Kombucha materials
Growing a cellulose pellicle from a living microbial culture, using the Acetobacter bacteria found in a fermented tea drink called kombucha. Kombucha material can be paper or leather-like and molded.
GENERAL INFORMATION
This recipe describes in step #1 how to cultivate a kombucha SCOBY (Symbiotic Culture Of Bacteria and Yeast), which is often used to ferment sugary tea, because it can transform sugars into acids. Acetobacter is one of the important bacteria in the bacteria/yeast culture, and requires oxygen to live and grow; it is aerobic. As a result it slowly forms a cellulose pellicle where the liquid is in contact with air (i.e. at the surface).
Step #2 describes how to prepare and dry the cellulose pellicle so that it can be used as leather alternative or paper-like thin material. Following this procedure will grow a thin pellicle to start with, it will get thicker as you start to use it more.
Note: this recipe is meant to provide tips on how to make a microbial material. Whereas the process is safe to do, it does not cover a process for human consumption per se, and cannot guarantee food safe practices. Don't consume your SCOBY or kombucha tea until you have thoroughly informed yourself on safe fermentation processes. When in doubt, throw it out.
Step #1: Cultivating your Kombucha SCOBY
Ingredients
There are various ways to do this and different methods work for different people, also depending on the temperature in your home. Here we use the living culture from store-bought kombucha and add some extra nutrients by preparing some sugary black tea for it to grow a little faster. This recipe helps you start, but growing a healthy culture can take multiple cycles, so don't give up!
Try to work as sterile as possible throughout.
Kombucha drink with live culture (raw), without flavouring
used here: Yaya Kombucha Original (Ekoplaza supermarket)
660 ml (2x 330 ml) or just make sure to make a 2:1 ratio of raw kombucha and sugary tea).
we will cultivate the live bacteria in the drink and grow them into a solid cellulose pellicle
some say it's best to find a bottle that already has some blobs of culture (baby scoby's) sitting at the bottom.
Denatured alcohol 96%, or white vinegar to desinfect all your tools and pots
Two large round coffee filters, or clean cloth like a tea towel, to prevent contamination by fruit flies
Two rubber bands to prevent contamination by fruit flies
Water - 330 ml, to make black tea
1 tea bag of black tea, organic simple black tea such as ceylon, darjeeling or English breakfast are good options.
(organic) sugar - 30 g, white sugar or cane sugar.
Optional: a splash of vinegar if your water is alkaline
Tools
Two glass jars try to get a wider ones, min 10 cm diameter
A pot
Kitchen paper
Anti-bacterial soap to wash your hands
A scale
A spoon
A thermometer
PH paper
Method
Create a sterile environment
Wash your hands with soap for at least 20 seconds
Sterilize all your tools with 95% denatured alcohol or white vinegar.
If you don't have alcohol: sterilize with hot water. Don't put cold glass inside hot water! It will break. Heat up slowly.
Prepare the sugary tea
Boil the water
Add the teabag and turn off the heat. Let the tea brew for 5 minutes (for black tea, or 3 minutes for green tea)
Take out the teabags with a sterile tool
Let it cool all the way down to 30 degrees Celcius (so you don't kill the bacteria of the kombucha).
Mix in the kombucha and seal
Make sure all is sterile - maybe wash your hands again?
Mix in the store-bought kombucha and stir
Measure the PH of the mixture. It should be between PH 4 - PH4.5 if it is more acidic than that (lower values) make more tea to bring the values up. The fermentation process will produce acids that bring the PH down eventually.
Distribute your kombucha/tea mix into the sterilized jars
Seal them with a coffee filter and a rubber band to prevent fruit flies from going in. You don't want their larvae in your SCOBY. You want to ensure air flow without letting any bugs in. You can also do this with a clean cloth, but make sure the mesh is small enough.
Let it grow
Put it in a warm place but away from direct sunlight (preferably in the dark, like a cupboard), and leave it for 2-3 weeks, or until it has grown 5-8 mm thick (to create paper-like cellulose) or closer to 10-15 mm thick, to grow for leather-like pellicles.
Do NOT move the jars, the pellicle will sink and you will have to start over
Check regularly for unusual growth. Ideally your SCOBY becomes a thick white-ish film floating on top of the liquid. But it takes many forms and can definitely look funny. Learn how to discriminate between a heathy SCOBY and fungal or yeast growth. The resources from Kombucha Kamp are a good starting point.
Use your SCOBY
If it has grown to a thickness of minimum 5 mm you can use your SCOBY pellicle to make paper or leather, as descibed in the recipe below. Take it out with clean hands!
and/or: re-use the liquid to grow more pellicles, it now has more living culture in it.
wash your hands and sterilize your tools again?
make some more sugary tea as described above and add it to the liquid from the previous brew. Use at least 25-75% sour liquid from a previous brew (it smells like vinegar). More mature culture = faster pellicle growth.
instead of adding tea, you can also continue brewing by adding sugar and beer. You don't need to dissolve the sugar.
If you are not using your SCOBY right away, make a SCOBY hotel to store it for later use:
For long term storage, perform maintenance every 2-6 months.
Step #2: Making Kombucha paper or leather
Ingredients
Kombucha SCOBY pellicle - 1 piece of 5-7 mm thickness for paper-like materials, or 8-15 mm for leather-like material.
Coconut oil - 1 tbsp (15 ml)
Beeswax, melted - 1 tbsp (15 ml)
Tools
Gloves
A glass jar, to mix the treatment
A pot, big enough to put the glass jar in (bain marie)
A spoon, for stirring
A cooker
A silicone mat, to dry the paper on, baking paper also works.
Optional: a brush
Yield
One sheet of kombucha paper or leather.
Method
Preparing the after-treatment for a kombucha sheet
Take the kombucha sheet out of its bath, wash in soapy cold water and dry it off with some kitchen paper. Put it on the silicone mat. Some kombucha SCOBY's will be a bit uneven and might have a hole or a tear. You can rearrange it a bit and put these bits back together, in the drying process these parts will reattach if they're overlapping.
Melt the beeswax so you can take one tablespoon of it. (Put a chunk of wax in a glass jar that I melt au bain marie. You can then let it cool inside the jar where I store it for later).
Warm up a bit of coconutoil so it becomes liquid (you can use the bain marie)
Mix the liquid bees wax and coconut oil and store in a container.
Applying the water-proofing treatment
Place the kombucha pellicle on a smooth surface
Apply the coconut oil/beeswax mixture to one side of the kombucha sheet with a brush or with your fingers. Massage it in.
Let the kombucha sheet dry for a few days
Peel the sheet off, turn over, and apply the treatment to the other side.
Drying and pressing
You can place the kombucha sheet over a mold to let it dry in a certain shape.
Leave to dry on a smooth surface for a flat sheet.
When the sheet is fully dehydrated, any excess treatment can be wiped off with a paper towel.
Once dry, you can press it between baking paper under a stack of heavy books if you need it to become totally flat and even.
Drying/curing/growth process
Thickness before drying: 5 mm for thin paper-like sheets, 8-12 mm for leather-like material
Shrinkage thickness 70-80%
Shrinkage width/length 0-10 %
sources:
Kombucha Kamp Kombucha SCOBY by Loes Bogers Kombucha Paper by Loes Bogers
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