Microwave hydrolysis, as a sustainable approach in the processing of seaweed for protein and nanocellulose management

Anna Trubetskaya*, Huy Quang Lê, Jenni Leppiniemi, Tetyana Koso, Teemu Välisalmi, Markus B. Linder, Italo Pisano, Jinze Dou, J. J. Leahy, Eero Kontturi*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

The nature of marine biomass is very complex for a material scientist due to the large seasonal variation in the chemical composition that makes it difficult to prepare standardized products. A systematic investigation of the interaction of microwave irradiation with seaweed from Norway and Caribbean region was performed, covering a broad temperature range (130 → 170 °C) and without and with addition of ℽ-valerolactone (GVL) in ratios of 1:4 and 1:2. The temperatures above 150 °C and without addition of GVL led to the closure of mass balances up to 90 % that includes polysaccharides, “pseudo-lignin” fraction, fatty acids, and proteins. Fucoidan and mannose represented >50 % of all detected polysaccharides in ascophyllum nodosum (AN), while aegagropila linnaei (AL) contained mostly glucose. The presence of arabinose and rhamnose in the upper surface of the cell wall hinders the glucose release during microwave treatment. The differences in the polysaccharide composition among both algae samples hindered the definition of a parameters set that can be used in microwave treatment of various seaweed species. A large fraction of protein (> 95 %) remained in the seaweed solid residue. Higher amount of protein was determined in AL, which was dominated by leucine and lysine. Another potential barrier to the application of seaweed in industry is the limited knowledge on the chemical composition of “pseudo-lignin” and extractives. The total amino acid analysis was identified as the most accurate to characterize the protein yield and composition. The results showed that microwave treatment of seaweed is indeed a viable method for producing bioactives in the temperature range 120–150 °C, and proteins and nanocellulose at temperatures above 170 °C without using GVL. The microwave temperature and seaweed type played a dominating role in the mass closure balances leading to >95 % identified compound.

Original languageEnglish
Article number103406
Number of pages11
JournalAlgal Research
Volume78
Early online date26 Jan 2024
DOIs
Publication statusPublished - Mar 2024
MoE publication typeA1 Journal article-refereed

Keywords

  • Alginate
  • Cellulose nanocrystals
  • Microwave hydrolysis
  • Protein
  • Seaweed

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