Depolymerized alginic acid

Depolymerized Alginic Acid Solution NMR Studies. Studies are being conducted with depolymerized alginic acid. In these samples, the MG blocks were removed by acid hydrolysis lea dng shorter chains contmning mostly GG or MM blocks. For whole alginic acid, complexation of one ion to a GG block leads to a zipper effect. If two or more metal ions bind to GG blocks that are separated by one... 

In the sodium depolymerized alginic acid sample, Figure 10, some resolution of the signals is possible. Through studies of GG and MM homopolymeric samples, it is possible to attribute the signals occurring at 67 ppm and -53 ppm to G-residues. 

Preliminary studies of depolymerized alginic acid indicate that the GG-preference of the divalent alkaline earths remains in mixtures of homopolymeric blocks. One conclusion from our data might be that there is a minimum chain length required for maximum metal ion binding. Until further studies are completed, the extent of binding for the divalent ions and depolymerized alginate cannot be determined. 

Alginic acid dispersions are susceptible to microbial spoilage on storage, which may result in some depolymerization and hence a decrease in viscosity. Dispersions should therefore be preserved with an antimicrobial preservative such as benzoic acid potassium sorbate sodium benzoate sorbic acid or paraben. Concentrations of 0.1-0.2% are usually used. 

Depolymerization of Alginic Acid. Alginic acid depolymerization is a process that removes the MG blocks by cleaving the MG glycosidic bond which is more susceptible to acid hydrolysis than the glycosidic bonds in homopolymeric blocks. The resulting solid is a mixture of the two homopolymeric GG blocks and MM blocks. The method used was a modification of the procedure described by Penman and Sanderson (10). 

The seaweed polyglycosiduronic acid alginic acid, whichj is composed of D-mannuronic and L-guluronic acid residues, when treated with a partially purified preparation of a cell-free extract of an adapted pseudomonad, is initially depolymerized to a series of oligosaccharides each of which contains a 4-deoxy-L-er2/terminal position, and then to the h-erythro isomer of the ulosonic acid (107), which is the product formed from both of the constituent residues. 

Other properties of algin reported include conductivity (252 253), contact angles of various solvents on different metal alginate films 175), depolymerization rates for alginic acid in various acids (251, 25U, 255), a pK of 2.95 for the dissociation constant of alginic acid in normal potassium chloride solution (208), absorption spectra of algin (202), and properties determined in connection with molecular weight studies, such as sedimentation and diffusion velocity and partial specific volumes (209),... 

The sequence and composition of uronate residues in intact alginate samples have been determined by high resolution H n.m.r. spectroscopy. Problems encountered owing to the viscosity of the samples were overcome by controlled and slight depolymerization before n.m.r. at 90 °C. The D-mannuronic acid L-guluronic acid molar ratio was obtained from the intensities of the signals from... 

The gel strength of pectin increases with the increase in the molecular weight of the pectin used thus, any treatment that leads to depolymerization of the pectin chains results in weaker gels [39]. Pectins can gel in different ways based on molecule type and structure. Acid or crosslinking with calcium ion, or reaction with alginate, can induce gelling of pectin [3]. 

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