In this post I run down different ways to store pickles mold-free while they ferment. Storage is a crucial aspect of making pickles and there’s more than one way to do it. Every technique achieves the same essential goal, though: keeping the pickles from being exposed to the air for too long. Otherwise, mold may gain a foothold and begin to grow. In most cases this means you want to keep the pickling food submerged in brine, away from the air.
On the other hand, it’s important to keep the surface of that brine open to the air. If you seal the pickle tightly with a lid, carbon dioxide—a natural byproduct of fermentation—will build up and create pressure that could cause leaks or even spray pickle juice everywhere when you open the lid. Salt-brine pickles ferment at room temperature, not in the fridge, and it’s best to leave them in a dark place like a cabinet. Because the jars stand open to the air, it’s a good idea to cover them with a towel to keep out dust and random flies. It is also wise to put your jar on top of a kitchen towel or in an open tupperware that will catch any drips.
Pickling can take as little as a week and as long as a month (or even longer) depending on the size and density of the food you’re pickling. The bigger and harder it is, the slower it pickles. The temperature of your storage space influences the timing too. The hotter it is, the faster the microorganisms will do their work. The good news is that it’s hard to over-pickle something. If you’re not sure your pickle is ready, give it a taste. When it tastes the way you like, remove your seal, put a lid on the pickle, and put it in the fridge. This will stop the fermentation, although the flavors of your spices will continue to soak into the pickle.
So, here are some techniques for keeping your food mold-free while it ferments:
1) My favorite technique is to use a weight, preferably a sealed jar full of water that is small enough to fit into the mouth of your pickling jar. In this picture, a jar is keeping fermenting herring below a brine of salt water and whey.
Here the jar is at work keeping curing olives under a salt brine. You can also use a rock or any other heavy object that you feel won’t affect the flavor of your vegetables. When using this technique, it’s a good idea to leave at least an inch of clearance between your food and the top of the pickling jar so that the weight can sit well inside.
When the food is finely shredded, like the sauerkraut in the picture above, it is helpful to use a plate, glass lid, or wooden round that fits closely to the sides of your fermenting crock or vessel. Then you weigh down the plate with something heavy, like a jar (or jars) full of water. If the seal isn’t close enough to the edge of the vessel, the pickle will float up around the edges.
2) Another option is to use a larger piece of vegetable as your seal. In the picture above, I’ve cut two long, thick slices of radish.
Then I packed them cross-wise into the jars so that they folded under the edges of the jar top. This forms a barrier that holds the other vegetables down, even when the jar is filled with brine to the level of the seal or above. Large, hard vegetables like carrots, radishes, and beets work best.
If your brine covers the seal continuously throughout the pickling process, you’ll be able to eat it too. If some part of the seal pokes above the water, I recommend throwing it away when you move the pickles to the fridge.
3) Sometimes you pack your pickling jar so tight that it doesn’t seem like anything will budge, like with these squash pickles. In that case, just fill the brine above your food and let fermentation happen. If you go this route, though, be careful to check your jar often (every day is good). Veggies tend to soak up the brine, swell, and float loose while the brine level sinks. What you thought were well jammed veggies may start poking out into the air in a few days. Keep track of them and add more brine or stick on a weight if this happens.
4) You can also keep mold at bay by shaking your jar once or twice a day. A vigorous shake (with the lid firmly sealed, of course) will move your pickle around, sending the food at the surface deeper into the jar, where any mold will be doomed. You can also flip your jar once a day, turning the top into the bottom every 24 hours. When the jar is upright, leave the lid only loosely tightened to allow carbon dioxide to escape.
This works best with a pickle that comes in smaller pieces and is meant to be soft and mushy, like these pickled lemon slices, or Indian lemon pickle.
5) If you want to get even more hands on you can use your fingers to push the vegetables under the brine every day. This is most effective when making a mushier pickle like kimchi. I’ve heard this recommended but never tried it myself. I prefer the confidence of sealing my pickles with a jar and knowing they’ll be safe from mold until I’m ready to eat them.