Valorization of long-neglected spruce bark and bark-press effluents through integrated utilization of stilbenoids and pectin

Abstract

Wood bark has exclusively been used for energy at pulp mills, while long-neglected, this huge biomass resource has great potential for valorization. To maximize its value in new ways, here we propose using both fresh (industrial) spruce bark and its bark-press effluents as sustainable sources of natural stilbenoids and pectin. Ultrafiltration removed approximately 90% of the high molecular weight polyphenols as well as enriched stilbenoids from bark-press effluents. Based on a techno-economic analysis, the forest industry would obtain greater revenue potential up to €100 per ton of bark by processing bark side streams compared to their traditional combustion-based strategy if implementing the improved debarking technology. Overall the valorization of stilbenoids and pectin from bark-press effluents or spruce bark offers a promising strategy to produce bio-based, high-value UV-filter ingredients as alternatives to fossil-based ones, and high-grade pectin in an economic feasible and potentially environmentally friendly bolt-on process to the existing mills.