Preliminary Investigation of Different Drying Systems to Preserve Hydroxytyrosol and Its Derivatives in Olive Oil Filter Cake Pressurized Liquid Extracts López Salas, Lucía Cea, Inés Borras Linares, María Isabel Emanuelli, Tatiana Robert, Paz Segura Carretero, Antonio Lozano Sánchez, Jesús Olive oil by-products Hydroxytyrosol PLE Freeze-drying Spray drying HPLC-MS Bioactive compounds Phenolic compounds present in extra virgin olive oil (EVOO) could be retained in its byproducts during processing. Among them, hydroxytyrosol and its derivatives deserve special attention due to their health benefits recognized by The European Food Safety Authority (EFSA). In the present research, the presence of these compounds in the filter cake byproduct was studied by combining pressurized liquid extraction (PLE) and high-performance liquid chromatography coupled to time-of-flight mass spectrometry (HPLC-TOF-MS). The applied optimum extraction parameters were 1500 psi, 120 ◦C and aqueous ethanol (50:50, v/v). The influence of different drying methods (vacuum-, freeze- and spray-drying) in the recovery of phenolic compounds was also evaluated. A total of 16 compounds from EVOO were identified in the extracts, 3 of them being hydroxytyrosol-related compounds, 6 substances of oleoside and elenolic acid derivatives, together with 6 secoiridoids and 1 lignan. The results highlighted the great number of phenolic compounds recovered from filter cake with these techniques, being even higher than the reported content in EVOO and other byproducts. The combination of PLE and freeze-drying resulted in being the best procedure for the recovery of phenolic compounds from filter cake byproduct 2021-07-01T10:56:06Z 2021-07-01T10:56:06Z 2021 info:eu-repo/semantics/article López-Salas, L.; Cea, I.; Borrás-Linares, I.; Emanuelli, T.; Robert, P.; Segura-Carretero, A.; Lozano-Sánchez, J. Preliminary Investigation of Different Drying Systems to Preserve Hydroxytyrosol and Its Derivatives in Olive Oil Filter Cake Pressurized Liquid Extracts. Foods 2021, 10, 1407. https:// doi.org/10.3390/foods10061407 http://hdl.handle.net/10481/69458 10.3390/foods10061407 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España MDPI