Of galactomannan

Morris G.A., Patel T.R., Picout D.R., Ross-Murphy S.B., Ortega A., Garcia de la Torre J., Harding S.E. 2008. Global hydrodynamic analysis of the molecular flexibility of galactomannans. Carbohydrate Polymers 72, 356-360. 

A review of uses of galactomannan thickening agents, of which some 23 000 tons were used worldwide in 1986, is available [354]. The use of borate ions to crosslink locust bean or guar mannose chains has been mentioned already. It has been shown that addition of borax... 

V. Interaction of Galactomannans with Carrageenan, Agar, and Other Polysaccharides. 284... 

A method for purifying certain neutral polysaccharides by precipitation in borate buffer with cetyltrimethylammonium bromide was developed by Stacey and coworkers,118 but it does not appear to have been used for the isolation of galactomannan gums. It has, however, been claimed119 that guar gum and locust-bean gum can be separated by carefully controlled precipitation of the cetylpyridinium bromide complexes by 0.1 M sodium hydroxide. Guar gum is precipitated between pH 7.0 and 8.3, and locust-bean gum between 8.6 and 9.3. 

The possibility of there being branches in the mannan main-chain should not be excluded. Estimates from a number of methylation analyses of galactomannans have shown a slightly higher molar quantity of 2,3-di-O-methyl-D-mannose than 2,3,4,6-tetra-O-methyl-D-galactose53 78,79. However, if branching of the mannan main-chain is a feature of galactomannan structure, its extent seems to be fairly low. 

Two fundamental properties determine much of the behavior of polymers the molecular weight and the conformation (molecular shape). Because of the very high viscosities of even dilute solutions of galactomannans, determinations of the molecular weight are technically difficult. 

A number of problems arise in connection with the measurement of molecular weights of galactomannans. Firstly, it is very difficult to obtain true solutions of many of the gums, especially of locust-bean gum and guar gum consequently, the solutions must be filtered or centrifuged to remove undissolved or partially hydrated gum. This immediately raises the problem of fractionation of the sample, as the... 

The molecular weights published for a number of galactomannans are given in Table V. 

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