Perspectives on utilization of edible coatings and nano-laminate coatings for extension of postharvest storage of fruits and vegetables

It is known that in developing countries, a large quantity of fruit and vegetable losses results at postharvest and processing stages due to poor or scarce storage technology and mishandling during harvest. The use of new and innovative technologies for reducing postharvest losses is a requirement that has not been fully covered. The use of edible coatings (mainly based on biopolymers) as a postharvest technique for agricultural commodities has offered biodegradable alternatives in order to solve problems (e.g., microbiological growth) during produce storage. However, biopolymer-based coatings can present some disadvantages such as: poor mechanical properties (e.g., lipids) or poor water vapor barrier properties (e.g., polysaccharides), thus requiring the development of new alternatives to solve these drawbacks. Recently, nanotechnology has emerged as a promising tool in the food processing industry, providing new insights about postharvest technologies on produce storage. Nanotechnological approaches can contribute through the design of functional packing materials with lower amounts of bioactive ingredients, better gas and mechanical properties and with reduced impact on the sensorial qualities of the fruits and vegetables. This work reviews some of the main factors involved in postharvest losses and new technologies for extension of postharvest storage of fruits and vegetables, focused on perspective uses of edible coatings and nano-laminate coatings.María L. Flores-López thanks Mexican Science and Technology Council (CONACYT, Mexico) for PhD fellowship support (CONACYT Grant Number: 215499/310847). Miguel A. Cerqueira (SFRH/BPD/72753/2010) is recipient of a fellowship from the Fundação para a Ciência e Tecnologia (FCT, POPH-QREN and FSE Portugal). The authors also thank the FCT Strategic Project of UID/ BIO/04469/2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and the project ‘‘BioInd Biotechnology and Bioengineering for improved Industrial and AgroFood processes,’’ REF. NORTE-07-0124-FEDER-000028 Co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP, CE Brazil (CI10080-00055.01.00/13)

Mémoire qui a remporté le prix de la Société d'Emulation Patriotique de Neuchâtel en 1795

par Henri-François Henriod de Couve

Ce que faire coopérer les élèves veut dire : le point de vue des enseignants au travail

La présente étude s’intéresse aux perceptions et aux pratiques de 10 enseignants genevois en termes de démarches coopératives entre élèves. De nombreuses recherches témoignent de l’efficacité des dispositifs de type coopératif sur les apprentissages des élèves. Cependant, les enseignants ont de bonnes raisons de faire ou de ne pas faire coopérer les élèves. Le raisonnement professionnel de chaque enseignant dépend d’un ordre de priorités propre à sa personne (rapport au contrôle, à l’autorité, à la hiérarchie, etc.). C’est ce que nous tentons de démontrer à travers les pratiques enseignantes déclarées recueillies lors d'entretiens. Deux catégories de professionnels sont régulièrement comparées : les enseignants « novices » en coopération et les « experts ». La voix leur est principalement laissée afin de mettre en lumière les enjeux lorsque de nouvelles démarches d’enseignement sont mises en place et de comprendre leur cheminement professionnel