TY - JOUR
T1 - 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
AU - Foerst, Petra
AU - Kulozik, Ulrich
N1 - Funding Information:
Acknowledgements This research project was financially supported by the German Ministry of Economics and Technology (via AiF) and the FEI (Forschungskreis der Ernährungsindustrie e.V., Bonn); Project AiF 15616N. The technical assistance of Marianne Holzmann and Maria Muranyi is gratefully acknowledged.
PY - 2012/8
Y1 - 2012/8
N2 - 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.
AB - 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.
KW - Inactivation kinetics
KW - Lactobacillus
KW - Modeling dynamic inactivation
KW - Temperature
KW - Vacuum drying
KW - Water activity
UR - http://www.scopus.com/inward/record.url?scp=84864411074&partnerID=8YFLogxK
U2 - 10.1007/s11947-011-0560-4
DO - 10.1007/s11947-011-0560-4
M3 - Article
AN - SCOPUS:84864411074
SN - 1935-5130
VL - 5
SP - 2419
EP - 2427
JO - Food and Bioprocess Technology
JF - Food and Bioprocess Technology
IS - 6
ER -