Physicochemical characterization and valorization potential of açaí berry (Euterpe precatoria) and bataua (Oenocarpus bataua) seeds: lignocellulosic biomass and antioxidants from Bolivian Amazon agroindustrial residues

Açaí berry ( Euterpe precatoria ) and bataua ( Oenocarpus bataua ) are palms whose fruits are harvested in the Bolivian Amazon for pulp production, generating large volumes of seed residues that are currently discarded without further processing. This study presents a comparative physicochemical characterization of both seed types, evaluating their proximate composition, structural fractions (cellulose, hemicellulose, lignin), dietary fiber, lipids, proteins, and antioxidant properties. Characterization was performed following internationally recognized methods (AOAC, ISO, NB). Results confirmed a predominantly lignocellulosic matrix in both species, with total dietary fiber exceeding 84% on a dry basis. Açaí seeds exhibited higher cellulose content (51.44 ± 0.56% dry basis) and considerable antioxidant activity (IC 50 = 4.56 ± 0.11 mg/mL by DPPH; TEAC = 4,975.68 ± 56.21 μmol TE/g), açaí seeds exhibited a high total phenolic content (3,565.95 ± 21.78 mg GAE/100 g), while bataua seeds showed a balanced cellulose–hemicellulose ratio (32.58 ± 0.15% and 31.89 ± 0.59%, respectively), high total phenolic content (797.25 mg GAE/100 g), and moderate antioxidant capacity (TEAC = 1,567.10 ± 16.10 μmol TE/g). A multi-criteria valorization matrix identified cellulose and antioxidant compounds as the priority fractions in both species, supporting an integrated extraction cascade. Alkaline extraction experiments using NaOH demonstrated effective delignification and cellulose enrichment, with temperature identified as the dominant factor controlling cellulose yield in bataua seeds. FTIR spectroscopy and polarized-light microscopy confirmed cellulose structural integrity and crystallinity in both species. The integrated valorization of these residues—antioxidant extraction followed by cellulose recovery from the remaining solid—is proposed as a circular-economy strategy aligned with sustainable bioeconomy principles and Bolivian environmental legislation for the Amazonian region.