E425II - Konjac glucomannan

At a glance

• What it is: A high‑molecular‑weight soluble fiber from the konjac root (Amorphophallus konjac).
• What it does: Works as a thickener, stabiliser, emulsifier, humectant, and carrier.
• E-number: E425ii. It is different from konjac gum (E425i), although both come from the same plant.
• Texture notes: Forms firm, springy gels when set with alkali or calcium; excellent at holding water.
• Typical uses: Konjac noodles (shirataki/konnyaku), jelly-type desserts, sauces, meat and plant-based products, and dietary-fiber supplements.
• Label names: “Konjac,” “konjac glucomannan,” “konjac flour,” or “E425ii.”

Why is Konjac glucomannan added to food?

Manufacturers add konjac glucomannan to control thickness, suspend particles, bind water, and create heat‑stable gels. In the presence of alkali or calcium salts, it sets into elastic, sliceable gels used in konnyaku and similar products.¹ Its strong water‑holding capacity helps keep foods moist and improves freeze–thaw stability.¹

What foods contain Konjac glucomannan?

You’ll most often find it in:

• Konjac noodles (shirataki/konnyaku blocks and noodles)
• Jelly-type desserts and fruit gels (mini-cup jelly products are restricted or flagged in several regions; see safety section)
• Sauces, dressings, and dips for body and cling
• Processed meat and seafood products for binding and yield
• Plant-based meats for bite and juiciness
• Bakery and gluten‑free items to improve structure
• Fiber supplements, drink mixes, and capsules

Related texturizers that may appear alongside it include xanthan gum, guar gum, gellan gum, carrageenan, locust bean gum, pectins, and sodium alginate.

What can replace Konjac glucomannan?

No single additive matches konjac in every recipe, but these are common swaps:

• For thickening sauces: xanthan gum or guar gum
• For firm, bouncy gels: gellan gum or carrageenan
• For fruit systems: pectins
• For cold-set, sliceable gels: sodium alginate with calcium Expect to adjust levels, pH, and processing, since each hydrocolloid behaves differently.

How is Konjac glucomannan made?

Konjac glucomannan is obtained from dried, milled konjac tubers. The soluble polysaccharide is extracted with water, purified (often by alcohol precipitation), dried, and milled into a fine powder. Its gel strength and behavior depend on molecular weight and acetyl groups present in the polymer. When mixed with alkali or calcium, such as a small amount of calcium hydroxide, it forms elastic, heat‑stable gels typical of konnyaku products.¹

Is Konjac glucomannan safe to eat?

Regulators in the EU have re‑evaluated konjac glucomannan (E425ii) and found no safety concern at reported uses and use levels as a food additive.¹ However, jelly “mini‑cup” candies containing konjac have been restricted in the EU due to choking incidents, because the gels can be swallowed whole and do not readily dissolve.² In the United States, the FDA flags mini‑cup gel candies that contain konjac as a choking hazard and subjects them to import detention.³

Like other fibers, high intakes may cause gas or bloating in sensitive people. Tablets or capsules should be taken with plenty of water to avoid choking.

Does Konjac glucomannan have any benefits?

Konjac glucomannan is a non‑digestible carbohydrate that the FDA recognizes as meeting the dietary fiber definition for labeling, based on evidence of beneficial effects on health.⁴ In the EU, specific authorized health claims state that glucomannan contributes to the maintenance of normal blood cholesterol and to weight loss when used under defined conditions as part of an energy‑restricted diet.⁵

Who should avoid Konjac glucomannan?

• Young children and anyone with swallowing difficulties should avoid konjac mini‑cup jelly products due to choking risk.²³
• People who experience digestive discomfort with fiber should start with small amounts and increase slowly.
• If you use fiber supplements, take them with plenty of water.

Myths & facts

• Myth: Konjac is the same as gelatin. Fact: Konjac is a plant fiber; it forms gels without animal protein.
• Myth: All konjac jellies are banned. Fact: The concern focuses on mini‑cup jelly candies that can be swallowed whole; rules vary by region.
• Myth: Konjac always makes food rubbery. Fact: In small amounts it simply thickens or stabilizes; gel texture comes from specific recipes.
• Myth: It has a strong taste. Fact: Konjac is virtually tasteless and mainly changes texture and moisture.

Konjac glucomannan in branded foods

You’ll commonly see “konjac,” “konjac flour,” “glucomannan,” or “E425ii” on labels for:

• Konnyaku and shirataki noodles
• Jelly desserts and fruit gels
• Ready meals, sauces, and dressings
• Plant-based meat alternatives
• High‑fiber drink mixes and supplements

Check the ingredient list and, for supplements, follow serving directions and take with water.

References

Footnotes

1. Re-evaluation of konjac gum (E 425 i) and konjac glucomannan (E 425 ii) as food additives — EFSA Journal. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2017.4727 ↩ ↩² ↩³ ↩⁴

2. Commission Decision 2004/374/EC on emergency measures regarding jelly mini-cups containing konjac — EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32004D0374 ↩ ↩²

3. Import Alert 33-15: Detention Without Physical Examination of Mini-Cup Gel Candy Containing Konjac — U.S. FDA. https://www.accessdata.fda.gov/cms_ia/importalert_115.html ↩ ↩²

4. FDA to Allow the Use of Additional Isolated or Synthetic Non-Digestible Carbohydrates as Dietary Fiber — U.S. FDA. https://www.fda.gov/food/cfsan-constituent-updates/fda-allow-use-additional-isolated-or-synthetic-non-digestible-carbohydrates-dietary-fiber ↩

5. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods — EUR-Lex. https://eur-lex.europa.eu/eli/reg/2012/432/oj ↩