Viscosity, unfrozen water (w nc) and glass transition temperature of the maximally freeze-concentrated material (Tg') of sherbet mixtures and the overrum of the sherbets with different concentrations of guar gum (from 0.2% to 0.5%) and mangaba pulp (21.1%, 25.8% and 28.5%) were evaluated. Apparent viscosity ranged from 85.8 to 286.1 cP, increasing with guar gum concentration and mangaba pulp. Thermal analysis using differential scanning calorimetry of sherbets mixture showed that w nc was from 12% to 20%, decreasing with the increasing of mangaba pulp concentration. The Tg' ranged from -57.65ºC to -53.45ºC and was not different between the samples. The overrum was from 20.1% to 40.59%. Sherbets containing the same pulp concentration presented different values of this variable, however a relationship between the increasing of guar gum concentrations and the air incorporation was observed only for sherbets with 25.8% of mangaba pulp. The stabilizer modified the viscosity of the mixture and overrum and the pulp concentration influenced thermal properties. Higher overrum is better for product smoothness. Higher pulp concentration decreases the w nc so, the product concentrates less water available to form great ices during the changes in the temperature which may cause losses in the product quality.
ice cream; viscosity; overrum; unfrozen water; differential scanning calorimetry
