Konjac mannan gums

Anderson, D. M. W., Howlett, J. F., and McNab, C. G. A. (1986). The amino acid composition of the proteinaceous components of konjac mannan, seed endosperm galactomannans and xanthan gum. Food Hydrocoll. 1 95-99. 

Interaction of xanthan with guar gum in solution leads to enhanced viscosity, whereas elastic thermo-reversible gels are obtained with LEG and konjac mannan sofP (Figure 26.5). Since xanthan may contain cellulases, it cannot be used with cellulose derivatives. 

Undergoes a coil-helix transition and forms highly elastic thermoreversible gels on cooling in the presence of locust bean gum and konjac mannan. Strong gels, which melt at 50°C are produced in water. In the presence of electrolyte the gels formed are weaker and form at lower temperatures ( 40°C). 

Figure 4.9 Cel strength as a function of xanthan concentration for mixtures with locust bean gum (squares) and konjac mannan (circles) in water (open symbols) and 40 mM NaCI (closed symbols). Reprinted from [27]. Copyright 1991, with permission from Elsevier.

As noted above, konjac mannan modifies the properties of kappa carrageenan gels and interacts with xanthan gum to form thermally reversible gels. 

This group of polysaccharides is represented by locust bean and guar gums (1,4-P-D-mannan with 1,6-a-D-galactose substituents) and konjac gum (l,4-(3-D-glucomannan). These gums are remarkable for the synergistic effect they have on other polysaccharides and proteins and their tendency to self-associate. Locust bean gum is also called carob gum. 

The only commercially important glucomannan is konjak gum also known as konjak mannan. Konjak flour is obtained from the starchy tubers of the plant Amorphophallus konjac (Araceae), grown in subtropical to tropical eastern Asia (Japan, China and Indonesia). 

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