Fermentation in Cosmetics Manufacturing — From SK-II Pitera to Fermented Rice Water

Fermentation has accompanied humankind for millennia — beer, yoghurt, kimchi. In cosmetology, fermentation is enjoying a renaissance driven by the success of the SK-II brand and the explosion of Korean K-beauty. But behind the buzzword lies a real biochemical technology that changes the properties of cosmetic ingredients at the molecular level.

What is fermentation in the context of cosmetics?

In cosmetic manufacturing, fermentation means the controlled biotransformation of raw materials by microorganisms (bacteria, yeasts, fungi). These microorganisms secrete enzymes (proteases, lipases, amylases) that break down complex macromolecules into smaller, more bioavailable forms.

The key mechanism: large molecules that normally cannot penetrate the stratum corneum are broken down into fragments of lower molecular weight that can either penetrate the skin or interact more effectively with its surface. At the same time, the microorganisms produce their own metabolites — organic acids, vitamins, peptides — which enrich the finished product.

Key microorganisms in cosmetology

Lactobacillus — lactic acid bacteria

Bacteria of the genus Lactobacillus are the most commonly used in cosmetic fermentation. Their principal action is the production of lactic acid, which lowers the pH of the fermented medium and at the same time acts as a natural AHA (alpha-hydroxy acid) in the finished product.

On the INCI list, Lactobacillus ferments appear as:

• Lactobacillus Ferment — the unfiltered fermentation product.
• Lactobacillus Ferment Lysate — a lysate (ruptured bacterial cells) containing intracellular components.
• Lactobacillus/Soybean Ferment Extract — a soy fermentation extract rich in isoflavonoids of lower molecular weight.

A study published in the Journal of Microbiology and Biotechnology (2015) showed that lactic fermentation of soybean extract increased the content of free isoflavonoids (genistein, daidzein) by 300–400% compared with non-fermented extract. Free isoflavonoids have higher bioavailability and stronger antioxidant activity.

Saccharomyces — yeasts

Saccharomyces cerevisiae (baker's/brewer's yeast) is the second pillar of cosmetic fermentation. Yeasts are rich in B-group vitamins, amino acids, minerals and β-glucans. Yeast fermentation also produces ethanol (which is then removed or remains in trace amounts) as well as unique metabolites.

INCI: Saccharomyces Ferment Filtrate, Saccharomyces/Xylinum/Black Tea Ferment (kombucha), Saccharomyces Lysate Extract.

Galactomyces Ferment Filtrate — the SK-II Pitera phenomenon

The most iconic example of fermentation in cosmetics is SK-II Facial Treatment Essence, whose main ingredient (over 90% of the formula) is Galactomyces Ferment Filtrate, known as Pitera™.

Galactomyces is a genus of fungi from the order Saccharomycetales. The discovery of Pitera is rooted in the observation that workers at Japanese sake breweries had youthful, smooth skin on their hands — despite their advanced age. Scientists at P&G isolated a Galactomyces strain and developed a controlled fermentation process.

The composition of Galactomyces Ferment Filtrate includes:

• Vitamins — niacinamide (B3), pantothenic acid (B5), folic acid.
• Amino acids — serine, glycine, alanine, proline.
• Organic acids — lactic acid, citric acid, pyruvic acid.
• Minerals — zinc, magnesium, manganese.

A clinical study by Hakozaki et al. (2005, British Journal of Dermatology) found that Galactomyces Ferment Filtrate applied daily for 12 weeks reduced the visibility of pigmentation by 40% and improved skin texture. The effect was attributed mainly to the synergy of niacinamide with other fermentation metabolites.

Fermented rice water and inositol

The traditional use of rice water in skin and hair care dates back to ancient Japan (the Heian period) and China. Modern science explains why it works: fermentation of rice water by natural microorganisms produces inositol (myo-inositol) — a cyclic sugar alcohol that plays an important role in cellular signalling.

Inositol in the context of the skin:

• Strengthens the skin barrier — it supports the synthesis of ceramides, the key intercellular lipids.
• Regulates keratinocyte differentiation — as a precursor of phosphatidylinositols, which participate in the PKC signalling cascade.
• Antioxidant action — it chelates iron ions, reducing oxidative stress.

Fermenting rice increases the concentration of inositol three- to fivefold compared with simply soaking rice in water (Lee et al., 2018). This is why properly fermented rice water is significantly more effective than ordinary water left over from rinsing rice.

The influence of K-beauty on cosmetic fermentation

The Korean cosmetics industry (K-beauty) has played a key role in popularising ferments. Brands such as COSRX, Missha, Benton and Innisfree have introduced a wide range of products with fermented ingredients, building on several pillars:

• Tradition — Korean cuisine (kimchi, gochujang, makgeolli) is based on fermentation, which makes consumer acceptance easier.
• Innovation — Korean companies invest in fermentation biotechnology, patenting specific strains and processes.
• Narrative marketing — the story of SK-II's discovery (the sake brewery workers) became the archetype of the "natural wisdom confirmed by science" narrative.

It is worth distinguishing, however, between well-researched ferments (Galactomyces, fermented soy extracts) and ingredients where fermentation is mostly a marketing gimmick. "Fermented lavender extract" or "fermented shea butter" also lack solid scientific evidence of any advantage over their non-fermented forms. You will find a detailed ingredient analysis in the PurScore database.

What to look out for when choosing?

When buying a cosmetic with fermented ingredients, check:

• The position on the INCI list — if the ferment is at the end of the list, its concentration is negligible.
• The type of ferment — Ferment Filtrate (filtered liquid, cell-free) vs Ferment Lysate (cell lysate, containing intracellular components) vs Ferment Extract (a fermentation extract).
• The microorganism strain — Galactomyces and Saccharomyces have the best scientific documentation.
• The fermented raw material — rice, soy and black tea have proven benefits from fermentation. Exotic raw materials — not necessarily.

Check whether your favourite product with fermented ingredients really contains them in an effective concentration — type the name into the PurScore search and discover a detailed analysis of its composition.