Polyphenol extraction from industrial water by-products: a case study of the ULTIMATE project in the fruit processing industry

This study investigates the sustainable management and utilization of water resources in the fruit processing industry, focusing on a case study from the EU-funded ULTIMATE project. Conducted in a juice factory in Nafplio, Greece, the primary objective is to explore the recovery of polyphenols from water by-product streams generated during orange juice production. The research aims to evaluate the effectiveness of a mobile wastewater treatment unit in selectively adsorbing polyphenols onto a polymeric resin. The following three extraction methods are compared: conventional solvent extraction, subcritical water extraction (SWE), and supercritical CO₂ extraction (SFE). To determine the most efficient extraction method, the polyphenol profiles of the extracts were analyzed using UHPLC-Q-Orbitrap-MS/MS, identifying flavonoids, terpenes, coumarins, and anthocyanins. SFE not only was the most efficient method but provided the most diverse and abundant profile. The research highlights the potential of converting industrial by-products that would otherwise be treated as wastewater, into valuable resources that generate revenue, promote circular economy practices, and enhance sustainability in the fruit and vegetable processing sector. The economic viability of polyphenol extraction is also discussed, emphasizing its significance and impact on various industries. The findings support integrating advanced extraction technologies to maximize resource recovery and minimize environmental impact.