title: Fermentation profile of Saccharomyces cerevisiae and Candida tropicalis as starter cultures on barley malt medium.
abstract: Saccharomyces cerevisiae C8-5 and Candida tropicalis F0-5 isolated from traditional sorghum beer were tested for kinetic parameters on barley malt extract, YPD (863 medium) and for alcohol production. The results showed that C. tropicalis has the highest maximum growth rate and the lowest doubling time. Values were 0.22 and 0.32 h(-1) for maximum growth rate, 3 h 09 min and 2 h 09 min for doubling time respectively on barley malt extract and YPD. On contrary, glucose consumption was the fastest with S. cerevisiae (-0.36 and -0.722 g/l/h respectively on barley malt extract and YPD). When these two yeasts were used as starters in pure culture and co-culture at proportion of 1:1 and 2:1 (cell/cell) for barley malt extract fermentation, we noticed that maltose content increased first from 12.12 g/l to 13.62-16.46 g/l and then decreased. The highest increase was obtained with starter C. tropicalis + S. cerevisiae 2:1. On contrary, glucose content decreased throughout all the fermentation process. For all the starters used, the major part of the ethanol was produced at 16 h of fermentation. Values obtained in the final beers were 11.4, 11.6, 10.4 and 10.9 g/l for fermentation conducted with S. cerevisiae, C. tropicalis, C. tropicalis + S. cerevisiae 1:1 and C. tropicalis + S. cerevisiae 2:1. Cell viability measurement during the fermentation by using flow cytometry revealed that the lowest mean channel fluorescence for FL3 (yeast rate of death) was obtained with C. tropicalis + S. cerevisiae 2:1 after 48 h of fermentation.
authors.affiliation: Centre Wallon de Biologie Industrielle (CWBI) Unité de Bio-industries, Université de Liège, Gembloux Agrobio-Tech, Passage des Déportés 2, 5030 Gembloux, Belgium ; Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire.
authors.forename: Wazé Aimée Mireille
authors.initials: WA
authors.lastname: Alloue-Boraud
authors.affiliation: Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire.
authors.forename: Kouadio Florent
authors.initials: KF
authors.lastname: N'Guessan
authors.affiliation: Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire.
authors.forename: N'Dédé Théodore
authors.initials: NT
authors.lastname: Djeni
authors.affiliation: Centre Wallon de Biologie Industrielle, Bd du Rectorat, 29, B.40 - P.70, 4000 Liège, Belgium.
authors.forename: Serge
authors.initials: S
authors.lastname: Hiligsmann
authors.affiliation: Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire.
authors.forename: Koffi Marcellin
authors.initials: KM
authors.lastname: Djè
authors.affiliation: Centre Wallon de Biologie Industrielle (CWBI) Unité de Bio-industries, Université de Liège, Gembloux Agrobio-Tech, Passage des Déportés 2, 5030 Gembloux, Belgium.
authors.forename: Franck
authors.initials: F
authors.lastname: Delvigne
keywords: Barley malt extract; Candida tropicalis; Flow cytometry; Kinetic culture; Saccharomyces cerevisiae