The inside of my Tervis cup sort of looks like a planet…

While I have been trying to convince Ryan to buy a conical fermenter for some time now, I bought one before he did. It is kinda of a crazy jump up in equipment for me. But I need a new toy. The thing about kombucha is that the gelatinous scoby forms at the top of the liquid and covers the entire surface area. So if the vessel then constricts at the top, it is rather difficult to man handle around the scoby. Such as when you drain the kombucha, or when you remove the scoby.

Blichmann sells a 7 gallon conical fermenter for $600. One weird thing is that the price does not scale up linearly as the volume increases. A 14 gallon fermenter is $640. I went for a cheaper version made by Stout Tanks (the 7.3 Gallon Conical Fermenter with wheels and thermometer for $479).

The build quality is quite nice except for a couple of issues. The first major one is that the center of gravity is not in the middle of the three wheels. One of the three sides is off balance, where if you push it, the conical will tip over. This is not fun when it is full of liquid. The other problem is with the default sanitary ball valves. These are cheaply made and have slightly inconsistent dimensions of the wrench fittings. Also, the o-ring that they use have a major flaw in them. When you tighten the valve back up, the o-ring will squeeze out of the gap rather than stay against the side. This is incredibly frustrating during a brew day after I have broken down everything to clean it and then discover that it cannot hold liquid. Fortunately, Stout Tanks took them back and gave me the better butterfly valves.

I have been wondering whether kombucha needs to ferment in an open air container. Even though a cloth towel is covering the vessel, I know very well that dust, dirt, and micro organisms are able to travel through the “barrier.” Also, the kombucha is sitting in my guest bathroom. And, while the bathroom doesn’t get used, it seems more sanitary if the vessel is hermetically sealed.

In one bucket, I oxygenated the liquid, oxygenated the air, sealed up the top, and then placed an airlock in the hole. In the other bucket, I placed a cheesecloth over the top. After a couple of weeks, the scobies were dramatically different. Clearly, the gelatinous mass is a protection barrier to oxygen.

I wondered if kombucha could eat different sugars than sucrose. So I brewed a batch of kombucha with dry malt extract (DME). It was not a problem at all it seem. Although there is one noticeable difference. When the CO2 is generated and bubbles out of the liquid, the DME is foamier than sugar. And you can see the dried foam along the edges. The taste also has a slightly different mouth feel.

I have now experimented with three different scoby cultures. The first one was from the Meetup group. The second one which I bought via Amazon was the Oregon Kombucha Complete Starter Kit. The third one I got from Kombucha Kamp and was two scoby cultures as 2 Full Size Kombucha Mothers.

I bought two new ones so that I could run an experiment. One kombucha batch will be sealed to the outside air and the second will be open.