Vacuum-assisted headspace solid-phase microextraction for volatile profiling of avocado puree: Application to post-harvest ripening

• Vac-HS-SPME is a powerful tool for post-harvest and quality monitoring of avocados • Vac-HS-SPME improved sesquiterpene extraction and revealed additional analytes • Unripe avocados exhibited richer and cultivar-specific volatile profiles • Sesquiterpene concentrations in the headspace sharply declined during ripening • Hass and Fuerte cultivars showed comparable headspace profiles during ripening Vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) was developed and applied for the first time to monitor free volatile emissions during post-harvest ripening of Hass and Fuerte avocados. The parameters of extraction time and temperature were optimized using 24 analytes identified in unripe Hass puree. Through this optimization, the advantages of vacuum conditions were confirmed by comparing Vac-HS-SPME with conventional headspace solid-phase microextraction (HS-SPME). Vacuum conditions improved the extraction of sesquiterpenes and enabled the unique detection of octanal and (Z)-2-octen-1-ol under milder conditions. Under optimal conditions (30 min at 40°C), Vac-HS-SPME successfully revealed cultivar-specific and ripening-related changes in volatile profiles. At the unripe stage, Fuerte showed higher relative abundances of sesquiterpenes compared to Hass, while (E)-2-heptenal, hexyl acetate and β-bisabolene were detected exclusively in unripe Hass. Ripening was associated with a marked reduction in sesquiterpenes, alcohols, and higher molecular weight aldehydes. The decline of sesquiterpenes is likely driven by the increasing oil content of the mesocarp during ripening, as lipophilic compounds preferentially remain in the lipid matrix rather than partitioning into the headspace. Aldehydes such as hexanal and (E)-2-hexenal became dominant at the ripe stage, and both cultivars displayed similar profiles. Overall, this study demonstrates that Vac-HS-SPME is a powerful and robust method for monitoring volatile changes in avocado ripening, with potential applications in harvest, storage, and quality management.