## 4 Conclusions  
In this study, volatile compounds in the green seaweed _Ulwa_ sp. and the brown seaweed _Laminaria_ sp. fermented by GRAS microorganisms were presented by using HS-SPME and GC-MS. The aromatic profiles of the seaweeds were successfully modified by fermentation, particularly with BS and SC. Categories and total contents of aldehydes were significantly reduced in fermented seaweeds by BS and SC, respectively. Moreover, fermentation with BS could improve ketone content, while fermentation with SC could enhance alcohol content in _Ulwa_ and _Laminaria_. These results are supported by the PCA results, revealing that the ketones in BS fermentation and alcohols in SC fermentation play critical roles in causing differences in the volatile compound profile compared with the unfermented seaweeds. Finally, through GC-O analysis, BS and SC could enhance pleasant odors (e.g., floral, fruits, and sweet) and weaken unpleasant odors (e.g., grassy, fatty, and fishy) from the unfermented seaweeds. This study exhibits the potential of modifying the aromatic profiles of _Ulwa_ and _Laminaria_ by fermentation, including improving pleasant odors and diminishing unpleasant odors. These achievements can expand the potential of utilizing seaweeds for agricultural and food industries.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/fermentation9020135/s1](https://www.mdpi.com/article/10.3390/fermentation9020135/s1)]([https://www.mdpi.com/article/10.3390/fermentation9020135/s1](https://www.mdpi.com/article/10.3390/fermentation9020135/s1)), Figure S1: The viable cell counts of various microbial strains in (A) green seaweed _Ulwa_ sp. and (B) brown seaweed _Laminaria_ sp. during fermentation.  
[PERSON] and [PERSON] conceived and designed the experiments; [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] performed the experiments; [PERSON] and [PERSON] analyzed the data; [PERSON] and [PERSON] wrote the paper. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**Odor Description \({}^{\textbf{a}}\)**} & \multicolumn{3}{c}{**Odor Intensity \({}^{\textbf{b}}\)**} \\ \cline{3-5}  & & **UF** & **BS** & **SC** \\ \hline Unknown 5 & Tea & M & W & W \\ \hline Unknown 6 & Bitter & M & W & W \\ \hline Unknown 7 & Herbal & M & M & M \\ \hline Unknown 8 & Herbal & M & M & W \\ \hline UF: unfermented; BS: _Bacillus subtilis_; SC: _Saccharomyces cerevisiae_. \({}^{\textbf{a}}\) Odor description perceived at the olfactory detection port. \({}^{\textbf{b}}\) The perceived odor intensity was evaluated and recorded using the degree of strong (S), medium (M), and weak (W). & \\ \end{tabular}
\end{table}
Table 4: _Cont._  
**Funding:** This research was funded by the Center of Excellence for the Oceans, National Taiwan Ocean University from the Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan (NTOU-RD-AA-2021-1-02018).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Acknowledgments:** We thank [PERSON] from National Taiwan Ocean University for providing the lactic acid bacteria strains.  
**Conflicts of Interest:** The authors declare no conflict of interest.