Alternative industrial processing of seaweed meal from Ascophyllum nodosum: Value adding and product development potential of liquid side-streams obtained with different separation methods

Abstract

The brown algae Ascophyllum nodosum is harvested from wild sources and used in seaweed meal production. It contains multiple valuable compounds, including polyphenols, polysaccharides and carotenoids that have bioactive properties. In current uses of biomass e.g. as raw material for alginate production, these compounds are not of any special interest, hence there is an opportunity for better utilization of the biomass. Therefore, the aim of the study was to investigate the potential of producing and upscaling production of a byproduct (a targeted seaweed extract produced with mixture of fresh seaweed and water) from the unutilized liquid side-streams obtained within traditional seaweed meal processing. That was performed by evaluating the efficiency of the liquid/solid separation (screw press vs decanter), centrifugation as a secondary separation step, as well as drying methods (spray drying vs freeze drying) on the obtained liquid extracts. Chemical and antioxidant properties were evaluated throughout the alternative processing and mass balances calculated. The results suggest that the decanter was more efficient for separation compared to the screw press due to higher yield of liquid retrieved. The chemical composition and antioxidant properties did not differentiate significantly, neither between the separation methods nor during further processing of the liquids (e.g. centrifugation or drying methods). Furthermore, the alginate remained in the solid phase during separation, and main components extracted with the liquid phase included salt, minerals, polyphenols, and carbohydrates. The results indicate that alternative processing with a decanter as primary separation step could be a feasible solution to meet the demands of full utilization and no-waste policies within seaweed production.