Changes in bioactive and aroma compounds in flower elderberry as affected by innovative drying method

Elderberry (Sambucus nigra) flowers are a rich source of flavonoids, polyphenols, higher terpenoids, sterols, essential oils and fatty acids, widely used in the food, pharmaceutical and cosmetic industries. However, the effect of drying method on the composition of essential oils remained unexplored. This research aimed to evaluate the effect of different drying methods (convective drying, vacuum microwave drying, microwave convective drying, vacuum drying and freeze drying) on the content and profile of the bioactive compounds mentioned above. The analytical method used in the study was validated for accuracy, precision and repeatability, ensure results reliability. Concerning volatile compounds, the importance of defining targeted compounds was highlighted, since the studied groups of volatile compounds show different relationships in the context of the drying methods. The highest retention on volatiles was obtained in microwave-convection drying in variants 60°C+ 360 W and 40°C+ 120 W. Highest volatile loses (58 %) where observed in freeze-drying process, identifying this drying method as the most unsitable method in terms of extraction yield. Predominated polyphenolic compounds where 3,5-O-dicaffeoylquinic acid, chlorogenic acid and rutin. Polyphenols, flavonoids and sterols contents remained stable at lower temperatures, while the fatty acid profile, dominated by palmitic, linoleic and α-linolenic acids, remained relatively constant regardless of the drying method used. Across all drying conditions, no significant quantitative or qualitative alterations were observed in polyphenols, sterols, triterpenoids, or fatty acids. The high stability of non-volatile bioactive compounds across all drying methods underscores the potential of elderberry flowers as a valuable raw material for applications in the food, pharmaceutical, and cosmetic industries. Among the tested techniques, convective drying at moderate temperature and low-power vacuum-microwave drying proved to be the most effective in preserving both non-volatile and selected volatile constituents.