Life Cycle Assessment and Circular Economy Evaluation of Extraction Techniques: Energy Analysis of Antioxidant Recovery from Wine Residues

Global wine production reached about 226 million hectolitres in 2024, with Europe as the largest producer. The winemaking industry generates substantial amounts of by-products, presenting both economic and environmental challenges, as approximately 30% of processed grapes are discarded as waste. This study evaluates various polyphenol extraction techniques from wine residues, utilising data from the literature. Techniques assessed include subcritical water extraction, ultrasound-assisted extraction, conventional solvent extraction, and microwave-assisted extraction, each preceded by a suitable pretreatment. Results show that the extraction method, temperature, solvent, and feedstock type have a strong influence on environmental impacts. Microwave extraction from exhausted grape marc had the highest impact due to its low yields and high energy use during freeze drying. In contrast, subcritical water extraction from red wine residues was the most sustainable, benefiting from its high efficiency, use of water as a solvent, and the rich polyphenol content of red grape residues. When included, drying was the primary contributor to greenhouse gas emissions. Climate change and energy demand were key impact categories, with a renewable energy scenario potentially reducing impacts by up to 90%. Results demonstrate that no single extraction method is universally best; choices must balance efficiency and energy use. This work supports optimising sustainable polyphenol recovery within circular economy and climate goals.