SUSTAINABLE VALORIZATION OF TOMATO WASTE THROUGH LIFE CYCLE ASSESSMENT OF LYCOPENE EXTRACTION METHODS

Abstract

Tomato processing produces substantial quantities of residues that constitute both an environmental challenge and a potential resource for recovery. This study assessed the environmental performance of four lycopene extraction strategies from tomato discards through a Life Cycle Assessment approach. Conventional and ultrasound-assisted extractions were compared with either a hexane:acetone:ethanol (50:25:25, v/v) mixture or ethyl acetate as solvent, defining four scenarios: Scenario 1 (C-HAE, conventional extraction with hexane:acetone:ethanol); Scenario 2 (C-EA, conventional extraction with ethyl acetate); Scenario 3 (U-HAE, ultrasound-assisted extraction with hexane:acetone:ethanol); Scenario 4 (U-EA, ultrasound-assisted extraction with ethyl acetate). The functional unit was defined as 1 kg of lycopene-equivalent extract. Environmental impacts were calculated with the ReCiPe 2016 Midpoint (H) method, considering eighteen impact categories. Scenario 4 exhibited the lowest environmental impact (117.3±27.6 mg/100g of lycopene yield; 1187.9±103.5 µg Txeq/gww) whereas Scenario 2 the highest, with the lowest lycopene yield (18.6±18.5 mg/100g) but the highest antioxidant capacity per unit of lycopene. A sensitivity analysis based on the antioxidant activity-to-lycopene ratio confirmed Scenario 4 as the most favorable option. Beyond energy efficiency and solvent selection, the extraction process also affected lycopene isomerization: ultrasound-assisted methods promoted Z-isomers formation over E- ones, with increases of 41% for the hexane:acetone:ethanol solvent mixture and 140% for ethyl acetate. Since Z-isomers are more bioaccessible and display comparable or higher antioxidant activity than E- isomers, this shift may further enhance the functional value of the recovered pigment. Overall, combining green solvents with ultrasound technologies can reduce the environmental burdens and support sustainable valorization of tomato waste.