Structural Properties\nof Globulin: A Critical Parameter\nfor Sunflower Meal as Wood Panel Adhesives

Alternative biobased adhesive formulations are currently\nbeing\ninvestigated to replace urea-formaldehyde (UF) as wood panel adhesives.\nIn this regard, oilseed meals are valuable alternatives, as it is\nanticipated that the sticky potential of these meals is linked to\ntheir protein content. This work focuses on the protein parameters\n(primary and/or secondary structures) that could impact the adhesiveness\nof sunflower meals. The proteins contained in these meals were first\nseparated from the other components and identified using electrophoresis.\nOilseed meals contain several families of proteins: globulins, albumins,\nprolamins, and oleosins. Sunflower meal is mainly composed of globulin\n(53%) and albumin (45%). The protein structures have then been either\noxidized with H<sub>2</sub>O<sub>2</sub> (in the presence or not of\nNaOH) or physically treated by microwave (MW). The oxidation treatment\ncleaves the protein backbone and creates smaller peptides, while the\nMW process converts α-helices into random coils. The adhesive\npotential of these treated proteins was evaluated by using shear tests\nonto wood panels. The results demonstrate that the primary and secondary\nstructures of globulins are key parameters toward the sunflower protein\nmeal adhesivity.