title: Immobilized salt-tolerant yeasts: application of a new polyethylene-oxide support in a continuous stirred-tank reactor for flavour production.
abstract: Immobilization of salt-tolerant yeasts considerably decreases the total time required for the flavour development in soy-sauce processes. For immobilization of cells, alginate gel is mostly used as support material. However, alginate is not very suitable for use in soy-sauce processes because alginate is sensitive to abrasion and chemically unstable towards the high salt content of the soy-sauce medium. In contrast, a newly developed polyethylene-oxide gel seems to be more suitable, but this gel has not been used so far for flavour production in a bioreactor with a high salt content. Therefore, this gel was applied with immobilized salt-tolerant yeasts in a continuous stirred-tank reactor, containing more than 12.5% (w/v) salt. In this reactor, the polyethylene-oxide gel particles did not show any abrasion for several days, while alginate gel beads were already destroyed within 1 day. In addition, the polyethylene-oxide gel particles with immobilized salt-tolerant yeasts Candida versatilis and Zygosaccharomyces rouxii showed a good flavour production. From this work, it was concluded that the application of polyethylene-oxide gel in long-term soy-sauce processes is attractive in the case the sticking together of polyethylene-oxide gel particles can be controlled.
authors.affiliation: Food and Bioprocess Engineering Group, Department of Agrotechnology and Food Sciences, Wageningen University, PO Box 8129, 6700 EV, Wageningen, Netherlands. catrinus.vandersluis@algemeen.pk.wau.nl
authors.forename: C
authors.initials: C
authors.lastname: van der Sluis
authors.forename: C J
authors.initials: CJ
authors.lastname: Stoffelen
authors.forename: S J
authors.initials: SJ
authors.lastname: Castelein
authors.forename: G H
authors.initials: GH
authors.lastname: Engbers
authors.forename: E G
authors.initials: EG
authors.lastname: ter Schure
authors.forename: J
authors.initials: J
authors.lastname: Tramper
authors.forename: R H
authors.initials: RH
authors.lastname: Wijffels
mesh_terms: D000464:Alginates / Q000737:chemistry; D019149:Bioreactors; D002175:Candida / Q000502:physiology; D018914:Cells, Immobilized; D000431:Ethanol / Q000378:metabolism; D005782:Gels; D020723:Glucuronic Acid; D006139:Guaiacol / Q000031:analogs & derivatives* / Q000378:metabolism; D006603:Hexuronic Acids; D007218:Industrial Microbiology / Q000295:instrumentation / Q000379:methods*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012492:Salts / Q000737:chemistry / Q000378:metabolism; D015003:Yeasts / Q000502:physiology*; D020068:Zygosaccharomyces / Q000502:physiology
chemical_list: D000464:Alginates; D005782:Gels; D006603:Hexuronic Acids; D012492:Salts; D000431:Ethanol; D011092:Polyethylene Glycols; D006139:Guaiacol; D020723:Glucuronic Acid; C084991:4-ethylguaiacol