Green-sustainable extraction techniques for the recovery of antioxidant compounds from “citrus Limon” by-products

Abstract

In this work, optimized techniques of conventional, ultrasound and microwave-assisted extraction were applied for the recovery of antioxidant compounds from lemon by-products (Citrus limon L). Specifically, the effect of solvent, temperature, microwave power, time and their interaction on the extraction was investigated. Among the tested solvents, the hydroalcoholic mixture (ethanol:water, 50:50) was the optimal one for all extraction techniques: in particular assisted by ultrasounds at 70 °C for 30 minutes (total phenolic content: 6.93 mg GAE g⁻¹, total flavonoids: 2.07 mg CE g⁻¹, ABTS assay: 18.36 µM TE g⁻¹). Also, the other techniques allowed to obtain valuable extracts, although with relative lower amounts. The analyses of individual phenols revealed hesperidin and eriocitrin as the main compounds (respectively about 1650 and 1150 mg kg⁻¹) after ultrasound assisted and conventional extraction. Results of this work can be useful to valorize an industrial by-product by sustainable techniques for the high-added value substances recovery.

Keywords:

• Antioxidant activity
• lemon
• microwave-assisted extraction
• phenolic extract
• UHPLC
• ultrasound-assisted

Acknowledgements

This work was supported by PRIN 2017- GOOD-BY-WASTE. Obtain GOOD products exploit BY products reduce WASTE and by “European Commission, European Social Fund and the Calabria Region”.

Data availability statement

The data that support this study are available from the corresponding author, [ADB], upon request.

C (30′, 70 °C), conventional solid-liquid extraction for 30 minutes at 70 °C; C (120’, 70 °C), conventional solid-liquid extraction for 120 minutes at 70 °C; UAE (30′, 70 °C), ultrasound-assisted extraction for 30 minutes at 70 °C; UAE (120’, 70 °C), ultrasound-assisted extraction for 120 minutes at 70 °C; MAE (5′, 250 W), microwave-assisted extraction for 5 minutes at 250 W.

Funding

The author(s) reported there is no funding associated with the work featured in this article.