The rheology and melting of mixed p

The rheology and melting of mixed polysaccharide gels containing konjac glucomannan (KGM), locust
bean gum (LBG) and -carrageenan (KC) were studied. Synergy-type peaks in the Young’s modulus at
optimal mixing ratios were found for both KC/LBG and KC/KGM binary gels at a fixed total polysaccharide
content (1:5.5 for LBG:KC and 1:7 for KGM:KC). The Young’s modulus peak for KC/KGM was higher than
for KC/LBG gels. The same stoichiometric mixing ratios were found when either LBG or KGM was added to
KC at a fixed KC concentration, where the Young’s modulus increased up to additions at the stoichiometric
ratio, but leveled off at higher LBG or KGM additions. Addition of KGM or LBG to the 2-component gels
beyond the stoichiometric (optimal) mixing ratio at a fixed total polysaccharide content led to a decrease
in the Young’s modulus and an increase in the rupture strain and stress in extension, and both trends
were stronger for KGM than for LBG.
Differential scanning calorimetry of the gels revealed the development of a second melting peak for
the KC/KGM gels that increased with KGM addition up to higher KGM contents than the stoichiometric
ratio. For the KC/LBG gels, only a slight broadening and shift to a higher temperature were observed.
When the three polysaccharides were mixed, the DSC endotherms reflected only the main features of
the interaction between KC and KGM, and the same was true for the fracture in extension. The different
trends led to higher Young’s moduli at intermediate KC concentrations when a 1:1 addition of LBG:KGM
was used than when either only KGM or LBG was added at a fixed total polysaccharide concentration.
This suggests that no special interactions arise when the three polysaccharides are mixed and the binding
mechanisms are simply a sum of the bindings observed for KC/KGM and KC/LBG two-component gels.