title: Formation of ethyl acetate by Kluyveromyces marxianus on whey: studies of the ester stripping.
abstract: Kluyveromyces marxianus is capable of converting lactose into ethyl acetate offering a chance for an economical reuse of whey. The microbial formation of ethyl acetate as a bulk product calls for an aerobic process and, thus, the highly volatile ethyl acetate is discharged from the aerated bioreactor. This stripping process was modeled and investigated experimentally. The stripping rate was proportional to the gas flow and nearly independent of the stirring rate since the stripping was governed by the absorption capacity of the exhaust gas rather than the phase transfer. Cooling the exhaust gas did not noticeably influence the stripping. One batch experiment is presented in detail to demonstrate the formation of ethyl acetate by K. maxianus DSM 5422 on whey. Further batch experiments showed that a substantial formation of ethyl acetate only occurred when the yeast growth was limited by a lack of trace elements. The highest product yield observed was 0.25 g ethyl acetate per g lactose which is nearly 50% of the theoretical maximum.
authors.affiliation: Food Technology and Bioprocess Engineering, Dresden University of Technology, Dresden, Germany.
authors.forename: Thanet
authors.initials: T
authors.lastname: Urit
authors.forename: Christian
authors.initials: C
authors.lastname: Löser
authors.forename: Martin
authors.initials: M
authors.lastname: Wunderlich
authors.forename: Thomas
authors.initials: T
authors.lastname: Bley
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000332:Aerobiosis; D019149:Bioreactors; D003470:Culture Media / Q000737:chemistry; D003611:Dairy Products; D005285:Fermentation; D007218:Industrial Microbiology / Q000379:methods*; D007716:Kluyveromyces / Q000254:growth & development / Q000378:metabolism; D007785:Lactose / Q000378:metabolism*; D008956:Models, Chemical; D014131:Trace Elements / Q000737:chemistry
chemical_list: D000085:Acetates; D003470:Culture Media; D014131:Trace Elements; C007650:ethyl acetate; D007785:Lactose