Application of bio-nanocomposite films and edible coatings for extending the shelf life of fresh fruits and vegetables

Food packaging materials are traditionally expected to contain foodstuffs and protect them from deteriorating agents. Although petroleum-derived polymers have been widely used for this purpose, the rising concern with their nonrenewable and/or nonbiodegradable nature paves the route for the development of greener alternatives, including polysaccharides and polypeptides. The use of these food-grade biomacromolecules, in addition to fruits and vegetables, provides edible packaging with suitable physical-mechanical properties as well as unique sensory and nutritional characteristics. This text reviews the chronological development pathway of films based on fruit and vegetable purees, pomaces, and extracts. Recent advances are extensively reviewed with an emphasis on the role that each film component plays in the resulting materials, whose production methods are examined from a technical standpoint and essential properties are compiled and contrasted to their conventional, synthetic counterparts. Finally, this comprehensive review discusses advantages and limitations of edible films based on fruits and vegetables.

Polymer nanocomposites incorporating metal or metal oxide nanoparticles have been developed to improve their characteristics (flexibility, gas barrier properties, antimicrobial or antioxidant properties, etc.). Among them silver nanoparticles are used because of their antimicrobial effect in many daily life materials, i.e. food packaging. However, there is not any reference to the migration of nanoparticles to the food. In this paper the results of migration studies (with different simulant solutions and times) in three commercial nanosilver plastic food containers are shown. Migration solutions were evaluated by ICP-MS and SEM-EDX analysis and silver in dissolved form and silver as nanoparticles were analyzed, a key aspect for the toxicity. Silver migration was observed for all samples studied, with the total silver migration values ranging between 1.66 and 31.46 ng/cm(2) (lower than the permissible limits). Size and morphology of the silver nanoparticles changed for the different samples (ranging between 10 and 60 nm) and migration of other nanosized materials was also confirmed.