My super cheap fermentation indicator

Sometimes, you just don’t have the gear. I lost my airlock the other morning… It’s somewhere around but will probably turn up along with all those misplaced pens…

I was making Beet kvass – a delicious, easy to make ferment.

So… I got to thinking how to make an airlock, then realized I didn’t need one for this short time ferment.

Airlocks are used in fermentation to let the carbon dioxide produced by the anaerobic bacteria out of the system while preventing oxygen from getting in.

But, I asked myself, is there any reason to let it out?

What did I do? I merely squished the bottle a little with my thumb, expelling some air. Then I tightened up the top. The result is a slight indent in the bottle that fills out when the CO2 is produced.

When you see the indent full, that shows that the fermentation has worked and the CO2 has pushed the bottle back to its proper form. Open the top of the bottle and you will be rewarded by a welcome hiss as the CO2 escapes.

Sometimes things just come together for you…