Optimization of mucilage extraction conditions from Plantago major L. seed using response surface methodology

Identification of a new source of hydrocolloids is of interest due to their important effects on the textural attributes of food products. The objective of this study was to investigate the extraction conditions of Plantago major L. seed mucilage using a central composite rotatable design of response surface methodology. Temperature (25–85°C), pH (3–9) and water to seed ratio (50:1-50:4) were the factors investigated. Results showed that temperature was major factor in the extraction yield, whereas water to seed ratio and pH had minor effects on the yield. The maximum and minimum yields were 18.95% (conditions: temperature= 85 °C, water to seed ratio = 31.3 and pH= 6) and 6.35% (conditions: temperature = 25 °C, water to seed ratio= 31.3 and pH= 6), respectively. The optimal conditions were obtained at the temperature of 60 °C, water to seed ratio of 48.9 and pH of 3 in which predicted value for the 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 300s-1. Mucilage dispersions showed non-Newtonian shear-thinning behavior at all studied concentrations. The Power law model well described the rheological behavior of the mucilage 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. Overall, Plantago major L. seed mucilage could be attended as a new beneficial source for use as a food thickening agent.