Special Issue "Coatings and Interfacial Films for Food Applications"

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (31 August 2019).

Special Issue Editors

Prof. Dr. Loredana Mariniello
E-Mail Website
Guest Editor
Department of Chemical Sciences, University of Naples “Federico II”, 80126 Naples, Italy
Interests: biopolymers; edible films; reticulating enzymes
Dr. C. Valeria L. Giosafatto
E-Mail Website
Guest Editor
Department of Chemical Sciences, University of Naples “Federico II”, 80126 Naples, Italy
Interests: biodegradable materials; bioplastics; digestion
Dr. Julia Maldonado-Valderrama
E-Mail Website
Guest Editor
Department of Applied Physics, University of Granada, Campus de Fuentenueva sn, 18071 Granada, Spain
Interests: monolayers; interfacial tension; film imaging; foams and emulsions; digestion

Special Issue Information

Dear Colleagues,

Since the last decade, large amounts of plastic materials have been used for disposable materials, such as food and beverage packages. However, for environmental reasons, there is a desire to replace petroleum-based plastic materials with materials based on renewable resources. This has led to a growing interest in edible films to be used for the protection of food products, in substitution of materials consisting of synthetic polymers. Edible packaging films and coatings have been particularly considered in food preservation, because of their capability to improve global food quality. An edible coating or film has been defined as a thin, continuous layer of edible material formed or placed on or between foods or food components. Edible films can act as mechanical protection, moisture and gas barriers and, at the same time, can preserve the color, texture, and moisture of the coated product. Coating materials that are currently used include polysaccharides, proteins, and lipids. The functional properties of edible coatings are greatly influenced by parameters such as formulation, film forming technology, solvent characteristics, and additives. Moreover, increasing interest in the food industry has been drawn to the development of novel active films/coatings as food packaging materials.

Fundamental interfacial aspects of solutions used for film preparations can have enormous implications in the manufacture of coatings. Accordingly, understanding the interfacial behavior of polysaccharides, proteins, and/or lipids provides basic knowledge, which is important for the rational design of novel materials. The interfacial aspects of dispersed systems can determine the texture and stability of food products, and monolayers provide a model system for understanding interactions at the interface.

We invite investigators to contribute original research articles, as well as review articles, focused on the development strategies for rationally designing packaging systems with potential health and environmental benefits. Achieving this requires a multidisciplinary approach, bringing together Life and Material Science. Fundamental aspects of Material Science are required to characterize the engineering properties of the solutions utilized for film preparation.

Potential topics include, but not limited to:

(1)  Production of edible coatings based on renewable sources, such as carbohydrates, proteins, and lipids;

(2)  Recent advances in active coatings containing different additives, to enhance the functional and organoleptic properties of the packaged products:

  • antioxidants;
  • anti-browning agents;
  • nutraceuticals;
  • texture enhancers, flavors;
  • color ingredients.

(3)  Development of specific edible coatings to enhance the shelf-life and quality of different foods;

(4)  Interfacial characterization of films with technological applications in food products and monolayers.

Prof. Dr. Loredana Mariniello
Dr. C. Valeria L. Giosafatto
Dr. Julia Maldonado-Valderrama
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (8 papers)

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Research

Open AccessArticle
Characterization and Testing of a Novel Sprayable Crosslinked Edible Coating Based on Salmon Gelatin
Coatings 2019, 9(10), 595; https://doi.org/10.3390/coatings9100595 - 20 Sep 2019
Abstract
The aim of this study was to develop and characterize a sprayable edible coating using salmon gelatin (SG) and its stabilization by photopolymerization using riboflavin (Rf). Suspensions of SG with Rf at pH values of 5.0 and 8.5 were exposed for 2 min [...] Read more.
The aim of this study was to develop and characterize a sprayable edible coating using salmon gelatin (SG) and its stabilization by photopolymerization using riboflavin (Rf). Suspensions of SG with Rf at pH values of 5.0 and 8.5 were exposed for 2 min to visible light (VL) and ultraviolet (UV) light and further characterized to determine structural changes of the different gelatin formulations. Rheology analysis showed that at pH 5, the loss modulus (G″) was higher that the storage modulus (G’) for crosslinked samples (VL and UV light). However, at pH 8.5 G’ values increased over G″, showing a strong crosslinking effect. Interestingly both moduli did not intersect at any point and their maximum values did not change upon cooling with respect to the gelatin suspension without light exposure, demonstrating that triple helix formation was not affected by the reaction. In fact, neither the gelation temperature nor the enthalpy values were significantly affected. Viscosity measurements confirmed the hydrogel formation using VL, showing higher viscosity values after exposure at increasing temperatures. Transmittance (T%) measurements showed an increase in T% in the suspensions after VL exposure, with only a 10% decrease compared to SG without riboflavin. For validation, the coating was sprayed in fresh salmon fillets, showing a 37% delay in spoilage and reduced weight loss. Therefore, photopolymerization of low viscosity gelatins would allow to manage viscoelasticity of the biomaterial stabilizing it as coating and preventing the deterioration of salmon fillets. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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Open AccessFeature PaperArticle
Poly (Lactic Acid)/Thermoplastic Starch Films: Effect of Cardoon Seed Epoxidized Oil on Their Chemicophysical, Mechanical, and Barrier Properties
Coatings 2019, 9(9), 574; https://doi.org/10.3390/coatings9090574 - 08 Sep 2019
Abstract
In this work, biodegradable films based on poly (lactic acid) (PLA) and corn thermoplastic starch (TPS), additivated with epoxidized cardoon oil plasticizer (ECO) at 3% by weight with respect to PLA mass fraction, were prepared by melt extrusion process and compression molding. The [...] Read more.
In this work, biodegradable films based on poly (lactic acid) (PLA) and corn thermoplastic starch (TPS), additivated with epoxidized cardoon oil plasticizer (ECO) at 3% by weight with respect to PLA mass fraction, were prepared by melt extrusion process and compression molding. The effect of ECO on structural, thermal, mechanical, barrier, and spectral optical properties of the films was investigated. Spectroscopic analysis evidenced the development of physical interaction between oil and polymers, mainly PLA. In addition, no oil migration occurrence was detected after six months of film preparation, as evidenced by oil mass evaluation by precipitation as well as by 1H-NMR methods, thus highlighting the good inclusion of oil inside the polymeric network. The plasticizing action of the oil induced a lean improvement of the interfacial adhesion between hydrophobic PLA and hydrophilic TPS, particularly accentuated in PLA80_ECO composition, as evidenced by morphological analysis of blend fracture surfaces. TGA data underlined that, differently from TPS-based films, PLA-based systems followed one degradative thermal profile suggesting a slight compatibilization effect of epoxidized oil in these films. The shifting of Tg values, by differential scanning calorimetry (DSC) analysis, indicated a weak miscibility at molecular level. Generally, in the investigated blends, the phase separation between PLA and TPS polymers was responsible for the mechanical properties failing; in particular, the tensile strength evidenced a negative deviation from the rule of mixtures, particularly marked in TPS-based blends, where no physical entanglements occurred between the polymers since their immiscibility even in presence of ECO. The epoxidized oil strongly improved the barrier properties (water vapor permeability (WVP) and oxygen permeability (O2P)) of all the films, likely developing a physical barrier to water and oxygen diffusion and solubilization. With respect to neat PLA, PL80 and PL80_ECO films evidenced the improvement of surface wettability, due to the presence of polar groups both in TPS (hydroxyl residues) and in epoxidized oil (oxirane rings). Finally, following to the conditioning in climatic chamber at T = 25 °C and RH = 50%, PLA80 film became opaque due to TPS water absorption, causing a light transmittance decreasing, as evidenced by spectral optical analysis. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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Open AccessFeature PaperArticle
Coating of Nanolipid Structures by a Novel Simil-Microfluidic Technique: Experimental and Theoretical Approaches
Coatings 2019, 9(8), 491; https://doi.org/10.3390/coatings9080491 - 02 Aug 2019
Abstract
Nanolipid vesicular structures are ideal candidates for the controlled release of various ingredients, from vitamins for nutraceutical purposes to chemoterapic drugs. To improve their stability, permeability, and some specific surface properties, such as mucoadhesiveness, these structures can require a process of surface engineering. [...] Read more.
Nanolipid vesicular structures are ideal candidates for the controlled release of various ingredients, from vitamins for nutraceutical purposes to chemoterapic drugs. To improve their stability, permeability, and some specific surface properties, such as mucoadhesiveness, these structures can require a process of surface engineering. The interaction of lipid vesicles with oppositely charged polyelectrolytes seems to be an interesting solution, especially when the negatively charged liposomes are complexed with the cationic chitosan. In this work, a novel simil-microfluidic technique was used to produce both chitosan-coated vesicles and a vegan alternative composed of cholesterol-free liposomes coated by Guar Hydroxypropyltrimonium Chloride (Guar-HC). The combination between the experimental approach, based on experimental observations in terms of Z-potential, and size evolutions, and the theoretical approach, based on concepts of saturation, was the methodology applied to define the best polycation concentration to fairly cover (vegan or not) liposomes without aggregation. The smart production of coated nanolipid structures was confirmed by characterizations of morphology, mucoadhesiveness, and stability. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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Open AccessFeature PaperArticle
Starch/Poly (Glycerol-Adipate) Nanocomposite Film as Novel Biocompatible Materials
Coatings 2019, 9(8), 482; https://doi.org/10.3390/coatings9080482 - 30 Jul 2019
Abstract
Starch is one of the most abundant polysaccharides on the earth and it is the most important source of energy intake for humans. Thermoplastic starch (TPS) is also widely used for new bio-based materials. The blending of starch with other molecules may lead [...] Read more.
Starch is one of the most abundant polysaccharides on the earth and it is the most important source of energy intake for humans. Thermoplastic starch (TPS) is also widely used for new bio-based materials. The blending of starch with other molecules may lead to new interesting biodegradable scaffolds to be exploited in food, medical, and pharmaceutical fields. In this work, we used native starch films as biopolymeric matrix carriers of chemo enzymatically-synthesized poly (glycerol-adipate) (PGA) nanoparticles (NPs) to produce a novel and biocompatible material. The prototype films had a crystallinity ranging from 4% to 7%. The intrinsic and thermo-mechanical properties of the composite showed that the incorporation of NPs in the starch films decreases the glass transition temperature. The utilization of these film prototypes as the basis for new biocompatible material showed promise, particularly because they have a very low or even zero cytotoxicity. Coumarin was used to monitor the distribution of the PGA NPs in the films and demonstrated a possible interaction between the two polymers. These novel hybrid nanocomposite films show great promise and could be used in the future as biodegradable and biocompatible platforms for the controlled release of amphiphilic and hydrophobic active ingredients. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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Open AccessArticle
Condensation of Model Lipid Films by Cholesterol: Specific Ion Effects
Coatings 2019, 9(8), 474; https://doi.org/10.3390/coatings9080474 - 27 Jul 2019
Abstract
The condensing effect and the ability of cholesterol (CHOL) to induce ordering in lipid films is a question of relevance in biological membranes such as the milk fat globule membrane (MFGM) in which the amount of CHOL influences the phase separation and mechanical [...] Read more.
The condensing effect and the ability of cholesterol (CHOL) to induce ordering in lipid films is a question of relevance in biological membranes such as the milk fat globule membrane (MFGM) in which the amount of CHOL influences the phase separation and mechanical resistance to rupture of coexisting phases relevant to emulsified food systems. Here, we study the effect of different salts (NaCl, CaCl2, MgCl2, LaCl3) on monolayers made of a model mixture of lipids (DPPC:DPPS 4:1) and CHOL. To this end, we apply Langmuir Film Balance to report a combined analysis of surface pressure-area (π-A) and surface potential-area (ΔVA) isotherms along with Micro-Brewster Angle Microscopy (Micro-BAM) images of the monolayers in the presence of the different electrolytes. We show that the condensation of lipid by CHOL depends strongly on the nature of the ions by altering the shape and features of the π-A isotherms. ΔVA isotherms provide further detail on the ion specific interactions with CHOL. Our results show that the condensation of lipids in the presence of CHOL depends on the combined action of ions and CHOL, which can alter the physical state of the monolayer. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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Open AccessFeature PaperArticle
The Effect of Transglutaminase to Improve the Quality of Either Traditional or Pectin-Coated Falafel (Fried Middle Eastern Food)
Coatings 2019, 9(5), 331; https://doi.org/10.3390/coatings9050331 - 23 May 2019
Abstract
In this study, the effect of transglutaminase (TGase) (5 or 20 U/g of chickpea proteins) on falafel dough was investigated. The resulting falafel balls were either treated or not by dipping them into a pectin (PEC 1%) coating solution. Acrylamide (ACR), oil, and [...] Read more.
In this study, the effect of transglutaminase (TGase) (5 or 20 U/g of chickpea proteins) on falafel dough was investigated. The resulting falafel balls were either treated or not by dipping them into a pectin (PEC 1%) coating solution. Acrylamide (ACR), oil, and water content were then evaluated. Texture profile analyses and in vitro gastric digestion experiments were also carried out. The ACR content was reduced by 10.8% and by 34.4% in the samples prepared with 5 and 20 U TGase/g, respectively. In PEC-coated samples, the reduction of ACR was equal to 59.3%, 65.3%, and 84.5%, in falafel balls prepared either without TGase or containing 5 U or 20 U of the enzyme, respectively. However, TGase treatment did not affect oil content, while the PEC coating reduced oil uptake by 23.5%. No difference was observed in the texture properties between the control sample and the one dipped in PEC, while these properties changed in samples prepared with the enzyme. Finally, digestion studies, carried out under physiological conditions, demonstrated that the falafels prepared in the presence of TGase were efficiently digested in the gastric environment. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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Open AccessArticle
Coating Effects of ε-Polylysine and Rosmarinic Acid Combined with Chitosan on the Storage Quality of Fresh Half-Smooth Tongue Sole (Cynoglossus semilaevis Günther) Fillets
Coatings 2019, 9(4), 273; https://doi.org/10.3390/coatings9040273 - 22 Apr 2019
Cited by 2
Abstract
The study was to evaluate the effects of chitosan-based coating combined with rosmarinic acid (RA) with different concentrations of ε-polylysine (ε-PL) on flavor retention and sensorial properties of half-smooth tongue sole fillets during storage at 4 °C. Results showed that chitosan-based coatings combined [...] Read more.
The study was to evaluate the effects of chitosan-based coating combined with rosmarinic acid (RA) with different concentrations of ε-polylysine (ε-PL) on flavor retention and sensorial properties of half-smooth tongue sole fillets during storage at 4 °C. Results showed that chitosan-based coatings combined with ε-PL and RA contributed to the reduction of off-flavor compounds, such as total volatile base nitrogen (TVB-N), trimethylamine (TMA), and ATP-related compounds, and accumulation of free amino acids (FAAs). Nineteen volatile organic compounds were analyzed by gas chromatography-mass spectrometer (GC/MS) during storage, including seven alcohols, six aldehydes, and six ketones. The coating treated fresh half-smooth tongue sole (HTS) fillets significantly reduced the relative content of off-odor volatiles, such as 1-octen-3-ol, propanal, hexanal, and octanal. According to sensory evaluation results, chitosan-based coating combined with ε-PL and RA was an effective way to maintain quality of HTS fillets during refrigerated storage. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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Open AccessFeature PaperArticle
Effect of Mesoporous Silica Nanoparticles on Glycerol-Plasticized Anionic and Cationic Polysaccharide Edible Films
Coatings 2019, 9(3), 172; https://doi.org/10.3390/coatings9030172 - 05 Mar 2019
Cited by 1
Abstract
This study describes the production of reinforced polysaccharide (PS)-based films, by adding mesoporous silica nanoparticles (MSNs), to either pectin (PEC) or chitosan (CH) film forming solutions, either containing glycerol (GLY) as a plasticizer, or not. Film characterization demonstrated that MSNs and GLY were [...] Read more.
This study describes the production of reinforced polysaccharide (PS)-based films, by adding mesoporous silica nanoparticles (MSNs), to either pectin (PEC) or chitosan (CH) film forming solutions, either containing glycerol (GLY) as a plasticizer, or not. Film characterization demonstrated that MSNs and GLY were able to significantly increase the plasticity of both PS-based biomaterials and that the interactions between PSs and nanoparticles were mainly due to hydrogen bonds. Moreover, MSN-containing films were less transparent, compared to controls prepared with either PEC or CH, in the absence of GLY, while all films containing MSNs, but obtained with the plasticizer, were as transparent as the films prepared with PEC or CH alone. MSN addition did not influence the thickness of the PEC-based films, but increased that of CH-based ones, prepared both in the absence and presence of GLY. MSN-containing PEC-based films possessed a more compact and homogeneous morphology, with respect to both control films, prepared, with or without GLY, and to the CH-based films, containing MSNs, the structure of which showed numerous agglomerations. Finally, moisture content and uptake were reduced, in all films prepared in the presence of MSNs. The suggested addition of MSNs might have given rise to novel biomaterials for food or pharmaceutical applications. Full article
(This article belongs to the Special Issue Coatings and Interfacial Films for Food Applications)
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