Radish Root

What Is Radish Root in Skincare?

In skincare, radish root almost always means radish root ferment filtrate: radish (Raphanus sativus) fermented with a lactic acid bacterium, the same family of microbes used to make kimchi, then filtered. Its job is to help protect water-containing products from spoiling, so it is used as a naturally derived antimicrobial in place of, or alongside, conventional preservatives. Leucidal Liquid is the best-known trade version.

EWG Skin Deep rating for Radish Root

Radish Root Ferment Quick Facts

How Radish Root Ferment Works

Lactic acid bacteria protect fermented foods by lowering pH and by making small antimicrobial peptides called bacteriocins. Radish root ferment filtrate is made to carry that protective effect into cosmetics. Unlike most ingredients in this glossary, its main job is to protect the product, not to change the look of the skin.

Independent testing shows these ferments can work, with limits. In a 2024 study in Applied Sciences, Juliano tested a radish root ferment filtrate (INCI: Lactobacillus/Radish Root Ferment Extract Filtrate) against bacteria and fungi. The minimum concentration that stopped growth ranged from 0.78% to 6.25% for bacteria and 1.56% to 5% for fungi. In an oil-in-water cream it met challenge test criterion A, with a 3-log (99.9%) drop in bacteria by day 7 and a 2-log (99%) drop in fungi by day 14. The wide range tells you that some microbes need more than others, which is why the usage rate and challenge testing matter.

There has also been debate about where the activity comes from. In 2015, a study in the Journal of Agricultural and Food Chemistry, as reported by Plastic Surgery Practice, found that the antimicrobial activity of some commercial kimchi-type ferment ingredients came from salicylic acid and didecyldimethylammonium salts that were most likely added synthetically. Ask your supplier for a current certificate of analysis and composition, and test your finished formula.

The Skin Perfection product page describes Leucidal Liquid as a mild antimicrobial that gives a degree of protection against mold, yeast and bacteria. For full broad-spectrum protection in a water-based product, pair it with a second preservative or choose a broad-spectrum blend.

How to Use Radish Root Ferment in Formulas

• Rate: use 4%, the top of the 2-4% range and the rate recommended for beginners: 36 drops (about 1.2 ml) per fl oz at the house rate of 9 drops = 1% per fl oz.
• When to add: stir into the water phase at room temperature or during the cool-down phase of an emulsion. No heating is needed.
• pH: keep the finished product within about pH 3-8.
• Broad spectrum: for water-rich serums and lotions, use Leucidal Complete, which pairs radish root ferment with a coconut ferment, or add a second preservative such as gluconolactone with sodium benzoate.
• Anhydrous products: pure oil blends and balms contain no water and do not need a water-phase preservative; use an antioxidant such as vitamin E instead.
• Testing and storage: challenge test your formula when you can, store finished products cool and away from light, and use clean tools and airless packaging.

For a full comparison of natural options, see natural preservatives for DIY skincare, and browse the preservatives collection.

Who Radish Root Ferment Suits

It suits formulators and DIY makers who want a naturally derived, Ecocert-approved antimicrobial for lotions, creams, serums, toners, gels and hair care. Finished products made with it suit all skin types. Avoid it if you have a known radish allergy.

Sensitive skin: radish root ferment is generally well tolerated, but patch test any new product on the inner arm for 24 hours. If you are formulating for sensitive skin, start at the lowest rate of the range, 2% (18 drops per fl oz), and only in a formula that also has a second preservative or has passed a challenge test at that level, so the product stays protected.

Frequently Asked Questions

What is radish root ferment filtrate used for in skincare?

It is used to help protect water-containing products from spoiling. It is made by fermenting radish with lactic acid bacteria and works as a naturally derived antimicrobial.

Is radish root ferment a natural preservative?

It is a naturally derived antimicrobial, approved by Ecocert for certified organic cosmetics. On its own it gives a mild degree of protection, so it is often paired with a second preservative for broad-spectrum coverage.

Is radish root ferment broad spectrum?

Not reliably on its own. Testing shows different microbes need very different amounts, so for water-based products use a broad-spectrum blend such as Leucidal Complete or add a second preservative.

What percentage of radish root ferment should I use?

Use 2-4%, and 4% if you are new to formulating. That is 36 drops, or about 1.2 ml, per fl oz.

Is radish root ferment safe for sensitive skin?

It is generally well tolerated and mild. Patch test any new product for 24 hours, and avoid it if you are allergic to radish.

Does radish root ferment smell?

It has a faint fermented, pickle-like scent in the bottle. At 2-4% in a finished product the scent is usually not noticeable.

What pH does radish root ferment work at?

It works in products from about pH 3 to 8, which covers most skincare.

Shop Radish Root Ferment at Skin Perfection

Choose Leucidal Liquid Radish Root for a mild antimicrobial, or Leucidal Complete for broad-spectrum protection. This collection also includes the Hyaluronic Acid Plumping Serum and the Expression Line Deep Wrinkle Serum.

Sources

• Juliano CCA. A radish root ferment filtrate for cosmetic preservation: a study of efficacy of Kopraphinol. Applied Sciences. 2024;14. University of Sassari repository
• Plastic Surgery Practice news report, April 17, 2015, on a 2015 Journal of Agricultural and Food Chemistry study of kimchi-fermentation preservative products. kimchi-based preservative research (Plastic Surgery Practice)
• Skin Perfection, Leucidal Liquid Radish Root product page: 2-4% usage, 4% for beginning formulators, Ecocert approval.
• Skin Perfection, Leucidal preservative Q&A (supplier and product notes): pH 3-8, room-temperature and cool-down addition.

These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

About the Author
Written by Kari Thomas, cosmetic formulator and founder of Skin Perfection.