TRANSPORT PHENOMENA AND FLUID MECHANICS Oxygen Transfer in Co-Extruded Multilayer Active Films for Food Packaging Luciano Di Maio, Francesco Marra , Tesfaye F. Bedane, and Loredana Incarnato Dipartimento di Ingegneria Industriale, Universit a degli Studi di Salerno, Via Giovanni Paolo II 132, Fisciano, Salerno 84084, Italy Sam Saguy Dipartimento di Ingegneria Industriale, Universit a degli Studi di Salerno, Via Giovanni Paolo II 132, Fisciano, Salerno 84084, Italy Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel DOI 10.1002/aic.15844 Published online in Wiley Online Library (wileyonlinelibrary.com) Oxygen scavenger applications in flexible food packaging are still limited due to the difficulty to ensure scavenging activity during storage and throughout the product shelf life. To avoid fast inactivation of the scavenger, multilayer active structures can be realized by inserting the active layer between two or more inert layers. In this work, an unsteady-state 1D reaction-diffusion mass transfer model was developed for predicting and optimizing the barrier-to- oxygen performance and the physical configurations of the co-extruded multilayer active films. The film configuration was a three-layers structure composed of polyethylene terephthalate (PET) as external inert layers, and PET with a polymeric oxygen scavenger as the core reactive layer. Scavenging activity of the multilayer film increased with the reactive layer thickness. Oxygen absorption reaction at short times decreased proportionally with the thickness of the external layers. The most appropriate combinations of inert-to-active film thickness were studied and analyzed. V C 2017 American Institute of Chemical Engineers AIChE J, 00: 000–000, 2017 Keywords: active packaging, modeling, oxygen scavenger, multilayer polymeric film Introduction The gas composition of the atmosphere surrounding a pack- aged food, especially for perishable fruits and vegetables, should be kept at optimal concentrations in order to preserve and minimize deterioration of its quality attributes. 1–3 Oxygen plays a significant and major role in the deterioration of pack- aged food products. Its presence provides favorable conditions for the growth of aerobic microorganisms, favors enhanced respiration for fruits and vegetables as well as enzymatic reac- tions. This could lead to adverse quality deterioration such as loss of ascorbic acid, browning, increased respiration in fruits and vegetables, oxidative rancidity of unsaturated fats, darken- ing of fresh meat pigments, fostering the growth of mold and aerobic spoilage microorganisms to count only a few. Con- versely, inadequate oxygen concentration around the food product could promote the growth of anaerobic pathogens microorganisms, such as C. botulinum. 4 In recent years, active packaging has been preferred over passive packaging due to its versatility and capability to pre- serve the food product and protect it from external influences that could cause quality losses and deterioration. Polymeric films with active materials inserted in the package (i.e., scav- enger sachets) have been used to extend shelf life and extend- ing its shelf life. 5 In addition to sachets, oxygen-scavenging compounds can also be incorporated directly into the packag- ing material itself. These materials include flexible films, rigid plastics (e.g., injection, blow molded polymers 6 ) and liners in closures. The development of multilayer films has introduced better barrier performance to achieve the desired packaging requirement according to the unique needs of the food product during storage. Furthermore, the inclusion of scavenger mate- rials in multilayer films in combination with the various pro- cesses (e.g., co-extrusion, lamination, coating) have been shown to increase the barrier performance. 7–11 The addition of one or more reactive layers in the heteroge- neous structure of the packaging provides better barrier prop- erties by reducing permeation rates through the structure, compared to homogeneous barriers. For instance, a multilayer films scavenging activity and the influence of the different concentration of the scavenger on the structure and barrier properties of a polyethylene terephthalate (PET) film loaded with of oxygen scavenger (OS) at 10% showed better oxygen scavenging capacity in comparison with its counterpart PET film. 12,13 Carranza et al. 7 considered the barrier behavior of films composed of a blend of reactive particles and an inert polymer matrix by following the shrinking core model approximation Correspondence concerning this article should be addressed to F. Marra at fmarra@unisa.it. V C 2017 American Institute of Chemical Engineers AIChE Journal 1 2017 Vol. 00, No. 00