Preparation and functional properties of fish gelatin–chitosan blend edible films

Composite edible films and coatings from food-grade biopolymers

The development of edible films and coatings from food-grade biopolymers has advanced significantly during the past decade. The current state-of-the-art lies in the formulation of composite edible films and coatings from such biomolecules. Composite films and coatings refer to systems where multiple biopolymers have been combined to achieve beneficial properties. Carbohydrate, protein, and lipids have been preferred for developing such systems. Binary films and coatings have been prepared from multiple combinations including protein-protein, carbohydrate-carbohydrate and protein-carbohydrate. Similarly, ternary films and coatings have been prepared from protein-protein-carbohydrate combinations. In addition, several active ingredients including antimicrobial compounds have been loaded to these systems for the preparation of functional films and coatings. Therefore, the goal of this manuscript is to review the multitude of composite systems that are currently available for food packaging purposes. In addition, we discuss the application of composite coatings to fruits and vegetables, dairy, meat and seafood as model food systems.

Chitosan, gelatin and methylcellulose films incorporated with tannic acid for food packaging

In this work, chitosan, gelatin and methylcellulose films incorporated with tannic acid (TA) were synthesised, characterised and applied for the first time to preserve cherry tomatoes (Solanum lycopersicum var. cerasiforme) and grapes (Vitis vinifera). The addition of TA at 15% (w/w) increased the transparency value of biopolymer films. The highest increment of transparency value was obtained for MC-TA film, increased from 0.572 to 4.73 A/mm. Based on antimicrobial study, the addition of TA improved the antibacterial properties of biopolymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The ability of films to preserve both fruits was evaluated in a 14-day preservation study. The application of biopolymer films treated with TA has decreased the weight loss and browning index of fruits, as compared to control films. A significant reduction in the weight loss of cherry tomatoes wrapped with chitosan (from 21.3 to 19.6%), gelatin (from 22.1 to 15.5%) and methylcellulose (26.2 to 20.5%) films were obtained following TA treatment. Overall, results obtained from this study highlight the effects of TA on physiochemical properties of biopolymer films and their ability to preserve fruits.

Influence of Various Phenolic Compounds on Properties of Gelatin Film Prepared from Horse Mackerel Trachurus japonicus Scales

Influence of various phenolic compounds on physical properties and antioxidant activity of gelatin film from horse mackerel Trachurus japonicus scales was investigated. Tensile strength (TS) of the film was enhanced whereas elongation at break was declined by adding 1% to 5% phenolic compounds. Rutin was the most effective to improve the TS compared to the other tested phenolic compounds including ferulic acid, caffeic acid, gallic acid, and catechin. Gelatin films with the phenolic compounds showed the excellent UV barrier properties. FTIR spectra exhibited that wavenumber of amide-A band of films decreased with formation of hydrogen bonding between amino groups of gelatin and hydroxyl groups of the phenolic compounds. Gelatin film incorporated with rutin which has the largest number of hydroxyl groups among the tested compounds demonstrated the lowest wavenumber for the amide-A peak. It is indicated that hydroxyl groups contained in the phenolic compounds contribute to formation of hydrogen bonds involved in improvement of the mechanical properties of the films. The incorporation of the phenolic compounds with gelatin films also led to the increasing of total phenolic contents and DPPH radical scavenging activities. Thus, it is concluded that phenolic compounds can promote the quality of gelatin film.

PRACTICAL APPLICATION

Properties of gelatin film derived from horse mackerel scales can be improved by adding of phenolic compounds. Phenolic compounds containing a large number of hydroxyl groups should be selected to enhance physical properties of the gelatin film. A biodegradable film prepared from horse mackerel gelatin incorporated with phenolic compounds, which has good physical properties and antioxidant properties, can solve environmental problems caused by synthetic plastic materials.

Influence of Codium tomentosum Extract in the Properties of Alginate and Chitosan Edible Films

The growing search for natural alternatives to synthetic food packaging materials and additives has increased, and seaweed extracts’ bioactivity has made them suitable candidates for incorporation in novel edible films. This study aims to investigate the effect of Codium tomentosum seaweed extract (SE) incorporation in alginate and chitosan edible films. Alginate- and chitosan-based films with and without the incorporation of 0.5% SE were characterized according to their physical, optical, mechanical, and thermal properties. Seaweed extract incorporation in chitosan films resulted in an increase of film solubility (50%), elasticity (18%), and decrease of puncture strength (27%) and energy at break (39%). In alginate films, the extract incorporation significantly decreased film solubility (6%), water vapour permeability (46%), and elasticity (24%), and had no effect on thermal properties. Depending on the type of application, the addition of SE in edible films can bring advantages for food conservation.

Film-forming ability of collagen hydrolysate extracted from leather solid wastes with chitosan

Discharges of huge quantities of leather solid wastes by leather industries and the increased use of synthetic packaging films have raised serious concerns on account of their environmental impacts. The paper focuses on the development and characterization of potential environmentally friendly composite films using collagen hydrolysate (CH) extracted from leather solid wastes and chitosan (C) to assess the feasibility of producing polymeric materials suitable for applications in packaging and wrapping purposes. Solid collagen-based protein hydrolysate was extracted from chromium-tanned leather wastes and analyzed to determine its chemical properties. With the goal of improving the physico-chemical performance of CH, three types of composite films (CH75/C25, CH50/C50, CH25/C75) were prepared with increasing concentrations of C, and some of their physical and functional properties were characterized. The results indicated that the addition of C caused increase (p < 0.05) in the thickness, tensile strength (TS), elasticity modulus (EM), and water vapor permeability (WVP), leading to stronger films as compared with CH film, but significantly (p < 0.05) decreased the elongation at break (EAB) and solubility of films (p < 0.05). The light barrier measurements present low values of transparency at 600 nm of the CH/C films, indicating that the films are very transparent and they have excellent barrier properties against UV light. The structural properties investigated by FTIR and DSC showed total miscibility between both polymers. Scanning electron micrographs revealed that CH/C composite films showed a compact homogeneous structure. These results demonstrate the potential application of CH/C composite films in packaging industry.

Physico-mechanical and structural properties of eggshell membrane gelatin- chitosan blend edible films

This study investigated the physico-mechanical and structural properties of composite edible films based on eggshell membrane gelatin (G) and chitosan (Ch) (75G:25Ch, 50G:50Ch, 25G:75Ch). The results demonstrated that the addition of Ch increased elongation at break significantly (p<0.05), but resulted in no significant change in tensile strength (TS) using 75G:25Ch, 50G:50Ch mixtures in comparison with gelatin-based film. The water solubility and water vapor permeability of the 50G:50Ch film decreased significantly compared to plain films (100G:0Ch and 0G:100Ch) and other composite films (p<0.05). Fourier transform infrared spectroscopy evaluation of structural properties showed that both polymers are totally miscible. Scanning electron microscopy was used to study the morphology of the composite films; it revealed a homogenous and compact structure in 75G:25Ch and 50G:50 Ch. Also, the chemical interactions introduced by the addition of chitosan to eggshell membrane gelatin as new resources could improve the films' functional properties.

Emerging Chitosan-Based Films for Food Packaging Applications

Recent years have witnessed great developments in biobased polymer packaging films for the serious environmental problems caused by the petroleum-based nonbiodegradable packaging materials. Chitosan is one of the most abundant biopolymers after cellulose. Chitosan-based materials have been widely applied in various fields for their biological and physical properties of biocompatibility, biodegradability, antimicrobial ability, and easy film forming ability. Different chitosan-based films have been fabricated and applied in the field of food packaging. Most of the review papers related to chitosan-based films are focusing on antibacterial food packaging films. Along with the advances in the nanotechnology and polymer science, numerous strategies, for instance direct casting, coating, dipping, layer-by-layer assembly, and extrusion, have been employed to prepare chitosan-based films with multiple functionalities. The emerging food packaging applications of chitosan-based films as antibacterial films, barrier films, and sensing films have achieved great developments. This article comprehensively reviews recent advances in the preparation and application of engineered chitosan-based films in food packaging fields.

Development of Antimicrobial Packaging Film Made from Poly(Lactic Acid) Incorporating Titanium Dioxide and Silver Nanoparticles

Polylactide (PLA)/nano-TiO₂ and PLA/nano-TiO₂/nano-Ag blends films were prepared by a solvent volatilization method. Compared to pure PLA film, the nano-blend films have low water vapor permeability (WVP) and a poor transparency. With the increase of the NPs in the PLA, the tensile strength (TS) and elastic modulus (EM) decreased, while the elongation at break (ε) increased. SEM analysis indicated a rougher cross-section of the nano-blend films. According to the FTIR analysis, no new chemical bonds were formed in the nano-blend films. By using DSC to examine the crystallization and melting behavior, the result shows that the NPs have no effect on the glass transition (Tg) and melting temperature (Tm), but they caused an increase on the cold crystallization (Tc) and crystallinity (Xc). TGA results show that the addition of nanoparticles significantly improved the thermal stability. The PLA nano-blend films show a good antimicrobial activity against. E. coli and Listeria monocytogenes. Most important, we carried out migration tests, and verified that the release of NPs from the nano-blend films was within the standard limits.