Dedicated microwave extraction allows uniform energy distribution to efficiently solubilize Ascophyllum nodosum

Abstract

Considering the current transition to biobased carbon sources and the search for viable extraction procedures, the microwave-assisted solubilization of seaweed biomass was explored. Hereto, the brown North Sea native species Ascophyllum nodosum was processed using water as green extraction solvent. Response surface methodology was used to determine the best solubilization conditions towards maximizing the solubilization efficiency and minimizing the applied energy per mass of solubilized seaweed by varying (i) temperature, (ii) time and (iii) solid to liquid ratio (S/L). It was found that a temperature of 120°C, a processing time of 15min and a 1.03 w:v S/L are most suitable to achieve the pre-set criteria. Concurrently, mass balances were developed with respect to total lipid, polysaccharide, protein, mineral and heavy metal contents. Moreover, zeta potential measurements were performed to link the obtained values and the antimicrobial characteristics of the extracts. Finally, antimicrobial tests on S. aureus and E. coli were conducted and with results indicating up to 97% inhibition of bacterial growth after 8h, antimicrobial characteristics were indeed observed.