Basil seed (Ocimum basilicum L.) is cultivated in large quantities in different regions of Iran. This seed has reasonable amounts of gum with good functional properties which is comparable with commercial food hydrocolloids. A central composite rotatable design was applied to evaluate the effects of temperature, pH and water ⁄ seed ratio on the yield, apparent viscosity and protein content of water-extracted Basil seed gum. All of the variables significantly (P < 0.05) affected the extraction yield, whereas the effect of water ⁄ seed ratio on apparent viscosity and the effects of pH and water ⁄ seed ratio on protein content were not significant (P > 0.05). Numerical optimisation determined the optimum extraction conditions based on the highest yield and viscosity and the lowest protein content as being temperature 68.71 C, pH 8.09 and water ⁄ seed ratio 65.98:1. Power law model well described non-Newtonian pseudoplastic behaviour of BSG. Flow behaviour index (n) and consistency index (K) of 1% crude and pure BSG samples were 0.306, 0.283 and 17.46, 20.22 Pa sn, respectively.

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