Food safety · 7 min read · 6 September 2026

The brew-day log: what to record, and why an auditor asks for it

A recipe says what you meant to do. The brew-day log says what happened, when, and to which lot. It is the one record that turns a good batch into a defensible one, and the first thing an inspector opens.

Most kombucha breweries keep some kind of log. The difference between a log that protects you and one that does not is rarely the format. It is whether the entries were made at the time, whether the critical numbers are there, and whether a stranger could follow a bottle back to the tea it came from. This guide walks the day in order and says, for each entry, what to write and why anyone would ask.

Before the first drop: what the log identifies

The top of the page pins the batch to the world. Without it, everything below is a number without an owner.

• Batch code, date, operator. One code per vessel and per fill. Initials of whoever ran the day.
• Recipe and its version. The version matters: a recipe edited next month must not silently rewrite what this batch was made from.
• Vessel and its last cleaning, or a reference to the cleaning log.
• Ingredient lots. Tea, sugar, and water treatment if you use any. The supplier lot number, not just the product name. This is the backward half of traceability: which deliveries went into this batch.
• The culture. Which starter you pitched, its pH before pitching, and the volume as a share of the batch. A mature, low-pH starter at 20 percent or more of the volume is what makes the early pH drop reliable; the log should show you had it.

At pitch: the two numbers that decide CCP 1

Acidification is the critical control point that carries the safety case, and it is decided in the first hours. Two entries at pitch time tell the story.

• Tea temperature at pitch. Cool the sweet tea before the starter goes in; hot tea stresses or kills the culture and delays the pH drop. Write the number, not "cool".
• Starting pH and the time. The pH right after pitching is your baseline. With a strong starter it already sits well below the tea's own pH, and the clock for the early drop starts here.

During fermentation: readings on a schedule, not on a hunch

A single end reading proves the batch got acidic eventually. A curve proves the barrier was there early, which is the actual food-safety argument. So the log needs readings at set intervals, each with a time.

• pH at least daily in the first days, and whenever you touch the batch after that. Note the reading at which the batch crossed your critical limit, and when. The KBI-aligned target is below roughly 4.2, early, commonly within about 48 hours.
• Brix alongside pH: sugar going down while acidity goes up is what a healthy ferment looks like, and the pair catches a stalled batch that pH alone hides.
• Titratable acidity if you measure it. pH tells you how acidic; TA tells you how much acid. Both together explain why two batches at the same pH taste different.
• Temperature of the ferment, especially in summer and in a cold cellar. Most breweries hold somewhere between 21 and 32 °C; what matters is that you wrote it down.
• Deviations and what you did. A slow drop, a temperature excursion, an off smell: one line for the observation, one for the corrective action, and the initials of who decided. This is the line auditors look for and rarely find.

Transfer and second ferment: the split becomes new records

When one base becomes several flavours, the log has to follow the liquid. Each second-ferment vessel or bottling run gets its own entry that points back to the base batch.

• Transfer time and volume out of the base, so the base batch can be closed with a yield.
• Additions with lot numbers. Juice, fruit, botanicals, priming sugar: the amount and the supplier lot of each. This is where most traceability gaps live, because flavouring feels like cooking, not like production.
• Conditioning conditions. Days, temperature, and for bottle-conditioned product a pressure or a test-bottle check. Over-carbonation is a safety issue as much as a quality one.

At packaging: alcohol, lots, retention sample

Packaging is where the second critical control point is checked and where the outward half of traceability begins.

• Alcohol result and the method. The number, the method you used, and the date. Below 0.5 percent by volume is the line for non-alcoholic in most markets; some allow more. An unmeasured batch is an unknown batch.
• Lot number on the label and the count of units, by format. The lot printed on the bottle must be findable on this page.
• Retention sample kept, and where. It is what you test when a complaint comes in.
• Cold chain. The temperature the finished product went into, since raw kombucha keeps fermenting when warm.
• Sign-off. Who released the lot. A release without a name is a release nobody made.

What an auditor reads first

Inspectors do not read logs the way brewers write them. Going by what the food-safety guidance for kombucha asks for, and by how inspections tend to run, the order is roughly this.

1. Are the critical limits written down, and were they met? The pH crossing and the alcohol result, with times. Blanks here are the finding.
2. Were entries made at the time? Same pen, same day, values that vary the way real measurements do. A page filled in afterwards looks like one.
3. What happened when something went wrong? A log with no deviations ever is less credible than one with three deviations and three corrective actions.
4. Is the instrument trustworthy? The pH meter's calibration log: buffers used, date, and who did it. A reading from an uncalibrated meter is a guess with decimals.
5. Can they trace a bottle both ways? From a lot on a shelf back to the tea delivery, and from a suspect ingredient forward to every customer who received product made from it. Time yourself: minutes is the target.
6. Are old logs still there? Retention periods vary by country. Brazil's producer decree asks for records to be kept for 18 months; other authorities ask for six months to two years. Keep the longest period that applies to you, and know what it is.

Paper, spreadsheet or software

Paper works when the discipline is there, and it fails quietly when it is not: a page left in the cellar, a reading remembered later. Spreadsheets add arithmetic and lose history, because editing a recipe or a cell rewrites the past with no trace. Software helps most when the log is not a separate document but the batch itself: readings with time stamps, lots consumed as they are used, the deviation and the action in the same place, and the HACCP record built from entries that already exist. Whatever you use, the test is the same. Open a random lot from three months ago and try to answer the six questions above without leaving the page.

The one-page checklist

Pin this next to the tank until it is habit.

• Batch code · date · operator · recipe and version · vessel
• Ingredient lots: tea, sugar, water treatment
• Starter: which culture, its pH, share of volume
• Pitch: tea temperature · starting pH · time
• Readings with times: pH · Brix · TA · temperature, until packaging
• The pH crossing: value and time
• Deviations: what you saw · what you did · who decided
• Transfer: time · volume · destination vessels
• Additions: amount and lot number of every juice, fruit, botanical, sugar
• Packaging: alcohol result and method · lot on the label · unit count · retention sample · storage temperature · sign-off

Frequently asked questions

Related reading

• Calibrating the pH meter: the record behind every reading
• Measuring alcohol in kombucha: which method gives you a number you can defend
• Culture lineage: keeping a starter alive, and knowing which one went into the batch
• HACCP for kombucha: the two control points that matter
• Kombucha batch tracking and recall-ready records
• Editing a recipe should not change last month's batch
• Keeping kombucha under 0.5% ABV

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