Rheological properties of salep beverage samples were evaluated in relation to four processing variables: aspartame concentration, 2-6 g/100 mL; lemon fiber concentration, 0.5-2.5 g/100 mL; cooking time, 5-25 min and serving temperature 25-65C. The power law model fitted the shear stress-shear rate data. Salep beverage samples exhibited a shear-thinning behavior. A second-order composite design was used to investigate the effects of the four processing variables on the consistency index (k) and sensory score (Ss) of the samples to find the optimum levels of these processing variables. The aspartame and lemon fiber concentration had the most significant increasing effect on the consistency index and Ss, while serving temperature had a decreasing effect on these values. Based on Ss, optimum conditions were determined as aspartame concentration = 6.0 g/100 mL, lemon fiber concentration = 2.1 g/100 mL, cooking time = 11.6 min and serving temperature = 26C. © 2010 Wiley Periodicals, Inc.