Optimisation of microwave-assisted extraction of flavonoids and phenolics from celery (Apium graveolens L.) leaves by response surface methodology

Abstract

The conditions for microwave-assisted extraction (MAE) of total flavonoids (TF) and total phenols (TP), and antioxidant activity from celery (Apium graveolens L.) leaves by response surface methodology (RSM) were optimised. The 3-level, 3-factorial Box-Behnken design (BBD) was employed to study three main extraction conditions: microwave power (300–500 W), solid-solvent ratio (15–30 ml/g), and ethanol concentration (50–80%). It was found that microwave power of 500 W at 30 ml/g solid-solvent ratio with 75.6% (v/v) ethanol concentration was the most optimum conditions for the extraction of TF and TP from celery leaves with the consequent high antioxidant activity measured by the DPPH inhibition rate. Using the optimum extraction conditions, the extraction yields of TF and TP were 0.62 g RUE/100 g DW, 3.01 g GAE/100 g DW, respectively, and the DPPH inhibition rate was 88%. The results indicated that the nutritional quality of celery (Apium graveolens L.) leaves could be improved significantly by optimising the extraction process of MAE using response surface methodology.