Effect of the addition of Gellan, Tragacanth and High-Methoxyl Pectin on the Stabilization of Doogh

The use of hydrocolloid is a method for suspension stabilization and solid particle suspending in drinks. In this study, the effects of adding three different hydrocolloids including gellan, tragacanth and high-methoxy pectin at three levels: 0.02, 0.05 and 0.08 of the binary combination on the stability, rheological properties, zeta potential and the activation energy were examined. The results showed that the addition of all hydrocolloids increased the stability and prevented the serum separationand also precipitation of protein. All the treatment prevented the serum separation significantly (p < 0.05). The least serum separation and the best sensory properties were gained by the formulations containing 0.02-0.08% (pectin-tragacanth) and 0.02-0.08% (tragacanth-gellan), respectively. Power law was the suitable mathematical model to predict the flow behavior of stabilized doogh. Zeta potential and activation energy were determined in the range of 9.10 to -16.6 mV and 9.37 to 18.34 kJ/ mol, respectively.