Extraction optimization of a hydrocolloid extract from cress seed (Lepidium sativum) using response surface methodology

Extraction conditions for maximum values of yield, viscosity and minimum protein content of hydrocolloid extract from Lepidium sativum seed were investigated using response surface methodology. A Central Composite Face Design (CCFD) with four independent variables: temperature (25–85 °C); pH (3–10); extraction time (10–25 min) and water to seed ratio (10:1–80:1) was used to study the response variables (yield, viscosity and protein content). Data analysis showed that all the variables significantly (p < 0.05) affected the extraction yield and viscosity, whereas the effect of water to seed ratio on protein content was not significant (p > 0.05). Applying a desirability function method the optimum parameters were: extraction temperature 35 °C, pH 10, water to seed ratio of 30:1 and an extraction time of 15 min. At this optimum point, apparent viscosity, yield and protein content were 0.2 Pa s, 6.46% and 0.57%, respectively. The experimental values were very close to the predicted values and were not statistically different (p > 0.05).