If you're brewing 'buch these days, you might notice that higher summer temperatures can lead to proliferation of yeast in your brew. These useful microorganisms, if overactive, can result in some unwanted consequences.
Yeasty kombucha SCOBY
The consumption of sugar by yeast leads to the creation of alcohol as well as CO2. These can be friends and foes in kombucha brewing for a few reasons. Read this blog for more information on sugar, alcohol and kombucha.
Alcohol is an absolutely necessary facet of brewing kombucha. But much like the initial sugar you put in your brew, alcohol serves the SCOBY, not you, the end consumer. When yeast creates alcohol, bacteria consume it and create the various acids that make up the classic kombucha profile - acetic, glucoronic, hyaluronic, butyric, succinic, usnic etc. Excess alcohol that is not consumed by the bacteria does end up in your belly, but not to any great extent.
Overactive yeast can increase alcohol production and CO2, especially in secondary fermentation. So, it can be good to get rid of as much yeast as possible if you want to try to bottle up your kombucha.
But, alcohol isn't the only reason one would want to mitigate the passage of yeast into your bottle for secondary fermentation. Lots of people are averse to what many call the "stringy," or "floaty things" in kombucha - brown strands of yeast are very common in 'buch, however. Just the sight of them, can elicit cringes from the most discerning would-be 'buch drinkers. And if you're trying to get skeptics to drink your home brew, the aesthetic can be a making or breaking factor.
And while most of us enjoy the simple, wholesome flavor of yeast (this can be biscuity, bready etc.), it's not necessarily everyone's favorite aspect.
Highly yeasty 'buch in secondary fermentation can also make for faster production of CO2, which, while producing the lovable effervescence home brewers strive for, can make for higher volatility - most seasoned home brewers have experienced at least a bottle explosion or two as a result of this effect.
It is for these reasons that we choose to strain our 'buch before we bottle it up. Greater consistency comes in secondary fermentation when you strain your 'buch the same way every time, all while keeps skeptics relatively appeased.
We love to use a simple, sturdy strainer - the yeast / tea strainer. Not only does it get the yeasties out of our brew, but it also catches any leftover tea particulate that may have made it in from your steep.
Click image to see the straining in action!
Here's a look at what is left in the strainer:
Yeast and tea particulate strained from home brew
You can use the strainer in combination with a nylon mesh filter bag to maximize your filtration:
So, if your 'buch has been overactive in carbonation, aesthetically coarse, or a little too boozy for your liking, consider simply straining it! It's the combination of these small steps that will turn you into a master 'buch brewer. Happy brewing!