Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food on a request from the Commission related to an application on the use of partially depolymerised guar gum as a food additive

The European Food Safety Authority has been asked to provide a scientific opinion on the safety in use of partially depolymerised guar gum as a thickener, emulsifier and stabiliser in food. Guar gum (E412) is authorised for use as a food additive in the European Union (EU) by European Parliament and Council Directive 95/2/EC. It is currently used as a thickener, emulsifier and stabiliser in a range of food categories. A 'not limited' ADI was originally set for guar gum by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1973, which was further confirmed by JECFA in 1975. Specifications for guar gum have been established by the Commission and are laid down in Commission Directive 96/77/EC. The description included within the specification for guar gum in this Directive states that guar gum is the ground endosperm of the seeds of the natural strains of the guar plant, Cyamopsis tetragonolobus (L.) Taub. (family Leguminosae). It consists mainly of a high molecular weight hydrocolloidal polysaccharide composed of galactopyranose and mannopyranose units combined through glycosidic linkages, which may be described chemically as galactomannan. A manufacturer has made a request to use partially depolymerised guar gum as a food additive. Partially depolymerised guar gum is produced from guar gum by one of three manufacturing processes which consist of heat treatment, acid hydrolysis or alkaline oxidation, which all exert a partial depolymerisation of the native guar gum. The result is guar gum which is chemically cut into smaller molecular weight sizes and has different viscosity properties. Partially depolymerised guar gums have been shown to be very similar to native guar gum with respect to the structure of the galactomannan polysaccharide and the composition of the final products, except for the level of salts present in the samples made by acid hydrolysis and alkaline oxidation because of the neutralisation step involved in the manufacturing process. The resulting salts, either sodium citrate (E311) or sodium phosphate (E339) have well established safety records when used as a food additive in food products (Directive 95/2/EC Annex IV). Data have been provided by the petitioner from which it follows that all depolymerised guar gum preparations have average molecular weights that match the criteria set for the molecular weight of food grade guar gum specified to be between 50 000 g/mol and 8 000 000 g/mol by the EU and FAO/WHO/JECFA. Based on detailed analysis of the polydispersity, the petitioner also provided estimates of the percentage of components with molecular mass below 50 000 g/mol. For the preparations produced by heat treatment or acid hydrolysis this percentage was reported to be 0%. For the depolymerised guar gum prepared by alkaline oxidation this percentage amounts to 7.6 %. Taking into account that the specifications for guar gum defined by JECFA indicate that the molecular weight of food grade guar gum should be mainly between 50 000 g/mol and 8 000 000 g/mol it would appear that the depolymerised guar gum prepared by alkaline oxidation matches these specifications. Potential products resulting from the production process, including furfural, organic peroxides and small molecular weight organic acids, are controlled below specific levels and are not of safety concern. The safety of native guar gum has been documented. Since the molecular weight of partially depolymerised guar gum appears to fall within the specifications of native guar gum, which is the guar gum already accepted for food use, the Panel concludes that there is no safety concern for the partially depolymerised guar gum prepared by either heat treatment, acid hydrolysis or alkaline oxidation at estimated levels of intake. The safety of the partially depolymerised guar gum is also supported by the outcome of a 90-day study in rats with a depolymerised guar gum prepared by alkaline oxidation which revealed no adverse effect up to dose levels of 50 g/kg diet estimated to amount to 2500 mg/kg bw/day. The Panel considers that the specifications for guar gum may need to be modified to take account of the increased level of salts and the possible undesirable byproducts e. g. furfural and peroxides, that may result from the described processes for the production of partially depolymerised guar gum.