Rheological properties of food gums as related to their water binding capacity and to soy protein interaction

Abstract

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 gum (40 mL/g) and sodium alginate (25 mL/g). Propylene glycol alginate and locust bean gum (LBG) were the poorest water binders (15 and 11.6 mUg). 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 mixed systems over the expected values from 81 to 139%. For the xanthan gum 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.