Enhancing Lycopene Extraction and Isomer Selectivity From Tomato Pomace: A Study of Particle Size, Drying Technique, and Supercritical Fluid Extraction Processing Variables

The growing demand for functional ingredients and the food industry waste burden have increased interest in recovering valuable compounds, such as lycopene, particularly its bioavailable form (cis), from tomato pomace, a by-product of the tomato industry. Supercritical fluid extraction (SFE) using supercritical CO2 offers an eco-friendly alternative to conventional solvent extraction (SE) methods. This study evaluated the effects of drying method (freeze-drying [FD] vs. oven-drying [OD]), particle size (<0.5 vs. <2 mm), thermal pretreatment (1 h at 120°C), and extraction temperature (50°C vs. 90°C) on lycopene extraction using SFE at 200 bar. A conventional SE with hexane–acetone–ethanol (2:1:1 v/v) was used as a reference. Lycopene yield and cis-isomer content obtained by SE and SFE were quantified using high-performance liquid chromatography. Extraction temperature was the most influential factor: SFE at 50°C yielded significantly more lycopene than at 90°C. At 50°C, lycopene yield increased by approximately 1.6 times with both particle size reduction and thermal pretreatment. FD also enhanced yield, showing a 1.2–1.3-fold increase compared to OD. Although overall lycopene yields were lower with SFE compared to SE, the proportion of cis-isomers was consistently higher in SFE extracts across all treatments. In conclusion, the optimal SFE conditions for lycopene extraction from tomato pomace, balancing high yield and enhanced cis-isomer content, include low extraction temperature (50°C), reduced particle size, thermal pretreatment, and FD.