Continuous fermentation of kombucha (cfko) 23/6/2012

  • Goal of this experiment: start up of a continuous fermentation of kombucha probiotic culture which should results in following:

– increase in the speed of growth of the kombucha SCOBY
– increase in biodiversity and resistance of the culture against possible contaminants
– decrease of the time needed for the upkeep of the culture, harvesting and handling in general
– improvement of the flavour of the beverage produced
– increase in the variety and amount of health benefiting compounds
– shortening the time needed to produce the beverage when needed

  • Concerns

– increase in waste of beverage if the beverage get over fermented
– amount of time needed to re-establish the balance of the culture if the equilibrium gets disturbed

  • Ingredients

culture volume, Vc = 11 l
dark rich brown sugar (sugar cane) – 6 % (w/v), 660 g
ceylon loose tea (black) – 0.6 % (w/v), 66 g
kombucha mother (SCOBY) – 2 % (w/v), 220 g (two bigger younger top layers, one smaller, half circle SCOBY)
kombucha vinegar – 5 % (v/v), 550 ml (kombucha harvested on 23/5/2012 and left to ferment at room t, anaerobicly; very acidic flavour)

  • Equipment

induction stove
digital scales (max weight up to 1 kg or more)
plastic fermentation vessel with spigot in the bottom (12 l final total volume)
bowl (holding around 0.5-1 l) (to weigh the tea)
bowl or pot (holding around 2-3 l) (to weigh the sugar)
bowl or pot (holding around 6 l) (to dissolve the sugar)
spoon (stainless)
3-5 l pot (2x) (to boil the water for the tea and steep it)
strainer (to strain the tea)
bag for the waste
cheesecloth or muslin (to cover the final brew)
string (to keep the cheesecloth tight)

  • Procedure

– clean the place for the experiment and prepare the equipment and ingredients
– label by tape and permanent marker the water level in the fermentation vessel, especially from 7 l up
– start to heat up 1.5 – 2 l of the water in the pot
– simultaneously weigh out the tea and to another bowl the sugar to have them ready
– when the water boils, switch it off and add the tea, steer it in so it is submerged
– let to steep up to 10 minutes
– strain the tea using the strainer to another bowl and dispose the leaves to compost bin
– add the sugar to the hot brew and mix it till dissolved
– add around 2 l of cold water to cool it down (transferring to glass or plastic container)
– transfer the tea-sugar syrup to the fermentation vessel
– add another five litres or so (up to 80% of Vc)
– measure the temperature making sure that the liquid is not too warm (less than 30°C)
– add the kombucha vinegar and stir a bit
– bring the volume to very close to the final culture volume Vc = 11 l
– add the kombucha SCOBY’s by the new whitish side up being in touch with air
– cover the wide mouth opening by cheesecloth and attach it tightly by a string to the vessel, so no insect can get in
– let the kombucha ferment at room temperature, preferably within the range 20-30°C
– wait 3-5 days and taste every day waiting for the culture to be ready for the first harvest
– observe the kombucha mother SCOBY making sure that the culture doesn’t get contamintated with mold, examples: SCOBY contamination 1,  SCOBY contamination 2 and SCOBY contamination 3.
– once is the brew ready, bottle around 20-30% of the brew (around 2-4 l)
– replace with the same amount of a sugar tea brew (based on the 6% (w/v) ratio for sugar and 0.6% (w/v) ratio of tea; for 3 l = 180 g of sugar and 18 g of black tea)

  • Links to more information:

Curtin L. V. (1983) Molasses – General Considerations.

Jayabalan R., Malini K. and Yun S.E. (2010) Biochemical characteristics of tea fungus produced during kombucha fermentation. Journal of Food Science and Biotechnology
19(3), 201-205.

Jayabalan R., Subathradevi P., Marimuthu S., Sathishkumar M. and Swaminathan K. (2008) Changes in free-radical scavenging ability of kombucha tea during fermentation. Journal of Agricultural and Food Chemistry 109, 227-234.

Mayser P., Fromme S., Leitzmann C. and Gründer K. (1995) The yeast spectrum of the ‘tea fungus Kombucha’. Mycoses 38(7-8), 289-295.

Olbrich H. (1963) Molasses

I would like to thank to Susubori Academy for a support of this pilot experimental project.

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~ by algoldor on June 28, 2012.

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