Make a Fermentation Swamp Cooler

This is a fermentation swamp cooler.  I needed something to ferment my Butternut salad in that was cooler than room temperature, which makes fermenting vegetables mushy, but warmer than a refrigerator, which stops fermentation--something about 50-60 degrees F.  A regular swamp cooler for keeping drinks and such cold can get down to 40 degrees, the temperature at which water begins to evaporate.  I figured if I made one that allowed outside air in under the wet towel, it would stay a bit warmer than that, and it does.

It starts with a very large bowl.  This one is never used except to mix vegetable salad for ferment, which was handy.  Put a flat 9" cake pan in the bowl, set the jars of vege salad in the pan, and pour water in the bowl outside the pan until it reaches almost to the top of the pan.

I just happened to have this white-painted metal screen cake cover that has holes big enough for fruit flies and ants to get through, making it fairly useless as a cover, which I thought would be useful for keeping the wet towel elevated above the jars.  (A colander would work as well.)  Looking at the first photo, it works beautifully.  It has a hole in the coverage on each side of the wet kitchen towel that covers it, allowing some room-temperature air in too keep it from getting too cold.  The towel hangs just outside the pan, which keeps it sitting in the water, but not wicking water into the pan.  

It would probably work just fine if the water did wick into the pan, or even if the pan was not there.  But I like that this arrangement keeps the fermenting juice out of the water.  Jars of fermenting vegetables tend to leak their salty, acid juice out under their loose lids, which have to be left loose to keep fermentation from breaking the jars.  You have to open them and press the vegetables down every few days to push the CO2 out of the mix as well.  After a week, tighten down the lids and put them in the fridge to stop the ferment and enjoy.  They keep a long time in the fridge.

I also enjoy the salad when they are freshly mixed with salt.  Salt and lack of oxygen is what make fermented vegetables safe to eat, killing all the salt-sensitive bacteria and those that need oxygen.  Germs that like high-salt environments and are killed by oxygen just happen to be the lactic acid producers that are safe to eat, which is why sauerkraut works with just salted cabbage, well pressed and weighted down into its juice.  Salt also pulls out some water from the vegetables, keeping them crisp as they ferment and providing the juice to keep out oxygen.

Too little salt or too high fermentation temperatures will both tend to make a mushy ferment, which is not enjoyable.  I find that one and a half percent salt by weight is perfect; under one percent is not safe.  You'll need a good digital kitchen scale to figure out how much for each batch.  Weight the salad in grams, and multiply by 1.5% or 0.015.  I use Himalayan pink salt for its milder flavor and its minerals.  It is important to work the salt in with gloved hands, squeezing the vegetables in your hands, to help the salt and bacteria penetrate them.  Press the salad into the jars hard to exclude the air as you fill them until they are 1/2 inch from the top and covered with juice.  Press a plastic baggy into the top to keep air off the mix.  A Brie's salad dressing bottle with the label removed works very well for pressing it into jars.

These three quart jars of Butternut salad were made with a very long Butternut squash, peeled, seeded and grated with the large grater on the Saladmaster salad maker I got last year; two red and yellow sweet peppers, seeded and chopped; and a large white onion, peeled and chopped.

Swamp coolers, from large desert air conditioners down to a pan of water with a jug of drink in it covered with a wet towel draping into the water, works by wicking water up wet cloth and evaporating it down to 40 degrees F.  This is a trick I picked up while living in the Arizona desert; it comes in handy anywhere the summers are not humid.  

During monsoon season in Arizona, swamp coolers become fairly useless, but not in Southern Oregon, because we don't have real monsoons.  Southern Oregon used to regularly get wet summer thunderstorms from irrigation humidity when water was cheap and nearly everyone in the city watered their yards, which doesn't compare to true ocean moisture sucked into the interior by hot mountains from a warm ocean.  Our ocean is cold, and we have a coast range to stop the coastal fog from getting this far inland, so our hot mountains cannot bring us summer rain from our ocean, creating high pressure instead that blocks ocean storms.  

Over the last 15-30 years of high water unit prices increasing far faster than inflation all over the nation and the world, we haven't been irrigating our cities enough to make many summer rainstorms, making dry lightning and wildfires instead, so swamp coolers and misters can work really well to cool houses and yards.