Simultaneous extraction and separation of bioactive compounds from apple pomace using pressurized liquids coupled on-line with solid-phase extraction

The objective of this work was the development of an on-line extraction/fractionation method based on the coupling of pressurized liquid extraction and solid-phase extraction for the separation of phenolic compounds from apple pomace. Several variables of the process were evaluated, including the amount of water of the first stage (0–120 mL), temperature (60–80 °C), solid-phase extraction adsorbent (Sepra, Isolute, Strata X and Oasis) and activation/elution solvent (methanol and ethanol). The best results were observed with the adsorbent Sepra. The temperature had a small effect on recovery, but significant differences were observed for phlorizin and a quercetin derivative. Results indicate that ethanol can be used to replace methanol as an activation, extraction/elution solvent. While using mostly green solvents (water, ethanol, and a small amount of methanol that could be reused), the developed method produced higher or similar yields of acids (2.85 ± 0.19 mg/g) and flavonoids (0.97 ± 0.11 mg/g) than conventional methods.