What a state food safety bureau asks of kombucha

This is a four-page hazard document written by the Bureau of Food Safety and Laboratory Services for people who sell kombucha in Pennsylvania. It is not written for home brewers, and a home brewer is not bound by it.

It is still the clearest list in print of what can go wrong, because a regulator has to name every hazard rather than the interesting ones.

The pH window has a floor, not just a ceiling

Most home guidance gives an upper limit and stops. This document gives both.

The target is pH 4.2 or below. Kombucha starts near pH 5, and the drop below 4.2 is what makes it a food that does not need refrigeration to stay safe.

The floor is 2.5. The document sets the operational target there and says the pH keeps falling as fermentation continues. Past that point the drink is not a stronger version of itself. The guidelines describe over-fermented kombucha as equivalent to “drinking undiluted vinegar”, and name acidosis as the hazard, with a specific warning for people who already have a health condition.

It also gives a decision rule worth borrowing. If the pH has not reached 4.2 within seven days, the batch is discarded and a new one started from a fresh commercial culture. Not left longer. Discarded.

Alcohol: the document says what most pages will not

Unpackaged kombucha is typically under 1% alcohol by volume. A long ferment can take it to 3%.

Bottled, unpasteurized kombucha will most likely exceed 0.5%, and the document explains the mechanism: yeast keep fermenting in the sealed bottle, and the carbon dioxide that builds up stops the alcohol being converted to acetic acid. The alcohol accumulates because the bottle is closed.

This is why our own safety wording never claims a home brew stays under 0.5%. The state that regulates the drink does not claim it either.

A sealed bottle is treated as a physical hazard

The guidelines classify bottling an actively fermenting kombucha as a physical hazard requiring a control, in the same list as biological and chemical hazards.

The reason is pressure. Carbon dioxide builds inside the container. When it exceeds what the container can hold, the bottle leaks or breaks. The document describes bottles and caps becoming projectiles.

The three controls it allows are pasteurization, chemical preservatives, and refrigeration at 41°F or below, and it rates refrigeration alone as the least reliable of the three.

For a home brewer the practical translation is narrow but firm. Use bottles rated for pressure. Refrigerate once the carbonation is where it should be. Do not leave a sealed bottle at room temperature because the drink might improve.

Where it differs from our guidance

The document describes incubation at 60–70°F for 7 to 10 days, which is cooler than the 75–80°F the brewing sources recommend and that our own suggestions assume. It is written for a commercial process with pH monitoring at every step, where a slower, cooler ferment is easier to control and measure.

We follow the 75–80°F figure, which comes from Cultures for Health and Kombucha Kamp and matches the Colorado State fact sheet. The difference is process control, not disagreement about the drink.

Its ten-day caution is worth keeping in mind regardless. Beyond ten days, acidity climbs toward the range the document warns about.

Worth knowing about the source

This is a regulator writing for licensed producers. It requires a HACCP plan, a calibrated digital pH meter, specific gravity logs and written records for every batch. None of that applies to a jar on a kitchen shelf.

Read it for the hazards and the thresholds, which are the same chemistry at any scale. Do not read it as a home brewing method. And if there is any thought of selling a bottle, read it in full first, because the licensing and testing requirements are not optional.