Steady shear flow behavior of gum extracted from Ocimum basilicum L. seed: Effect of concentration and temperature

Steady shear flow behavior of basil seed gum (BSG) was investigated between 0.5% and 2% (wt/wt) concentration and temperatures of 5-85 degrees C. BSG showed shear thinning behavior at all concentrations and temperatures. The Herschel-Bulkley model was employed to characterize flow behavior of BSG solutions at 0.1-1000 s(-1) rate. The pseudoplasticity of BSG increased markedly with concentration. Flow behavior of 1% BSG indicated a higher viscosity of this gum at low shear rates compared to xanthan, konjac and guar gum at similar concentration. The activation energy of BSG quantified using an Arrhenius equation increased from 4.9 x 10(3) to 8.0 x 10(3) J mol(-1) as concentration changed from 0.5% to 2% wt/wt. This indicated a heat-resistant nature of BSG. Increasing the apparent viscosity of BSG as temperature increase from 60 degrees C showed a sol-gel behavior of BSG based on dynamic oscillatory measurements. The static yield stress was obvious between shear rates 0.001-0.1 s(-1) (9.98 Pa for 1% BSG at 20 degrees C). The existence of the yield stress, high viscosity at low shear rates and pseudoplastic behavior of BSG make it a good stabilizer in some food formulations such as mayonnaise and salad dressing. (c) 2010 Elsevier Ltd. All rights reserved.