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)

Immobilization of b-galactosidase from kluyveromyces lactis onto a polysiloxane–polyvinyl alcohol magnetic (mPOS–PVA) composite for lactose hydrolysis

β-Galactosidase from Kluyveromyces lactis was covalently immobilized onto a mPOS–PVA, using glutaraldehyde as activating agent and its properties were evaluated. The enzymatic water insoluble derivative displayed the same optimum pH (6.5) and optimum temperature (50 °C) of the soluble enzyme. The apparent Km app and activation energy for both soluble and immobilized enzyme derivative were found to be not significantly different. The mPOS–PVA β-galactosidase preparation presented a higher operational and thermal stability than the soluble enzyme. This immobilized β-galactosidase also was effective in hydrolyzing lactose from milk. Hence, one can conclude that mPOS–PVA is an attractive and efficient support for β-galactosidase immobilization.Alban, the European Union Programme of High Level Scholarships for Latin America; Brazilian National Research Council (CNPq)

Development and characterization of an active chitosan-based film containing quercetin

This work aims at developing an active chitosan film through the incorporation of quercetin and the evaluation of physical and functional properties of the films made thereof. The addition of quercetin showed to influence films properties in terms of surface morphology, tensile strength, and opacity while elongation-at-break, thickness, water vapor, and oxygen permeability were not significantly affected with incorporation of quercetin. The color parameters of chitosan films were affected by quercetin incorporation with a decrease of the values of L* and a*. The film exhibited a high free-radical scavenging activity, showing antioxidant activity. The film-forming solutions of chitosan with or without quercetin showed antibacterial activity against four Gram-negative and three Gram-positive bacteria. These results showed that quercetin incorporation in chitosan-based films has potential to be used as a solution for active food packaging.Author Marthyna Pessoa de Souza thanks the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES/PDEE-Brazil) and Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE, Brazil) for fellowships. Miguel A. Cerqueira and Helder D. Silva (SFRH/BPD/72753/2010 and SFRH/BD/81288/2011, respectively) are recipients of a fellowship from the Fundacao para a Ciencia e Tecnologia (FCT, POPH-QREN and FSE Portugal). This research was financially supported by research grants and fellowships from the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), as well as the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) and Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE). 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 Agro-Food processes," REF. NORTE-07-0124-FEDER-000028 Co-funded by the Programa Operacional Regional do Norte (ON. 2-O Novo Norte), QREN, FEDE

Development and characterization of lactoferrin-GMP nanohydrogels : evaluation of pH, ionic strength and temperature effect

Lactoferrin (Lf) and glycomacropeptide (GMP), two bioactive proteins from milk, were used to produce nanohydrogels by electrostatic interaction and thermal gelation. Parameters such as protein concentration, molar ratio, pH, temperature and heating time were evaluated in order to develop the nanohydrogels, which were characterized in terms of morphology (Transmission Electron Microscopy TEM, Dynamic Light Scattering DLS, Atomic Force Microscopy AFM and Confocal Laser Scanning Microscopy CLSM) and stability. The aggregation of the mixture between Lf and GMP increased with the increase of temperature, resulting in particles with lower hydrodynamic diameter and polydispersity index (PdI). Nanohydrogels were obtained from the mixture of Lf and GMP solutions (0.02% (w/w) in molar ratio 1:7) at pH 5.0, and subsequently stirred and heated at 80 °C, during 20 min. Results showed that nanohydrogels have a spherical shape with a hydrodynamic diameter around 170 nm, a PdI of 0.1 and a swelling ratio of 30. The minimum size of nanohydrogels depends on protein concentration and molar ratio. Decreasing the protein concentrations and increasing the content of GMP molecules in solution, the hydrodynamic diameter and PdI of nanohydrogels decreased. The electrical charge values of nanohydrogels at different pH values suggest that Lf molecules are in the surface and GMP molecules are mostly in the core of the structure (confirmed by confocal microscopy). Also, it was observed that nanohydrogels' hydrodynamic diameter and PdI, after formation, are influenced when submitted at different conditions of pH, ionic strength and temperature. Lf-GMP nanohydrogels showed properties that indicate that they are a promising delivery system for food and pharmaceutical applications.The authors Ana I. Bourbon, Ana C. Pinheiro, Ricardo N. Pereira and Miguel A. Cerqueira are recipient of fellowships from the Fundacao para a Ciencia e Tecnologia, POPH-QREN and FSE (FCT, Portugal) through grants SFRH/BD/73178/2010, SFRH/BD/48120/2008, SFRH/BPD/81887/2011 and SFRH/BPD/72753/2010, respectively. Maria G. Carneiro-da-Cunha express is gratitude to the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) for research grant. The authors would like to acknowledge to Jorge Padrao from Centre of Biological Engineering, University of Minho and Andre Coelho from Federal University of Ceara for helping in electrophoresis measurements and to Rui Fernandes from IBMC, University of Porto for assistance in taking the TEM pictures. Also, the authors thank the FCT Strategic Projects PEst-OE/EQB/LA0023/2013 and PEst-C/EQB/LA0006/2013 (FCT and FEDER funds through COMPETE). The work also received financial support from the European Union (FEDER funds) under the framework of QREN (Programa Operacional Regional do Norte (ON.2 - O Novo Norte; FEDER) through projects NORTE-07-0124-FEDER-000028 and NORTE-07-0124-FEDER-000069

Quercetin-loaded lecithin/chitosan nanoparticles for functional food applications

This study aimed at the encapsulation of quercetin into lecithin/chitosan nanoparticles using the electrostatic self-assembly technique, followed by evaluation of their functionality (antioxidant activity) and stability at different environmental conditions. These nanoparticles were characterized in terms of: average size, morphology, zeta potential, encapsulation efficiency, loading, and spectroscopic characteristics. Quercetin has been successfully encapsulated in lecithin/chitosan nanoparticles with an efficiency of 96.13 ± 0.44 %. Nanoparticles presented a spherical morphology with an average size of 168.58 ± 20.94 nm and a zeta potential of 56.46 ± 1.94 mV. Stability studies showed that nanoparticles are stable to temperatures ranging between 5 and 70 °C and a pH variation from 3.3 to 5.0. Moreover, encapsulated quercetin showed improved antioxidant properties when compared to free-quercetin. Our results suggest that quercetin-loaded lecithin/chitosan nanoparticles can be used in the manufacture of functional foods.Author Marthyna Pessoa de Souza thanks Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES/PDEE-Brazil) and Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE, Brazil) for granting her scholarships. Miguel A. Cerqueira is recipient of a fellowship from the Fundacao para a Ciencia e Tecnologia (SFRH/BPD/72753/2010, FCT, POPH-QREN, and FSE Portugal). This research was financially supported by research grants and fellowships from the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), as well as the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) and Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE).The support of EU Cost Actions FA0904 and FA1001 is gratefully acknowledged

Physical properties of edible coatings and films made with a polysaccharide from Anacardium occidentale L.

The effect of the concentrations of the polysaccharide from Anacardium occidentale L. (Policaju) and a surfactant (Tween 80) on relevant properties of edible coatings/films, in view of their application on apples (cv. Golden) was evaluated. The influence of the interactions between those two constituents on apples’ surface properties and on the coating/film’s wettability, water vapor permeability, opacity and mechanical properties was evaluated. The effects of the studied variables (polysaccharide and surfactant concentrations) were analyzed according to a 2² factorial design. Pareto bar charts were used to understand the most significant factors on the studied properties. The addition of surfactant reduced the cohesion forces, therefore reducing the surface tension and increasing the wettability; this resulted in an improved compatibility between the solution and the fruit skin surface. The opacity was also reduced. The results of each of the analyzed properties were adjusted to a polynomial, multifactor model, which provided a good fitting accuracy. This model is important once it will reduce the characterization work needed in subsequent applications of these coatings/films on foods.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes, Brazil)Fundação para a Ciência e a Tecnologia (FCT)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazi

Production and characterization of protease from Penicillium aurantiogriseum URM 4622

Proteases with new properties are required due to their increasing industrial importance. In this work, the optimal fermentation conditions for the production of a protease from Penicillium aurantiogriseum dierchx (URM-4622) are presented together with partial characterization of the protease catalytic properties. The batch fermentation conditions that allow for the highest specific proteolytic activity are 26 ºC, pH 7.0, and 25 % saturation dissolved O2 concentration. The obtained protease is stable over a wide range of pH (5.8 to 9.5) and temperature (25 to 40 ºC) values. In the presence of Zn2+ a 26 % reduction in the enzyme proteolytic activity occurs and, in contrast, Mn2+ enhances its activity by 28.9 %. 96.2 % and 70.8 % of the protease activity are maintained after 90 min incubation in 5 and 10 % (v/v) H2O2 aqueous solutions, respectively. PMSF inhibition reveals that this enzyme is a serine protease. Protease is able to hydrolyze different proteins

Development and characterization of hydrogels based on natural polysaccharides : policaju and chitosan

The development of hydrogels based on natural polysaccharides was investigated by preparing mixtures of policaju/chitosan at weight ratios of 1:4 and 2:3. Utilizing dynamic light scattering (DLS) techniques for these mixtures, an increase on the hydrodynamic particle radius was observed varying their pH from 3.0 to 12.0. Furthermore, a reduction of ζ-potential was also observed for the same pH interval. Following rounds of drying/hydration cycles at a specific pH value, hydrogel matrices were formed. The pore size distribution of these formed hydrogels was examined using scanning electron microscopy. Further FT-IR analyses confirmed a physical interaction between the polysaccharides policaju and chitosan. Swelling experiments revealed water uptake values, after 24h of immersion in water, close to 270% for 1:4, and 320% for 2:3 hydrogels. Finally, rheological measurements were then conducted in order to confirm hydrogel viscoelastic features. These results indicate a promising road to biomaterials fabrication and biomedical applications. Copyright © 2014 Elsevier B.V. All rights reserved.Paulo A.G. Soares is a recipient of a scholarship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) and the author Ana I. Bourbon is a recipient of a fellowship from the Fundacao para a Ciencia e Tecnologia, POPH-QREN and FSE (FCT, Portugal) through grant SFRH/BD/73178/2010. Maria G. Carneiro-da-Cunha, Maria T.S. Correia, Cesar AS, Andrade and Adalberto Pessoa Jr express their gratitude to the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) for research grants. The authors are grateful to the Centro de Tecnologias Estrategicas do Nordeste (CETENE) of the Ministerio da Ciencia e Tecnologia for technical assistance and the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES/PROCAD) for financial suppor