Kombucha in stainless corny keg?

Hello,

My brother would like to brew a first batch of Kombucha and asked me if he could use one of my corny kegs to do so. I use the corny kegs for brewing but have seen that most people suggest staying away from stainless and using glass instead. Could anyone here expand on this?

Thanks for your help.

I'm not going to be too much help on the "why" of it, but I know you definitely want to stay away from anything metal when brewing kombucha. Do a quick google search on kombucha culture and metal and most sources tell you it's a bad idea. They even say not to use metal utensils or let anything metal touch the mother culture, so brewing in stainless would probably end badly. Maybe someone else can expand on why, but the short answer is you probably don't want to try it.

That is what I have seen looking around the web. It appears to have something to do with the low pH during fermentation. Metals and plastics can leach. Now looking for a glass container...

I'm not sure if stainless would be a problem. I can't think of why it would be. Stainless is basically inert for most intents and purposes. Now aluminum I can see, and when it comes to Internet "knowledge" I can see how aluminum being bad could translate to "don't use metal". But as far as the steel leaching I don't see this being a risk. Since it will not corrode appreciably while the kombucha is brewing there is no way that there will be a transfer. If there was, steel wouldn't be so popular as a food safe material.

It could pit the stainless steel just like you can pit it by storing Star San in it for an extended period of time, and if it gets pitted it can ruin the keg and make it so that it wont hold pressure. I use a glass sun tea jug with a spigot on it, makes bootlegging a breeze!

I don't think that kombucha has anywhere near the acidity of Starsan...

bottlebomber said:

I don't think that kombucha has anywhere near the acidity of Starsan...

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it doesnt but extended storage of any acid can pit stainless.

bottlebomber said:

I don't think that kombucha has anywhere near the acidity of Starsan...

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Maybe pure starsan, but by the time you dilute it to their recommended levels I'm guessing it would be pretty similar. Kombucha is quite acidic. I could be wrong, I definitely haven't taken PH tests of starsan after dilution... but you're adding only 1 1/4 oz starsan per gallon of water so that has to bring it down quite a bit.

I'm going to have to take a PH meter to some kombucha now

bottlebomber said:

I'm going to have to take a PH meter to some kombucha now

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Let us know exactly how acidic it really is, i know it can be sour as all get out, but that doesnt mean its a super strong acid since it doesn't eat your skin off lol.

Vance71975 said:

It could pit the stainless steel just like you can pit it by storing Star San in it for an extended period of time, and if it gets pitted it can ruin the keg and make it so that it wont hold pressure. I use a glass sun tea jug with a spigot on it, makes bootlegging a breeze!

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I use sun tea jars, too, and I love them! I found six of them for under $40 from an online hardware store. I've never had leaks, but I did tighten the spigots before use.

http://www.ronshomeandhardware.com/71132-120OZ-Waterme-Bev-Taper-p/535369.htm

what are the spigots on your tea jars made out of? mine are stainless.

spearko520 said:

what are the spigots on your tea jars made out of? mine are stainless.

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I'm curious about this too,because I can't find a solid 1 gallon glass jar anywhere!!!

target has solid jars - 1g - 2 1/2 g- the 2 1/2 are 20 bucks- they have a silicone seal that works great - you just take the handle off, drill the hole out larger so it fits a grommet (like the kind on a bucket lid) put the grommet in the plastic silicone part and glue it onto the metal lid. they work great...

spearko520 said:

target has solid jars - 1g - 2 1/2 g- the 2 1/2 are 20 bucks- they have a silicone seal that works great - you just take the handle off, drill the hole out larger so it fits a grommet (like the kind on a bucket lid) put the grommet in the plastic silicone part and glue it onto the metal lid. they work great...

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Thanks I appreciate the help!! Is it better to have a stainless spout or a plastic for bottling?

Here's someone selling 4 1-gallon jars for $30.
http://www.happyherbalist.com/4one-gallonjarswithplasticlids.aspx

hxcpunk71 said:

Thanks I appreciate the help!! Is it better to have a stainless spout or a plastic for bottling?

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im also curious about this?

, i just bought 2, 1gal suntea jugs from st. vinnies, they have plastic spouts. ive read that plastic is bad for the culture, but i doubt that the tiny bit of plastic, that is considered food safe sticking into the bottle, will leach any toxins if at all into your tea. insight is always nice

SikboarderTy said:

im also curious about this?

, i just bought 2, 1gal suntea jugs from st. vinnies, they have plastic spouts. ive read that plastic is bad for the culture, but i doubt that the tiny bit of plastic, that is considered food safe sticking into the bottle, will leach any toxins if at all into your tea. insight is always nice

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I wouldn't worry about the plastic. If you're not fermenting the whole thing in an entirely plastic container, you should be fine. Metal, bad. Plastic, not best. But when you're only pouring through it not fermenting in it, I wouldn't worry about it at all.

ChessRockwell said:

I wouldn't worry about the plastic. If you're not fermenting the whole thing in an entirely plastic container, you should be fine. Metal, bad. Plastic, not best. But when you're only pouring through it not fermenting in it, I wouldn't worry about it at all.

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On this note: after fermentation of the kombucha is done, do you all think there should be cause for concern in transferring to a CO2 pressurized keg and into a kegerator? Fermentation's over, cold temp, etc. At this point, are we OK w/ a neutralized, non-active substance or is the acidity still a factor in leeching metal from the keg?

There's mention, however rare, on the internet about kombucha on tap at some Whole Foods and restaurants so it's certainly being done. Wondering if there's something they may be doing differently. Would be awesome to have the beer / kombucha (healthier drink) combo to add some balance to a kegerator.

I wouldn't ferment kombucha in a stainless container... I'd look for a glass jug. Maybe a 3 gallon carboy?

Where'd you find your recipe? I've actually been interested in doing this.

A local company in Vermont sells their Kombucha in bulk out of kegerators. I've never opened one up to look but I'm pretty sure they are distributing from sixtels or sankes. If you click on "wholesale" on their website, a picture pops up that at least makes it look like they are using cornys:

http://www.aquaviteakombucha.com

2.5 to 3.5 pH

I wouldn't bother using a corny. Best thing you can do is a continuous ferment in a food grade plastic carboy with spigot.

These are the best two professional pieces I've seen online. The plastic used in these can sustain acids way stronger than vinegar. Which is pretty much as acidic as Kombucha can get if left unmanaged.

https://ca.vwr.com/store/catalog/product.jsp?catalog_number=16117-984

http://www.minibrew.com/index.php?main_page=product_info&cPath=5&products_id=6

Alternately you could make your own like this guy http://frugalconicalfermenter.blogspot.ca/ you have to get in to his photostream on flickr to actually see the pictures.

Myself I'll likely buy the nalgene carboy or just buy one of the aforementioned ice tea jars with spigot. Never go steel

KegOutlet said:

I wouldn't ferment kombucha in a stainless container... I'd look for a glass jug. Maybe a 3 gallon carboy?

Where'd you find your recipe? I've actually been interested in doing this.

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Grab a bottle of gts kombucha tea from a local health food store. Boil 1 litre of water, remove from heat and drop in 4 green tea bags and 2 black tea bags. steep for 15 min, add 1 cup of sugar (or between 3/4-1-1/3) and dissolve. add 2 litres of cold water. make sure it's under 30c before adding the gts (under 28 Celsius to be safe). cover your fermenting medium with cloth (i use a coffee filtre) wait 8-10 days and drink. if you get gut rot (too acidic) chances are you're fermenting it too long, or drinking way too much

next batch do the same thing but make it 2.5L cold water now that you no longer need the gts for a starter.

on your first batch it wouldn't hurt to add 1tsp of apple cider vinegar. the acid will promote growth and inhibit unwanted baterium.

i think you can make a kombucha mother by using only apple cider vinegar. i haven't experimented to find out.

Kombucha is very resilient and flexible enough that you can use this recipe and then play around with variables such as temp and sugar and duration of ferment, according to your taste.

right now i've got a 3 week old batch that's turned to vinegar. i dumped nearly all of it save for enough to keep the mother floating. then I dropped about 1 tsp of sugar in it to keep it a little less starved. not having a continuous ferment set-up i can get a bit lazy

this is a 4L jar I found at a restaurant. it's scaled from hard water because i used to sit it in a heated aquarium to keep it at 26C, and I don't remove the old mothers until i get 3-6 of them. despite how disgusting this all looks, it's perfectly healthy and clean inside haha