Optimizing antioxidant and thermal stability in olive mill wastewater through Hydroxypropyl-β-Cyclodextrin complexation: A comprehensive study

The study investigates the enhancement of thermal stability and antioxidant activity of olive mill wastewater (OMWW) by complexing it with hydroxypropyl-beta-cyclodextrin (HP-β-CD) in different molar ratios (1:1, 1:2, and 1:3). OMWW is rich in phenolic compounds with significant antioxidant properties but suffers from low bioavailability and thermal sensitivity. The inclusion complex formation was assessed using FT-IR, XRD, and DSC analyses. FT-IR results showed the disappearance of OH stretching vibrations in the 1:2 molar ratio complex, indicating successful interaction. XRD confirmed the absence of OMWW's characteristic peaks, and DSC revealed that the melting point of OMWW increased from 192.3 °C to 211.1 °C, 228.0 °C, and 224.7 °C for the 1:1, 1:2, and 1:3 ratios, respectively, demonstrating improved thermal stability. The 1:2 molar ratio complex exhibited the highest antioxidant activity and phenolic content. SEM and ¹H NMR spectroscopy further validated the successful formation of the inclusion complex. The OMWW/HP-β-CD complex, especially at the 1:2 ratio, shows promise for use in pharmaceutical products and fortified foods due to its enhanced stability and antioxidant properties.