Table 1.
Commission Regulation (EU) No 231/1012 and JECFA (2006) specifications for konjac gum (E 425 i), konjac Glucomannan (E 425 ii) and konjac Flour (INS 425)
| Commission Regulation (EU) No 231/2012 konjac gum (E 425 i) | Commission Regulation (EU) No 231/2012 konjac glucomannan (E 425 ii) | JECFA (2006) konjac Flour (INS 425) | |
|---|---|---|---|
| Definition | Konjac gum is a water‐soluble hydrocolloid obtained from the konjac flour by aqueous extraction. Konjac flour is the unpurified raw product from the root of the perennial plant Amorphophallus konjac. The main component of konjac gum is the water‐soluble high‐molecular‐weight polysaccharide glucomannan, which consists of d‐mannose and d‐glucose units at a molar ratio of 1,6:1,0, connected by β(1‐4)‐glycosidic bonds. Shorter side chains are attached through β(1‐3)‐glycosidic bonds, and acetyl groups occur at random at a ratio of about 1 group per 9–19 sugar units | Konjac glucomannan is a water‐soluble hydrocolloid obtained from konjac flour by washing with water‐containing ethanol. Konjac flour is the unpurified raw product from the tuber of the perennial plant Amorphophallus konjac. The main component is the water‐soluble high‐molecular‐weight polysaccharide glucomannan, which consists of d‐mannose and d‐glucose units at a molar ratio of 1,6:1,0, connected by β(1‐4)‐glycosidic bonds with a branch at about each 50th or 60th unit. About each 19th sugar residue is acetylated | The hydrocolloidal polysaccharide obtained from the tubers of various species of Amorphophallus; principal component is a high‐molecular‐weight, slightly branched, non‐ionic glucomannan consisting of mannose and glucose, connected by β‐1,4 linkages, at a respective molar ratio of approximately 1.6‐4:1; acetyl groups along the glucomannan back‐bone contribute to solubility properties and are located, on average, every 9–19 sugar units |
| Molecular weight | The main component, glucomannan, has an average molecular weight of 200,000–2,000,000 | 500,000–2,000,000 | The main component, glucomannan, has an average molecular weight of 200,000–2,000,000 |
| Assay | Not less than 75% carbohydrate | Total dietary fibre: not less than 95% on a dry weight basis |
Not less than 75% carbohydrate The remainder, after subtracting from 100% the sum of the percentages of total ash, loss on drying and protein, represents the percentage of carbohydrate (glucomannans) in the sample |
| Description | A white to cream to light tan powder | White to slightly brownish fine particle size, free flowing and odourless powder | White or cream to light tan powder |
| Identification | |||
| Solubility | Dispersible in hot or cold water forming a highly viscous solution with a pH between 4.0 and 7.0 | Dispersible in hot or cold water forming a highly viscous solution with a pH between 5.0 and 7.0. Solubility is increased by heat and mechanical agitation |
Dispersible in hot or cold water forming a highly viscous solution with a pH between 4.0 and 7.0 Solubility is increased by heat and mechanical agitation. Addition of mild alkali to the solution results in the formation of a heat‐stable gel that resists melting, even under extended heating conditions |
| Gel formation | Add 5 mL of a 4% sodium borate solution to a 1% solution of the sample in a test tube, and shake vigorously. A gel forms | – | Add 5 mL of a 4% sodium borate solution to a 1% solution of the sample in a test tube, and shake vigorously. A gel forms |
| Formation of heat‐stable gel | Prepare a 2% solution of the sample by heating it in a boiling water bath for 30 min, with continuous agitation and then cooling the solution to room temperature. For each gram of the sample used to prepare 30 g of the 2% solution, add 1 mL of 10% potassium carbonate solution to the fully hydrated sample at ambient temperature. Heat the mixture in a water bath to 85°C, and maintain for 2 h without agitation. Under these conditions, a thermally stable gel is formed | Prepare a 2% solution of the sample by heating it in a boiling water bath for 30 min, with continuous agitation and then cooling the solution to room temperature. For each gram of the sample used to prepare 30 g of the 2% solution, add 1 mL of 10% potassium carbonate solution to the fully hydrated sample at ambient temperature. Heat the mixture in a water bath to 85°C, and maintain for 2 h without agitation. Under these conditions a thermally stable gel is formed | Prepare a 2% solution of the sample by heating it in a boiling water bath for 30 min, with continuous agitation and then cooling the solution to room temperature. For each gram of the sample used to prepare the 2% solution, add 1 mL of 10% potassium carbonate solution to the fully hydrated sample at ambient temperature. Heat the mixture in a water bath to 85°, and maintain for 2 h without agitation. Under these conditions, a thermally stable gel is formed. Related hydrocolloids such as guar gum and locust bean gum do not form thermally stable gels and are negative by this test |
| Purity | |||
| Loss on drying | Not more than 12 % (105°C, 5 h) | Not more than 8% (105°C, 3 h) | Not more than 15% (105°, 5 h) |
| Starch | Not more than 3% | Not more than 1% | – |
| Protein | Not more than 3% (N × 5.7) |
Not more than 1.5% (N × 5.7) Determine nitrogen by the Kjeldahl method. The percentage of nitrogen in the sample multiplied by 5.7 gives the percent of protein in the sample |
Not more than 8% Proceed as directed under Nitrogen Determination (Kjeldahl method). The percentage of nitrogen in the sample multiplied by 5.7 gives the percent of protein in the sample |
| Viscosity (1% solution) | Not less than 3 kg/m·s at 25°C | Not less than 20 kg/m s at 25°C | – |
| Ether‐soluble material | Not more than 0.1% | Not more than 0.5% | – |
| Sulphite (as SO2) | – | Not more than 4 mg/kg | – |
| Chloride | – | Not more than 0.02% | – |
| 50% Alcohol‐soluble material | – | Not more than 2.0% | – |
| Total ash | Not more than 5.0% (800°C, 3–4 h) | Not more than 2.0% (800°C, 3–4 h) | Not more than 5% (800°, 3–4 h) |
| Arsenic | Not more than 3 mg/kg | – | – |
| Lead | Not more than 2 mg/kg | Not more than 1 mg/kg |
Not more than 2 mg/kg Determine using an atomic absorption technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the method described in Volume 4, ‘Instrumental Methods’ |
| Microbiological criteria | |||
| Salmonella spp. | Absent in 12.5 g | Absent in 12.5 g | – |
| Escherichia coli | Absent in 5 g | Absent in 5 g | – |