Kombucha is a fermented tea drink that has become increasingly popular in recent years due to its potential health benefits. The key ingredient that makes kombucha Kombucha is a SCOBY, which stands for “symbiotic culture of bacteria and yeast.” The SCOBY looks like a thick, rubbery pancake and contains the bacteria and yeast needed to ferment the tea and create kombucha.
What exactly is a SCOBY?
A SCOBY is a symbiotic culture of bacteria and yeast that work together to ferment the sweetened tea into kombucha. The acronym SCOBY stands for “symbiotic culture of bacteria and yeast.”
The makeup of a SCOBY can vary somewhat, but generally contains:
- Yeasts – Primarily the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe
- Bacteria – Mainly lactic acid bacteria such as Lactobacillus and Gluconacetobacter species
- Acetic acid bacteria – Like Acetobacter and Gluconobacter species
- Cellulose – The SCOBY produces cellulose which forms its structure
During the fermentation process, the yeasts convert the tea’s sugars into alcohol and the bacteria further ferment the alcohol into organic acids like gluconic and acetic acid. This gives kombucha its signature sour taste.
Where does a SCOBY come from?
A SCOBY is formed when a kombucha culture is first made. To make a new kombucha culture, sweetened tea is combined with some already finished kombucha containing the symbiotic culture. Over a few weeks, the bacteria and yeasts will multiple to form a new SCOBY “baby” or “mother” which thickens to form a rubbery pancake shape.
This SCOBY can then be transferred to fresh sweet tea to brew a new batch of kombucha. With each subsequent batch, the SCOBY will grow thicker as more yeast and bacteria are produced. SCOBYs vary in color from off-white to brown.
How do you store and handle a SCOBY?
Properly storing your SCOBY between batches of kombucha is important to keep it healthy and active. Here are some tips:
- Keep the SCOBY in some already brewed kombucha at room temperature out of direct sunlight. The kombucha provides food for the culture.
- Only handle the SCOBY with clean hands to avoid contamination.
- Do not wash or rinse the SCOBY – just transfer it from batch to batch.
- Avoid freezing the SCOBY which can damage it.
- Harvest a new SCOBY to start fresh every 3-6 months.
Signs of a healthy SCOBY
A healthy, active SCOBY will:
- Have a smooth, circular shape
- Be white, off-white or light brown in color
- Feel firm and rubbery
- Be free of black or dark spots of mold
- Ferment a batch of kombucha in 7-10 days
If your SCOBY shows signs of problems like mold, a very thin pancake or overly brown color, it’s best to discard it and start fresh with a new culture.
How long can you keep a SCOBY?
With proper storage and handling, a healthy SCOBY can be kept and reused indefinitely. There is no fixed lifespan for a SCOBY. In fact, some sources report SCOBYs being used continuously for decades when cared for correctly.
That said, most sources recommend replacing your SCOBY about every 3-6 months with a freshly grown culture. This helps prevent mutations in the culture that could produce off-flavors in your kombucha over a long period of time.
Tips for long-term SCOBY storage
To maximize the lifespan of your SCOBY, follow these best practices:
- Brew new batches every 2-3 weeks to keep the SCOBY active.
- Store the SCOBY in cooled, brewed kombucha between batches.
- Keep the kombucha at a stable room temperature around 70-75°F.
- Avoid mold contamination by using clean hands and equipment.
- Discard thin or damaged SCOBYs and replace with a fresh culture periodically.
- Split and share portions of the SCOBY to limit overgrowth.
Reasons to discard an old SCOBY
While SCOBYs can technically be kept indefinitely with proper care, most sources advise replacing your culture every 3-6 months. Here are some reasons you may want to discard an old SCOBY and start fresh:
- Mold contamination – Black or colored spots indicate harmful mold. Discard SCOBY immediately.
- Yeast overgrowth – Thin or brown SCOBYs signal excessive yeast. Start fresh.
- Off-flavors – Mutations may produce strange tastes over time.
- Slow brew times – Older SCOBYs may ferment slower.
- Damage – Tears, holes or a deflated appearance are problematic.
- Long storage – Periodic replacement avoids culture degradation.
If you notice any of these issues, it’s time to discard the old SCOBY, thoroughly clean equipment, and acquire a fresh kombucha culture.
Storing a SCOBY long-term or indefinitely
For extended storage of several months or longer, a few additional precautions should be taken to maintain SCOBY viability:
- Store the SCOBY in a stabilized liquid such as previously brewed kombucha rather than plain sugary tea which may allow mold growth.
- Seal the culture in an airtight glass jar and refrigerate to slow fermentation and yeast/bacteria growth.
- Refresh the liquid every 1-2 months to replenish nutrients.
- Check regularly for signs of problems like mold, yeast overgrowth, etc.
- Plan to discard and replace the SCOBY after 6-12 months maximum.
Extreme long-term storage of multiple years is not recommended. Even refrigerated, mutations and yeast overgrowth can occur over years. Best practice is to replace SCOBYs annually.
Drying and preserving a SCOBY
While live SCOBY cultures kept in kombucha are ideal, some brewers dry and preserve excess SCOBYs for future use via:
- Dehydration – Drying on parchment paper until completely desiccated.
- Freezing – Freezing in very thin slices then vacuum sealing.
- Canning – Layering dry pieces in sugar syrup in a mason jar.
Dried and preserved SCOBYs have a longer shelf life of 12-24 months. Rehydrate in sugary tea for 1-2 weeks to revive before brewing kombucha.
Signs your stored SCOBY may no longer be viable
With extended storage, even refrigerated or frozen cultures eventually degrade. Signs an old SCOBY is no longer usable include:
- Failed revival after rehydration
- Very slow fermentation times
- Production of stringy brown yeast growth
- Formation of mold, holes, or a deflated appearance
- Sour vinegar smell instead of fruity aroma
- Unpleasant or extremely sour taste
A SCOBY displaying these qualities should be composted. A healthy culture will brew crisp, palatable kombucha in 7-21 days.
What’s the shelf life of dried or frozen SCOBYs?
Properly dried or frozen SCOBYs can remain viable for up to:
- Dried SCOBYs – Approximately 12-24 months when stored airtight in a cool, dark place.
- Frozen SCOBYs – Around 18-24 months when vacuum sealed and continuously frozen.
Take care not to allow dried SCOBYs to rehydrate prematurely. Frozen SCOBYs must remain fully frozen. Failure to maintain proper storage conditions can shorten the shelf life considerably.
Reviving dormant SCOBYs
To revive a dried or frozen SCOBY after long-term storage:
- Rehydrate dried SCOBYs by submerging in room temperature sweetened tea for 1-2 weeks, changing tea each week.
- Thaw frozen SCOBYs by placing in the refrigerator 1-2 days before use.
- Transfer rehydrated or thawed SCOBY to fresh room temperature sweet tea.
- Allow 1-2 weeks for revival fermentation to begin.
- Monitor for signs of renewed SCOBY activity like bubbles, film, or baby formation.
- Discard and replace SCOBY if no activity observed after 2 weeks.
When revived, the SCOBY should brew a batch of kombucha in its normal timeframe of 7-21 days. Refrigerate between uses.
Can you reuse a SCOBY after storage?
Yes, a SCOBY can be reused multiple times after proper storage if it remains healthy and active. However, there is a limit to how long storage can extend a SCOBY’s lifespan.
With ideal refrigerator storage in kombucha, a SCOBY may be reused for up to 6-12 months. Dried or frozen SCOBYs can typically be reused for one year after revival.
In all cases, the SCOBY should be discarded and replaced if it shows signs of poor health like mold, slow brewing, or off-flavors.
Troubleshooting problems with stored SCOBYs
Some common problems encountered when using or reviving stored SCOBYs include:
Mold growth
- Discard SCOBY immediately if any black, green or colored mold is spotted
- Thoroughly clean all brewing equipment with vinegar to inhibit further mold growth
- Acquire a fresh SCOBY from a trusted source
Yeasty flavor/odor
- Thin out the SCOBY by harvesting and discarding excess layers
- Replace some of the starter tea with fresh sweet tea
- Brew the next batch in a cooler environment (64-68°F)
Vinegar aroma/sour flavor
- Switch to a glass or ceramic brewing vessel if using plastic
- Replace some starter tea with fresh sweet tea
- Brew for less time, taste checking at 5-7 days
No carbonation
- Brew for at least 7-10 days
- Remove pellicle before bottling
- Add a little extra sugar at bottling
- Ensure bottles are well sealed
- Refrigerate for at least 2-3 days of secondary fermentation
If troubleshooting does not restore a healthy, flavorful product, the best option is to discard the damaged SCOBY and start again with a fresh culture.
Frequently Asked Questions
Can you reuse a SCOBY indefinitely?
No, SCOBYs should not be reused indefinitely. To maintain a healthy, active culture,SCOBYs should be replaced every 3-6 months. Older SCOBYs risk contamination, mutation, and loss of vitality though periodic revival may extend lifespan up to 1-2 years.
What is the longest a SCOBY has been stored and successfully revived?
While unusual, there are reports of SCOBYs remaining viable for up to 10 years when expertly preserved. However, most sources recommend storing SCOBYs for no more than 1-2 years maximum before replacing with fresh cultures.
Can you freeze a SCOBY multiple times?
Repeated freezing and thawing should be avoided. The ice crystals formed during freezing can damage the cell structure each time. Limit SCOBYs to one freeze-thaw cycle for best results.
Is a SCOBY or starter tea required to brew kombucha?
Yes, both a SCOBY and some amount of starter tea from a previous batch are required to brew kombucha. The mature SCOBY contains the yeast and bacteria needed for fermentation while the starter provides acidity to prevent contamination.
Can you use a SCOBY after taking antibiotics?
It’s best to avoid brewing with a SCOBY while taking antibiotics. The antibiotics may kill beneficial bacteria and yeast in the SCOBY. Replace the SCOBY or rest it for 1-2 weeks after finishing antibiotics.
Conclusion
While a healthy SCOBY can technically be maintained indefinitely with proper care and handling, most sources recommend replacing your culture every 3-6 months to limit the chances of contamination or mutation. Dried or frozen SCOBYs may extend viability up to 1-2 years.
To maximize lifespan, store SCOBYs refrigerated in cooled kombucha, split and share to limit yeast overgrowth, and discard at the first signs of mold or poor health. Adhering to strict cleanliness and using fresh cultures periodically will ensure a healthy SCOBY and great tasting kombucha for years to come.
