Novel Cascade Process for Recovery of Valuable Compounds from Tomato Processing Waste, Using Supercritical CO2 and Subcritical Water as Sequential Solvents

Italy stands as the largest producer of tomatoes in Europe, with a total area of approximately 75 thousand hectares dedicated to this crop. The environmental impact of tomato production is a growing concern, with many studies devoted to the carbon footprint associated with different cultivation practices. Pressure on the environment could be alleviated by turning waste from tomato processing into useful products, according to circular economy principles. Among many different substances, tomatoes contain significant amounts of carotenoids (e.g., lycopene) and proteins/peptides. This work proposes and evaluates a novel valorisation route for tomato waste, consisting of supercritical CO2 extraction followed by subcritical water extraction. Such an approach can enhance the recovery of lycopene, with its concentration in the recovered oil reaching 0.66 mg/g, due to its high solubility in lipid-like phases which are efficiently extracted by supercritical CO2. Subcritical water extraction of the residual solids allows the recovery of proteins and peptides.