α-Cyclodextrins for stability enhancement of bioactive-rich tomato oil extracted with supercritical CO2: Emulsion performance under thermal and UV-C treatments

Supercritical CO2 (SC-CO2) extraction offers a sustainable method for obtaining solvent-free oils rich in bioactive molecules, valuable for nutraceutical and functional food products. However, the limited stability of certain extract components can hinder their application. This study explores α, β, and γ cyclodextrins (CDs) as emulsifiers to enhance SC-CO2-extracted tomato oil (TO) stability. TO/CD emulsions with high oil volume fractions (φ) of 60 %, 65 %, 70 %, and 75 % were prepared using the three types of CDs. Only α-CDs formed gel-like, stable emulsions up to φ = 70 %. Confocal microscopy revealed that increasing φ led to morphological changes, including reduced droplet size, decreased roundness, and larger coalescence zones, affecting stability and functionality. Emulsions at φ 60 % showed optimal performance with reduced phase separation, high viscosity, smaller droplet size, and lower coalescence. The stability of carotenoids and tocopherols was evaluated under heat (50 °C) and UV-C exposure to simulate accelerated aging and sterilization. Emulsions improved carotenoid stability at elevated temperatures compared to bulk TO. Tocopherols were highly stable in bulk TO and moderately stable in TO/α-CD emulsions. Under UV-C exposure, TO/α-CD emulsions enhanced carotenoid and tocopherol stability for up to 9 h, compared to pure TO. Further analysis with α-CDs and synthetic glyceryl trioctanoate (GTO) at φ = 60 %, 65 %, and 70 % replicated the concentrations of lycopene and α-tocopherol in TO. These results suggest that TO/α-CD emulsions can serve as stable, high-quality ingredients for nutraceutical and functional food applications.