Species variation in the effects of dewatering treatment on macroalgae

Joe A Gallagher,Jessica M M Adams,Lesley B Turner,Michael K Theodorou,Sara Barrento,Philip W Dyer

doi:10.1007/s10811-018-1420-7

Abstract

Seaweeds can be a valuable resource for biorefinery and biotechnology applications, but their high water content is a recurrent problem and one of the key bottlenecks for their sustainable use. Treatments to increase dry matter content of the kelp Laminaria digitata were recently described by the authors. However macroalgae are an extremely diverse group of organisms and compositional variation between species may influence the effects of particular treatments. In this study, potential dewatering treatments including drying, osmotic media, and the application of both organic and mineral acids all followed by screw-pressing have been tested on two other species of kelp (Laminaria hyperborea and Saccharina latissima) and a red seaweed (Palmaria palmata). Conditions that dewatered these species were identified and the data have been combined with the previous results for L. digitata. There were significant differences between species across all the traits of interest. However dewatering was highly dependent on specific interactions with both treatment and season of collection. Nevertheless, the dry matter content of brown seaweeds was widely and successfully increased by air drying or acid treatment followed by screw-pressing. The results for P. palmata were quite different, particularly with regard to juice production. For this species, acid treatment did not result in dewatering, but dry matter content could be increased by screw-pressing immediately after harvest. Together the data presented here demonstrate that dewatering pre-treatments need to be specific for the type of seaweed to be processed; important knowledge for the future use of this sustainable biomass resource.

Highlights

Macroalgae are a valuable food resource in Asia, in the western world, they have traditionally been used mainly for the extraction of chemicals including hydrocolloids and minerals
Main effect treatment means across all four species were similar to the previous data for L. digitata (Fig. 1)
The only substantial differences observed were for the effects of the mineral acid treatments on fresh weight, water content and final biomass %dry matter (DM) content, and that juice was produced during screw-pressing following more of the treatments

Summary

Introduction

Macroalgae are a valuable food resource in Asia, in the western world, they have traditionally been used mainly for the extraction of chemicals including hydrocolloids (e.g. alginates) and minerals. Many processes have concentrated on obtaining single products but macroalgae have the potential to provide a range of products and by-products, some with high value (Jiang et al 2016). Macroalgae have several advantages over land biomass crops such as sugar cane, soya and corn, as do they not require fresh water, agricultural land, fertilizers and pesticides (Adams et al 2017) but their cultivation can be used to provide valuable ecosystem services (Buschmann et al 2017; Chung et al 2017; Gajaria et al 2017; Raven 2017) such as bioremediation, carbon sequestration and mitigation of ocean acidification. The supply of macroalgae for processing has grown steadily and in the past 14 years

Methods

Results

Discussion

Conclusion