MECHANICAL AND MORPHOLOGICAL FEATURES OF AGAROSE GUAR GUM GELS

Young's modulus, maximum rupture stress and compression energy to break values were determined for pure agarose (5g/1 and 10g/1) and 1:1 agarose-guar gum mixed gels of 10g/1 total polymer concentration. The enhancing effect of guar gum was noticed particularly on the tenacity parameter, Transmission electron microscopy, TEM, was used to image the supramolecular structure of 1:1 agarose-guar gum gels. Before sample preparation for TEM, the hot aqueous solutions have been submitted to slow cooling until a determined temperature was reached, and then quenched to -78 degrees C. When this temperature was higher than the critical temperature of gelation, agarose-guar gum mixed samples formed aggregated structures, promoted by freezing. Below gelation, although guar gum continued producing aggregates, agarose appeared as continuous network structures. This result was related to the stabilizing role of guar gum.