Skincare University

Formulating fermented cosmetics — from strain selection to quality control

LEVEL 5
The World of Fermented Ingredients

※ The information in this section is based on Japanese cosmetics regulations (Pharmaceutical and Medical Device Act / 薬機法). Ingredient classifications, permitted concentrations, and labeling requirements may differ in your country or region.
LEVEL 5 The World of Fermented Ingredients

The quality of fermented cosmetics is determined by precise control at every stage, from strain selection through medium design, culture condition optimization, scale-up, and quality control.

1. Strain selection — reverse-engineering from the goal

Representative strains used in cosmetics include Lactobacillus (lactic acid production, pH adjustment, barrier strengthening), Bacillus (protease production, gentle exfoliation), and Saccharomyces (vitamin and amino acid-rich culture filtrate). Strains are selected based on the desired effect, with metabolite profiles evaluated at the strain level.

2. Medium design — "what you feed them" determines the product

The composition of carbon sources (glucose, sucrose, rice-derived polysaccharides) and nitrogen sources (soy peptone, yeast extract) determines the types and quantities of metabolites. Even with the same strain, changing the medium dramatically alters the amino acid composition and vitamin content.

3. Optimizing culture conditions

Four parameters control the direction of fermentation: temperature (25-37 degrees C), pH (4.0-7.0), oxygen concentration (aerobic/anaerobic/microaerobic), and culture duration (24-168 hours). Lactic acid bacteria maximize lactic acid production under anaerobic conditions, while yeast promotes B vitamin production under microaerobic conditions.

4. Scale-up challenges

Scaling from lab (several liters) to manufacturing (hundreds to thousands of liters) faces key challenges: oxygen transfer rate (kLa), shear stress from agitation, and temperature uniformity. These variations directly affect metabolite composition, requiring re-optimization of process parameters during scale-up.

5. Quality control — ensuring lot-to-lot consistency

Quality control of fermented products requires metabolite profiling (quantitative analysis via HPLC, GC-MS) and lot-to-lot consistency evaluation. Organic acid composition, amino acid content, vitamin content, pH, and total viable count (confirmed zero post-sterilization) are measured for each lot.

Fermented Cosmetics QC Flowchart 1. Strain Selection & Identification 16S rRNA analysis / Metabolite screening 2. Medium Design & Condition Optimization C/N source selection / Temp, pH, O2, time 3. Fermentation & Culture Bioreactor control / Monitoring 4. Sterilization & Filtration Heat sterilization or membrane filtration 5. Quality Control & Release HPLC/GC-MS analysis / Lot consistency NG: Re-optimize Over-heat: Activity loss

6. Balancing sterilization/filtration with activity preservation

Post-fermentation sterilization is essential for product safety, but excessive heat treatment degrades vitamins and amino acids. Membrane filtration (0.22 micrometer filter) offers cold sterilization that removes microorganisms while preserving heat-sensitive active compounds.

KAIAN's fermentation complex (3-strain blend) design philosophy

KAIAN employs a Lactobacillus (barrier strengthening) x Saccharomyces (nutrition supply) x Bacillus (gentle exfoliation) 3-strain fermentation complex.

Pursuing multifaceted effects unattainable with a single strain, each fermentation product is cultured individually under optimal conditions, then blended at the formulation stage. The design philosophy: "Protect (barrier) x Balance (turnover) x Support (nutrition)" — three functions achieved through the power of fermentation.

KAIAN develops skincare products formulated with a 3-strain fermentation complex.
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