French Brittany macroalgae screening: Composition and methane potential for potential alternative sources of energy and products

•P. palmata, G. verrucosa, U. lactuca and U. pinnatifida are attractive for human consumption.•The biochemical composition of P. palmata is favorable for anaerobic digestion.•The best algae for alginate extraction are S. polyschides and S. latissima. Macroalgae are biomass resources that represent a valuable feedstock to be used entirely for human consumption or for food additives after some extractions (mainly colloids) and/or for energy production. In order to better develop the algal sector, it is important to determine the capacity of macroalgae to produce these added-values molecules for food and/or for energy industries on the basis of their biochemical characteristics. In this study, ten macroalgae obtained from French Brittany coasts (France) were selected. The global biochemical composition (proteins, lipids, carbohydrates, fibers), the presence and characteristics of added-values molecules (alginates, polyphenols) and the biochemical methane potential of these algae were determined. Regarding its biochemical composition, Palmaria palmata is interesting for food (rich in nutrients) and for anaerobic digestion (0.279LCH4/gVS). Saccharina latissima could be used for alginate extraction (242g/kgTS, ratio between mannuronic and guluronic acid M/G=1.4) and Sargassum muticum for polyphenol extraction (19.8g/kgTS).