A comparative assessment of microwave assisted (MAE) and conventional solid-liquid (SLE) techniques for the extraction of phloroglucinol from brown seaweed

Brown seaweeds are rich in polyphenols with a basic building block of 1,3,5-trihydroxybenzene (phloroglucinol) and were investigated as a bioresource for the extraction of polyphenols for biopolymers and bioproducts. Species of seaweed with high contents of polyphenols were identified through meta-analysis and selected for the comparative assessment of the extraction efficiency of polyphenols using microwave assisted (MAE) vs. conventional solid-liquid (SLE) extraction. Out of ten species from Australia and New Zealand screened by SLE, Carpophyllum flexuosum (8.6%) and C. plumosum (7.5%) had the highest contents of polyphenols and were selected for MAE along with commercially available Ecklonia radiata. C. flexuosum was identified as the key species for extraction of polyphenols, with a 70% increase in yield using optimized MAE (aqueous, biomass:solvent ratio 1:30, 160°C, 3 min) compared to SLE. The cell-wall bound fraction of polyphenols in brown seaweed may be larger than previously thought and is accessible through MAE.