In this study, the rheological properties of Melissa officinalis seed gum (MOSG) as a function of temperature (25, 35, 45, 55, and 65 degrees C) and salt concentrations (10, 50, 100, and 200 ppm NaCl and CaCl2) were investigated. The power law and HerschelBulkley models could describe the rheological behavior of gum dispersions. The results showed that the intrinsic viscosity of the samples significantly decreased with increasing temperature and salt concentration. Steady-state analysis of the samples revealed a non-Newtonian, shear-thinning behavior at tested temperatures and concentrations. The apparent viscosity increased with increasing salt concentrations and decreasing temperature. The results obtained from the frequency sweep test showed that the loss modulus (G '') values were higher than storage modulus (G ') in the concentrations of 0.25% to 0.5%, but beyond these concentrations, G ' values were greater than G ''. The elasticity and viscosity of the gum samples increased with increasing concentration. The results of this study confirmed that MOSG has good rheological properties and can be used in food and pharmaceutical systems. Practical Applications The rheological behavior is the most important functional property of natural colloids. This property is related to the capacity of hydrocolloids in improving viscosity and the formation of gel structure at low concentrations. The thickening property of hydrocolloids has a determinant role in consumer acceptance. Furthermore, the consumer acceptance of different food products such as fruit juices, sauces, ready jells, and desserts is mainly dependent on rheological behavior. Therefore, investigation of rheological properties of the new source of food hydrocolloids is interested in food industries.
