2. Effect of mixtures of xanthan gum and CMC on viscosity, lightness and cloudiness of mangosteen juice
Gum concentrations of 0.05X, 0.05X+0.05C, 0.05X+0.15C and 0.05X+0.25C led to precipitation (Figure 2). Hydrocolloid-aqueous phase separation could be explained by thermodynamic incompatibility of hydrocolloid and component in beverage (Dickinson, 2003). Xanthan gum alone provided higher separated hydrocolloid phase (Figure 2a) than mixtures of xanthan and CMC (Figure 2 b-d) did. This was probably because xanthan gum was rich in disperse phase while continuous phase was solely CMC (Boyd, 2005). The mangosteen juice with the addition of 0.10% xanthan gum (Figure 2e) appeared a collared ring in the middle of the tube. Moreover, the mangosteen juice with addition of 0.10% xanthan gum and 0.05% CMC (Figure 2f) appeared a precipitate of pulp at the bottom after storage at 4°C for 30 days. Therefore, these concentrations were not used for further study.