Marine Macroalgae Waste from Northern Portugal: A Potential Source of Natural Pigments?

Abstract

Marine macroalgae waste, which results from the accumulation of drifted marine macroalgae at the beaches, was studied as an alternative source of natural pigments. For that, macroalgae waste was collected in a Northern Portugal beach, dehydrated using different procedures (freeze-drying, oven-drying and sun-drying), physiochemically characterized and after subjected to the chemical extraction of pigments. Six solvents and different amounts of biomass were studied, and the pigments quantification was made by UV spectrophotometry. Saccorhiza polyschides (brown algae) was the most represented species in the collected biomass. The differences found in the biomass characterization under different dehydrating conditions were not relevant. The obtained results showed marine macroalgae waste as a promising source of natural pigments and acetone was the best solvent for extraction, followed by methanol. Chlorophyll a was the predominant pigment found, regardless the dehydrating conditions employed. Freeze-dried biomass had significantly higher pigments concentrations (1685 μg chlorophyll a g−1; 174 μg carotenoids g−1; 252 μg fucoxanthin g−1) and there were no differences comparing the concentration of chlorophyll a from oven-dried and sun-dried biomass; however, between them, concentration of carotenoids was higher for oven-dried biomass (125 μg g−1), and fucoxanthin concentration was higher for sun-dried biomass (25 μg g−1).