Nathalie Gontard

Performance and environmental impact of biodegradable polymers as agricultural mulching films

In the aim of resolving environmental key issues such as irreversible soil pollution by non-biodegradable and non-recoverable polyethylene (PE) fragments, a full-scale field experiment was set up to evaluate the suitability of four biodegradable materials based on poly(butylene adipate-co-terephtalate) (PBAT) to be used as sustainable alternatives to PE for mulching application in vineyard. Initial ultimate tensile properties, functional properties during field ageing (water vapour permeability and radiometric properties), biodegradability and agronomical performance of the mulched vines (wood production and fruiting yield) were studied. In spite of their early loss of physical integrity that occurred only five months after vine planting, the four materials satisfied all the requested functional properties and led to agronomic performance as high as polyethylene. In the light of the obtained results, the mulching material lifespan was questioned in the case of long-term perennial crop such as grapevine. Taking into account their mulching efficiency and biodegradability, the four PBAT-based studied materials are proven to constitute suitable alternatives to the excessively resistant PE material.

On the extraction of cellulose nanowhiskers from food by-products and their comparative reinforcing effect on a polyhydroxybutyrate-co-valerate polymer

Abstract The present work reports on the characterization of cellulose nanowhiskers (CNW) extracted from three different food by-products, i.e., wheat straw (WSCNW), Brewer’s spent grains (BGCNW) and olive pomace (OPCNW), by using an optimized hydrolysis method similar to that developed to extract bacterial cellulose nanowhiskers (BCNW). WSCNW and BGCNW were seen to present optimal properties, with aspect ratio, crystallinity and thermal stability values comparable to those of BCNW. Additionally, the optimized hydrolysis treatment led to extraction yields higher than those previously reported for food by-products. The CNW were subsequently incorporated into a commercial polyhydroxybutyrate-co-valerate polymer (PHBV) by solution casting, and the produced nanocomposites were characterized. Although the addition of BGCNW and WSCNW was advantageous in terms of mechanical performance in comparison with OPCNW, no significant enhancement of the pure PHBV mechanical properties was reported because of the low nanofiller loadings used and the inherent difficulty of achieving a high degree of dispersion by the casting method. Interestingly, BGCNW and WSCNW presented reduced moisture sensitivity as compared with BCNW, leading to greater barrier performance and resulting in oxygen permeability reductions up to 26xa0% with WSCNW and 44xa0% with BGCNW.

New Packaging Materials Based on Renewable Resources: Properties, Applications, and Prospects

More and more in our daily lives new words are appearing with specific prefixes, such as “green-,” “eco-,” or “bio-,” that refer to sustainable management. The new wordage does not exclude packaging science and industry, as they should contribute to the environment’s protection by promoting recycled, but also renewable materials. These new products are called “bio-based materials” or “bio-plastics,” which are full of other materials with the same nomenclature. One of the major concerns and questions is where are we now in the “bio-plastics” world? Are they all from renewable resources? Are they biodegradable? What about their availability? Another aspect is the use of bio-plastics. They must be reserved for high value and specific materials, with original and unique properties, and not used for substitution of petrochemical materials. All of these points are discussed as a critical review in this chapter and allow the emergence of several questions for the future, as pointed out in the conclusion.

A global visual method for measuring the deterioration of strawberries in MAP

Graphical abstract

Relationship Between Multiscale Food Structure and Moisture Transfer Properties

The structure of the food materials has a major impact on the diffusion rate and, consequently, on the value of effective diffusivity or water vapor permeability. On the contrary, water sorption at equilibrium is less or not affected by the structure. Among structure type, porosity particularly affects the diffusion rate. In a porous domain, molecules are allowed to transfer more quickly because of several mechanisms of moisture transfer (e.g., capillary action), vapor diffusion in the pores, and so forth, along with liquid diffusion. In low-porosity materials, liquid diffusion is the main means of moisture transport. The smaller the pores’ size in the matrix of the food domain, the slower the moisture migration. In addition, membranes, crystals, and lipids all contribute as barriers to moisture migration. In such dense materials, elements of structure affecting the diffusion rate are in the nano- or microscale, whereas for porous materials, structural elements at the micro- and macroscales are more predominant.