HETEROTYPIC INTERACTIONS OF DEACETYLATED XANTHAN WITH A GALACTOMANNAN OF HIGH GALACTOSE SUBSTITUTION DURING SYNERGISTIC GELATION

摘要: 1 ABSTRACT Physical thermoreversible gels of deacetylated xanthan (DX) mixed with varying concentrations galactomannan extracted from mesquite (Prosopis spp.) seed endosperm (MSG) (M/G ~ 1.1; Mw 2.1 × 106) set and melt co-operatively at 23-27°C in 5 mM NaCl. The liquid-like character the 20°C (tan δ20°C) gelling temperature δcritical), attained their minima values when concentration MSG was ~0.4-0.5 g L-1, while holding fixed that DX ~1.0 L-1. Mechanical elasticity (G'), increased progressively as proportion incorporated mixture 0 up to ~0.5 L-1 beyond this concentration, G' showed little further change increasing concentration; initial behaviour is related a progressive cross-linking leading establishment temporary gel network. Both onset formation (Tg) DSC midpoint thermal transition (Tm), are good agreement (Tg ~23.3°C Tm ~26.0°C) vary slightly mixtures within range composition. However, amount unbound for MSG/DX weight ratio ≥ 0.6, Tg ~27.0°C, also break-point pattern setting melting function For MSG:DX < ~0.5, interaction system has characteristics an heterotypic association process, resulting creation coupled optimum stoichiometric seems involve 1:1 polymer chain pair (based on contour length) high galactose disordered species. Greater values, composition may result increase solvent viscosity due surplus galactomannan.