and similar “cheese-like” substance, I mean real cheese here) is done by adding [rennant,](http://www.straightdope.com/columns/read/1951/how-did-cheese-originate) an enzyme collected either from [calves stomachs](http://www.straightdope.com/columns/read/1774/is-rennet-a-cheese-ingredient-made-from-calves-stomachs), or from genetically altered bacteria (for vegetarians) or from certain plants (rare, for those who are against GM, too). And of course there’s [special cheese with mold](http://www.straightdope.com/columns/read/2186/what-makes-blue-cheese-blue)on it! On purpose, so it’s the right kind and not any old mold. ---
**Author:** ![Banquo](https://avatars.discourse-cdn.com/v4/letter/b/b9e5f3/32.png) [@Banquo](https://boards.straightdope.com/u/Banquo)\ **Post date:** [March 29, 2010, 4:08am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/34 "2010-03-29T04:08:59Z")
Is it pertinent to this discussion weather or not we are talking about raw or pasteurized milk? As I understand it, the bacteria and enzymes present in each differs greatly ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [March 29, 2010, 4:17am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/35 "2010-03-29T04:17:24Z")
I make cream of wheat for breakfast. You bring the milk to a boil (froths up in the pan) and whisk in the cream of wheat. Takes 2 minutes to cook. I’ve tried it with milk that has soured. The cream of wheat didn’t taste good and it gave me the shits afterward. I learned the hard way not to use bad milk. The milk I used was only a couple days soured. I can only imagine what curdled milk would do to someones gastrointestinal tract. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 29, 2010, 5:13am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/36 "2010-03-29T05:13:42Z")
There was a major food poisoning incident in 2000, from milk sold by the Yukijirushi company in Japan. It was caused by staphylococci contamination in the processing plant. The contamination occurred _before_ pasteurization, so the staphylococci _were_ killed. But enough toxins remained in the milk to make over 13,000 consumers sick. (The only English-language cite I found is [this abstract](http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=141885), but I think that’s clear enough.) ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [March 29, 2010, 5:31am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/37 "2010-03-29T05:31:31Z")
I used to use boiled unpasteurized sour milk (bought out of gourds from nomads!) to make ricotta cheese on a regular basis- you don’t have to add any extra acid, so it’s much easier than the normal way, just boil and strain. Yummy! > [@constanze](#): > > But normal cheese (I don’t know what chemical ingredients are used for aberrations like Kraft and similar “cheese-like” substance, I mean real cheese here) is done by adding [rennant,](http://www.straightdope.com/columns/read/1951/how-did-cheese-originate) an enzyme collected either from [calves stomachs](http://www.straightdope.com/columns/read/1774/is-rennet-a-cheese-ingredient-made-from-calves-stomachs), or from genetically altered bacteria (for vegetarians) or from certain plants (rare, for those who are against GM, too). Lactobacteria is responsible for the fermentation of cheese, not rennet. Rennet simply lowers the temperature at which curds will form to a point that some backteria can survive to continue the fermenting process as the cheese ripens. This is why fresh cheeses like paneer do not have the sharp tang that a hard cheese will have. ---
**Author:** ![Alan\_Smithee](https://avatars.discourse-cdn.com/v4/letter/a/2acd7d/32.png) [@Alan\_Smithee](https://boards.straightdope.com/u/Alan_Smithee)\ **Post date:** [March 29, 2010, 5:32am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/38 "2010-03-29T05:32:52Z")
It seems to be a general rule that the things that make us ill and the things that cause visible spoilage to food are more-or-less non-overlapping groups. Of course, if food has visibly spoiled, that’s a sign that it has been kept in conditions that allow bacteria or mold to propagate, but that could be true even without visible spoilage. People die every year from drinking raw (unpasteurized) milk that has been found to contain pathogens. Of course, many times as many drink raw milk without ill effect. Drinking pasteurized milk that is no longer sterile (though technically, despite \*\*WhyNot’s experience, pasteurized milk is not _necessarily_ sterile) would seem to be running the same sort of risk. The type of bacteria milk is most hospitable to is completely harmless and possibly beneficial. But you don’t _know_ that’s what got in there. Having said that, I’m neither very young nor elderly and not otherwise immunocompromised, so most common food pathogens won’t cause me more than a couple days diarrhea. I therefore feel safe eating spoiled milk, and in fact the best cottage cheese I’ve ever tasted was made by leaving a jar of raw milk out for several days. If you’re more risk averse, you can easily use a starter from some yogurt or buttermilk you buy at the store. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 29, 2010, 7:16am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/39 "2010-03-29T07:16:13Z")
> [@Alan\_Smithee](#): > > It seems to be a general rule that the things that make us ill and the things that cause visible spoilage to food are more-or-less non-overlapping groups. > > Of course, if food has visibly spoiled, that’s a sign that it has been kept in conditions that allow bacteria or mold to propagate, but that could be true even without visible spoilage. I wish the SDMB could just _get_ this. Any ‘Is my [whatever] still safe to eat?’ thread is almost guaranteed to get a pile of (wrong) answers to the effect ‘if it smells/looks good, it’s OK’. ---
**Author:** ![dogeman](https://avatars.discourse-cdn.com/v4/letter/d/71e660/32.png) [@dogeman](https://boards.straightdope.com/u/dogeman)\ **Post date:** [March 29, 2010, 7:46am UTC](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419/40 "2010-03-29T07:46:48Z")
> [@even\_sven](#): > > I used to use boiled unpasteurized sour milk (bought out of gourds from nomads!) to make ricotta cheese on a regular basis- you don’t have to add any extra acid, so it’s much easier than the normal way, just boil and strain. Yummy! [nitpick]Are you talking about straining the curds and eating them? That’s not ricotta, ricotta is made from the strained whey.[/nitpick] [Previous page](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419.md?page=1) [Next page](https://boards.straightdope.com/t/if-i-boiled-spoiled-milk-could-i-safely-drink-it/499419.md?page=3)