Guar gum galactomannans

To illustrate some characteristrics of polysaccharide utilization systems of Bacteroides species, we will compare the systems involved in utilization of a host-produced mucopolysaccharide (chondroitin sulfate), a plant galactomannan (guar gum) and polygalactaronic acid. Bacteroides thetaiotaomicron... 

Morris et al. conducted a work studying hydrodynamics and chain flexibility of galactomannan (guar gum] [152], and Mimosa scabrella in 0.1 M NaNOo were realized by Mazeau and Rinaudo [153]. 

Polymer chains of guar gum and its derivatives, in fact of all galactomannans, are readily cross-linked with borate and titanium ions. Gels formed in this way are mbbery in nature. 

Guar gum is a galactomannan used like locust bean gum and at approximately the same levels. However, unlike locust bean gum, it swells in cold solution and requires no heat for complete hydration. It also induces mix separation which may be controlled with carrageenin. It is well suited for use in HTST systems. 

Anionic galactomannans, which are derived from guar gum, in which the hydroxyl groups are partially esterified with sulfonate groups that result from 2-acrylamido-2-methylpropane sulfonic acid and l-allyloxy-2-hydroxypropyl sulfonic acid [1872], have been claimed to be suitable as thickeners. The composition is capable of producing enhanced viscosities, when used either alone or in combination with a cationic polymer and distributed in a solvent. 

Galactomannan-1,2 (m = 1) Guar gum from Cyamopsis tetragonoloba seeds... 

X-Ray diffraction patterns for the galactomannans from guar, locust-bean, and tara gums show, with relative humidity, continuous variation of only the a dimension of the base plane. For guar gum, the a axis varies from 1.35 nm at 0% r.h. to 3.32 nm at 78% r.h., whereas, for lo-... 

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. 

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... 

---