Is My Ferment Safe to Eat?

When it comes to food, you want to be safe. And when it comes to food preservation, experience is the best education you can get. When I first started canning our food, I questioned everything. I constantly called my neighbor to run over and look at something to make sure I was doing it right. Abigail has the experience. And in this post, she lets you know if your ferment is safe to eat.

How Can I Tell When a Ferment Has Gone Bad?

When you are new to fermenting, one of the most common questions you are likely to have is this: “How do I know if it’s still good? Is my ferment safe to eat?” After all, fermentation is one of the only food preservation processes in which you are supposed to leave food out at room temperature and it’s supposed to smell and taste strange and strong when it’s done. So how can you tell a fermenting success from a fermenting failure?

While it’s unlikely that a properly controlled ferment will spoil, it is important to know what’s normal and what’s not when you open up a finished jar.

Is my ferment safe to eat?

A Normal Ferment:

  • Pleasantly sour taste. Think sourdough bread or plain yogurt. Now transfer that tangy, potent taste to fermented vegetables or fruits and you’ve got the right idea. Fermented foods can range from slightly tangy to zingy to downright strong, but in a good way! Each fruit or veggie combo has its own fermented flavor profile.
  • Strong smell when you open the jar. If you have to take a deep breath of fresh air when you first open a jar of fermented food, fear not. That’s normal, so long as the smell isn’t that of spoilage. (You’ll be able to tell; spoiled ferments smell quite rotten.) As the food is exposed to air before serving, the smell will become less odorous.
  • White film on top of the liquid in the jar. This is just a natural yeast by-product of the fermentation process. Skim it off the top and you’re good to go.
  • Sediment at the bottom of the jar or cloudy liquid. This is simply the presence of good bacteria and isn’t a cause for concern.
  • Brine overflow. Sometimes the release of carbon dioxide will cause your jar to overflow during fermentation. While it might be messy, it’s not a problem with the food itself. Unpack a little bit of the brine and vegetables to give a bit more headspace in the jar (1-2” is ideal), ensure that the veggies are still under the brine, and proceed as usual.
  • Brightly colored vegetables. Beets and radishes can turn an entire jar pink or purple and garlic can turn green or blue. This is normal.

An Unsafe Ferment:

  • Visible fuzz, or white, pink, green, or black mold. Get rid of it. This means your ferment was exposed to too much oxygen, bad bacteria was introduced during preparation, or it was too warm. Either way, it shouldn’t be consumed.
  • Extremely pungent and unpleasant stink. This differs significantly from the normal smell of fermented veggies. We had a jar of sauerkraut go bad once in our early fermenting days, and while it looked perfectly fine from the outside, the smell quickly told us it was no good. If it makes you want to gag, discard the whole thing and sanitize your jar.
  • Slimy, discolored vegetables. While bright color changes frequently occur during fermentation, very brown or slimy vegetables are a sign of spoilage. (Note that green veggies like cabbage may brown and pale somewhat.)
  • A bad taste. Remember, even though the taste of fermented veggies is unfamiliar to many of us, it shouldn’t be unpleasant. If the food tastes spoiled, spit it out!

Practice Makes Confidence

As you practice, you will become more familiar with the normal tastes and smells of lacto-fermented foods. Soon you will be able to easily identify the full range of fermented-normal!


DISCLAIMER: Because we are not able to see or smell your ferments, we are not able to tell you that your particular food is safe to eat. The best motto to follow is “When in doubt, don’t.” Please use your own best judgment.


When you have a variety of several different foods to ferment, you want to have more fermentation lids for Mason jars on hand. Fermentools lids are made to last a lifetime, of surgical steel. Get a 12-pack in our store!


Abigail is an aspiring homesteader, homeschooler, and music-maker. She lives with her husband and three children on her acre-and a half homestead in scenic Pennsylvania. You can visit her blog about living the homegrown life (and seeking contentment while doing it) at They’re Not Our Goats.

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