Optimization Of Total Phenolic Content And Antioxidant Capacity From The Extract Of Thai Basil (Ocimum Basilicum Var. Thyrsiflora) Leaves With The Aid Of Microwave By Using Response Surface Methodology

Abstract

In this study, the microwave-assisted extraction variables were optimized using a Box-Behnken design of response surface methodology for the optimal values of DPPH antioxidant capacity and total phenolic content of Thai basil (Ocimum basilicum var. thyrsiflora) leaves. The independent variables were ethanol content (10-70 %), microwave power level (80-800 W), and extraction time (2-12 min). The results showed that the optimum conditions were analysed with 37% ethanol in water, microwave power of 435 W for 7 min. The value of R2 and adjusted R2 were > 0.98, indicating the good fitting of the models. These optimum conditions were applied to obtain the predicted antioxidant capacity of 302.77 μmol Trolox/g dry weight of sample and the total phenolic content of 41.64 mg GAE/g dry weight of sample. Meanwhile, the experimental values were 300.15 ± 2.31 μmol Trolox/g dry weight of sample and 39.41 ± 0.87 mg GAE/g dry weight of sample, respectively. There were no significant differences between the predicted and experimental values. This implies that the experiment design of Box-Behnken design and response surface methodology is suitable in optimization of extraction process.