EUBCE 2026 - Matiss PALS - Catechol-rich Tree Bark Extracts as Biomass-Derived Crosslinkers for Enhanced Gelatin Film Performance

Catechol-rich Tree Bark Extracts as Biomass-Derived Crosslinkers for Enhanced Gelatin Film Performance

Short Introductive summary

This study investigates the potential of aqueous extracts from black alder (Alnus glutinosa) and Baltic pine (Pinus sylvestris) bark as sustainable crosslinking agents to enhance the mechanical properties of gelatin-based biopolymers. Aqueous extraction at 85°C yielded 14.1% and 23.8% (w/w) for alder and pine, respectively. Chemical analysis revealed that black alder extract was exceptionally rich in catechol moiety-bearing compounds (0.70 g·g?¹), primarily oregonin, while pine extract contained 0.50 g·g?¹ of proanthocyanidins. Crosslinking was achieved via oxidation of catechol moieties into o-quinones, which subsequently formed covalent bonds with gelatin amino groups. Mechanical testing demonstrated that 20% black alder extract produced high-stiffness films (Et: 792 MPa; tensile strength: 40 MPa) due to dense crosslinking. Conversely, 20% pine bark extract induced a unique dual effect, acting as both a crosslinker and an internal plasticizer. These pine-modified films achieved an elongation at break of 449% at low glycerol concentrations (10%), a significant advancement over standard biomass-derived films.

M. Pals, Latvian State Institute of Wood Chemistry, Riga, LATVIA
J. Ponomarenko, Latvian State Institute of Wood Chemistry, Riga, LATVIA
M. Lauberts, Latvian State Institute of Wood Chemistry, Riga, LATVIA
K. Radovska, Latvian State Institute of Wood Chemistry, Riga, LATVIA