The Ingredient Files

Fermented actives, and why we have not used one.

Updated September 2026 Six minute read In none of our formulas, so far

Fermentation is one of the more genuinely interesting things happening in cosmetic chemistry, and there is not a single fermented active in the PureNeem range. Both of those statements are true. This is the explanation, including what we would need to see before that changes.

Fermented actives in the current PureNeem range, across all seven formulas

1980s

The decade ferment filtrates moved from Japanese laboratories into mainstream skincare

Broad categories on a label, ferment filtrates, ferment lysates and postbiotics

01 What fermentation actually is

Microorganisms, doing the first pass.

Fermentation is a metabolic process. Bacteria or yeast are introduced to a substrate, usually a plant material or a sugar, and as they feed they break complex molecules into simpler ones and leave behind their own metabolites. Kimchi, kombucha, sourdough and sake all work this way (Marco et al., 2017).

In cosmetics the appeal is straightforward. Smaller molecules are easier to formulate with. The process can also produce compounds that were not in the starting material, including amino acids, organic acids and short peptides, so a ferment filtrate is chemically not the same thing as the plant it came from.

That last point is the one people miss. Fermented green tea is not green tea with a marketing adjective. It is a different ingredient, with a different profile, and it should be assessed on its own evidence rather than inheriting the evidence of green tea.

02 What the research examined

Real findings, on a narrow base.

There is genuine work here. Published research has examined a Bifidobacterium fermented soy milk extract and hydration in human skin cells (Miyazaki et al., 2003). Later work looked at lysates of Lactobacillus rhamnosus and barrier function in a reconstructed human epidermis model (Jung et al., 2019). Oral work exists too, in animal models (Kim et al., 2014).

Read those carefully and a pattern appears. Most of the evidence sits in cell culture, reconstructed tissue or animals. The human data on finished cosmetic products is thinner than the category's confidence suggests, and a great deal of the marketing rests on a small number of proprietary filtrates with commercial reasons not to publish.

That is not a dismissal. It is a description of where a field currently is. Fermented actives look promising, the mechanism is plausible, and the human evidence is still arriving.

03 Why we have held off

Three practical reasons, none of them ideological.

The first is standardisation. A ferment filtrate is defined by its process as much as its input, and batch to batch consistency depends entirely on the supplier's control of that process. We are a small range and every formula has to be reproducible.

The second is that fermented actives are usually sold on a broad, vague benefit rather than a specific one. Our formulas are built by asking what job an ingredient does and whether something already in the formula does it better. So far, for the jobs we have, something already did.

The third is scent and stability. Ferments carry their own character and can shift a formula's smell and colour over its shelf life. That is solvable, but it is a cost, and it has to buy something real.

We would rather tell you what is not in the bottle than imply something that is not.

04 What you are reading on other labels

The four names worth recognising.

If you are comparing products, these are the ingredients the category is built on. The right hand column is the honest answer for our range.

Ingredient	Where it comes from	In PureNeem
Galactomyces ferment filtrate	A yeast fermentation associated with sake brewing	No
Bifida ferment lysate	Bifidobacterium cultures, broken down and filtered	No
Lactobacillus ferment	Lactic acid bacteria on a plant or dairy substrate	No
Fermented rice or green tea	Familiar botanicals put through a culture step	No

Four rows, four honest answers. We could put a token ferment into one formula tomorrow and add a line to the front of the box, and the temptation to do exactly that is precisely why we are writing this page instead. An ingredient earns its place by doing a job, or it stays out.

05 In our formulas

What we use instead.

The appeal of fermentation is mostly about bioavailability, comfort and a light, absorbent feel. Those are real goals and there is more than one route to them. Here are the two formulas where we took a different one.

Mucina Silk Hydration Cream With snail secretion filtrate, snow mushroom, centella and peptides

A filtrate, but not a fermented one. Snail secretion filtrate brings humectants, glycoproteins and film formers together in one raw material, and centella covers the comfort side. The result is the silky, clean finish that fermented hydrators are usually bought for.

Luminara C Radiance Serum With ethyl ascorbic acid, alpha arbutin, niacinamide and licorice root

Where a ferment filtrate would be doing vague work on the look of tone, we used four ingredients that each have a specific, documented one. Ethyl ascorbic acid solves the stability problem that made vitamin C difficult in the first place, without needing a culture step.

A practical note on filtrates

If the appeal of fermented skincare is that light, absorbent, slightly cushioned feel, the closest thing in our range comes from a different filtrate entirely. It is the reason our hydrating cream wears the way it does.

Our guide to the best snail mucin skincare in Australia covers what to look for on a label, which percentages matter, and how to tell a real formula from a name on a box.

Common questions

Fermented skincare, answered plainly.

What is fermented skincare?

Skincare built around ingredients that have been through a controlled culture step, where bacteria or yeast break down a substrate and leave their own metabolites behind. The result is a different ingredient from the material it started as.

Are fermented ingredients better than regular ones?

Sometimes, for specific jobs, on a narrower evidence base than the category suggests. Fermentation is a process, not a guarantee of quality, and a poorly built formula with a ferment in it is still a poorly built formula.

Does PureNeem use fermented ingredients?

Not currently. None of our seven formulas contains a fermented active, and we would rather say that plainly than lean on the word. If we add one it will be because it did a job nothing else in the formula could.

Is fermented skincare good for sensitive skin?

Fermentation can make some reactive plant materials gentler, which is one of the more credible arguments for it. That said, ferments carry their own character, so sensitivity is worth testing rather than assuming either way.

Is kombucha in skincare the same as drinking it?

No. What goes into a cosmetic is a standardised filtrate produced under controlled conditions, not the drink. The overlap is the process, and very little else.