Fenugreek seed gum: extraction optimization and evaluation of antioxidant properties

In the present study, optimization of fenugreek gum extraction for maximum values of yield, viscosity, total carbohydrate and minimum value of protein was done using response surface methodology. A central composite design with three independent variables including extraction temperature (25-75 ℃), extraction time (1-4 hr), and water to seed ratio (20-60 ml/g) was used to study the behaviour of variables. ANOVA results showed that second-order polynomial model was the best for interpretation of responses' behaviour. Statistical analysis revealed that all the variables significantly (p0.05). Applying numerical optimization method, optimum extraction conditions were found to be extraction temperature of 60.71 °C, extraction time of 3.33 hr, and water to seed ratio of 44.6 ml/g. At the optimum point, extraction yield, viscosity, total carbohydrate and protein content were evaluated to be 21.18 %, 29.06 m Pa.s, 70.98%, and 4.19%, respectively. Furthermore, the antioxidant activity of the extracted gum at optimum point was evaluated by determining DPPH radical scavenging activity, Ferric reducing antioxidant power (FRAP) and hydroxyl radical scavenging activity. All the above antioxidant evaluation indicated that fenugreek gum exhibited reasonable antioxidant activity in a concentration dependent manner. The fenugreek gum showed 43.23% DPPH radical scavenging activity, 650.76 μΜ FRAP and 46.95 hydroxyl radical scavenging activity at concentration of 1 mg/ml which were 50, 67 and 53.50% of ascorbic acid, respectively.