Many of our wild fermentations (a style of fermenting that uses naturally occurring yeast in the air) require the same step – cover the vessel with cheesecloth to allow wild yeasts to enter the jar but keep the flies at bay (if you’re struggling with the terminology surrounding different types of fermentation, check this out). We use mason jars to do a lot of our fermentation and were looking for an alternative to cheesecloth to cover the ferments in the early stages.
While cheesecloth (or other cloths) work, I find it frustrating. It ‘feels’ flimsy, ends up as garbage, I often use several pieces before a ferment finishes, a fan can blow it off and I find it looks ugly. I know these are minor issues but they are things I think about.
Or thought about. Because my woes are well behind me now:
A reusable coffee filter is a perfect replacement!
I don’t know how large a yeast molecule is but have been used this a few times and it’s been very successful. The yeast either easily passes through the filter (which I suspect to be the case) or enters the jar as I lift the filter to stir or smell the contents (in this case, the starter for homemade ginger beer).