title: Using a simplex centroid to study the effects of pH, temperature and lactulose on the viability of Bifidobacterium animalis subsp. lactis in a model system.
abstract: This paper reports on the effects of lactulose (0-10 g/l) on Bifidobacterium animalis subsp. lactis, along with the influence of pH (4.5-8.5) and temperature (15-45 °C); the three factors were combined through a simplex centroid. The experiments were performed in a laboratory medium and the data of cells counts were modeled through the Weibull equation for the evaluation of the first reduction time, the shape parameter and the death time. These fitting parameters were used as input values to build a desirability profile and a second-order model through the DoE approach (Design of Experiments). The medium containing glucose was used as control. The prebiotic enhanced the viability of the microbial target, by prolonging the first reduction time and inducing a shoulder phase in the death kinetic; moreover, in some combinations the statistical analysis highlighted a kind of interaction with the pH.
authors.affiliation: Department of the Science of Agriculture, Food and Environment (SAFE), University of Foggia, Via Napoli 25, 71122 Foggia, Italy. Electronic address: clelia.altieri@unifg.it.
authors.forename: Clelia
authors.initials: C
authors.lastname: Altieri
authors.forename: Antonio
authors.initials: A
authors.lastname: Bevilacqua
authors.forename: Marianne
authors.initials: M
authors.lastname: Perricone
authors.forename: Milena
authors.initials: M
authors.lastname: Sinigaglia
mesh_terms: D001644:Bifidobacterium / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007792:Lactulose / Q000378:metabolism*; D050296:Microbial Viability / Q000187:drug effects* / Q000528:radiation effects*; D008962:Models, Theoretical; D013696:Temperature
chemical_list: D007792:Lactulose
keywords: Bifidobacterium spp.; Combined effects; Lactulose; Simplex centroid