DETERMINATION OF THE PHYSICAL FUNCTIONALITY OF GALACTOMANNANS IN XANTHAN GUM GALACTOMANNAN MIXED SYSTEMS BY PERIODATE-OXIDATION

Galactomannan samples of different origins (tara gum and locust bean g ums), with mannose to galactose (M/G) ratios ranging from 2.8 to 5.0, have been characterized. They exhibited strong differences with respec t to their fine structure (M/G). Mixed gels of xanthan gum and galacto mannans (tara gum, whole and fractionated locust bean gum) were compar ed by means of oscillatory shear measurements. Whatever the galactoman nan, a synergistic maximum was observed when the ratio of xanthan to g alactomannan was 1:1. However, the magnitude of this maximum varied wi th the galactomannan sample used. A linear relation between the maximu m synergism G' of 1% 1:1 xanthan/galactomannan mixed gels versus MIG r atio of galactomannans was described. All galactomannans were submitte d to periodate oxidation. The periodate oxidation of galactomannan sam ples was characterized by the liberated formic acid. As expected, the liberated formic acid was directly related to M/G ratio of galactomann ans. It was demonstrated that the galactomannan periodate oxidation, a s a measure of the M/G ratio, can be directly related to the physical functionality of galactomannans in terms of synergistic interactions b etween the xanthan gum and the galactomannans.