RHEOLOGICAL PROPERTIES OF FOOD GUMS AS RELATED TO THEIR WATER BINDING-CAPACITY AND TO SOY PROTEIN-INTERACTION

Water binding capacity and hydration time of several food gums were measured by the Baumann method. Xanthan gum was by far the best water binder (232 mL/g) followed by guar grim (40 mL/g) and sodium alginate (25 mL/g). Propylene glycol alginate and locust bean grim (LEG) were the poorest water binders (15 and 11.6 mL/g). Hydration time ranged from 50 min for sodium alginate to 3500 min for guar gum. A good correlation was obtained between the consistency coefficient of gum dispersion and the imbibed water fraction calculated from Baumann measurements Soy protein (20 g/kg) showed synergism with xanthan and guar gum (1.5 or 3 g/kg) as shown by the increase of the consistency coefficients of mired systems over the expected values from 81 to 139%. For the xanthan grim and soy protein systems, yield stress was greatly enhanced too. The interaction between locust bean gum and soy protein changed from antagonism at 20 g/kg soy protein and 1 g/kg LBG to synergism for 1.5 and 3 g/kg gum concentration. When soy protein interacted with a blend (1:1) of xanthan and guar, the synergistic increase in the consistency coefficient and yield stress was also apparent. However, soy protein showed an antagonistic interaction with the blend xanthan/LBG (2 g/kg) as it decreased gel properties of the system. (C) 1995 Academic Press Limited