Glucomannan polysaccharides

Gelling Mechanisms of Glucomannan Polysaccharides and Their Interactions with Proteins... 

Konnyaku flour obtained from plant cultivars of Amorphophallus konjac K. Koch is an important food material because of its remarkable gelling properties at very low solids concentrations in water (less than 0.5%). It has been employed in certain regions of Asia, such as Japan, to make a variety of foods that were claimed to have significant health benefits. Glucomannan polysaccharides (GP) are the main active component of Konnyaku flour, and can... 

Konnyaku flour was obtained from tubers of plant cultivars of Amorphophallus konjac K. Koch that were kindly provided by Ajinomoto Co. Glucomannan polysaccharides were extracted from konnyaku flour and further purified from precipitates in ethanolic mixtures. The range of glucomannan oligosaccharides that are obtained by partial hydrolysis of GP is illustrated in Table I. 

Gelling mechanisms of glucomannan polysaccharides (GP) extracted from konnyaku flour obtained from plant cultivars of Amorphophallus konjac K. Koch... 

Figure 2. Near Infrared (NIR) spectrum of glucomannan polysaccharide...

The polysaccharides constitute 0.2-0.3% of the fresh gel (0.8-1.2% of dry matter content). Postproduction autodegradation of the glucomannan polysaccharides produces mainly mannans. The gel polysaccharides, consisting mainly of mannose and glucose in a 1 3 ratio, can degrade in 48 h at room temperature, with a decrease in glucose content and an increase in mannose glucose ratio to >10. ... 

Glucomannans (GM) and galactoglucomannans (GGM), common constituents of plant cell walls, are the major hemicellulosic components of the secondary cell walls of softwoods, whereas in the secondary cell walls of hardwoods they occur in minor amounts. They are suggested to be present together with xylan and fucogalactoxyloglucan in the primary cell walls of higher plants [192]. These polysaccharides were extensively studied in the 1960s [6,193]. 

Fig. 22.— 13C-N.m.r. Spectra of Polysaccharides from Ceratocystis paradoxa (A) and the Preponderant Glucomannan from Ceratocystis hrunnea (B). (Solvent, DjO temperature, 70° chemical shifts expressed as 8C, relative to external tetramethylsilane.)...

The most characterised D-mannan degrading enzymes are the endo- -mannanases (5). These enzymes act on a range of 1,4-p-D-mannan-type polysaccharides including D-mannan, glucomannans (acetylated and deacetylated), galactomannans and galacto-glucomannans. The extent and... 

Figure 3. Distribution of polysaccharides through the cell wall. C, cellulose M, galacto-glucomannan X, arabino-4-O-methylglucuronoxylan.

OE097 Tejero Mateo, M. P., A. Gil Serrano, and ]. PemandeZ Blanos. Polysaccharides in olives. VII. Study a galacto-glucomannan isolated from olive pulp of the variety Gordal. Ann Quim Ser C 1986 82(2) 158-161. OEllO... 

The enzymatic esterification of polysaccharides, e.g., glucomannan, a copolymer of glucose and mannose, has also been reported [118]. 

In describing and interpreting some of the more important properties of plant galactomannans, comparisons will be made with structurally similar polysaccharides, including the closely related glucomannans and galactoglucomannans, and those based on (1 — 4)-/3-D-xylan main-chains (for example, the arabinoxylans) and (1 — 4)-/3-D-glucan main-chains [for example, the amyloids and sodium 0-(carboxymethyl)cellulose]. 

Similar structural problems exist for the distribution of side chains in galactoglucomannans, xyloglucans, arabinoxylans, and 4-0-methylglucuronoxylans, and even for the distribution of acetyl groups in glucomannans and for related features in many other polysaccharides. 

The linear, but highly branched, molecular structure of the galactomannans is the reason for some specific properties which are quite different from those of the unbranched cellulose-like and water-insoluble mannans and glucomannans. Galactomannans are hydrated in cold water and give stable solutions even in acidic formulas. The interactions of galactomannans with other polysaccharides are the base of a variety of industrial applications. 

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