Assessing the safety and biodegradability of biodegradable biosourced packaging
Audrey GRATIA
Thesis to obtain the degree of Doctor awarded by L'Institut des Sciences et Industries du Vivant et de l'Environnement (AgroParisTech)
Specialty: Food science and processes
Thesis supervisor: Violette DUCRUET (IR-INRA)
LNE supervisors: Cédric Lyathaud
CIFRE thesis carried out in collaboration between UMR 1145 "Génie Industriel Alimentaire" (INRA/AgroParisTech) and the "Chimie et Physico-chime des Matériaux" cluster (LNE)
Period: September 2011 - September 2014
Summary
In recent years, driven by societal demand and new environmental constraints, biodegradable biosourced polymers have appeared in the food packaging sector. The aim of this thesis is to assess the safety and biodegradability of these packaging materials, and to design an approach that can be generalized to all such materials. Our study focused on characterizing formulations of commercial polymer materials based on Polylactide (PLA) using a global methodology based on Nuclear Magnetic Resonance (NMR) combined with spectral databases. The significant presence of oligomers during extraction interferes with the identification and quantification of additives. Purification methods have been optimized on the extract, enabling in-depth analysis by 1H NMR and 2D NMR. Couplings with generic chromatographic techniques have enabled us to develop a comprehensive approach to the identification of substances in complex extracts. Structural characterizations of PLA terminations were carried out using 1H and 2D NMR polymer chain deletion sequences. A quantification methodology using qNMR combined with graphical resolution was validated on custom-formulated PLA. An approach for estimating the biodegradation of polymeric materials has been developed. The principle is based on the optimization of physical, chemical and biological parameters of the biodegradation environment, as well as their interactions. The improvements made are based on the use of an inert support and activation doses based on the "vaccine" principle for microbial development. An increase in mineralization and a reduction in the lag phase were obtained for the optimized medium. These new conditions can be proposed to certification bodies as part of their certification process.
Key words : NMR, Biodegradation, PLA, packaging, food safety, additive, food contact materials
Summary
Driven by growing concerns for environment and sustainable development the exploration of new materials has led to the availability of novel biobased and biodegradable polymers for food contact material (FCM). The thesis aims to assess the food safety and the biodegradation of these packaging and to develop an which can be approach generalized to all these materials. Our study focused on the characterization of formulations of the commercial packaging based on polylactide (PLA) using a comprehensive Nuclear Magnetic Resonance (NMR) approach associated with spectral databases. The significant presence of oligomers during extraction interferes in the identification and quantification of additives. Purification methods applied on the extract have been optimized allowing extensive analysis by 1H and 2D NMR. Conventional chromatographic methodologies were coupled to develop a global and comprehensive approach for the identification of additives in complex extracts. Structural characterizations on the end-chain PLA were conducted from NMR experiments (1H and 2D) by signal suppression on the polymer chain. A quantitative NMR approach combined with graphical computation was validated as a reference method on formulated PLA. A new methodology to assess the biodegradation of the FCM has been developed. The principle is based on the optimization of physical, chemical and biological parameters and their interactions in the biodegradation mechanisms. Improvements were made using inert solid medium and activation doses based on the principle of "vaccine" for microbial growth. Both an increase in mineralization and a decrease in the lag phase were obtained for the optimized medium. These new conditions will be proposed to labeling organizations in their certification process.