Structural characterization of interpenetrating network formation of high acyl gellan and maltodextrin gels

A mixed-gel of high acyl (HA) gellan gum and maltodextrin (MD) (potato DE2) demonstrated a range of physical properties with a proposed interpenetrating network. Mixed hydrocolloid gels allow for the development of novel properties that neither polymer alone could create allowing unique functionality in textures or controlled release. The aim of this work was to identify the type of network formation by examining material properties and the contribution from of each polymer. Material properties of quiescently set composite gels were characterized through bulk fracture, small deformation rheology, DSC, and microscopy. A continuous shift in fracture strain and modulus were created through mixed gels of the soft and flexible HA gellan with the firm and brittle MD. By adding MD (from 0 to 40%) at a constant 0.5% gellan, the gel true strain at fracture decreased from 0.50 to 0.18 while the Young's Modulus increased from 3 to 1780 kPa. No indication of phase separation or chemical complexation was measured. Analysis of the time-dependant MD contribution and composite material properties hypothesized a gelation mechanism in which HA gellan forms a network first and MD aggregates within the pores without phase separation. MD dominated the small deformation rheology while HA gellan appeared to dominate the fracture point. Material properties were indicative of the type of structural organization in the HA gellan MD mixed gel network.