Fermenting in a ziplock bag

[acrossthedesert]

A couple of months ago we wanted to get into fermentation, but we're moving cross country shortly, so we didn't want to invest in crocks or glass jars before the move. Our local Korean grocery store sells homemade kimchi in gallon ziplock bags, so we jumped in and started experimenting. 20+ pounds of kraut, 6 gallons of pickles, and several batches of escabeche later, this is our experience:

Getting all the air out of a normal gallon ziplock bag filled with pickles and brine can be a little annoying, so we switched to vacuum bags after the first batch. 

The vacuum bags that you can buy with a little pump work well for fermentation, but not for storage. Every time you serve some out, you have to pump the air out. Eventually the plastic seal on the bag wears out and you have to replace the bag. Definitely not reusable, so it's not an Eco-friendly method. This is my biggest complaint. 

Since we remove all the air every time we close the bag, we've had no problems with mold.

Gas does build up during the early fermentation stages. We had to remove the air once or twice a day during the most active fermentation. Sweeter veggies like carrots and peppers seemed to produce the most gas. With vacuum bags, the seal gives first if you forget to "burp" the bag. If the bag isn't standing upright, this could be a mess. But we had no explosions. 

We only fill the bags about half way to leave room for the gas buildup. For kraut that's about 900g of cabbage, one cup of water, and 30g of salt  in our experience. Once the cabbage settles it's just right.

You can store the bags vertically in a box or crate, like file folders. They flatten nicely, so you have a compact storage system for the fridge. Our thought is that this will work well for travel also, just use a cheap cooler. We're excited about being able to take multiple fermented items on our camping trips this fall.

The bags have to be protected during storage. I just finished cleaning out the fridge where I got lazy and didn't put a bag of pickles back in the box. Something poked a pinhole in it and it leaked some. Not too bad, though. 

It's a convenient short-term solution, or way to experiment if you aren't sure you really want to commit to the crock and everything. Since it's not an environmentally conscious method, I don't suggest it for the long term. But it's worked great for us, and until our living situation settles down we're pretty happy with it.