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Before there were reliable ways to seal fermented beverages kombucha was consumed once it had acidified and used most of the easily fermented sugar in the liquid. It was not flavored with fruit juices or other various types of flavorings we use today. Rather it was a slightly fizzy fermented tea drink. It is thought to have originated in China and is now prepared at home and commercially worldwide.
There is nothing in the ingredients or the process of making kombucha which preclude it from being consumed at any time in the fermentation process. As it ages the sugar content drops and the acetic acid increases. The alcohol level increases peaks and then declines as the sugars are depleted.
The second fermentation process is completely optional. This is where the active yeast in the kombucha is fed a little extra sugar and sealed into a bottle of some sort. The yeast produces carbon-dioxide and pressurizes the bottle.
Benefits of consuming kombucha after the first ferment
Lower alcohol level
Kombucha is a symbiotic culture, meaning that the various species of bacteria and yeast found in the culture work together to create a strong and stable population. When you bottle kombucha with added sugar you are effectively removing the influence of one of the species in the culture, the acetic acid.
Yeasts produce more alcohol when placed into an anaerobic environment, like in a sealed bottle, than when they have free access to oxygen but acetic acid bacteria is aerobic. Without oxygen it cannot convert the alcohol the yeast produces into acetic acid and the alcohol level rises.
Lower sugar content
When kombucha is bottled additional sugar is added to the bottle to facilitate the production of carbon dioxide which makes it fizzy. This sugar can be in the form of fruit juice, white sugar, tree syrup or any other sources of high concentrated sugars. During second fermentation not all of this sugar is used by the yeast to make carbon dioxide and the total sugar content can be higher.
Flavor flexibility
Kombucha can be flavored with a variety of flavoring agents. Fruit juice, herbs, flavor extracts or any other flavoring you can imagine but when it is second fermented this flavoring needs to be done days before it is consumed.
To flavor first fermented kombucha all you need to do is add the desired flavor when you go to drink it. Mix it with some fruit juice in the morning, or make it into a tangy lemon drink by adding freshly squeezed lemon juice in the afternoon. You will not be limited in any way even if you like your kombucha carbonated you can add soda water and flavoring to make it fizzy.
Will not over carbonate
If you have been making kombucha for a while you will have had the experience of opening a bottle of kombucha and being greeted with a fountain of kombucha all over the place. Homemade kombucha is tricky. The temperature, remaining sugar and source of flavoring affects the amount of carbon dioxide which is formed in the second fermentation stage.
Sometimes this leads to a highly carbonated batch of kombucha which literally explodes out of the bottle when opened. This is not a problem with first fermented kombucha as the carbon dioxide does not build up in the container but escapes into the atmosphere.
Over carbonation can cause other problems besides loss of kombucha and a big mess to clean up. It can actually burst the bottles and send glass in all directions which is very dangerous. If you are second fermenting your kombucha be sure to use bottles which are meant for holding pressure and keep them in a closed cupboard out of direct sunlight.
Kombucha first ferment timeline
There are several stages of kombucha fermentation which occur in order as the batch matures. As each stage happens your kombucha changes to become the slightly tangy, sweet and effervescent beverage which has become so popular.
Kombucha inoculation (one hour)
The inoculation stage happens once you have prepared the sweet tea and it has cooled to room temperature. Then the starting kombucha is added and the SCOBY is placed into the container.
The sweet tea needs to be inoculated with enough reserved kombucha to do two things:
- Lower the pH of the tea to below 4.5
This will protect the tea from unwanted microbial growth as most spoilage bacteria prefer a basic environment.
- Provide the tea with live microbial culture
The live culture found in the starter liquid is inhabited by the yeast, lactic acid bacteria and the acetic acid bacteria which convert the sweet tea into kombucha.
Rapid Yeast growth
The yeast will have a day or two of lag time where it is acclimatizing itself to the new environment. This can take one or two days before the yeast really begins to multiply. The length of time the yeast population grows depends on the amount of sugar used in the tea, the temperature of the fermentation and its access to oxygen.
Most yeast species like a temperature range of 20-35℃ so a warmer ambient temperature will speed up this stage whereas a high sugar concentration will prolong it as there is more fuel for the yeast to consume. Yeast can grow in an aerobic or anaerobic environment but their metabolism is more efficient in the presence of oxygen therefore if the yeast has easy access to oxygen it will grow faster and shorten this stage of the process.
With a ratio of one cup of sugar per gallon of tea, an ambient temperature of 20℃ and a wide mouthed container this stage will take two to four days.
The various yeast species which line in a kombucha culture perform an important role in the production of kombucha. There function is three fold:
- Produce alcohol which the acetic acid bacteria use to make acetic acid.
Kombucha is a weak vinegar like solution which is consumed before the fermentation process is complete. It has a small amount of alcohol left in it depending on when it is consumed and how much sugar was used in the solution.
With more sugar there will ultimately be more acetic acid produced.
- Produce various vitamins
Yeast species are known for their production of B vitamins which are used by the body to maintain energy levels throughout the day, support mucous membranes and help the brain.
Kombucha culture has a wide variety of yeast species living in it which produce many other vitamins and convert inorganic minerals into organic minerals and therefore available to the body.
- Compete for fuel with lactic acid bacteria and unwanted spoilage bacteria
Lactic acid bacteria are a part of the kombucha culture and perform a useful function but too much lactic acid in kombucha makes for a very sour drink.
Since both the yeast strains and the lactic acid bacteria strains consume the same fuel they keep one another in check. This limits the amount of alcohol produced as well as lowering the lactic acid concentration.
Rapid Lactic acid growth
Although lactic acid bacteria are not in high populations in most kombucha cultures they are present and perform a valuable service in kombucha fermentation. They have a longer lag time than the yeast species as they grow best in anaerobic conditions.
When the tea is first made it is very well aerated giving it a higher amount of oxygen dissolved into the liquid, as it ferments the yeast uses much of this oxygen in its respiration and the solution becomes oxygen poor. Once the oxygen level of the tea drops the yeast species need some time to acclimate to anaerobic respiration. This is when the lactic acid bacteria begin to grow rapidly.
Rapid growth happens three to four days after the inoculation of the tea and continues until the yeast species begin to compete in the anaerobic environment.
Lactic acid bacteria are also producers of a wide range of vitamins especially those of the B vitamin family including B12 which is produced by Lactobacillus rossiae which is often found in the kombucha culture.
Rapid Acetic acid growth
The acetic acid bacteria is present in all kombucha cultures and begins to grow rapidly once the yeast begins to produce alcohol. This can take anywhere from three to four days. When the alcohol level begins to rise the acetic acid bacteria have the fuel to grow rapidly which continues until the alcohol concentration levels off and declines.
The time this takes is again dependent on the amount of sugar, temperature and access to oxygen the fermentation has. Rapid growth of acetic acid bacteria will last anywhere from four to ten days.
Acetic acid bacteria are aerobic bacteria meaning they need oxygen to grow. This is why they grow mostly on the top of the kombucha fermentation where the SCOBY forms.
Once the acetic acid bacteria begin to grow rapidly a new SCOBY will form on the surface of the tea. It is produced mostly by a subspecies of acetic acid bacteria gluconobacter and acts as a barrier between the culture and unwanted bacteria. As the kombucha matures the SCOBY thickens and yeast strings form on the bottom as the sugar content is reduced.
Yeast die off
Yeast die off will start between 10-12 days again depending on temperature and available sugar. In alcoholic fermentations another limiting factor is the alcohol concentration but in kombucha the alcohol is being consumed by the acetic acid bacteria so it does not limit the yeast growth.
Once the yeast has consumed most of the easily fermentable sugar its population will plateau and begin to fall off. This will start anywhere from 6 days onward, as the sugar content drops so will the yeast population.This is when you will begin to see new sediment on the bottom of the container and yeast strings form on the bottom of the SCOBY. These yeast bodies are full of vitamins and minerals so consume them with the finished kombucha or use them in baking.
Bacteria die off
The bacteria species will die off at a different rate due to the source of energy they use. Lactic acid bacteria will die off in tandem with the yeast species as they use the same fuel. The acetic acid bacteria will slow their growth once the alcohol level in the kombucha begins to fall.
Kombucha maturation
Kombucha can be consumed throughout the fermentation process. Each stage has a different ratio of vitamins, minerals and beneficial probiotics. New kombucha is relatively high in active probiotic cultures whereas as it ages the population of the culture falls but the vitamin and available mineral content increases.
Depending on how you like your kombucha and what you are drinking it for will determine when you should consume it.