That changed in the twentieth century.

The industrial revolution in vinegar

In the 1930s the German engineer Heinrich Frings developed submerged fermentation, a way of making vinegar with industrial aeration. The idea was straightforward. If acetic acid bacteria need oxygen to convert alcohol into acetic acid, pump air through the liquid and make the whole thing go as fast as possible.

The Frings acetator transformed the industry. A process that had taken weeks or months could be finished in a day or two. Yield improved sharply, consistency became achievable at scale, and the economics were hard to argue with. Today the overwhelming majority of commercial vinegar, including nearly all mass market apple cider vinegar, is made this way.

What surface fermentation looks like

Before the acetator, vinegar was made on the surface. The process runs like this:

1. Hard cider goes into open or partly open vessels.
2. Acetic acid bacteria colonise the surface of the liquid from the air.
3. They form a film, the mother, that floats on top.
4. Over weeks, the bacteria slowly convert the alcohol to acetic acid.
5. The process finishes when the alcohol is exhausted.

This is still how traditional balsamic is made in Modena and Reggio Emilia, how Orleans method wine vinegar is made, and how small cider vinegar producers work. It is slow, it takes up a great deal of space, and it needs far more time and labour than the industrial route.

Why the method matters

Temperature. Industrial aeration generates real heat, and many operations run warm on purpose to keep bacterial activity high. Surface fermentation happens at or near ambient temperature, which preserves volatile aromatic compounds that heat drives off.

Time. Speed and character tend to pull against each other in fermented food, and vinegar is no exception. A slow conversion leaves room for the secondary reactions that build complexity. Fast aeration produces acetic acid very efficiently and not much else.

Aeration. Forcing air through the liquid exposes the entire batch to oxygen at once, with a good deal of turbulence. Surface fermentation exposes it gradually, through the film, which is gentler on the tannin and the aromatics that came in with the fruit.

The mother. In surface fermentation the mother forms by itself, because it is the bacteria building their own raft. In industrial production the bacteria stay suspended and no raft forms. A mother can be added back afterwards, and some producers do, but that is not the same as one that was never removed.

What this means for POME

We use the slow Orleans method. Once the alcoholic fermentation is finished, the cider goes into vessels and acetification happens over weeks at ambient temperature. Which means:

• We make far less vinegar per unit of time than an industrial operation of the same footprint.
• Our flavour varies more between batches, which we manage by tasting and blending rather than by standardising.
• The mother forms naturally and stays in the bottle.
• The tannin and aromatics from the fruit come through more intact.

We take those trade offs deliberately. The constraint is also the point: you cannot rush this without changing what comes out.

One misconception worth clearing up

Industrial acetification is sometimes described as aerating the vinegar, which sounds like the pleasant thing you do to a glass of wine. It is not that. It is force oxygenating a liquid at speed, often warm, to get as much bacterial throughput as possible. The endpoint is the same acetic acid. The path is not, and the path is where everything else is either kept or lost.

Is traditional always better?

No, and we would rather say so.

Industrial vinegar is consistent, safe and efficient. For pickling, for cleaning, for cooking where the vinegar is a background acid, it does the job perfectly well and costs a fraction of what ours does.

What the slow method preserves is the complexity that comes from a gentler conversion. If vinegar is a commodity ingredient to you, the production method is not worth paying for. If it is an ingredient you taste, in the way you would taste the difference between a good olive oil and a cooking oil, then it is. POME is made for the second case.

POME is made by the slow Orleans method, not industrial aeration, and bottled undiluted with the mother intact.

It sounds unappetising. It is completely harmless, entirely natural, and it tells you something useful about how the vinegar was made.

What it actually is

The mother is a colony of acetic acid bacteria, mostly species of the genus Acetobacter, together with the cellulose they produce.

Those bacteria are what turn alcohol into acetic acid, the compound that makes vinegar sour. During surface fermentation they colonise the top of the liquid and build a floating raft, a biofilm held together by bacterial cellulose. That raft is the mother.

As fermentation continues it can grow substantial, thick and leathery and cloudy. In traditional vinegar houses a piece of the mother is often carried into the next batch as a starter, passing the culture forward from one batch to the next across years.

Why it looks the way it does

It is largely bacterial cellulose, a structure the bacteria build for themselves. That is the same kind of material, though not the same organism, that forms the gel in kombucha. It is dense enough to float, slightly translucent, and it ranges from thin and stringy to thick and leathery depending on how long fermentation ran and under what conditions.

In a bottle it usually settles to the bottom over time, so you may find it as sediment, or as a floating mass, depending on how the bottle has been handled.

Why most commercial vinegar does not have it

Most commercial apple cider vinegar is filtered before bottling. Filtering takes out the mother and any suspended solids, which gives a clearer and more uniform product that looks the same on the shelf for longer. That is a reasonable commercial decision and it is why the vinegar most people grew up with is bright and clear.

Industrial submerged fermentation also produces less cohesive mother in the first place. Because the bacteria are suspended throughout the liquid rather than forming a raft on the surface, what they build is more dispersed and largely disappears in filtration.

Some producers add mother back into filtered vinegar afterwards. It can look similar in the bottle. The production history behind it is not the same.

Why we leave it in

POME is made by surface fermentation. The mother forms during acetification and stays in the bottle, unfiltered. Two reasons.

First, filtering costs something. Every time you push vinegar through a filter you lose volatile compounds along with the solids.

Second, the mother is evidence. A bottle with visible mother tells you the vinegar was fermented the old way, that the bacteria built their own structure rather than being driven through the liquid under pressure. It is a visible sign of an unprocessed product, which is difficult to fake and easy to check.

How to handle it

• Shake before use. It settles. A gentle shake puts it back through the bottle.
• It is edible. You can drink it without concern. It has almost no flavour of its own and tastes mainly of vinegar.
• It may grow. Leave an open bottle for a while and you may see new mother forming at the surface. That is the culture carrying on. It is not spoilage.
• If you would rather not have it in the glass, pour through a small strainer. The vinegar underneath is unchanged.

What the mother is not

It is not mould, not contamination, and not a sign that anything has gone wrong. Spoilage in vinegar is rare, because most organisms cannot survive at that acidity in the first place.

If your bottle has visible mother, that is exactly what it should look like.

POME is raw, unfiltered and bottled with the mother intact. It is a living product, made by living organisms.

Here is a plain explanation of what tannins actually are.

The basics

Tannins are naturally occurring plant compounds. They belong to a much larger family called polyphenols, which covers thousands of compounds found across the plant world, but tannins are the branch of that family you can actually taste.

You already meet them every day. They are what makes strong black tea grip the sides of your mouth, what gives red wine its structure and its ability to age, and what makes an unripe persimmon or a young Cabernet feel drying rather than merely bitter. In plants they serve as protection, against grazing animals, insects and ultraviolet light, which is why they concentrate in the parts most exposed to the outside world: skins, seeds and outer layers.

What they taste like

Tannin is not a flavour so much as a sensation. It is astringency: the drying, puckering feeling that arrives after the taste rather than during it. It happens because tannins bind to the proteins in your saliva, which is why the effect builds across several sips and why it is felt as texture.

Bitterness and astringency often travel together, which is why they get confused. Bitterness is a taste. Astringency is a physical grip. A good cider apple has both, in proportion, and that proportion is what growers were selecting for when they kept these varieties going.

At high concentration in fresh fruit, tannin is unpleasant. Through fermentation it becomes structure. It is the difference between a liquid that is merely sour and one that has shape.

Why cider apples carry more

How much tannin a fruit carries depends mostly on variety, and then on how it was grown. Varieties with thicker skins and more developed seeds tend to carry more.

Dessert apples were bred in the opposite direction. Over decades of selection, growers pushed toward sweetness, shelf life and mildness, and away from astringency, because astringency puts most eaters off. Cider varieties were selected for exactly what dessert breeding removed: tannin, acidity, and a complex phenolic profile. Those are the qualities that make good cider, and they are the qualities that make good vinegar.

This is the whole argument for making vinegar from cider fruit, and it is why the classification matters. A bittersweet apple is defined by being high in tannin and low in acid. A bittersharp is high in both. Neither is a description of flavour for its own sake. They are working categories that tell a cider maker what the fruit will do.

In vinegar specifically

When apples are pressed, tannin from the skins and seeds is extracted into the juice. During fermentation most of it stays in the liquid rather than being consumed, so the finished vinegar keeps a good share of what the pressed juice started with.

This is why vinegar made from cider apples is darker than the supermarket kind. Colour is a rough visual proxy for tannin, the same relationship that makes red wine darker than white. It is rough, not exact, but it is not a coincidence either.

We had ours measured rather than guessing. The laboratory figures are on our Tannins and Testing page, along with a straight account of what a comparison between two samples does and does not establish.

What we claim, and what we do not

We are a vinegar company, not a supplement brand. We will not tell you that tannins do anything for your health, and we will not tell you that POME treats, prevents or cures anything. If you see a vinegar sold on that basis, be sceptical of it.

What we will say is narrower and we can stand behind it. Tannin is what gives this vinegar its structure and its grip, it comes from the fruit rather than from anything we add, and cider apples carry more of it than dessert apples do. That is a statement about flavour and about source material. It is not a medical claim, and we are not going to dress it up as one.

POME Heritage Vinegars are made from Pacific Northwest heritage and cider apples. Nothing is fortified and nothing is added. Whatever structure is in the bottle came out of the fruit.