Transport mechanism of macromolecules on hydrophilic bio-polymeric matrices : diffusion of protein-based compounds from chitosan films

The transport mechanism of protein-based bioactive compounds (a peptide fraction from whey protein concentrate, glycomacropeptide and lactoferrin), from chitosan films to liquid medium, was studied. Mathematical models were used to discuss the transport mechanism. Data from release experiments was successfully described by a model which accounts for both Fick and Case II transport – the linear superimposition model. Results show that the mechanism of transport and the effect of temperature and peptide type could be related with physical properties of chitosan films where the tested bioactive compounds were incorporated. The approach presented here allows interpretation of the phenomena involved in mass transport in the systems studied and, once extended to other systems, may contribute to an understanding of transport in hydrophilic bio-polymeric matrices.This work was supported by Fundacao para a Ciencia e a Tecnologia through project PTDC/AGR/ALI/67194/2006. Authors Ana C. Pinheiro, Ana I. Bourbon and Mafalda A.C. Quintas gratefully acknowledge their Grants SFRH/BD/48120/2008, SFRH/BD/73178/2010 and SFRH/BPD/41715/2007, respectively

Κ-carrageenan/chitosan nanolayered coating for controlled release of a model bioactive compound

Multilayer nanocoatings composed of K-carrageenan, a sulphated anionic polysaccharide, and chitosan, a cationic polysaccharide, were produced by layer-by-layer deposition. The model cationic compound Methylene Blue (MB) was incorporated in different positions of the nanolayered coating and its loading and release behavior was evaluated. UV-VIS spectroscopy and quartz crystal microbalance analysis showed that the amount of MB loaded increased with the distance from the first layer, suggesting that the MB was able to diffuse into the K-carrageenan/chitosan nanolayered coating and not only adhered to the surface of the layer immediately below it. For most of the tested conditions, the MB release from the K-carrageenan/chitosan nanolayered coatings was successfully described by the linear superimposition model, which allowed concluding that MB transport is due to both concentration gradient and the polymer relaxation of the nanolayers. However, depending on temperature and pH of the medium and on the position of MB incorporated on the nanolayered coatings, different mechanisms prevail.Industrial relevance: The development of novel edible coatings with improved functionality and performance for e.g. fresh and minimally processed fruits is one of the challenges of the post-harvest industry. This work contributes to the understanding of the loading and release phenomena involved in structures at the nanoscale, which is useful for the development of bioactive compounds release systems for application in food industry. Moreover, the K-carrageenan/chitosan nanolayered coatings represent a promising platform from which the controlled release of different bioactive compounds may be explored.The authors Ana C. Pinheiro, Ana I. Bourbon and Mafalda A.C. Quintas are recipient of fellowships from the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) through grants SFRH/BD/48120/2008, SFRH/BD/73178/2010 and SFRH/BPD/41715/2007, respectively. This work was supported by Fundacao para a Ciencia e a Tecnologia through project NANO/NTec-SQA/0033/2007. The authors also acknowledge Dr. Edith Ariza from SEMAT/UM by the support in SEM analysis

Molecular mobility, crystallinity and barrier properties of chitosan films

Authors Joana F. Fundo and Mafalda A. C. Quintas acknowledge Fundacão para a Ciência e a Tecnologia grants SFRH/ BD / 62176 / 2009 and SFRH / BPD / 41715 / 2007 respectivelyinfo:eu-repo/semantics/publishedVersio

Evaluation of a hydrothermal process for pretreatment of wheat straw : effect of particle size and process conditions

Hydrothermal processes are an eco-friendly processes that provide an interesting alternative for chemical utilization of lignocellulosic materials, in which water and crop residues are the only reagents. In this work the effect of process conditions (size distribution of the wheat straw, temperature and time) was evaluated against production of fermentable products. RESULTS: The use of milled wheat straw fractions as a raw material containing blends of different particle size distribution showed that the latter had an influence on the final sugars in the hydrolysate. Improved values of glucose (21.1%) and xylose yields (49.32%) present in the hydrolysate were obtained with treatment severity factors of 2.77 and 3.36, respectively. Mathematical models were developed aimed at establishing the effect of process conditions on monosaccharide concentration and its degradation in the liquor. CONCLUSION: This work shows that the use of wheat straw blends with various particle sizes has a significant effect on the extraction of fermentable products. The effect of treatment severity, which takes into account both processing time and temperature was also evaluated. These results are of importance for process design.ALBAN programm

Physico-chemical characterization of chitosan-based edible films incorporating bioactive compounds of different molecular weight

Chitosan packaging films containing different bioactive compounds (a peptide fraction from whey protein concentrate (WPC) hydrolysate, glycomacropeptide (GMP) and lactoferrin) were produced and their mechanical and barrier properties were evaluated. The molecular weight of protein-based compounds was determined using SDS–PAGE. The addition of GMP and lactoferrin to chitosan film caused a significant reduction of tensile strength and the elongation-at-break significantly increased with the incorporation of lactoferrin. The addition of protein-based compounds also affected gas permeability: a significant decrease in water vapor permeability was observed with the incorporation of lactoferrin; oxygen permeability significantly decreased with the addition of GMP and lactoferrin and carbon dioxide permeability significantly decreased with the incorporation of all of the protein-based compounds. Such results were related with film’s hydrophilicity and crystallinity. This manuscript contributes to the establishment of an approach to optimize edible films performance based on physico-chemical properties, aiming at a higher benefit for the consumer.The authors gratefully acknowledge LoicHilliou for the fruitful discussions on the results and Ana Nicolau for helping in confocal analysis. The present work was supported by the project PTDC/AGR/ALI/67194/2006. The authors M.A. Cerqueira (SFRH/BD/23897/2005), M.C. Avides (SFRH/BPD/26913/2006) and M.A.C. Quintas (SFRH/BPD/41715/2007) were recipient of fellowships from the Fundacaopara a Ciencia e Tecnologia (FCT, Portugal)

Antioxidant potential of two red seaweeds from the Brazilian coasts

In this work, in vitro antioxidant activity of two Brazilian red seaweeds, Gracilaria birdiae and Gracilaria cornea, was characterized. The total phenolic content, the radical-scavenging activity and the antioxidant activity were determined in two solvent extracts of the algae. Liquid chromatography mass spectrometry (LC MS/MS) allowed identification of important antioxidant compounds. The ethanol extract of G. birdiae was found to have the highest value of total phenolic content: 1.13 mg of gallic acid equiv (GAE)/g of extract.The radical-scavenging activity of G. birdiae and G. cornea extracts has been evaluated at different extract concentrations; the IC50 values of ethanolic extracts of G. cornea and G. birdiae were 0.77 and 0.76mgmL 1, respectively, while formethanolic extracts, the IC50 values of G. cornea and G. birdiae were 0.86 and 0.76mgmL 1, respectively. The antioxidant activities of these two seaweeds’ extracts as assessed by the ß-carotene linoleic acid assay were equally high, achieving values of ß-carotene oxidation inhibition of up to 40%. Finally, in the methanolic extracts, LC MS/MS allowed identification in both algae of two important antioxidants: apigenin and gallic acid.B.W.S.S. is the recipient of a fellowship from the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil) M.A.C. and J.T.M. are recipients of fellowships from the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) (SFRH/BD/23897/2005 and SFRH/BD/32566/2006, respectively)

Fresh-cut melon quality during storage: an NMR study of water transverse relaxation time

Molecular mobility is a fundamental parameter which reflects the dynamic properties of food components and contributes to food degradation reactions comprehension. Fresh-cut fruits have become an important food market segment. However, processing of fruits promotes faster its physiological deterioration, biochemical changes and microbial degradation. The purpose of this work was to use NMR methodology as a tool to evaluate fresh-cut fruit quality, during storage at refrigerated conditions. The fresh-cut melon transverse relaxation time (T2) was measured for a period of 7 days of storage at 5 °C. The relationship between the obtained values, microstructure and quality parameters was investigated. In general, results show the existence of one class of water fluidity in the system, the one present in cells after processing. T2, a measure of this fluidity, is affected by the processing and storage time. Also, it is possible to find a close relationships between T2 and quality parameters of total colour difference (TCD), firmness and aw. As T2 increases TCD also increases, while firmness and aw decrease. These results highlight the usefulness of NMR methodology application in food science.Author Joana F. Fundo acknowledges Fundacao para a Ciencia e a Tecnologia (grant SFRH/BD/62176/2009). The authors acknowledge the Portuguese NMR Network and Strategic Project PEst-C/CTM/LA0025/2013-14. This work was supported by National Funds from FCT through project PEst-OE/EQB/LA0016/201