Bita Mohammadalami - Department of Food Science Engineerin, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran.
Hossein Ghahramani - Department of Chemical Engineering, Quchan Branch, Islamic Azad University, Quchan, Iran.
Maziar Sharifzadeh - Department of Chemical Engineering, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran.

Viscosity is one of the most important indices in evaluating general quality and customer acceptance tomato paste. This study was conducted to evaluate the effect of soy-protein isolation on the tomato paste viscosity by using response surface methodology. Treatments were soy-protein concentration (0, 1.5 and 3 percent), temperature (45, 60 and 75C ) and viscometer rotation (50,100 and 200 rpm).The graphic contours show that the most appearance viscosity at the range of (45-50 and70-75 C) temperature and (1.25-1.75%) soy-protein isolate concentration when the rotation was 50 rpm (P<0.05).Also quadratic equation was suitable model for viscosity response to estimate the viscosity equation versus variable research .As the base of results of this study adding 1.5 percent soy-protein significantly increased appearance viscosity.

response surface method, soy-protein isolated, tomato paste, viscometer, viscosity