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.
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.
References
Key peer-reviewed sources behind the scientific statements in this article.
- Rawlings AV, Davies A, Carlomusto M, Pillai S, Zhang K, Kosturko R, et al. Effect of lactic acid isomers on keratinocyte ceramide synthesis, stratum corneum lipid levels and stratum corneum barrier function. Arch Dermatol Res. 1996;288(7):383–390. PubMed
- Yan X, Tsuji G, Hashimoto-Hachiya A, Furue M. Galactomyces Ferment Filtrate Potentiates an Anti-Inflammaging System in Keratinocytes. J Clin Med. 2022;11(21):6338. PubMed