Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 23, 2025
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All information on this page is verified using The Personal Care Products Council's (PCPC) INCI database. Our ingredient analyses are based exclusively on PCPC's technical data to ensure accuracy and reliability.

What Is Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees?

Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees is a plant-derived ingredient created from the roots of the sweet potato, scientifically known as Ipomoea batatas. The roots are mashed and placed in a controlled environment with two microorganisms commonly used in food and beverage fermentation, Aspergillus and Saccharomyces. Over several days these microbes break down starches and other natural compounds in the root, producing a nutrient-rich liquid. The leftover solid material, called the lees, is then filtered, gently dried and milled into a fine powder that can be easily blended into cosmetic bases.

This fermented residue contains sugars, peptides, amino acids, organic acids and a small amount of natural lipids that collectively help soften and replenish the skin. The use of lees in topical products is inspired by traditional Asian sake and rice-wine brewing, where by-products of fermentation were historically applied to the face to improve texture and glow. Modern formulators adopted the sweet potato version for its mildness and sustainable supply.

You will typically spot Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees in hydrating sheet masks, soothing creams, lightweight gel moisturizers, brightening serums and leave-on treatments that aim to smooth rough patches or boost overall skin comfort.

Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees’s Cosmetic Benefits/Uses

In skincare formulas this fermented lees offers two key functions that translate into visible benefits

  • Skin conditioning – its blend of natural sugars and amino acids helps bind water to the surface of the skin improving softness and giving a healthier looking finish
  • Emollient – a touch of residual lipids forms a light protective film that fills in micro-cracks reinforcing the skin barrier and leaving a smooth supple feel

Who Can Use Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees

This ferment is generally well accepted by all skin types including dry, normal, combination, oily and sensitive thanks to its lightweight texture and soothing profile. Extremely reactive skin or anyone with known allergies to yeast or mold should approach with caution because the ingredient is produced with Aspergillus and Saccharomyces cultures.

It is plant based, uses no animal derivatives and the microorganisms employed are non-animal so the ingredient is considered suitable for vegans and vegetarians.

There is no research indicating that topical use poses a risk to women who are pregnant or breastfeeding. Absorption is minimal and the ferment contains no retinoids or salicylic acid. Still, this is not medical advice and pregnant or nursing individuals should have a doctor review any product they plan to use.

The lees do not make skin more sensitive to sunlight and can be used morning or night without increasing the chance of sunburn.

Potential Side Effects/Adverse Reactions

Responses to topical Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees vary from person to person. The issues listed below are only potential reactions and most users will not experience them when the ingredient is formulated and used correctly.

  • Mild redness or stinging skin that is already irritated may tingle when first exposed to fermented acids
  • Allergic contact dermatitis rare but possible in individuals allergic to yeast mold or sweet potato proteins
  • Small breakouts in very oil-prone skin if the formula surrounding the ingredient is overly rich
  • Fungal acne-like bumps extremely uncommon yet possible in people predisposed to pityrosporum overgrowth because of residual yeast compounds

If you notice persistent irritation rash or breakouts stop using the product and consult a healthcare professional.

Comedogenic Rating

Rating: 1 out of 5. Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees is mostly water-binding sugars, amino acids and a tiny amount of lightweight lipids that do not tend to clog pores. It neither leaves a heavy film nor traps oil, so the risk of congestion is very low.

Suitable for acne-prone or breakout-prone skin, provided the overall product is oil balanced.

The finished formula still matters: if the ferment is combined with rich butters or waxes the end product could feel heavier on oily skin even though the ferment itself is nearly non-comedogenic.

Summary

Aspergillus/Saccharomyces/Ipomoea Batatas Root Ferment Lees works as a skin conditioner and mild emollient. Its sugars and amino acids attract moisture while a whisper of lipids smooths the surface, leaving skin soft and comfortable. Although not a headline ingredient in most lines, niche K-beauty and clean beauty brands use it for its gentle, fermented appeal.

Current data shows it is safe for all skin types with only rare allergy concerns. As with any new skincare ingredient, do a quick patch test to make sure your skin agrees with it.

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