UR MaIAGE ( Mathématiques et Informatique Appliquées du Génome à l’Environnement) Jouy-en-Josas (78), France
Topic : Computer-based methods for extracting information from biological texts
- Manual and automatic annotations of scientific articles on molecular biology (specifically on seed development in Arabidopsis thaliana) and microbiology fields guided by a knowledge model.
- Prediction of entities on gene regulation of Arabidopsis thaliana
- Collecting and modifying resources (lexicon. ontologies)
- Analysis of the users’ need for text mining
- in molecular biology on the gene regulation of Arabidopsis thaliana
- in microbiology on microbial biodiversity and their phenotypes in foods
September 2011 – September 2014 (36 months)
UMR IATE (Ingénierie des Agropolymères et Technologies Emergentes) Montpellier (34), France
Topic : Characterization and modelling of gas (O 2 /CO 2) transfer in the food packaging system: impact of gases on microorganism growth (predictive microbiology)
Integrated into the project of the French National Research Agency Map’Opt (Modified Atmosphere Protection Optimisation)
- Study of oxygen and carbon dioxide transfer in food matrices (Solubility and Diffusivity).
- Development of easy-to-use, non-destructive methods to measure the solubility and diffusivity of Oxygen and CO2 in solid food products.
- Study of the impact of oxidation reactions, fat quantity, temperature, matrix structure or viscosity on transfer coefficients.
- Coupling of material transfer models and predictive microbiology to develop a packaging choice decision support tool.
Abstract: Packaging is a key player on reducing food losses. In Modified Atmosphere Packaging (MAP) of fresh produce, the gaseous composition of the headspace is chosen in order to prevent microorganism growth (usually low O2 and high CO2 concentrations are chosen). This work aimed at initiating and developing a generalised approach permitting to study and quantitatively model the impact of gas transfer (O2 /CO2 /N2 ) occurring in the food packaging system on microbial growth. In this purpose, existing models of predictive microbiology will be coupled to mass transfers (permeation through packaging and solubilisation/diffusion within food) using numerical methods such as ODE (Ordinary Differential Equation) solvers. If the permeation is relatively well known, the two other parameters, O2 and CO2 solubilities and diffusivities, required in mass transfer models are less known, especially for solid food matrices. Experimental acquisition of these parameters was thus required. Some dedicated methodologies have been developed in the framework of this study in order to gain missing data of solubility and diffusivity in solid food matrices for the two studied gases, O2 and CO2 . The methods of O2 diffusivity and solubility measurement relied on the use of luminescence-based sensors while for CO2 , the methodologies were based on chemical titration. A processed cheese was used as solid model food and the O2 and CO2 solubilities and diffusivities were characterized in this model food as in other real food products: cooked ham and butter. A peculiar attention was paid on the validation of Henry’s law in the case of CO2 that links CO2 partial pressure to the dissolved content into the product. The O2 diffusion within lipid-based model materials was studied with a deep analysis of the impact of temperature and viscosity. The energy of activation of oxygen diffusivity in model matrix (Miglyol 812) was found equal to 25 kJ. mol -1 for temperature ranging from 5 to 30°C. A mathematical model of gas transfer was developed for the overall food/packaging system and was coupled to existing equations of predictive microbiology. This generalised model was compared with experimental data obtained in the case of mono-directionnal transfers, on the mass transfer and microbiological part (on processed cheese voluntarily contaminated by Listeria monocytogenes with an initial biomass equal to 10^3 UFC g -1 ). This work had permitted to increase knowledge on the behaviour of O2 and CO2 solubilities and diffusivities into solid food products, to understand and quantify the impact of gas transfers in the food/packaging system on the microorganism growth and to build basements for a new decision support system aiming at helping the user in the choice and design of MAP for a given application.
February 2011 – July 2011 (6 months)
Université Montpellier 2
UMR IATE (Ingénierie des Agropolymères et Technologies Emergentes) Montpellier (34) , France
Topic: Study of oxygen and carbon dioxide transfer in food matrices (Solubility and Diffusivity)
- Measurement of oxygen diffusion in lipidic samples according to viscosity and identification of diffusivity by Matlab.
- Methodological research on obtaining the diffusion of CO2
March 2010 – September 2010 (7 months)
CIRAD LAVALETTE UMR QUALISUD , Montpellier (34), France
Under the management of Renaud Boulanger et Fabrice Davrieux
Topic: Analysis of the influence of maturity on aromas of Bourbon Pointu Arabica coffee (high value-added product) (290 samples)
- Extraction and identification of aromatic compounds from green coffee and roasted coffee using the SPME method coupled with GC-MS (45 compounds for green coffee, 54 for roasted coffee, 18 common to both coffees)
- Questioning of the SPME method for differentiation between different types of coffee, on all the measurements carried out using statistical processing (PCA) (approximately 1000 samples)
March 2008 – June 2008 (4 months)
SARL PATISSERIE MAZAS (18 salariés, 825K€), Foix (09), France
Under the management of Fabrice Mazas
Topic : Installation of the walking forward system in the production area
- Analysis of the processes used for pastry, pastries and chocolate production areas.
- Setting up displays summarizing basic hygiene concepts.