title: Use of a plant-derived enzyme template for the production of the green-note volatile hexanal.
abstract: Hexanal is a key organoleptic element of green-note that is found in both fragrances and flavors. We report a novel process for the production of hexanal using immobilized enzyme templates extracted from different plant sources in combination with hollow-fiber ultrafiltration for in situ separation. Enzyme templates, known to be responsible for the synthesis of hexanal from linoleic acid (18:2), were isolated from naturally enriched tissues including carnation petals, strawberry and tomato leaves. These templates were immobilized in an alginate matrix and used as a biocatalyst in a packed-bed bioreactor. Continuous product recovery was achieved using a hollow-fiber ultrafiltration unit. The effects of pH, reaction temperature, and substrate and enzyme concentrations were studied and their effects on hexanal generation identified and optimized. Utilizing optimized conditions, hexanal production 112-fold higher than endogenous steady-state levels in a corresponding amount of plant tissue could be achieved over a 30-minute period. Based on the reactor studies, product inhibition also appears to be an important factor for bioreactor-based hexanal production.
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G12.
authors.forename: Frank
authors.initials: F
authors.lastname: Schade
authors.forename: John E
authors.initials: JE
authors.lastname: Thompson
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Legge
mesh_terms: D000447:Aldehydes / Q000302:isolation & purification / Q000378:metabolism*; D019149:Bioreactors; D002384:Catalysis; D018929:Cell Culture Techniques / Q000379:methods*; D002478:Cells, Cultured; D020650:Combinatorial Chemistry Techniques; D029749:Dianthus / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000378:metabolism; D005163:Factor Analysis, Statistical; D035264:Flowers / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D031985:Fragaria / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018551:Solanum lycopersicum / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D008567:Membranes, Artificial; D018515:Plant Leaves / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D013696:Temperature; D014462:Ultrafiltration / Q000295:instrumentation / Q000379:methods*; D014835:Volatilization
chemical_list: D000447:Aldehydes; D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D010940:Plant Proteins; C010463:n-hexanal