Buyer questions · Purchase decisions
For a 'preservative-free' cleansing product, what stable alternative preservation systems do you recommend, and how will you prove they pass challenge tests?
Aqueous cleansing products cannot be truly preservative-free. Alternative systems rely on lowering water activity using polyols or organic acids. Efficacy must be proven via full ISO 11930 challenge tests, not just release tests. Specific systems depend on formulation ratios and target market regulations.
1Alternative preservation principles
Low-preservation routes use high ratios of polyols to lower water activity or utilize synergistic antimicrobials like hexanediol. These maintain cleaning efficacy while inhibiting microbial growth. Concentrations must adjust to pH and nutrient load.
2Challenge testing execution
Validation requires full ISO 11930 challenge tests covering bacteria, yeast, and mold strains. Tests simulate real-world usage contamination, not just release limits. Reports must specify methods and criteria as core evidence for shelf stability.
3Compliance and risk management
Avoid absolute claims to prevent fraud allegations. For EU or US markets, verify local preservative lists. If high-nutrient botanicals are included, increase preservation strength. Prioritize investigating microbial metabolism if pH drifts or viscosity drops.
Follow-up questions
- Q:Can shelf life be proven without release tests?
- A:No. Release tests prove production cleanliness; challenge tests prove resistance during use.
- Q:Does polyol system count as no-additives?
- A:Depends on definitions. If classified as preservatives by regulations, they must be listed; avoid absolute no-additives claims.
Updated 2026-09-18
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