Development and characterization of a nanomultilayer coating of pectin and chitosan : evaluation of its gas barrier properties and application on 'Tommy Atkins' mangoes

A nanomultilayer coating made of food-grade, bio-based materials (consisting of five nanolayers of pectin and chitosan) was produced. This coating was firstly characterized in terms of the water vapor, oxygen and carbon dioxide permeabilities; these parameters exhibited values of 0.019 ± 0.005 × 10−11, 0.069 ± 0.066 × 10−14 and 44.8 ± 32 × 10−14 g m/(Pa s m2), respectively, and are of the same order of magnitude of those found in other nanomultilayer systems. The nanomultilayer system was applied on whole ‘Tommy Atkins’ mangoes and the layers’ adsorption was confirmed by changes in the contact angle of the coated fruits’ skin. After 45 d of storage, uncoated mangoes presented a higher mass loss, higher total soluble solids and lower titratable acidity in comparison with coated mangoes. Uncoated mangoes had also a damaged and wrinkled appearance, showing evidence of microbial spoilage, and the flesh exhibited a slightly brownish color, in comparison with the coated mangoes. These results suggest a positive effect of the coating on gas flow reduction and on the consequent extension of the shelf-life of mangoes.The author Bartolomeu G.S. Medeiros was recipient of a scholarship from de Project Isac (Isac Mundus Cooperation, European Union) and is also a recipient of a scholarship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (Capes, Brazil). The author Ana C. Pinheiro is recipient of a fellowship (SFRH/BD/48120/2008) from the Fundacao para a Ciencia e Tecnologia (FCT, Portugal). The present work was supported by CAPES/PROCAD/NF/1415/2007

Polysaccharide/protein nanomultilayer coatings: construction, characterization and evaluation of their effect on 'Rocha' pear (Pyrus communis L.) shelf-life

Nanolayered coatings of κ-carrageenan, a polysaccharide with good gas barrier properties, and lysozyme, a protein with antimicrobial action, were in a first stage assembled on aminolysed/charged polyethylene terephthalate (PET) pieces, which acted as a support, by alternate five-layer deposition. This was performed to allow the characterization of the nanomultilayer system. PET aminolysis was confirmed by Fourier transform infrared spectroscopy and contact angle, and the subsequent layer adsorption on aminolysed PET surface was confirmed by absorbance, contact angle and SEM images. The water vapour permeability and the oxygen permeability (O2P) of the five layers were found to be 0.013 ± 0.003 × 10−11 and 0.1 ± 0.01 × 10−14 g m−1 s−1 Pa−1, respectively. The nanomultilayer system was subsequently applied (without PET support) directly on ‘Rocha’ (Pyrus communis L.) fresh-cut pears and whole pears. Uncoated fresh-cut pears and whole pears presented higher mass loss, higher total soluble solids (TSS) and lower titratable acidity when compared with coated fresh-cut pears and whole pears. Uncoated fresh-cut pears also presented a darker colour. These results showed that the nanolayered coating assembled on the fruits’ surface has a positive effect on fruit quality and contributed to extend the shelf-life.Author Bartolomeu G. de S. Medeiros was a recipient of a scholarship from the project Isac (Isac Mundus Cooperation, European Union) and is also a recipient of a scholarship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (Capes, Brazil). Author A. C. Pinheiro is recipient of a fellowship (SFRH/BD/48120/2008) from the Fundacao para a Ciencia e Tecnologia (FCT, Portugal)

Physical characterisation of an alginate/lysozyme nano-laminate coating and its evaluation on ‘coalho’ cheese shelf life

This work aimed at the characterisation of a nanolaminate coating produced by the layer-by-layer methodology and its evaluation on the preservation of ‘Coalho’ cheese. Initially, five alternate layers of alginate and lysozyme were assembled in an aminolysed/charged polyethylene terephthalate (A/C PET) and physically characterised by UV/VIS spectroscopy, contact angle, water vapour (WVTR) and oxygen (OTR) transmission rates and scanning electron microscopy. Afterwards, the same methodology was used to apply the nano-laminate coating in ‘Coalho’ cheese and its shelf life was evaluated during 20 days in terms of mass loss, pH, lipid peroxidation, titratable acidity and microbial count. UV/VIS spectroscopy and contact angle analyses confirmed the layers’ deposition and the successful assembly of nano-laminate coating on A/C PET surface. The coating presented WVTR and OTR values of 1.03×10−3 and 1.28× 10−4 g m−2 s−1, respectively. After 20 days, coated cheese showed lower values of mass loss, pH, lipidic peroxidation, microorganisms’ proliferation and higher titratable acidity in comparison with uncoated cheese. These results suggest that gas barrier and antibacterial properties of alginate/lysozyme nanocoating can be used to extend the shelf life of ‘Coalho’ cheese.The author Bartolomeu G. de S. Medeiros is recipient of a scholarship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES-Brazil). The author Marthyna P. Souza is recipient of a scholarship from Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE, Brazil) and was recipient of a scholarship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES/PDEE-Brazil). The authors Ana C. Pinheiro, Ana I. Bourbon and Miguel A. Cerqueira are recipients of a fellowship (SFRH/BD/48120/2008, SFRH/BD/73178/2010 and SFRH/BPD/72753/2010, respectively), supported by Fundacao para a Ciencia e Tecnologia, POPH-QREN and FSE (FCT, Portugal). Maria G. Carneiro-da-Cunha express is gratitude to the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) for research grant. The present work was supported by CAPES/PROCAD/NF/1415/2007. The support of EU Cost Action FA0904 is gratefully acknowledged

Interactions between K-carrageenan and chitosan in nanolayered coatings - Structural and transport properties

The interactions between -carrageenan and chitosan, two oppositely charged polysaccharides, have been investigated through microcalorimetric and quartz crystal microbalance measurements. Microcalorimetric measurements show that -carrageenan/chitosan interaction is an exothermic process and that the alternate deposition of -carrageenan and chitosan results in the formation of a nanolayered coating mainly due to the electrostatic interactions existing between the two polyelectrolytes (though other types of interactions may also be involved). Quartz crystal microbalance measurements confirmed that the alternating deposition of -carrageenan and chitosan resulted in the formation of a stable multilayer structure. The -carrageenan/chitosan nanolayered coating, assembled on a polyethylene terephthalate (PET) support, was characterized in terms of its surface (contact angle measurements) and gas barrier properties (water vapor and O2 permeabilities) and analyzed by scanning electron microscopy (SEM). The water vapor permeability (WVP) and the oxygen permeability (O2P) of the -carrageenan/chitosan nanolayers were found to be 0.020 ± 0.002 × 10−11 and 0.043 ± 0.027 × 10−14 g m−1 s−1 Pa−1, respectively. These results contribute to a better understanding of the type of interactions that play role during the construction of this type of nanostructures. This knowledge can be used in the establishment of an approach to produce edible, biodegradable multilayered nanostructures with improved mechanical and barrier properties for application in, e.g. food and biomedical industries.The authors Ana C. Pinheiro and Ana I. Bourbon are recipient of fellowships from the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) through grants SFRH/BD/48120/2008 and SFRH/BD/73178/2010, respectively. The Author Bartolomeu G. de S. Medeiros was recipient of a scholarship from de Project Isac (Isac Mundus Cooperation, European Union) and is also a recipient of a scholarship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior" (Capes, Brazil). The authors would like to acknowledge FINEP for the microcalorimeter and support by CAPES/PROCAD/1415/2007. The authors also acknowledge Dr. Edith Ariza from SEMAT/UM by the support in SEM analysis