**Acknowledgements**

[60]. Other strategies have been used to preserve the elderberries' bioactive components or to enhance their nutritional value, as for instance, their processing with pulsed ultraviolet light to enhance the phenolic content [61]. However, no studies were performed so far on mono

Storage time also plays an important role in the mono and sesquiterpenic composition illustrated by the fact that 15 compounds, including rose oxides, hotrienol, linalool, *α*-terpineol, hydroxylinalool, and limonene, partially or completely vanished during storage of dried elderflowers [33]. Cellular disruption might explain the release of volatile compounds in certain postharvest conditions, namely freezing storage [31, 71, 72]. Likewise, the packaging material might affect their profile, being reported that elderflower's tea bags made of aluminum had the highest average concentrations of rose oxide, linalool oxide, nerol oxide, and

Some components, such as hotrienol, were observed to increase during storage of elderflowers, which could be associated with the action of enzymes, such as glucosidases, that unbound the volatile components from glycosides present in the matrix [33]. Non-oxygen-containing structures, that is, monoterpenes and sesquiterpenes, also increased under certain postharvest conditions (**Figure 6**), again assuming that *de novo* biosynthesis of terpenes may play a

The modifications in *S. nigra* terpenic profile upon different postharvest conditions have a significant impact on sensorial characteristics of its products, being linked to a dynamic and complex network of enzymatic and physicochemical phenomena. Understanding the postharvest impact is a step forward to manage and control the production of elderflower and

Plant secondary metabolites play key role in the plants' protection and communication processes. Beyond that, these components, and particularly, mono and sesquiterpenic compounds, are nowadays explored in industrial sectors due to their pleasant aroma characteristics and potential on the prevention and management of human diseases. The exploitation of *S. nigra* L. plant has gained increasing attention in the last decade. Literature highlights that this plant has been used, both, for the formulation of food products and in folk medicine. More recently, herbal supplements and nutraceuticals are also available. Given the diversity of biological activities reported for mono and sesquiterpenic components, as hepatoprotection [12], anti-inflammatory [13], analgesic [14], and antioxidant [15], among others [16], it allows to infer strong potential to foster its economic value. Actually, to go further in that direction, several challenges have to be overcome, namely (1) to indepth know the mono and sesquiterpenic composition, (2) to study the impact of preharvest factors, and (3) to select the appropriate postharvest procedures to preserve bioactive molecules, as elderflower and elderberries seasonality requires handling and storage steps. Quality of crops, specifically elderberries and elderflowers, is a complex concept which could be defined by the yield efficiency, the organoleptic and the nutritional quality [46]. If,

and sesquiterpenic fractions of elderberries.

72 Secondary Metabolites - Sources and Applications

key role in this phenomenon [31, 33].

elderberry formulations [31].

**5. Concluding remarks**

hotrienol, when compared to paper and plastic bags [33].

Thanks to FCT/MEC for the financial support to the QOPNA Research Unit (FCT UID/ QUI/00062/2013), through national funds and where applicable co-financed by the FEDER, within the PT2020 Partnership Agreement. This work was developed within the scope of the project CICECO - Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/ CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. Â. Salvador thanks the grant AgroForWealth: Biorefining of agricultural and forest by-products and wastes: integrated strategic for valorization of resources toward society wealth and sustainability (CENTRO-01- 0145-FEDER-000001), funded by Centro2020, through FEDER and PT2020, and Operational Group Sambucus Valor: integrated valorization of elderberry plant according to the patterns of healthy consumption: from the plant to the formulation of new value-added food products, funded by PDR 2020, Measure 1, "Innovation," Formation of Operational Groups (PDR2020- 101-031117, Partnership no 146/Initiative no 341).
