Exploring the antioxidant and antimicrobial properties of the water-soluble fraction derived from pyrolytic lignin separation in fast-pyrolysis bio-oil

• Published in: Biomass conversion and biorefinery 2024-10, Vol.14 (19), p.24333-24344
• Main Authors: Dias, Ivana Amorim, Horta, Rayta Paim, Matos, Mailson, Helm, Cristiane Vieira, Magalhães, Washington Luiz Esteves, de Lima, Edson Alves, da Silva, Bruno José Gonçalves, de Muniz, Graciela Ines Bolzon, de Cademartori, Pedro Henrique Gonzalez
• Format: Article
• Language: English
• Subjects: Biotechnology; Energy; Original Article; Renewable and Green Energy
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-023-04561-7

Improving key biomass functionalities necessitates effective liquid-liquid fractionation methods for heavy bio-oil. Here, fast-pyrolysis bio-oil derived from eucalypt wood was fractionated in cold water to separate insoluble and water-soluble fractions. We focus on the water-soluble fraction, a promising renewable source of chemicals with potential antioxidant and antimicrobial approaches. Fast-pyrolysis bio-oil was fractionated in three oil-to-water ratios, 1:100, 1:50, and 1:35, separating the pyrolytic lignin and producing water-soluble fractions as byproducts. The water-soluble fractions were analytically investigated through physicochemical properties, chemical composition by chromatography, phenolic content, antioxidant activity, antimicrobial activity, and their storage stability. Higher water content in the pyrolytic lignin separation resulted in higher yield and higher molecular weight compounds concentration in the water-soluble fractions, with the presence of high-value-added chemicals, such as catechol, vanillin, and levoglucosan. Levoglucosan was the dominant chemical identified in the water-soluble fractions, notably for the 1:50 oil-to-water ratio. These remarkable chemicals and a high phenolic content contribute to both high antioxidant and antimicrobial activities. Despite the low concentration, all water-soluble fractions exhibited intense inhibition of Trametes versicolor and Gloeophyllum trabeum fungi. The fraction 1:50 completely inhibited the fungal activity. Both 1:100 and 1:50 fractions showed antibacterial activity for Escherichia coli and Staphylococcus aureus . Regardless of the oil-to-water ratio, water-soluble fractions exhibited a relative storage chemical stability under accelerated aging conditions for 43 days. Therefore, water-soluble fractions of fast-pyrolysis bio-oil derived from a simple method to separate pyrolytic lignin are functional materials with remarkable antioxidant and antimicrobial properties and, hence, upgrading bio-oil based on their functionalities. Graphical Abstract