Raw kombucha is alive, so it never sits still in the bottle: it keeps fermenting, slowly in the cold and fast in the warm. That makes it more sour, builds fizz, and nudges the alcohol up. Kept cold, a bottle stays good for weeks; left warm, it can pass the 0.5% alcohol line in days. So the date on kombucha is as much about the cold chain as the recipe. In the example below, a Portland brewer's refrigerated bottles passed every test through day 60, and they say best by 45 days, a 25% margin. Below is what ends kombucha's shelf life, cold against warm, the study, the date on the label, and a free template.
The short version
- Raw kombucha keeps fermenting in the bottle.
- It gets more sour and fizzier, and its alcohol creeps up.
- Keep it cold from the brewery to the customer's fridge.
- At 0.5% alcohol or more, it's an alcoholic beverage under federal law.
- Run a real-time study, refrigerated, and test alcohol at each pull.
- Print "Keep refrigerated" and a best-by date.
- TaroStack gives every batch its date from the shelf life you set. More below.
What ends its shelf life
| What ends it | What happens | What slows it |
|---|---|---|
| Souring | Acids build; it turns vinegary | Keep it cold; filter well before bottling |
| Fizz | Carbonation builds; bottles can gush | Cold storage; strong bottles and caps |
| Alcohol | Yeast keeps making a little alcohol | Cold storage; test each batch |
| Sediment | Yeast settles at the bottom | Filtering; it isn't harmful, and labels can say so |
The brewing itself is in how to make kombucha in bulk, and the license in kombucha license.
How it's stored
| Stored | In the example's tests | On the label |
|---|---|---|
| Refrigerated, 34 to 40°F | Passed every test through day 60 | Best by 45 days |
| Room temperature | Alcohol over 0.5% by day 14 in a side study | "Keep refrigerated" |
| Kegs at a café, refrigerated | Not part of the study | Kegs dated from filling, poured within a month |
The room-temperature side study is why the label says to keep it cold, and why a delivery van with no cooling isn't an option.
An example: a shelf life study
Brightwater Ferments, the made-up fermented foods maker in Portland, Oregon, I use in these examples, kept 16-ounce bottles from one batch in the cooler and opened two at each pull, sending one to a lab for alcohol:
| Test | Pass if | Day 0 | Day 15 | Day 30 | Day 45 | Day 60 | Day 90 |
|---|---|---|---|---|---|---|---|
| Taste score, 1 to 9 | at least 6 | 9 | 9 | 8 | 7 | 6 | 5 |
| Fizz, 1 to 5, 3 is right | at most 4 | 3 | 3 | 3 | 3 | 4 | 5 |
| Alcohol, % by volume, lab | at most 0.5 | 0.2 | 0.2 | 0.25 | 0.3 | 0.35 | 0.45 |
| pH | at most 3.5 | 3.1 | 3 | 3 | 2.9 | 2.9 | 2.8 |
| All pass? | Pass | Pass | Pass | Pass | Pass | Fail |
Everything passed through day 60; at day 90 the taste fell below 6 and the fizz was too strong. The alcohol stayed under 0.5% throughout, because the bottles stayed cold. Taking a 25% margin off day 60 gives 45 days. How the pulls and margin are planned is in shelf life testing.
The date on the label
Kombucha's date is a quality date, "Best by", with "Keep refrigerated" beside it. In California, food made from July 1, 2026 that shows a date uses "BEST if Used by" for quality, or "BB" on a beverage, in sell by date law. The year's numbers are in kombucha business plan.
Get the template
Download the kombucha shelf life study template. One sheet: the product, the lot tested, the day it was made, how it's stored and the margin to leave; then each test with its limit and the result at each pull. It marks each pull pass or fail, finds the last day everything passed, takes the margin off, and gives the shelf life for the label and the date for a batch made today. It's an ordinary Excel file with no macros, and it works in Google Sheets, LibreOffice and Numbers.
Where this stops working
The study gives one date for one kombucha. Four flavors, bottles and kegs, a batch every two weeks, and cafés that want 30 days left: someone has to date each batch and send the oldest out first.
How TaroStack does it
TaroStack gives every batch its date from the shelf life you set, and sends the oldest out first.
Dates from the shelf life. Each kombucha carries its shelf life in days, and each batch's lot gets its production date and the date that follows from it.
First-expired-first-out. Orders take the oldest lots first by default, and a café can be set to take only stock with enough days left.
What's coming up. A forecast shows what will expire unsold and what it costs, and anything thrown out is recorded with its reason, expired or spoiled, so waste shows by item.
| The job | Spreadsheet | In TaroStack |
|---|---|---|
| The date on a batch | Worked out by hand | From the shelf life, on the lot |
| Which batch goes out first | Dates on tape | First-expired-first-out |
| Stock with enough days for a café | Checked by hand | The customer's shelf-life rule |
| What expired last month | Not counted | Waste by reason |
Lots, dates, first-expired-first-out and the expiry forecast are on every plan, from $49 a month. The first 30 days are free, with no credit card. If you'd like a hand setting up, ask, and we'll do it with you.