I never worked with purple beans before this year. I couldn't decide what to do with the bounty of veggies in my garden. My family lives minestrone and vegetable beef. Problem solved. First I made 12 gallons of minestrone then 5 of the veggie beef. All spoiled over night. The only thing that I used in both that I never used before was the purple beans. Could they be the culprit? I'm going crazy trying to figure it out

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    No, meat was good as was the stock. We had some the night it was made. It did not have a bad smell at all. Both were "foaming" the next morning, with a very sour taste. They had no common meat. I gave some if the beans to a friend. She blanched them right away, and said they were bad the next. They were freshly picked I don't even wash them until I'm ready to use them.
    – Judy Lewis
    Sep 7, 2016 at 21:49
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    When you say "purple beans", do you mean the string beans with the purple fleshed pods (which turn back to green on cooking)? Or that the mature seeds inside the pods are purple ...Or is that their official name: "purple beans?" I'm just curious, but even the people who are able to answer your question might need to know this.
    – Lorel C.
    Sep 7, 2016 at 22:03
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    They are the purple pole beans that turn green when cooked
    – Judy Lewis
    Sep 7, 2016 at 22:37
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    Was it refrigerated or not, and if not, how was it stored? Sep 8, 2016 at 9:20
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    Can you confirm those quantities are actual gallons? That is a lot of soup and a potential serious challenge to cool down quickly. If the soup was too warm for too long, that could explain the rapid spoilage.
    – logophobe
    Sep 8, 2016 at 14:38

1 Answer 1


Purple beans just have slightly different pigments in them, and the purple actually goes away when you cook them.

There's nothing particular about that pigment that would cause your soup to go bad. While it's possible that the beans, or some other ingredient, caused it to go bad, it's not the color, itself, at fault.

The "foaming" and sour taste you describe in your comments suggests fermenting or bacterial activity. I'd guess something was off with dried beans that you soaked and cooked, since you see that kind of activity start if you let beans soak for way longer then needed just to re-hydrate them. Did they get both soaked, and then fully cooked?

Anyway, that's a more likely candidate vs. the color of a fresh or frozen snap bean.

EDIT - I see that the OP commented that she gave some of the snap beans to a friend, who blanched them right away and said they went bad. Sounds like the snap beans could be the culprit, though not because of their color, per se.

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    I agree that the foaming and sour sounds like a fermentation either yeast or bacterial. The beans and the powdered bullion sound like the potential candidates. Either potentially could have picked up a yeast or similar mold contaminant, or some bacteria. If two different soups did it, it would sure sound like a common source. I would tend to question the bouillon, except for the friend having blanched beans also sour. For it to be the beans, normally I would expect them to have been picked and stored wet or such, but they were fresh picked.
    – dlb
    Sep 8, 2016 at 15:16
  • One suggestion would be to use a bit of the bullion with just some other veggies to have something that could ferment. Let is set and see if it quickly does the same. Maybe a small pot with no bullion, but some beans and compare. If neither do it, then there may be hidden molds in the fridge that are acting as a contaminant and showed up in the soup because of the slow cooling.
    – dlb
    Sep 8, 2016 at 15:19
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    The OP also said it was gallons of soup and didn't mention any rapid cooling (ice bath, separating portions) so the ingredients might all have been okay, and might not cause issues in other uses if handled properly.
    – Cascabel
    Sep 8, 2016 at 16:21
  • Foaming in beans is inconclusive, because they are high in saponins. It still can be a case of fermentation, but the foam is not telling much about it either way.
    – rumtscho
    Sep 8, 2016 at 16:32
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    Both soups were cooked and cooled in several pots. As for the veggie beef, I made it in two pots. At one point, I saw one pot had a nice clear red broth, while the other was cloudy. the minestrone was made in several pots and mixed together in a large roasting pan. Then separated into different pots for cooling.
    – Judy Lewis
    Sep 9, 2016 at 11:30

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