Modelling the Dynamic Inactivation of the Probiotic Bacterium L. Paracasei ssp. Paracasei During a Low-Temperature Drying Process Based on Stationary Data in Concentrated Systems

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Abstract

In order to better understand inactivation of cells during a drying process, the inactivation kinetics of concentrated Lactobacillus paracasei ssp. paracasei (F19) was measured under stationary conditions for different combinations of water activities and temperatures in a water activity range of a w = 0. 23-a w = 0. 75 and temperatures between 4°C and 50°C. It was shown that the inactivation kinetics of the probiotic bacterium L. paracasei at moderate temperatures could, for all conditions, be formally described by a first-order reaction with activation energies that are much lower than for thermal inactivation (E a = 61 kJ/mol). With regard to the water activity, the reaction rate constants exhibit a maximum inactivation rate at intermediate water activity a w = 0. 52. As this behavior has direct implications for the stability of cells in a drying process, the stationary data were used to model the inactivation during test vacuum drying processes, where both temperature and water activity dynamically change. It is shown that-depending on the drying rate-dynamic effects have to be taken into account when modeling the survival during drying. Nevertheless, the model based on stationary inactivation data is capable to predict the characteristics of inactivation during a drying process. Therefore, it can serve as basis to optimize the drying process with regard to maximum survival of cells. However, a further refinement of the model with regard to the drying rate is necessary.

Original languageEnglish
Pages (from-to)2419-2427
Number of pages9
JournalFood and Bioprocess Technology
Volume5
Issue number6
DOIs
StatePublished - Aug 2012

Keywords

  • Inactivation kinetics
  • Lactobacillus
  • Modeling dynamic inactivation
  • Temperature
  • Vacuum drying
  • Water activity

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