Microwave hydrodiffusion and gravity: a green extraction technology for phenylethyl isothiocyanate from watercress by-products

• Main Author: Sousa, Ana Sofia
• Publication Date: 2025
• Other Authors: Sousa, Sérgio, Silva, Inês V., Reis, Celso A., Coscueta, Ezequiel R., Pintado, Maria Manuela
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10400.14/53279
• topic: Phenylethyl isothiocyanate – PEITC; Microwave hydrodiffusion and gravity – MHG; Multifactorial optimisation; Microgreens; Freezing process; Solvent-free technology; Antioxidant activity

Watercress is a cruciferous vegetable and the primary natural source of phenylethyl isothiocyanate (PEITC), a powerful health-promoting agent. Conventional extraction of PEITC relies on harmful solvents, which limits sustainability. This study introduces a novel, solvent-free method—microwave hydrodiffusion and gravity (MHG)—to extract PEITC from watercress by-products (WCBP). Results showed that freezing WCBP is fundamental for effective PEITC extraction via MHG. Using a three-level factorial experimental design, optimal MHG extraction conditions were determined (microwave power: 1.91 W g -1 ; extraction time: 29 min), yielding a PEITC content of 1818.26 μg g -1 WCBP (dry basis), along with extracts rich in polyphenols and possessing antioxidant properties. This work demonstrates that MHG is a sustainable method for extracting isothiocyanates, supporting a zero-waste approach since the clean residue from the extraction process can be reused to obtain new ingredients, thus enhancing resource efficiency and promoting a circular economy in the agro-food industry.