## 3 Results and Discussion
### Terpenes and Derivatives
It was the most abundant species in WDF_to, but it was not detected in any of the aged samples, probably because natural limonene is highly unstable and undergoes isomerization and autoxidation [51]. Another monoterpene is linalool (Figure S3), which is typically present in the essential oils of lavender, citrus, jasmine, and rosewood, to which it provides citrus and floral notes. This species undergoes epoxidation, followed by rearrangement, which leads to the formation of trans-linalo oxide. This explains the decrease of linalool and the increase of its oxidized product in the aged samples. B-Terpinene, \(\gamma\)-Terpinene, and \(\alpha\)-Terpineol (Figure S4) are cyclic monoterpenes only present in WDF_to, while isoterpinolene was detected only after 24 months of storage. We do not know whether this analyte is formed over time or if it was already present in WDF_to and had not been identified because of the high complexity of the chromatogram. Although present in modest quantities, they help enrich and complete the aroma of Gavina\({}^{\text{\textregistered}}\) WDF with floral, citrus, and woody notes. Cymene was identified only in WDF_to. It is an aromatic volatile compound that is very common in thyme and oregano essential oils but has been found in more than 100 plants and 200 fruits [1, 50]. It performs various biological functions, and it also possesses anxiolytic, anticancer, and antimicrobial properties, as well as antiviral and antifungal activities [1]. Borneol (Figure S5) is a bicyclic molecule with a fresh and woody fragrance, which was detected in WDF_to and t1 in comparable quantities. As shown in Figure 3, lycopene degradation gives rise to several VOCs, following various degradation pathways. With the term \"citral\", or 3,7-Dimethyl-2,6-ocatdienal, we mean the cis- and trans-mixture of the renal and geranial acyclic monoterpenes, unsaturated aldehydes that impart a \"citrus-like fresh and fruity\" aroma. In nature, they are found mainly in citrus fruits and are exploited in the food and cosmetic industries because of their characteristic pleasant fragrances. However, these are unstable molecules that are sensitive to oxidation [25]. Figure 3: Fragmentation scheme of lycopene and analytes of successive orders. The red line indicates the bond where the fragmentation of the molecule occurs. The highest concentrations of (Z)-3,7-Dimethyl-2,6-octadienal and (E)-3,7-Dimethyl-2,6-octadienal were detected in WDF_t0 (85.4 \(\times\) 10\({}^{6}\) and 89.8 \(\times\) 10\({}^{6}\) on a TIC basis, respectively). These quantities are reduced to approximately a quarter in WDF_t1 (21.6 \(\times\) 10\({}^{6}\) and 24.1 \(\times\) 10\({}^{6}\) for the (Z) and (E) isomer, respectively) and reduced to zero after 24 months of storage. In addition to watermelon, they are also detected in some cultivars of apples, tomatoes, and paprika [2, 29], and more generally, in species containing high levels of lycopene or its precursors [4]. Their formation is probably due to the interaction and subsequent degradation of lycopene with atmospheric [2, 25, 29]. We also identified 2,3-epoxy-geranial, the epoxidation product of citral, previously detected in similar matrices by other authors [25]. It is formed by a mechanism that is easily established in contact with atmospheric oxygen. Furthermore, only in WDF_t0, the citral structural isomer is present, isocitral, in a cis-trans mixture. The most abundant species associated with lycopene degradation was 6-methyl-5-hepten-2-one, which accounted for approximately 17% of the VOCs fraction of WDF_t0, with a TIC abundance of 810 \(\times\) 10\({}^{6}\). It imparts a fruity, waxy, green fragrance with citrus notes, and its abundance tends to decrease strongly (approximately \(-\)70%) after 30 days and remains almost constant over time up to 24 months. Several authors have correlated its formation with the oxidation or degradation of lycopene, \(\alpha\)-farnesene, citral, or conjugated trienols [2, 23, 29].