Effect of alkaline and deep eutectic solvents pretreatments on the recovery of lignin with antioxidant activity from grape stalks

Ana C. Cassoni, Inês Mota, Patrícia Costa, Marta W. Vasconcelos, Manuela Pintado*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Grape stalks are lignocellulosic residues that can be valorized through the extraction of lignin - an underutilized biopolymer with high potential. Two lignin extraction methods, alkaline and deep eutectic solvents (DES), were studied, and experimental designs were carried out to obtain the best extraction conditions. The defined parameters for alkaline extraction allowed the recovery of ~48 % of lignin with low purity that was further improved with an autohydrolysis pretreatment (~79 % purity; ~32 % yield). Optimum parameters of DES method rendered high purity lignin (~90 %) without the need of a pretreatment and with a better yield (50.2 % (±2.3)) than the alkaline method. Both lignin fractions presented high antioxidant activities, being close to the antioxidant capacity of BHT for DPPH scavenging. Structural analysis proved the presence of lignin in both alkaline and DES samples with similar morphology. Overall, DES method was more efficient in the extraction of lignin from grape stalks besides its greener and sustainable nature. This work uses DES to extract lignin from this biomass while comparing it with a commonly classical method, proving that grape stalks can be used to extract lignin with a sustainable and efficient method rendering a final ingredient with value-added properties.

Original languageEnglish
Pages (from-to)406-414
Number of pages9
JournalInternational Journal of Biological Macromolecules
Volume220
DOIs
Publication statusPublished - 1 Nov 2022

Keywords

  • Agro-food residues
  • Antioxidant
  • Lignin

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