Use of lignin as additive in polyethylene for food protection: Insect repelling effect of an ethyl acetate phenolic extract

Lignocellulose biorefinery processes, including the separation of plant cell-wall components, generate lignin-rich streams referred to as “lignin fractions”. Three lignin fractions with different phenol group content were dry blended with high density polyethylene (HDPE) and further extruded. The materials obtained were subsequently tested for their mechanical properties which were little affected even with 5wt% of lignin. The lignin fraction with the highest phenol group content, an ethyl acetate extract (EAL) from a technical soda lignin, showed the best performance when blended with HDPE. Besides antioxidant and antimicrobial properties (especially on S. Aureus) competing with other natural extract, the fraction conferred to the material insect repellent properties towards two types of insects, an invader (Sitophylus oryzae) and a penetrator (Plodia interpunctella). These combined properties make films made out of this material ideal candidates for protecting food that suffers attack from such insects.