## 4 Discussion
### Chemical Characterization
[128] conducted a study to examine the impact of dry (6% moisture) and semi-dry (20% moisture) storage on the red seaweed _Palmaria pulmata_ for 126 days. Similar to the observations for PU, heptadecane initially decreased until approximately halfway through the storage period, after which it exhibited an upward trend, whereas both (_E,E_)-2,4-heptadienal and (_E,Z_)-2,6-nonadienal appeared to increase in the processed seaweeds. Furthermore, 1-octen-3-ol, a significant component in PU characterization, demonstrated an increase over the storage period, which in our case was only observed for PU stored under vacuum conditions. In a study conducted by [PERSON] et al. [79], aiming to investigate the changes in VOCs in _Ulva_ _rigida_ during a 12-day storage period at 4 \({}^{\circ}\)C or 16 \({}^{\circ}\)C, it was observed that 1-octen-3-ol increased throughout the storage period, while 2,4-heptadienal initially exhibited an increase but subsequently showed a decreasing trend towards the end of the storage period, which is also consistent with our findings. In contrast to our study, where benzaldehyde, hexanal and 2-heptenal exhibited an increase, the research indicated that benzaldehyde, hexanal and 2-heptenal decreased during the storage period. However, in our case, hexanal showed some oscillation, with a decrease observed only in the MAP treatment. Furthermore, relevant compounds, such as 2,4-decadienal or 8-heptadecene, were absent in their characterization of _U. rigida_. The differences in the findings between our research and [PERSON] et al. can be attributed to the fact that the seaweeds in the above-mentioned study were subjected to freeze-drying during sampling, which may have promoted the loss of important VOCs. Although there were some variations in VOCs, it is important to emphasize that no significant alteration in the distinctive aroma of the seaweed appeared to have occurred. [PERSON] et al. [129], in their study regarding the characterization and differentiation of seaweeds based on their volatile composition, concluded that changes in VOCs tend to be more pronounced in relation to factors such as collection site, seasonal variations, and species differences, rather than changes resulting from pretreatments (preservationtechniques). Furthermore, VOCs normally associated with the \"fishy\" aroma, which often leads to sample rejection by evaluation panels, seemed to decrease with storage time [130]. Additionally, compounds associated with pleasant aromas (e.g., benzaldehyde and pentadecanal) increased. These changes can be interpreted as being indicative of an improvement in the organoleptic properties of the treated seaweeds. To confirm the key odorous components that contribute to the typical aroma of _P. umbilicalis_ and _U. lactuca_, additional research is needed, employing techniques such as gas chromatography coupled with olfactometry (GC-O) and sensory analysis. These methods would help in screening and determining the essential compounds responsible for the distinctive fragrances associated with these seaweed species, as well the remarkable changes throughout the storage period. The results allowed for the conclusion that both the MAP and VAC treatments appeared to be more efficient in maintaining the organoleptic properties of UL compared to PU, with no significant differences throughout the storage days. Despite the wide variety of VOCs identified by GC-TOF-MS, the PCA demonstrated that a few compounds could explain most of the variation in the samples of both seaweeds. Some of these compounds did not necessarily have any relevant impact on the sensory properties of PU and UL, and their generation was related to wound-healing processes and to the microbiome present in the seaweeds.