Optimization of subcritical water extraction of antioxidants from Coriandrum sativum seeds by response surface methodology

Abstract

Subcritical water extraction (SWE) of antioxidants from Coriandrum sativum seeds (CSS) was optimized by simultaneous maximization of the total phenolics (TP) and total flavonoids (TF) yield and antioxidant activity, using IC50 value. Box–Behnken experimental design (BBD) on three levels and three variables was used for optimization together with response surface methodology (RSM). Influence of temperature (100–200°C), pressure (30–90bar) and extraction time (10–30min) on each response was investigated. Experimentally obtained values were fitted to a second-order polynomial model and multiple regression. Analysis of variance (ANOVA) was used to evaluate model fitness and determine optimal conditions. Moreover, three-dimensional surface plots were generated from employed mathematical model. The optimal SWE conditions obtained in simultaneous optimization were temperature of 200°C, pressure of 30bar and extraction time of 28.3min, while obtained values of TP and TF yields and IC50 value at this experimental point would be 2.5452g GAE/100g CSS, 0.6311g CE/100g CSS and 0.01372mg/ml, respectively. Moreover, good and moderate linear correlation was observed between antioxidant activity (IC50 value) and total phenolics content (R2=0.965), and total flavonoids content (R2=0.709) which indicated that these groups of compounds are responsible for antioxidant activity of C. sativum extracts.