title: Micromorphological changes and mechanism associated with wet ball milling of Pinus radiata substrate and consequences for saccharification at low enzyme loading.
abstract: In this work, substrates prepared from thermo-mechanical treatment of Pinus radiata chips were vibratory ball milled for different times. In subsequent enzymatic hydrolysis, percent glucan conversion passed through a maximum value at a milling time of around 120min and then declined. Scanning electron microscopy revealed breakage of fibers to porous fragments in which lamellae and fibrils were exposed during ball milling. Over-milling caused compression of the porous fragments to compact globular particles with a granular texture, decreasing accessibility to enzymes. Carbon-13 NMR spectroscopy showed partial loss of interior cellulose in crystallites, leveling off once fiber breakage was complete. A mathematical model based on observed micromorphological changes supports ball milling mechanism. At a low enzyme loading of 2FPU/g of substrate and milling time of 120min gave a total monomeric sugar yield of 306g/kg of pulp which is higher than conventional pretreatment method such as steam exploded wood.
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3046, New Zealand. Electronic address: Alankar.vaidya@scionresearch.com.
authors.forename: Alankar A
authors.initials: AA
authors.lastname: Vaidya
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3046, New Zealand.
authors.forename: Lloyd A
authors.initials: LA
authors.lastname: Donaldson
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3046, New Zealand.
authors.forename: Roger H
authors.initials: RH
authors.lastname: Newman
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3046, New Zealand.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Suckling
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3046, New Zealand.
authors.forename: Sylke H
authors.initials: SH
authors.lastname: Campion
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3046, New Zealand.
authors.forename: John A
authors.initials: JA
authors.lastname: Lloyd
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Rotorua 3046, New Zealand.
authors.forename: Karl D
authors.initials: KD
authors.lastname: Murton
mesh_terms: D002480:Cellulase / Q000737:chemistry / Q000378:metabolism; D002482:Cellulose / Q000032:analysis / Q000737:chemistry; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D008962:Models, Theoretical; D028223:Pinus / Q000737:chemistry* / Q000378:metabolism; D014934:Wood / Q000737:chemistry* / Q000378:metabolism; D001617:beta-Glucosidase / Q000737:chemistry / Q000378:metabolism
chemical_list: D002482:Cellulose; D001617:beta-Glucosidase; D002480:Cellulase
keywords: Ball milling; Enzymatic saccharification; Microscopy; Pretreatment; Softwood