Cascading Biorefinery of Araucaria angustifolia Residues: From Biomass Characterization and Green Processing to High-Value Bioproducts

Abstract

Araucaria angustifolia residues arise from a seasonal and geographically dispersed value chain. Brazilian pinhão production increased from 8393 t in 2015 to 13,493 t in 2024, corresponding to a theoretical 2699–2969 t of seed coats based on their 20–22% share of seed mass. No equivalent national inventory exists for sterile bracts or cooking water. Seed coats contain approximately 55% cellulose, 9% hemicellulose, 34% lignin, 7% extractives, and 1.6% ash, while sterile-bract extracts contain phenolics and show relevant DPPH and ABTS antioxidant activities. This review integrates compositional and production data with green extraction, product development, downstream compatibility, logistics, and conservation safeguards. Laboratory studies support phenolic recovery, cellulose and nanocellulose production, active films, cosmetic emulsions, fungal conversion, and adsorbents. However, continuous multiproduct cascades, pilot-scale mass and energy balances, techno-economic assessment, and life-cycle assessment remain unavailable. The proposed cascading framework distinguishes validated operations from prospective integration routes and identifies modular preprocessing near production centers as a plausible alternative to centralized refining. Residue valorization may strengthen sustainable pinhão value chains but cannot replace habitat protection, restoration, traceability, or responsible seed-harvesting practices.