- - نويسنده Assistant Professor of the Department of Food Industry Machines, Bu-Ali Sina University, Hamedan, Iran. Salehi F. , - - نويسنده Professor of the Faculty of Food Science & Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. Kashaninejad M.
ABSTRACT: The objective of this study was to investigate the effect of different thermal treatments (20-100°C at five levels for 20 min) on rheological properties of basil seed (Ocimum basilicum) and balangu seed (Lallemantia royleana) gums. Power law model well described the non-Newtonian pseudoplastic behaviour of the seeds gums. The apparent viscosity of balangu seed gum was dramatically affected by the temperature and decreased from 0.015 to 0.007 Pa.s with increasing temperature from 20 to 100°C (at 97.8 s-1). Apparent viscosity of basil seed gum decreased from 0.053 to 0.022 Pa.s with increasing temperature from 20 to 100°C (shear rate=97.8 s-1). Seeds gums showed shear thinning behavior at all temperatures. The Arrhenius relationship was used to describe the temperature dependency of rheological parameters of basil seed and balangu seed gums. The activation energy of basil seed and balangu seed gums was quantified using an Arrhenius equation and increased from 4297 to 17434 J mol-1 and 2210 to 11257 J mol-1 as shear rate changed from 6.12 to 245 s-1, respectively. The flow behavior index (n), that is related to non-Newtonian behavior (pseudoplasticity),increased significantly (P≤0.05) in basil seed gum after heating, however it was decreased significantly (P≤0.05) in balangu seed gum after heating.