The potential applicability of Himanthalia elongata fermentation for the production of nutraceuticals

Fermentation is a key biological process in which microorganisms convert carbon-rich substrates into smaller molecules (e.g., organic acids or ethanol) while generating metabolic energy. While extensively applied to terrestrial plant biomass, the fermentation of macroalgae remains relatively unexplored. The brown edible seaweed Himanthalia elongata is a rich source of bioactive compounds with health-promoting properties, making it a promising feedstock for the development of functional ingredients in nutraceutical applications. This review summarizes the biochemical composition of H. elongata and its associated biological activities, with consideration of its holobiont. Lactic acid fermentation is introduced in the context of brown seaweed substrates, together with analytical approaches and monitoring methods. The challenges of H. elongata bioconversion are discussed, including the limited accessibility of key biomolecules, the presence of potential inhibitors, and issues related to the complex seaweed matrix. The intrinsic richness and complexity of H. elongata biomass, along with the adaptive responses of lactic acid bacteria to brown seaweed substrates, present both obstacles and opportunities for fermentation. Optimizing biomass pretreatment, managing endogenous microbiota, and mitigating inhibitory compounds are critical to improve fermentation efficiency and product safety. Moreover, the biological activities of fermented extracts offer valuable prospects for the development of functional foods and nutraceuticals. Overall, this review underscores the need for further research to unlock the full potential of H. elongata as a substrate for lactic acid fermentation and to characterize the properties of the resulting bioproducts.