Optimization of gum extraction conditions from Plantago major L. seeds using response surface method

The extraction of Plantago major L. seed mucilage was investigated using a central composite rotatable design of response surface methodology. The temperature was major factor in the extraction yield, whereas water to seed ratio and pH had minor effects on this parameter. The maximum and minimum yields were measured 18.95% and 6.35% at conditions of temperature, 85 °C; water to seed ratio, 31.3 and pH 6 and temperature, 25 °C; water to seed ratio, 31.3 and pH 6, respectively. The optimal conditions were obtained at the temperature, 60 °C, water to seed ratio, 48.9 and pH 3, that predicted value for extraction yield was 11.84%. The rheological properties of the mucilage extracted at the optimal conditions were investigated as a function of concentration at three levels of 3, 4, and 5 % w/v, and shear rate ranged from 14 to 300 s-1. Gum dispersions showed non-Newtonian shear-thinning behavior at all concentrations studied. The power law model well described the rheological behavior of the gum solutions with high determination coefficients (r2>0.99). The flow behavior index (n) varied in the range of 0.30 to 0.36. The consistency coefficient (k) was in the range 6.13-17.81 Pa.sn.