title: A low pH does not determine the community dynamics of spontaneously developed backslopped liquid wheat sourdoughs but does influence their metabolite kinetics.
abstract: This study dealt with the influence of a crucial pH value of 4.0 on the microbiota of spontaneously fermented backslopped liquid wheat sourdoughs. Two spontaneously fermented wheat sourdough fermentation experiments were carried out, one without control of the pH and one with the pH kept constant at pH4.0, both during nine backslopping steps. In each case, two additional backslopping steps were carried out, with the pH kept constant at 4.0 and with free pH, respectively. Keeping the pH constant at 4.0 changed the microbial community dynamics and metabolite kinetics of the sourdough fermentations. A slower prevalence of sourdough-specific Kazachstania yeasts occurred. Nevertheless, in both experiments, Lactobacillus fermentum, Lb. plantarum/pentosus/paraplantarum, and Kazachstania exigua/bulderi/barnettii prevailed ultimately. The lactic acid and ethanol concentration profiles were affected positively by keeping the pH constant at a minimum of 4.0 as well as the l- and d-lactic acid ratio profile, a potential biological marker for sourdough stability and maturity. Also, the concentration and diversity of acetate esters and their precursors, in particular isoamyl acetate and isoamyl alcohol, were affected negatively by the pH control, indicating the role of pH stress in the sourdough aroma formation.
authors.affiliation: Vrije Universiteit Brussel, Faculty of Sciences and Bioengineering Sciences, Research Group of Industrial Microbiology and Food Biotechnology, Pleinlaan 2, B-1050 Brussels, Belgium.
authors.forename: Simon
authors.initials: S
authors.lastname: Van Kerrebroeck
authors.affiliation: Vrije Universiteit Brussel, Faculty of Sciences and Bioengineering Sciences, Research Group of Industrial Microbiology and Food Biotechnology, Pleinlaan 2, B-1050 Brussels, Belgium.
authors.forename: Francisca Casanova C
authors.initials: FC
authors.lastname: Bastos
authors.affiliation: Vrije Universiteit Brussel, Faculty of Sciences and Bioengineering Sciences, Research Group of Industrial Microbiology and Food Biotechnology, Pleinlaan 2, B-1050 Brussels, Belgium.
authors.forename: Henning
authors.initials: H
authors.lastname: Harth
authors.affiliation: Vrije Universiteit Brussel, Faculty of Sciences and Bioengineering Sciences, Research Group of Industrial Microbiology and Food Biotechnology, Pleinlaan 2, B-1050 Brussels, Belgium. Electronic address: ldvuyst@vub.ac.be.
authors.forename: Luc
authors.initials: L
authors.lastname: De Vuyst
mesh_terms: D000085:Acetates / Q000378:metabolism; D000093:Acetoin / Q000378:metabolism; D001939:Bread / Q000382:microbiology*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005433:Flour / Q000382:microbiology; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D019344:Lactic Acid / Q000378:metabolism*; D052197:Limosilactobacillus fermentum / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D064307:Microbiota / Q000502:physiology*; D014908:Triticum / Q000378:metabolism* / Q000382:microbiology; D015003:Yeasts / Q000378:metabolism
chemical_list: D000085:Acetates; D019344:Lactic Acid; D000431:Ethanol; D008353:Mannitol; C007650:ethyl acetate; D000093:Acetoin
keywords: 2-Methyl-1-propanol (PubChem CID: 6560); 3-Methyl-1-butanol (PubChem CID: 31260); Community dynamics; Ester; Ethanol; Ethanol (PubChem CID: 702); Glucose (PubChem CID: 5793); Isoamyl acetate (PubChem CID: 31276); Lactic acid; Maltose (PubChem CID: 6255); Wheat sourdough; d-Lactic acid (PubChem CID: 61503); l-Lactic acid (PubChem CID: 107689); pH evolution