Critical water activity and amorphous state for optimal preservation of lyophilised lactic acid bacteria

International audienceThe aim of this study was to investigate the influence of the water activity on the stability of lyophilised lactic acid bacteria, especially in the solid glassy region. Lactobacillus bulgaricus CFL1 was co-lyophilised with sucrose and stored under controlled relative humidity at 25 °C. Glass transition temperature (T g), water activity, water content and loss of specific acidification activity during storage were determined. The rates of bacteria degradation were analysed as a function of water activity and as a function of the temperature difference between storage temperature and T g. Above T g , the degradation rate appeared related to the physical changes of the amorphous matrix. Below T g , the optimal stability of the lyophilised bacteria was observed in the intermediate water activity range 0.1–0.214. An integrated analysis of the relationships between water activity, T g , water content and biological activity appeared as a promising approach for optimising the freeze-drying process and predicting the storage stability

An Interactive Tool for the Optimization of Freeze-Drying Cycles Based on Quality Criteria

International audienceAmong existing dehydration methods, freeze-drying has unique benefits for the stabilization and preservation of biological activity of pharmaceutical products but remains an expensive and time-consuming process. A user-friendly software tool was developed, allowing for interactive selection of process operating condition profiles in order to maximize process productivity while insuring product quality preservation. The software is based on a dynamic, one-dimensional heat and mass transfer model, which can accurately represent both the primary and secondary drying stages and the gradual transition between them. The model was validated in a wide range of operating conditions: − 25 to + 25°C shelf temperature and 10 to 34 Pa total pressure. By comparing a reference sucrose solution with a formulated pharmaceutical product containing polyvinylpyrrolidone (PVP), it is shown that controlling product properties such as glass transition temperature and sorption isotherm can reduce the minimum achievable cycle duration by 12 h (33%)

Freeze-drying of lactic acid bacteria

Lactic acid bacteria are of great importance for the food and biotechnology industry. They are widely used as starters for manufacturing food (e.g., yogurt, cheese, fermented meats, and vegetables) and probiotic products, as well as for green chemistry applications. Freeze-drying or lyophilization is a convenient method for preservation of bacteria. By reducing water activity to values below 0.2, it allows long-term storage and low-cost distribution at suprazero temperatures, while minimizing losses in viability and functionality. Stabilization of bacteria via freeze-drying starts with the addition of a protectant solution to the bacterial suspension. Freeze-drying includes three steps, namely, (1) freezing of the concentrated and protected cell suspension, (2) primary drying to remove ice by sublimation, and (3) secondary drying to remove unfrozen water by desorption. In this chapter we describe a method for freeze-drying of lactic acid bacteria at a pilot scale, thus allowing control of the process parameters for maximal survival and functionality recovery

The challenges for freeze-drying complex biological systems: State of the art and future

The challenges for freeze-drying complex biological systems: State of the art and future. 8. International Conference of Lyophilization and Freeze-Dryin

Real time control of the final quality of freeze-dried lactic acid starters

Real time control of the final quality of freeze-dried lactic acid startersStéphanie Passot, Ioan Cristian TréléaUMR 782 Génie et Microbiologie des Procédés Alimentaires (GMPA), AgroParisTech, INRA, Université Paris-Saclay, F-78850, Thiverval-GrignonFreeze-drying is a time- and energy-consuming process whose management at the industrial level is still not well controlled or optimised, leading to losses in starter quality.The aim of our work was to develop a mathematical model and a computer network architecture that would make it possible to control and optimise the process and the final quality of the starter in real time. During the first stage of the experiment, quantitative relationships between the functionalities of starters and the process variables were defined.We showed that the degradation rate of the biological activity of starters during freeze-dried storage could be linked to their thermal history during the process -especially to the temperature difference between the product and its glass transition temperature- and to their final water activity. We designed the management tool by combining process data with an optimisation algorithm in order to adjust process variables in real time and to remain as close as possible to the optimal quality defined beforehand. This tool was validated at the pilot scale level and can be easily transferred to other types of equipment.PartnershipUniversity of Rome Tor VergataSpanish Council for Scientifi c ResearchSoredabSocietà di Progettazione Elettronica e Software, Alctra, TelstarEuropean Project CAFE (Computer-Aided Food processes for control Engineering)Read moreL.T. Antelo, S. Passot, F. Fonseca, I.C. Tréléa, A.A. Alonso (2012). Toward Optimal Operation Conditions of Freeze-Drying Processes via a Multilevel Approach. Drying Technology 30:[email protected], [email protected] Génie et Microbiologie des Procédés Alimentaires, INRA-AgroParisTechhttp://www6.versailles-grignon.inra.fr/gmp

Freezing : a critical step for freeze-drying cycle development and product stability

International audienc

Freeze-drying modeling: prediction of spatial distribution of product quality

International audienceno abstrac

Freeze-drying of bacteria : state of the art and new perspectives

Communication orale sur invitationFreeze-drying of bacteria : state of the art and new perspectives. 7. International Conference of Lyophilization and Freeze-Dryin

Biophysical and chemical responses of Lb. bulgaricus to freezing by infrared microspectroscopy

Communications sans actes 3 - CEPIABiophysical and chemical responses of Lb. bulgaricus to freezing by infrared microspectroscopy . 7. Soleil User's Meetin