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ASPERGILLUS/SACCHAROMYCES RICE FERMENT LEES.

Valuable CAS - / SKIN CONDITIONING - EMOLLIENT

A nutrient-dense bio-ferment derived from the dual fermentation of rice by Aspergillus and Saccharomyces fungi, commonly known as Sake Kasu. This traditional byproduct is re-engineered through precision biotechnology to deliver high-performance hydration and barrier-strengthening metabolites to the skin.

Skin Conditioning Humectant Barrier Repair Brightening Antioxidant

Science

This ingredient functions as a multi-pathway biological modulator. It upregulates mRNA expression of Hyaluronan Synthase 1 (HAS1), Aquaporin 3, and Filaggrin to optimize cellular hydration and moisture transport. Simultaneously, it reinforces the physical skin barrier by increasing structural proteins like Claudin 1 and Involucrin while providing antioxidant defense and inhibiting melanin synthesis for a brightening effect.


Research

High confidence
Effective range 1.25–8.75%
Optimal

1.25%

Key findings

  1. 01 A 3D epidermal model study demonstrated that a 1.25% concentration significantly enhanced skin water content and HAS1 expression, noting that benefits plateau at higher concentrations.
  2. 02 Confocal Raman microspectroscopy confirmed that a related ferment filtrate achieves a deep skin penetration level of 8.75% within a four-hour window.

Transparency

Commonly dusted
Min. effective
1.25%
Red flag below
0.5%

Because it is a fermented extract, it is often included at negligible 'claim' amounts (below 1%). However, clinical data indicates that a minimum of 1.25% is required to trigger significant molecular changes in hydration markers.


The Formula

Solubility
Water
Optimal pH 4 – 6.5
0 7 14

Stability

Highly stable in water-based systems. While typically found in aqueous extracts, it can be freeze-dried into a stable powder for anhydrous formulations. Heat sensitivity occurs above 85°C.

Synergies

  • Niacinamide
  • Hyaluronic Acid
  • Ceramides
  • Panthenol

Conflicts

  • Strong oxidizers
  • Extreme heat

Safety

CIR Status
Safe as used
Pregnancy
Safe
Sensitization risk Low

The source organisms (Aspergillus oryzae and Saccharomyces cerevisiae) are FDA-GRAS rated. The CIR Expert Panel classifies yeast-derived ferments as safe for cosmetic application.


Your Skin

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Valuable

A highly effective bio-active for improving epidermal hydration and barrier integrity, provided it is formulated at the clinically relevant threshold of at least 1.25%.


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References