# Is It Safe To Eat Mouldy Bread? **URL:** \ **Category:** Factual Questions\ **Created:** [March 9, 2012, 7:52pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317 "2012-03-09T19:52:08Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [March 11, 2012, 7:03pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/21 "2012-03-11T19:03:33Z")
> [@GiantRat](#): > > Penicillin was first mold on a cheese sandwich. Penicillin likes cheese (which is why cheese is often Pasteurized). Pasteurized bread would be… gooey. It still grows on bread. Bread is what we grew it on in jr. high. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [March 11, 2012, 7:12pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/22 "2012-03-11T19:12:16Z")
> [@VOW](#): > > … > > And of course, it is the mold of rye bread that contains the precursor of LSD. > > ~VOW And the essential addition of “sourness” to Polish white borscht and Romanion ciorba. Mold. Yummy! ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [March 11, 2012, 11:28pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/23 "2012-03-11T23:28:28Z")
> [@Cheshire\_Human](#): > > Penicillin was first isolated from a mold grown on bread. Reproducing that is a standard middle school science project. I did it in school. I’m not arguing or disagreeing with you, just curious: Can you give more details about the middle school experiment? I mean, you grew penicillium mold on bread, and then what? About the allergy thing: we eat penicillium mold all the time, in cheese. Is this a problem for people who have a penicillin allergy? I thought penicillin came from a particular species of penicillium, but I could be wrong. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [March 11, 2012, 11:57pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/24 "2012-03-11T23:57:44Z")
> [@hibernicus](#): > > I’m not arguing or disagreeing with you, just curious: > Can you give more details about the middle school experiment? I mean, you grew penicillium mold on bread, and then what? > > About the allergy thing: we eat penicillium mold all the time, in cheese. Is this a problem for people who have a penicillin allergy? I thought penicillin came from a particular species of penicillium, but I could be wrong. I’ll let Cheshire answer for his class, but the version of the experiment I’m familiar with involves: 1. Growing mold on the bread and grinding it up. 2. Culturing bacteria on two (or more) petri dishes. One has just the bacterial culture added. The other has pieces of bread added. 3. Observing bacterial growth, which shows up as reduced or nonexistent in the culture with the mold additive. The actual dose of penicillin is extremely low if you’re eating cheese or bread normally. There’s a reason that we take pills instead of a DIY cure… but I know that allergies can be very sensitive so you should check with a doctor. ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [March 12, 2012, 12:43am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/25 "2012-03-12T00:43:56Z")
> [@dracoi](#): > > I’ll let Cheshire answer for his class, but the version of the experiment I’m familiar with involves: > > 1. Growing mold on the bread and grinding it up. > 2. Culturing bacteria on two (or more) petri dishes. One has just the bacterial culture added. The other has pieces of bread added. > 3. Observing bacterial growth, which shows up as reduced or nonexistent in the culture with the mold additive. Pretty close, except there was one more step 1a) Don’t grind up the bread. Identify the penicillin mold on the bread, draw a sharp knife through it, then lightly slice the skin of an unpeeled orange with it. The mold then grows in the orange skin, without other species interfering, and liquid oozes out of the cut after a couple of days. The liquid is much richer in penicillin than the original bread. Proceed with step two using that. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [March 12, 2012, 8:30am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/26 "2012-03-12T08:30:08Z")
> [@RealityChuck](#): > > In general, if you can see it or smell it, it probably won’t make you sick. That’s just basic evolution: an organism that needs to reproduce in your body won’t warn you away, and one that can’t get by your gastric juices will in order to keep from being destroyed. Only that evolution doesn’t work that way at all: Mould doesn’t need humans as host, so it doesn’t care what happens to them; gastric juices are geared against small amounts of bacteria, not the poision from mold; and people with sense enough don’t eat mould because of the taste and sight. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [March 12, 2012, 8:38am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/27 "2012-03-12T08:38:23Z")
> [@hibernicus](#): > > About the allergy thing: we eat penicillium mold all the time, in cheese. Is this a problem for people who have a penicillin allergy? I thought penicillin came from a particular species of penicillium, but I could be wrong. We don’t eat any penicillium mold on cheese. We eat a very specific brand that’s introduced on purpose. And the producers have to make damn sure that no other mold comes along and contaminates the cheese, because then the customers get sick and can even die. Cecil explains the differences in [this blue cheese column](http://www.straightdope.com/columns/read/2186/what-makes-blue-cheese-blue). > [@](#): > > The name Penicillium roqueforti sounds like penicillin because it’s related to the common and useful antibiotic mold. This relation is more than just skin-deep, as blue ripened cheeses do seem to inhibit the growth of harmful (and other) bacteria, such as Clostridium and Staphylococcus. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [March 12, 2012, 8:42am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/28 "2012-03-12T08:42:10Z")
> [@hibernicus](#): > > But that’s only relevant if bread mould makes aflatoxins. I never heard of bread mould producing any mycotoxin or being harmful by ingestion. “Mould” is a group name for ten thousands of different mold species. Some are beneficial like the strains used for blue cheese. Some are used to produce penicillin. Many are harmful because the produce aflatoxins. Unless you have the equipment and willingness to do a test, you don’t know if the green stuff growing on your bread is of the harmless or harmful, poisionous variety. Therefore, the recommendation of health professionals to be better safe than sorry and cut it out (hard bread) or throw it away (soft bread). It’s like bacteria: not all bacteria are harmful, but for the sake of your health you generally treat spoiled food as being dangerous, because it’s not worth the effort to test it. ---
**Author:** ![crowmanyclouds](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crowmanyclouds/32/19884_2.png) [@crowmanyclouds](https://boards.straightdope.com/u/crowmanyclouds)\ **Post date:** [March 12, 2012, 11:27am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/29 "2012-03-12T11:27:10Z")
> [@VOW](#): > > … it is the mold of rye bread that contains the precursor of LSD. IPS it’s rye infected with [ergot](http://en.wikipedia.org/wiki/Ergot) that’s been made into bread that contains the precursor of LSD. IAPS no matter how moldy rye bread (that’s made from grain with no ergot infection) gets, there’s no amount that will induce ergotism. CMC fnord! ---
**Author:** ![Guinastasia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guinastasia/32/5751_2.png) [@Guinastasia](https://boards.straightdope.com/u/Guinastasia)\ **Post date:** [March 12, 2012, 11:16pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/30 "2012-03-12T23:16:45Z")
> [@hibernicus](#): > > I’m not arguing or disagreeing with you, just curious: > Can you give more details about the middle school experiment? I mean, you grew penicillium mold on bread, and then what? > About the allergy thing: we eat penicillium mold all the time, in cheese. Is this a problem for people who have a penicillin allergy? I thought penicillin came from a particular species of penicillium, but I could be wrong. Anecdotal evidence, but my cousin, who has an allergy to penicillin, had an allergic reaction to blue cheese dressing. A google search seems to indicate that it’s rare, but it does happen. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [March 13, 2012, 12:24am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/31 "2012-03-13T00:24:20Z")
> [@Leo\_Bloom](#): > > And the essential addition of “sourness” to Polish white borscht and Romanion ciorba. > > Mold. Yummy! Mold is not desirable in Polish white borscht. Your rye bread shouldn’t get moldy when you’re doing it (and, for that matter, you don’t need any rye bread at all, although it helps the fermentation along.) A little bit of mold is okay if it’s white mold in making white borsht, but that’s not the source of the sourness. It’s lactic acid bacteria. Basically, when you make white borscht, you’re making a very liquid sourdough starter. Just rye flour, oats, and water will work well. Rye bread crusts are not needed, although a lot of traditional Polish recipes use them. I don’t. ---
**Author:** ![VOW](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/vow/32/3043_2.png) [@VOW](https://boards.straightdope.com/u/VOW)\ **Post date:** [March 13, 2012, 2:59am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/32 "2012-03-13T02:59:26Z")
> [@crowmanyclouds](#): > > IAPS no matter how moldy rye bread (that’s made from grain with no ergot infection) gets, there’s no amount that will induce ergotism. > > CMC fnord! Ergot is a fungus, mold is a fungus. Granted, ergot is a SPECIFIC fungus, but then, penicillin is also a specific fungus. If you don’t have the means to analyze the fuzzy stuff growing on your fruit, your cheese, or your bread, my rule of thumb is don’t eat it! I’d say there is a better chance the mold on the rye bread is ergot as opposed to penicillin, but I wouldn’t guarantee it. And neither would I eat it. ~VOW ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [March 13, 2012, 6:15pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/33 "2012-03-13T18:15:23Z")
> [@pulykamell](#): > > Mold is not desirable in Polish white borscht. Your rye bread shouldn’t get moldy when you’re doing it (and, for that matter, you don’t need any rye bread at all, although it helps the fermentation along.) A little bit of mold is okay if it’s white mold in making white borsht, but that’s not the source of the sourness. It’s lactic acid bacteria. Basically, when you make white borscht, you’re making a very liquid sourdough starter. Just rye flour, oats, and water will work well. Rye bread crusts are not needed, although a lot of traditional Polish recipes use them. I don’t. Huh. Thanks. I’ve wondered: some recipes call for wheat flour fermentation, some for rye flour. What are the differences in end result (and in application)? ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [March 13, 2012, 6:24pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/34 "2012-03-13T18:24:27Z")
> [@Leo\_Bloom](#): > > Huh. Thanks. > > I’ve wondered: some recipes call for wheat flour fermentation, some for rye flour. > > What are the differences in end result (and in application)? Rye flour ferments easier. I’m not sure exactly what it is about rye flour, but my conjecture is that it either has more of the microorganisms on it that help spontaneous fermentation along and/or it is better “food” for these beasties. The whole idea that you’re “catching the wild yeasts in the air” is a bit overstated. Most of your fermentation is due to what is already in the flour. You can read my method to [Polish sour soup here.](http://www.lthforum.com/bb/viewtopic.php?p=221326) (My name is “Binko” on that board.) As I state in there: “My father claims that żurek is always made on rye flour, while biały barszcz is made on whole wheat flour. The Polish Wikipedia page on the soup agrees that a segment of the Polish population uses this naming convention, but others say that żurek is a soured Lenten/Easter soup that’s served with potatoes and eggs, while biały barszcz is sour soup that’s cooked with bacon and sausage. For all practical purposes, these two names are interchangeable, and there are countless variations on the soured rye base.” ETA: I should add, that in that recipe I did use a little bit of a healthy sourdough starter to get things moving a little more quickly. You don’t need to do that, and you don’t need to use the rye bread, either, although it may take a little bit longer without it. ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [March 13, 2012, 7:02pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/35 "2012-03-13T19:02:45Z")
> [@Si\_Amigo](#): > > Of course the people who ate moldy bread and died aren’t posting . . . 😃 Heh. How true… 🙂 ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [March 13, 2012, 9:48pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/36 "2012-03-13T21:48:43Z")
> [@Cheshire\_Human](#): > > Pretty close, except there was one more step 1a) Don’t grind up the bread. Identify the penicillin mold on the bread, draw a sharp knife through it, then lightly slice the skin of an unpeeled orange with it. The mold then grows in the orange skin, without other species interfering, and liquid oozes out of the cut after a couple of days. The liquid is much richer in penicillin than the original bread. Proceed with step two using that. That sounds like a poorly controlled experiment. There’s no way to know whether it’s the orange oil or the mould that inhibits the bacterial growth. But it’s good that you did actual experiments in science class, rather than just reading about experiments, which is mostly what we did. ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [March 13, 2012, 9:55pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/37 "2012-03-13T21:55:53Z")
> [@constanze](#): > > We don’t eat any penicillium mold on cheese. We eat a very specific brand that’s introduced on purpose. And the producers have to make damn sure that no other mold comes along and contaminates the cheese, because then the customers get sick and can even die. Cecil explains the differences in [this blue cheese column](http://www.straightdope.com/columns/read/2186/what-makes-blue-cheese-blue). We do eat penicillium mould on cheese (both blue-veined cheese and the _fleur_ on cheeses like brie and camembert). At least where I live, the typical blue-white mould that grows on bread, fruit and cheese is penicillium species. As far as I know, it is completely harmless. Not that I deliberately eat mouldy bread, fruit or cheese, but I would not be in the least concerned if I accidentally did. ---
**Author:** ![mhendo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mhendo/32/3159_2.png) [@mhendo](https://boards.straightdope.com/u/mhendo)\ **Post date:** [March 13, 2012, 10:03pm UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/38 "2012-03-13T22:03:38Z")
> [@RealityChuck](#): > > In general, if you can see it or smell it, it probably won’t make you sick. That’s just basic evolution: an organism that needs to reproduce in your body won’t warn you away, and one that can’t get by your gastric juices will in order to keep from being destroyed. This seems like a rather odd interpretation of how evolution works. Not every substance comes with a visual warning against all possible dangerous encounters. ---
**Author:** ![Digital\_is\_the\_new\_Analog](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@Digital\_is\_the\_new\_Analog](https://boards.straightdope.com/u/Digital_is_the_new_Analog)\ **Post date:** [March 14, 2012, 1:45am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/39 "2012-03-14T01:45:08Z")
> [@Si\_Amigo](#): > > Of course the people who ate moldy bread and died aren’t posting . . . 😃 We just need to wait a few years and bring this thread back as a zombie..then they can post. -D/a ---
**Author:** ![VOW](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/vow/32/3043_2.png) [@VOW](https://boards.straightdope.com/u/VOW)\ **Post date:** [March 14, 2012, 2:39am UTC](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317/40 "2012-03-14T02:39:17Z")
> [@hibernicus](#): > > At least where I live, the typical blue-white mould that grows on bread, fruit and cheese is penicillium species. As far as I know, it is completely harmless. I repeat the comment I made upthread: If you are ALLERGIC to penicillin, you could have a reaction if you eat mold, specifically, the penicillium mold. ~VOW [Previous page](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317.md?page=1) [Next page](https://boards.straightdope.com/t/is-it-safe-to-eat-mouldy-bread/615317.md?page=3)