title: A model for the effect of pH on the growth of chalk yeasts.
abstract: Hyphopichia burtonii, Pichia anomala, and Saccharomycopsis fibuligera were isolated from spoiled packaged sliced bread. These chalk yeasts were characterized by a wide range of pH for which growth was almost optimum. Thus, the curve growth vs pH exhibited plateau and sharp profiles close to the minimum and the maximum pH. This study described a chalk yeast model (CYM) for the effect of pH derived from a new germination model for fungi (Dantigny, P., Nanguy, S., P.-M., Judet-Correia, D., and Bensoussan, M. 2011, International Journal of Food Microbiology, 146, 176-181). The CYM is asymmetric, versatile, based on parameters with biological significance, and compatible with the gamma concept. The CYM was compared to the cardinal pH model (CPM) which is widely used to describe the effect of pH on microbial growth. The CYM exhibited RMSE values two fold less than those obtained with the CPM for H. burtonii, and S. fibuligera for which plateaus were clearly observed. For P. anomala, the plateau was less obvious, but the RMSE value obtained with the CYM was similar to that found with the CPM. The CYM could extend its use to represent the effect of pH on mold growth.
authors.affiliation: Laboratoire des Procédés Alimentaires et Microbiologiques, UMR PAM A 02.102, Agro-Sup Dijon, Université de Bourgogne, 1 Esplanade Erasme, 21000 Dijon, France. Electronic address: phdant@u-bourgogne.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Dantigny
authors.affiliation: Laboratoire des Procédés Alimentaires et Microbiologiques, UMR PAM A 02.102, Agro-Sup Dijon, Université de Bourgogne, 1 Esplanade Erasme, 21000 Dijon, France.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Burgain
authors.affiliation: Centre de Ressources en Qualité et Sécurité dans l'Agriculture et les Industries Agro-Alimentaires, Technopôle Brest-Iroise, Parvis Blaise Pascal, 29280 Plouzané, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Deniel
authors.affiliation: Laboratoire des Procédés Alimentaires et Microbiologiques, UMR PAM A 02.102, Agro-Sup Dijon, Université de Bourgogne, 1 Esplanade Erasme, 21000 Dijon, France.
authors.forename: Maurice
authors.initials: M
authors.lastname: Bensoussan
mesh_terms: D001939:Bread / Q000382:microbiology; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D015003:Yeasts / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*
keywords: Hyphopichia burtonii; Pichia anomala; Predictive mycology; Saccharomycopsis fibuligera; pH