Other names for the additive (synonyms)
General Information
Food additive E425, known as konjac, is a natural plant-derived polysaccharide used in the food industry as a thickener, stabilizer, and moisture-retaining agent.
According to Regulation (EC) No 231/2012, the additive is divided into two subtypes with different technological properties:
- Additive E425(i) — Konjac gum;
- Additive E425(ii) — Konjac glucomannan.
Konjac is a natural plant-based additive. It is obtained from the tubers of the plant Amorphophallus konjac, widely cultivated in China, Japan, and other Asian countries.
Historically, glucomannan has been used in Asian cuisine for over 1,500 years, mainly for making “shirataki” noodles and jelly desserts. Interest in konjac in Europe and the USA emerged at the end of the 20th century due to its weight management properties and ability to improve food texture.
The main component of additive E425 is the high-molecular-weight polysaccharide glucomannan, composed of glucose and mannose residues in an approximate ratio of 1:1.6. The empirical formula of additive E425 is (C6H12O6)n.
Konjac dissolves well in hot water, forming a viscous gel. Additive E425 is characterized by a high swelling capacity, retaining 50–100 times its weight in water. The powder is usually white or slightly creamy. It has no taste or odor.
For food production, additive E425 is obtained industrially: plant tubers are cleaned, dried, and ground into powder. The glucomannan fraction is then extracted and undergoes purification and standardization. Depending on the degree of purification, either konjac gum (Additive E425(i)) or konjac glucomannan (Additive E425(ii)) is obtained.
Effects on the Body
Benefits of Additive E425
Konjac glucomannan is a natural dietary fiber. It is not absorbed intact by the human body but serves as a substrate for intestinal microbiota, supporting the growth of beneficial bacteria. Due to its high hydrophilicity, the additive slows gastric emptying, creates a feeling of fullness, and thus helps control body weight. Several clinical studies have shown that regular consumption of glucomannan in doses of 2–3 g per day may help reduce blood cholesterol and glucose levels and improve bowel function in cases of constipation.
However, in other studies involving overweight and obese adults, taking glucomannan at approximately 4 g per day for 8 weeks did not produce the expected effect. Participants did not show significant changes in body weight or biochemical parameters compared with the placebo group.
Risks of Additive E425
Despite its natural origin, excessive consumption of konjac may cause side effects. At doses above 3 g/day, some individuals may experience diarrhea, bloating, or, conversely, constipation. In EFSA clinical trials, cases of abdominal discomfort were reported when taking 3 g of the additive for 12 weeks.
According to JECFA, the toxicological database is limited, but 90-day studies on rats and dogs did not reveal significant adverse effects. The established NOEL (No Observed Effect Level) was 1250 mg/kg body weight per day. The FDA considers konjac glucomannan a safe ingredient in dietary supplements but warns against using large tablets or capsules due to choking risk.
EFSA concluded that there is no need to set a numerical Acceptable Daily Intake (ADI) for additive E425, as its current usage (up to 10 g/kg of product) does not pose a health risk. However, it is recommended that total daily intake from all sources does not exceed 3 g.
Uses
In the food industry, additive E425 is used as a thickener, stabilizer, emulsifier, and moisture-retaining agent. It efficiently forms a viscous structure and retains moisture, making it indispensable in low-calorie products. Konjac gum and glucomannan are used in the following product categories:
- jelly desserts and marmalade;
- dairy products (yogurts, ice cream, dessert creams);
- meat and fish products for moisture retention;
- baked goods and bread products to increase volume and maintain freshness;
- dietary “shirataki” noodles and other weight control products.
Due to its low calorie content and swelling ability, konjac is particularly in demand in dietetic and diabetic nutrition. However, when used in jelly candies for children, EFSA and FDA have noted a choking risk, so in some countries such products are restricted or prohibited.
Legal Status
The legal status of additive E425 depends on the country. In the European Union, it is permitted and included in the list of Regulation (EC) No 1333/2008, with usage limited to a maximum level of 10 g/kg of product.
In Ukraine, additive E425 is also permitted and used in the same categories as in the EU. In the United States, konjac is recognized as a safe additive (GRAS) and used in dietary supplements and certain foods, although the FDA has banned its addition to jelly candies for children due to choking risk.
In Canada, the additive is allowed in several categories, but restrictions similar to those in the U.S. apply to jelly desserts. In Japan, additive E425 is widely used as it is a traditional component of the national cuisine.
The Acceptable Daily Intake (ADI) has not been numerically established, as EFSA and JECFA experts consider the additive safe at current usage levels. It is recommended to limit total daily intake to no more than 3 g for an adult.