[ effect of two types of Iranian gum tragacanth on some rheological, physical and sensory properties of date milk beverage]

ABSTRACT

Date syrup, as a native and nutritious additive, is one of the best choices for milk flavoring. In this study, some of the rheological, physical and sensory properties of date milk made from three different concentrations of two types of Iranian gum tragacanth, as a substitute for imported gums, were determined. Rheological properties of samples of date milk containing three different concentrations [0.1%, 0.2%, 0.3% w/w] of two types of gum tragacanth [Astragalus. gossypinus and Astragalus. rahensis] were measured using a rheometer at 3°C, and at three different time periods [one, two and three days] after production. Particle size distribution was determined by laser diffractometry, and colorimetric assays were done by using reflection spectrometer. Sensory analysis was performed by 25 semi trained panelists, using a 5-point hedonic scale. Findings showed that flow behavior parameters, particle size and color parameters [L*, a*,b*] were significantly affected by concentration of the gum tragacanth and the impact severity was influenced by the type of gum. Based on sensory evaluation, samples containing 0.3% A.gossypinus and 0.2% A.rahensis showed higher desirability than others. Using an appropriate type and concentration of gum in date milk formulation can improve the milk texture and mouthfeel by affecting the particle size and flow behavior