Glucomannan

What it is

Glucomannan is a polysaccharide from the tubers of konjac, a plant of the Amorphophallus genus: a chain of mannose carrying glucose side units, acetylated every nine to nineteen sugars. The Cosmetic Ingredient Review groups it with the plant-derived polysaccharide gums, whose function in cosmetics is to increase viscosity. Food-science work pairs it with kappa-carrageenan, where the two gel together more strongly than either does alone. That is exactly the company it keeps here: every mask in this catalogue that lists glucomannan also lists a carrageenan-family gum and potassium chloride.

How it shows up on a label

What it does well

• A thickener the panel found safe as used

  The Cosmetic Ingredient Review reviewed 106 plant-derived polysaccharide gums, glucomannan among them, and concluded that most of them are safe in the present practices of use and concentration in cosmetics; only hydrolysed carrageenan was left undetermined for want of data. The panel's one reservation concerned the alkylating and other agents used to modify gums, and it asked industry to use good manufacturing practice to limit those impurities.

  Strong evidence

Worth knowing

• Everything known about it is texture, not skin

  The evidence base is food and materials science: gelation, viscosity, film-forming and its synergy with carrageenan. None of it measures an effect on skin, and the safety conclusion covers its use as a thickener rather than any benefit. A konjac mask is a firmer mask, not a treated face.

Where the EU stands

Sources (3)

Every link goes to the original: a journal, a PubMed record or an EU document.

1. [1]
   Safety Assessment of Plant-Derived Polysaccharide Gums as Used in Cosmetics

   Cosmetic Ingredient Review, Final Report · 2015

   The Expert Panel reviewed 106 ingredients that function as viscosity-increasing agents and concluded most of the polysaccharide gums are safe in the present practices of use and concentration in cosmetics, with the data insufficient for hydrolysed carrageenan. It defines glucomannan as the polymer of mannose containing side chains of glucose, derived from the tubers of konjac. The panel asked industry to limit impurities from the agents used to modify gums. Checked 6 September 2026.

2. [2]
   Extraction, structure, activity and application of konjac glucomannan

   Ultrasonics Sonochemistry · 2025 · doi:10.1016/j.ultsonch.2025.107315

   A review of konjac glucomannan, the main polysaccharide of the konjac plant, describing its gelling behaviour, biocompatibility and high viscosity, and its use in films and gels. Its applications are food, packaging and pharmaceutical; the review reports no skin measurement. Checked 6 September 2026.

3. [3]
   Gelation enhancement of konjac glucomannan/kappa-carrageenan composite gels induced by different potassium salts

   Food Chemistry · 2026 · doi:10.1016/j.foodchem.2026.149931

   Konjac glucomannan and kappa-carrageenan gel synergistically, and the study tested five potassium salts, potassium chloride among them, on the resulting network. Food processing rather than cosmetics, but it is the same combination of ingredients that the jelly masks here list. Checked 6 September 2026.