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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

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[PhD] Lucas Von-Gastrow

Dynamics of microbial communities in back-slopped leavens, a participatory study

Many foods like bred, wine or cheese are fermented. Different methods are available to begin the process.  It is possible to use a part of the precedent production as a starter. This technique is called back-slopping. The product is maintained without interruption and its microbial composition can change through time. Stability of the microbial communities is very important for the producers : products quality and taste can suffer from their evolution, or it can even become dangerous in case of development of a pathogen. Sometimes, adding the starter doesn't lead to any fermentation, meaning that the leaven and the production are lost which can have important economic consequences. I study back-slopped leavens in artisanal production of two foods : sourdough bread and a traditional fermented milk from Bretagne which is called Gwell. My research in centered around the evolution of microbial communities and their response to different perturbations. I compare different techniques in the production and their impact on the stability of the leavens. Working on these two products allows me to study an ecosystem with yeasts and bacteria in the bread and another one with mainly bacteria in the Gwell. I develop a participatory methodology : precise research topics are discussed and co-constructed with the farmers, who will take part in the experiments. This organisation allows me to get fundamental results on dynamics and stability of microbial communities, while at the same time directly applying these result to test new production processes for fermented foods. The leavens microbial composition are evaluated by metagenomic and culture dependant techniques. The technological interest of the new production processes is evaluated with the farmers, and the products organoleptic quality is assessed.

  • Period : 01/10/2018 – 30/09/2021
  • Supervisor: Delphine Sicard (INRA Montpellier, UMR SPO)
  • Co-supervisor: Florence Valence (INRA, UMR 1253, STLO, Centre International de Ressources Microbiennes - Bactéries d’Intérêt Alimentaire)
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