Effect of relative humidity on carvacrol release and permeation properties of chitosan based films and coating

The influence of water vapour conditions on mass transport and barrier properties of chitosan based films and coatings were studied in relation to surface and structural properties. Water contact angles, material swelling, polymer degradation temperature, barrier properties (PO2, PCO2, WVP) and aroma diffusion coefficients were determined. The solvent nature and the presence of carvacrol influenced the surface and structural properties and then the barrier performance of activated chitosan films. Increasing RH from 0% to 100% led to a significant increase in material swelling. The plasticization effect of water was more pronounced at high humid environment, while at low RH the matrix plasticization was induced by carvacrol. The deposit of a thin chitosan layer on polyethylene decreased PO2 and PCO2 both in dry and humid conditions. The carvacrol release from the chitosan matrix was strongly influenced by RH. A temperature increase from 4 to 37 C also had an impact on carvacrol diffusivity but to a lesser extent than RH

Relevance of interactions between starch-based coatings and plum fruit surfaces: A physical-chemical analysis

In order to extend the shelf life of the fruit, improve appearance, and to keep all nutrition properties of the plum from diminishing, edible coatings comprised of wheat starch and wheat starch–whey protein isolate (in ratio 80/20) were created. Stand-alone films were produced to assess properties which helped to understand the phenomena occurring on the surface level of coated plums. The properties of coatings based on starch are similar to starch coatings containing oil because the natural epicuticular wax layer of plums merges with coating materials. Adding oil doubled the contact angle value and the dispersive component of the surface tension. The workings of adhesion and cohesion, spreading coefficient, water absorption, water content, and solubility in water of the films decreased. Similar processes were observed on the fruits’ surface. In appearance, the coating process is similar to polishing the plum surface for removing crystalline wax. The color parameters of coated fruits did not significantly change. Newly formed bonds or interactions established between starch, whey proteins, water, glycerol, and oil are displayed by Fourier transform infrared (FTIR) analysis. This work revealed how the interactions between the epicuticular wax on the fruit’s surface and the hydrocolloid-based coatings affect the efficiency of the coatings. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Diabetes-Related Antibody-Testing is a Valuable Screening Tool for Identifying Monogenic Diabetes – A Survey from the Worldwide SWEET Registry

Aims: To evaluate access to screening tools for monogenic diabetes in paediatric diabetes centres across the world and its impact on diagnosis and clinical outcomes of children and youth with genetic forms of diabetes. Methods: 79 centres from the SWEET diabetes registry including 53,207 children with diabetes participated in a survey on accessibility and use of diabetes related antibodies, c-peptide and genetic testing. Results: 73, 63 and 62 participating centres had access to c-peptide, antibody and genetic testing, respectively. Access to antibody testing was associated with higher proportion of patients with rare forms of diabetes identified with monogenic diabetes (54 % versus 17 %, p = 0.01), lower average whole clinic HbA1c (7.7[Q1,Q2: 7.3-8.0]%/61[56-64]mmol/mol versus 9.2[8.6-10.0]%/77[70-86]mmol/mol, p < 0.001) and younger age at onset (8.3 [7.3-8.8] versus 9.7 [8.6-12.7] years p < 0.001). Additional access to c-peptide or genetic testing was not related to differences in age at onset or HbA1c outcome. Conclusions: Clinical suspicion and antibody testing are related to identification of different types of diabetes. Implementing access to comprehensive antibody screening may provide important information for selecting individuals for further genetic evaluation. In addition, worse overall clinical outcomes in centers with limited diagnostic capabilities indicate they may also need support for individualized diabetes management.info:eu-repo/semantics/publishedVersio

Utjecaj dodatka oksidiranog krumpirovog škroba na fizikalno-kemijska svojstva jestivih filmova proizvedenih od izolata proteina soje

The influence of oxidized starch on the physicochemical properties of cast soy protein isolate films is determined in this study. Films were cast from heated (70 °C for 20 min) alkaline (pH=10) aqueous solutions of 7 % soy protein isolate containing 50 % (by mass) glycerol as a plasticizer and different levels of added oxidized starch (0, 5, 10, 15, and 20 %, by mass). For all types of films, opacity, contact angle, tensile strength, elongation at break, water vapour permeability, measured at 25 °C for four relative humidity differentials (30–53, 30–75, 30–84 and 30–100 %), differential scanning calorimetry and microstructure were determined after conditioning film specimens at 25 °C and 30 % relative humidity for 48 h. Oxidized starch content significantly affected (p<0.05) tensile strength, from 0.95 to 1.51 MPa, temperature at maximum degradation rate from 64.8 to 74.2 °C and water vapour permeability from 1.08·10^–10 to 3.89·10^–10 g/(m·Pa·s) at relative humidity differentials of 30–50 and 30–100 %, respectively. Various internal arrangements were observed as a function of film composition (percentage of oxidized starch).U radu je ispitan utjecaj dodatka oksidiranog škroba na fizikalno-kemijska svojstva filmova dobivenih od izolata proteina soje. Filmovi su izrađeni od zagrijane (tijekom 20 minuta pri 70 ºC) lužnate (pH=10) vodene otopine izolata proteina soje (7 %) s dodatkom 50 % glicerola i različitih masenih udjela oksidiranog škroba (0, 5, 10, 15 i 20 %). Nakon kondicioniranja uzoraka na 25 ºC pri 30 % relativne vlažnosti tijekom 48 sati određene su sljedeće karakteristike filmova: prozirnost, kontaktni kut, rastezna i prekidna čvrstoća, te propusnost vodene pare pri 25 ºC i četiri raspona relativne vlažnosti (30-53, 30-75, 30-84 i 30-100 %). Također su određena toplinska svojstva filmova pomoću diferencijalne pretražne kalorimetrije, te je ispitana njihova mikrostruktura. Dodatak oksidiranog škroba bitno je povećao (p<0.05) rasteznu čvrstoću (s 0,95 na 1,51 MPa), temperaturu pri maksimalnoj brzini razgradnje (sa 64,8 na 74,2 ºC) i propusnost vodene pare (s 1,08•10^-10 g/(m•Pa•s) pri 30-50 % relativne vlažnosti na 3,89•10^-10 g/(m•Pa•s) pri 30-100 % relativne vlažnosti). Udjel oksidiranog škroba utjecao je na različita fizikalno-kemijska svojstva filmova

Modelling water vapor permeability through atomic layer deposition coated photovoltaic barrier defects

Transparent barrier films such as Al2O3 used for prevention of oxygen and/or water vapour permeation are the subject of increasing research interest when used for the encapsulation of flexible photovoltaic modules. However, the existence of micro-scale defects in the barrier surface topography has been shown to have the potential to facilitate water vapour ingress, thereby reducing cell efficiency and causing internal electrical shorts. Previous work has shown that small defects (≤ 3 μm lateral dimension) were less significant in determining water vapour ingress. In contrast, larger defects (≥ 3 μm lateral dimension) seem to be more detrimental to the barrier functionality. Experimental results based on surface topography segmentation analysis and a model presented in this paper, will be used to test the hypothesis that the major contributing defects to water vapour transmission rate are small numbers of large defects. The model highlighted in this study has the potential to be used for gaining a better understanding of photovoltaic module efficiency and performance

Release of coumarin encapsulated in chitosan-gelatin irradiated films

Chitosan and fish gelatin were used to formulate active biobased films containing an antioxidant (coumarin). After drying, the films were irradiated at 40 and 60 kGy using an electron beam accelerator. The effect of irradiation on the film properties as well as the coumarin release mechanism were investigated and compared with the control. Electron Spin Resonance (ESR) revealed free radical formation during irradiation in films containing coumarin. Antioxidant addition and/or irradiation treatment at a dose of 60 kGy resulted in a shift of amide A and amide B peaks. Furthermore a shift of amide II band was only observed for the control film at the same dose. Irradiation allowed improving the thermal stability of the control films. Both irradiation process and addition of coumarin increased the surface wettability (increase of the polar component of the surface tension). From the water barrier analysis, neither irradiation nor coumarin addition influenced the permeability at the lower RH gradient used (0e30% RH). Using the higher RH gradient (30e84%) induced a rise of the WVP of all films (containing or not coumarin) after irradiation treatment. At 60 kGy, the tensile strength of only the control films increased significantly. Considering coumarin release from the film in aqueous medium, the apparent diffusion coefficient of coumarin is two times reduced after irradiation. Irradiation also allowed to better protect the incorporated antioxidant. Indeed, the amount of coumarin in the non-irradiated film was significantly lowered compared to the initial quantity, which is probably due to chemical reactivity

Comparative evaluation of structured oil systems : shellac oleogel, HPMC oleogel, and HIPE gel

In lipid-based food products, fat crystals are used as building blocks for creating a crystalline network that can trap liquid oil into a 3D gel-like structure which in turn is responsible for the desirable mouth feel and texture properties of the food products. However, the recent ban on the use of trans-fat in the US, coupled with the increasing concerns about the negative health effects of saturated fat consumption, has resulted in an increased interest in the area of identifying alternative ways of structuring edible oils using non-fat-based building blocks. In this paper, we give a brief account of three alternative approaches where oil structuring was carried out using wax crystals (shellac), polymer strands (hydrophilic cellulose derivative), and emulsion droplets as structurants. These building blocks resulted in three different types of oleogels that showed distinct rheological properties and temperature functionalities. The three approaches are compared in terms of the preparation process (ease of processing), properties of the formed systems (microstructure, rheological gel strength, temperature response, effect of water incorporation, and thixotropic recovery), functionality, and associated limitations of the structured systems. The comparative evaluation is made such that the new researchers starting their work in the area of oil structuring can use this discussion as a general guideline

Combined effects of chemical dip and/or carrageenan coating and/or controlled atmosphere on quality of fresh-cut banana

The combined effect of chemical dip and/or edible coating and/or controlled atmosphere (CA) on quality of fresh-cut banana was investigated. Banana slices were subject to a 3-min dip into a solution containing 1% (w/v) calcium chloride, 0.75% (w/v) ascorbic acid and 0.75% (w/v) cysteine and/or combined with a carrageenan coating and/or combined with controlled atmosphere (3% O2 + 10% CO2). Physico-chemical and microbiological qualities were evaluated during 5 days of storage at 5 C. Dip combined with CA treatment prevented product weight loss and increase of polyphenol oxidase activity during the 5 days of storage. Colour, firmness, pH, tritatable acidity and total soluble solids values and total phenolic content presented the smallest changes. Microbial analysis showed that minimally processed bananas were within the acceptable limits during 5 days of storage at 5ºC

Antimicrobial properties of chitosan and galactomannan composite coatings and physical properties of films made thereof

The aim of this study was to produce antimicrobial coatings and films based on the mixture of chitosan and galactomannan from Adenanthera pavonina L., with the incorporation of sodium acetate. The antimicrobial activity of the coatings was evaluated against L. monocytogenes, S. aureus, P. aeruginosa and S. enteritidis. Then the films produced, based on the coating formulations, were characterized in terms of water vapour permeability (WVP), oxygen (O2) and carbon dioxide (CO2) permeability, moisture content (MC), water solubility (S), tensile strength (TS), elongation at break (EB), elastic modulus (EM), opacity and color. The composite coatings with Chi were effective against Gram-negative and Gram-positive bacteria. Films Chi presented the low water solubility and high values of component b*, which indicates the predominance of yellowish coloration and the highest TS values. Films of Chi-Gal-NaA present lower values of S, MC, WVP and EB and is the film presenting the higher value of EM. While for the films of Gal-NaA there was a reduction of the O2 permeability and an increase of CO2 permeability. Chi in combination with NaA can be used in the development of antimicrobial coatings and films for food applications, therefore contributing to food preservation and shelf-life extension.CNPq -Conselho Nacional de Desenvolvimento Científico e Tecnológico(undefined)info:eu-repo/semantics/publishedVersio

Enhancement of PLA-PVA surface adhesion in bilayer assemblies by PLA aminolisation

Data Availability: The raw/processed data required to reproduce these findings cannot be shared at this time due to legal or ethical reasons.Poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVA) present complementary barrier properties, and their combination in multilayer assemblies (laminates) could provide materials with more effective barrier capacity for food packaging purposes. However, their low chemical affinity compromises adequate polymer adhesion. Surface free energy modification of thermo-processed PLA films through treatment with 1,6-hexanediamine was used to enhance adhesion with polar PVA aqueous solutions. Treatments of 1 and 3 min increased the polar component of the solid surface tension, while treatments above 10 min provoked a corrosive effect in the films structure. Extensibility analyses of PVA solutions loaded with carvacrol (15 wt.%) and different Tween 85 ratios on PLA-activated surfaces allowed the selection of the 1-min aminolysed surface for obtaining PLA-PVA bilayers, by casting PVA solutions on the PLA films. This study revealed that despite aminolisation enhancing the PLA surface affinity for aqueous PVA solutions, casting-obtained bilayers presented limited oxygen barrier effectiveness due to heterogeneous thickness of PVA layer in the laminates.The authors acknowledge the financial support provided by the Ministerio de Economia y Competitividad (MINECO) of Spain (project AGL2016-76699-R). The author A. Tampau thanks MINECO for the pre-doctoral research grant #BES-2014-068100.info:eu-repo/semantics/publishedVersio