Discriminating Marine Macroalgae by Volatilomic Fingerprint and Bioactivity: A Chemometric Approach

Marine macroalgae are now considered potential sources of renewable feedstocks to produce valuable bioactive compounds. However, the species-specific volatilomes and their correlation with antioxidant capacity remains largely unknown. This study aimed to investigate the volatilomic fingerprint, total phenolic content (TPC), total flavonoids content (TFC) and antioxidant capacity of four macroalgae belonging to distinct taxonomic groups: Rugulopteryx okamurae (brown algae), Asparagopsis taxiformis (red algae), Caulerpa webbiana (green algae), and coralline algae. To achieve this purpose, the volatilomic fingerprint was established using headspace solid-phase microextraction tandem gas chromatography-mass spectrometry (HS-SPME/GC-MS), and the TPC, TFC, and antioxidant capacity were evaluated using in chemico assays. A total of 59 volatile organic compounds (VOCs) were identified across the marine macroalgae, encompassing carbonyl compounds (on average, 40.7 ± 13.4% of total volatilomic fraction), hydrocarbons (17.0 ± 8.3%), organohalogens (23.0 ± 10.8%), terpenoids (6.5 ± 2.0%), alcohols (4.5 ± 2.0%), and the remaining chemical families showed a contribution lower than 5% to the total volatilomic fingerprint. Multivariate statistical analyses revealed significant differences (p < 0.05) in the volatilomic fingerprint among the macroalgae investigated, allowing clear discrimination between species. Organohalogen compounds emerged as key discriminant features for C. webbiana and A. taxiformis algae, while hydrocarbons were characteristic of the R. okamurae. Despite taxonomic differences, hexanal, benzaldehyde and β-ionone were VOCs found across all samples. Regarding bioactivity, R. okamurae exhibited the highest TPC (144 mgGAE/100 g DW), TFC (69 ± 6 mg QE/100 g DW), and antioxidant capacity. These findings confirm the large variability of the volatilomes of the different species of macroalgae and demonstrate the power of the HS-SPME/GC-MS, chemometric, and antioxidant analysis strategy for the differentiation of species and the identification of VOCs with valorization potential, helping to transform invasive or unused biomass of these species into new, sustainable bioproducts through emerging technological and biorefinery applications.