Comprehensive characterisation of marine macroalgae waste and impact of oil extraction, focusing on the biomass recovery potential

Abstract Marine macroalgae waste was fully characterised considering the raw biomass as well as the extracted lipids and the remaining solid fraction, to provide information concerning the potential of these products to be incorporated in the economic sector. The characterisation of the biomass before (S1) and after (S2) oil extraction showed minor differences, especially due to the low lipid content of the raw biomass (0.30%). Both solid fractions have potential for agricultural applications due to their high mineral (S1: 15.39 wt%; S2: 18.26 wt%) and fiber (S1: 64.0 wt%; S2: 57 wt%) contents, combined with the low phenolic content (S1: 139 mg GAE/100 g; S2: 120 mg GAE/100 g). In addition, the high estimated carbohydrate content of the solid biomass (S1: 69.3 wt%; S2: 65.7 wt%) shows that the production of renewable fuels such as biogas or bioethanol could be explored. Lipids extraction for biodiesel production appears to be unfeasible not only due to the low lipid content but also due to their high acidity and low oxidation stability. However, considering the vitamin E content (85 mg/100 g of oil) and the quality of fatty acids (monounsaturated fatty acids: 19.33% and polyunsaturated fatty acids: 26.31%), the application in fish diets might be a relevant route to be further explored.