Gelatin Films Research Articles

Gelatin film cross-linked with laccase-catalyzed purple cauliflower extract and coated with Zn-carbon dots exhibits excellent physicochemical properties and functionality for intelligent and active packaging

Preparation of oxidized purple cauliflower extract (OPE) was conducted by laccase oxidation and served as a reinforcing agent for enhancing physicochemical properties of gelatin (Gel) films. Chitosan (CS) loaded with biowaste-derived Zn-carbon dots (Zn-CD) coating further enhanced the functionality and stability of Gel/OPE film. Structural characterization revealed that OPE and Gel form Schiff base bonds and hydrogen bonds. After the formation of CS/Zn-CD coating, hydrogen bonds formed between CS and Zn-CD, and CS and Gel were closely bonded through electrostatic interactions and hydrogen bonding. OPE crosslinking and CS/Zn-CD coating improve mechanical, barrier properties and water resistance of Gel films. CS/Zn-CD coating improved antibacterial and antioxidant ability and illumination stability of composite film, effectively reflected the freshness of salmon during storage. Hence, the functional Gel films developed in this study is hopeful candidate for intelligent and active food packaging application.

Antimicrobial gelatin-based films with cinnamaldehyde and ZnO nanoparticles for sustainable food packaging

Cinnamaldehyde (CIN), a harmless bioactive chemical, is used in bio-based packaging films for its antibacterial and antioxidant properties. However, high amounts can change food flavor and odor. Thus, ZnO nanoparticles (NPs) as a supplementary antimicrobial agent are added to gelatin film with CIN. The CIN/ZnO interactions are the main topic of this investigation. FTIR-Attenuated Total Reflection (ATR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were utilized to investigate CIN/ZnO@gelatin films. Transmission electron microscope (TEM) images revealed nanospheres morphology of ZnO NPs, with particle sizes ranging from 12 to 22 nm. ZnO NPs integration increased the overall activation energy of CIN/ZnO@gelatin by 11.94%. The incorporation of ZnO NPs into the CIN@gelatin film significantly reduced water vapour permeability (WVP) of the CIN/ZnO@gelatin film by 12.07% and the oxygen permeability (OP) by 86.86%. The water sorption isotherms of CIN/ZnO@gelatin were described using Guggenheim-Anderson-de Boer (GAB) model. The incorporation of ZnO NPs into the CIN@gelatin film reduced monolayer moisture content (M0) by 35.79% and significantly decreased the solubility of CIN/ZnO@gelatin by 15.15%. The inclusion of ZnO into CIN@gelatin film significantly decreased tensile strength of CIN/ZnO@gelatin by 13.32% and Young`s modulus by 18.33% and enhanced elongation at break by 11.27%. The incorporation of ZnO NPs into the CIN@gelatin film caused a significant decrease of antioxidant activity of CIN/ZnO@gelatin film by 9.09%. The most susceptible organisms to the CIN/ZnO@gelatin film included Candida albicans, Helicobacter pylori, and Micrococcus leutus. The inhibition zone produced by the CIN/ZnO@gelatin film versus Micrococcus leutus was 25.0 mm, which was comparable to the inhibition zone created by antibacterial gentamicin (23.33 mm) and cell viability assessment revealed that ZnO/CIN@gelatin (96.8 ± 0.1%) showed great performance as potent biocompatible active packaging material.

Chitosan-ginger essential oil nanoemulsions loaded gelatin films: A biodegradable material for food preservation

The alarming issue of food waste, coupled with the potential risks posed by petroleum-based plastic preservation materials to both the environment and human health necessitate innovative solutions. In this study, we prepared nanoemulsions (NEs) of chitosan (CS) and ginger essential oil (GEO) and systematically evaluated the effects of varying NEs concentrations (0, 10 %, 30 %, 50 %) on the physicochemical properties and biological activities of gelatin films. These films were subsequently applied to blueberry preservation. The scanning electron microscopy confirmed that the NEs were well-integrated with the Gel matrix, significantly enhancing the performance of the Gel films, including improvements of mechanical properties (tensile strength from 7.71 to 19.92 MPa; elongation at break from 38.55 to 113.65 %), thermal, and barrier properties (water vapor permeability from 1.52 × 10−9 to 6.54 × 10−10 g·m/Pa·s·m2). The films exhibited notable antibacterial and antioxidant activities due to the gradual release of GEO, thereby extending the storage life of blueberries. Moreover, the prepared composite films demonstrated excellent biodegradability and environmental friendliness, with the majority of the material decomposing within 30 days under soil microbial action. In conclusion, the active films loaded with NEs exhibit superior performance and hold significant potential for developing biodegradable materials for food preservation.

Insights into the effect of carboxylated cellulose nanocrystals on mechanical and barrier properties of gelatin films for flexible packaging applications

In this study, gelatin/carboxylated cellulose nanocrystal (cCNC) bionanocomposite films were developed as an eco-friendly alternative to non-biodegradable flexible plastic packaging. Cellulose nanocrystals were modified by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation (cCNC) to strategically interact with amino groups present in the gelatin macromolecular backbone. Gelatin/cCNC bionanocomposite films (0.5–6.0 wt% cCNC) obtained by solution casting were transparent to visible light while displayed high UV-blocking properties. The chemical compatibility between gelatin and cCNC was deepened by electrostatic COO−/NH3+ interactions, as detected by FTIR spectroscopy and morphologically indicated by scanning electron microscopy (SEM). Accordingly, Young's modulus and tensile strength of films were largely increased by 80 and 64 %, respectively, specifically near the cCNC percolation threshold (4 wt%), whereas the water vapor permeability (WVP) was reduced by 52 % at the optimum 6.0 wt% cCNC content in relation to the non-reinforced gelatin matrix (0.10 vs. 0.18 g H2O mm m−2 h−1 kPa−1). The oxygen transmission rates (OTR) of the gelatin/cCNC bionanocomposites were < 0.01 cm3 m-2 day−1, making them technically competitive to most promising biopolymers like polycaprolactone (PCL) and poly(lactic acid) (PLA). This study reveals how TEMPO-oxidized cellulose nanocrystals can broaden the performance of biodegradable gelatin films for use in packaging. The gelatin/cCNC bionanocomposites also represent an effective approach for designing newly sustainability-inspired flexible materials from the surface modification of nanocelluloses targeting specific interactions with protein structures.

Development of fish gelatin film for anti-fogging mushroom packaging

Mushrooms are extremely perspiring and transpiring commodities. The commonly used plastic films for packaging fresh mushrooms have lower water vapour permeability compared to the rate at which mushrooms transpire, resulting in excessive moisture accumulation inside the package which leads to fogging. This study aimed to investigate the properties of a fish scale gelatin-based film and its correlation with antifogging properties. To produce the gelatin-based film, gelatin was extracted from fish scales using chemical pretreatment and thermal denaturation of collagen. A film-forming solution (FFS) was prepared by dissolving 2% (w/v) gelatin in a solvent, with the addition of glycerol. The solution was then cast to form the film, which underwent tests for mechanical strength, thermal behaviour, barrier properties, and antifogging performance. The resulting film (G-Gly) exhibited reduced tensile strength (13.21 MPa) but increased elongation at break (82.4%). Differential scanning calorimetry revealed a lower glass transition temperature (59.91 °C) for G-Gly. Both gelatin films displayed high water vapour permeability (1.69–3.09x10-6 g m/m2.day.Pa), preventing condensation. Notably, the G and G-Gly films remained fog-free even under varying temperatures, unlike linear low-density polyethylene film (LLDPE). In conclusion, the gelatin-based films demonstrated strong barrier properties and effective antifogging capabilities, making them suitable for moisture-sensitive commodities like mushrooms.

Valorization of whey through green synthesis of silver nanoparticles for developing biodegradable plastic films with bactericide properties

This study explores the synthesis of silver nanoparticles (AgNPs) using untreated whey as a green approach, followed by their integration into biodegradable gelatin films for potential applications in antimicrobial packaging. UV–visible spectroscopy and scanning electron microscopy confirm the successful synthesis of AgNPs, which are seamlessly incorporated into flexible and semi-transparent gelatin films. Comparing films with and without AgNPs, subtle changes are observed in UV–visible and Fourier-transform infrared spectra that are attributed to the low AgNP concentrations. However, the resulting films with AgNPs exhibit effective bactericidal efficacy against E. coli. Moreover, soil burial tests demonstrate significant biodegradability, with up to 80% mass loss within two weeks, showing comparable rates between films with and without AgNPs. These results show the prospects of whey-derived AgNPs in the development of sustainable, antimicrobial biodegradable films with potential applications in various industries.

Fabrication and characterization of active gelatin-based films integrated with nanocellulose-stabilized Pickering emulsion containing Oliveria Decumbens Vent. essential oil

Stabilizing essential oils (EOs) within biodegradable matrices to create homogeneous and stable films with desirable properties is challenging due to the hydrophobic nature of EOs, which hinders their uniform infusion into the matrix. In this study, we investigated the feasibility of creating active films made of gelatin, infused with nanocellulose-stabilized Pickering emulsion (PE) containing Oliveria Decumbens Vent. essential oil (OEO). The Pickering emulsion effectively stabilized the 50% v/v of OEO, which was subsequently incorporated into a gelatin film at 0, 3, 5, 7, and 9% v/v, to produce active films. FTIR data showed that the OEO-PE was physically trapped in the film matrix through hydrogen bonds, which was also verified by SEM micrographs. The addition of OEO-PE notably changed the films' mechanical properties, leading to reduced tensile strength and enhanced elongation (P < 0.05) with no significant impact on their water vapor permeability. The incorporation of OEO endowed the film matrix with high antioxidant and antibacterial activity against E. coli and S. aureus. Thermal analysis using differential scanning calorimetry showed a 36–171 °C endothermic peak in all films, due to water evaporation and melting. The gelatin film containing 9% OEO-PE exhibited superior physical properties, enhanced water resistance, and excellent antibacterial and antioxidant activity.

Evaluation of phenolic compounds as cross-linkers to improve the qualities of halal gelatin from milkfish scales (Chanos chanos)

Gelatin is a versatile substance extensively used in medical and pharmaceutical industries for many applications, including capsule shells, X-ray film, infusion for plasma substitute, and the fabricating of artificial tissue. Fish scale gelatin is a profitable alternative source as a halal material despite its inferior quality. An addition of phenolic cross-linker may enhance the qualities of fish scale gelatin. The aim of this study was to determine the ability of phenolics to act as cross-linkers for fish scale gelatin and to identify the factors affecting this process. Gelatin production from fish scales (Chanos chanos) was carried out through basic pre-extraction and acidic pre-extraction. Thereafter, the gelatin was reacted with 10 different phenolics (phenol, pyrocatechol, resorcinol, α-naphthol, vanillin, L-tyrosine, curcumin, gallic acid, quercetin, and tannic acid). The resultant gelatins were characterized by infrared spectrum, X-ray diffraction pattern, swelling index, degree of cross-linking, viscosity, gel strength, mechanical profile, thermal profile, and water vapor permeability. Gelatin with the most favorable characteristics was further investigated for the effects of acidity (pH 4, 7, and 10) and cross-linker concentrations (2.5–10%). The findings revealed the formation of cross-linkage through shifted vibrational peaks of amide A, amide B, and amide II in the infrared spectrum. Shifted X-ray diffraction peaks in the gelatin with phenol addition also indicated the formation of cross-linkage. Significant improvement in the gelatin characteristics, such as swelling index, degree of cross-linking, viscosity, gel strength, mechanical profile, thermal profile, and water vapor permeability, could be attributed to the addition of phenolics cross-linkers. The highest improvement was observed in gelatin added with basic tannic acid 10%. Gelatin cross-linked with basic tannic acid 10% had a moisture content of 9.24±0.14%, swelling index of 323±17%, degree of cross-linking of 69.99±0.84%, viscosity of 8.48±0.23 cP, gel strength of 151.5±6.9 Bloom, melting temperature of 213.5°C, tensile strength of 7.00±0.54 N.cm-2, elongation at the break of 114.08±14.63%, elastic modulus of 58.45±8.20 N.cm-2 and water vapor permeability of 0.57±0.07 g.mm.m-2.h-1. kPa-1. The qualities of tannic acid-cross-linked gelatin films and film-forming gel increased when manufactured under basic conditions in comparison to acidic or neutral conditions. Furthermore, increasing the quantity of tannic acid to 10% improved the overall characteristics as compared to non-cross-linked gelatin. In conclusion, tannic acid has the ability to cross-link the fish gelatin, thereby enhancing its qualities.

Tilapia gelatin films by incorporating metal-polyphenol network formed by procyanidin and zinc ion for pork preservation

There is a lack of information about the application of metal polyphenol networks (MPN) in the food industry nowadays. Herein, the MPN was prepared by procyanidin (PC) and zinc ion (Zn2+), and introduced into tilapia gelatin films. The MPN-modified films showed broader thickness, higher UV-Vis light barrier property, and lower water sensitivity and water vapor property than PC-modified films. When the molar ratio of Zn2+ to PC being 3:8, the incorporation of MPN induced the highest tensile strength of films reaching 82.47 MPa, good activity against oxidation, and improved inhibition activity to Staphylococcus aureus and Escherichia coli. The MPN-modified gelatin films could suppress the bacteria growth, and attenuate the generation of total volatile basic nitrogen and thiobarbituric acid reactive substances, causing the shelf life of pork extended by five and three days compared with the control and PC-modified films, respectively. The results suggested that MPN provided great potential in the application of food packaging.

Development and characterization of a double-layer smart packaging system consisting of polyvinyl alcohol electrospun nanofibers and gelatin film for fish fillet

This study aimed to develop a double-layer film composed of an intelligent, gelatin-based film integrated with active polyvinyl alcohol electrospun nanofibers (PVANFs). Eggplant skin extract (ESE), a colorimetric indicator, was incorporated into the gelatin-based film at varying concentrations ranging from 0 % to 8 % w/w. The gelatin film containing 8 % ESE was identified as the optimal formulation based on its superior color indication, water barrier, and mechanical properties. Savory essential oil (SEO)-loaded PVANFs were electrospun onto the optimized gelatin film to fabricate the double-layer film. Analysis of the chemical and crystalline structures and the double-layer film's thermal properties confirmed the gelatin film's physical integration with PVANFs. Morphological examination revealed a smooth surface on the film and a uniform fibrillar structure within the PVANFs. Furthermore, the developed double-layer film effectively detected spoilage in trout fish while controlling pH, oxidation, and microbial changes during storage.

Effect of cold plasma treatment on physicochemical and functional properties of gelatin extracted from buffalo bone

The present investigation was carried out to evaluate the impact of cold plasma at various power levels (170, 200, and 230V) and for different times (5, 10, and 15 min) on gelatin extracted from buffalo bone to ascertain the difference in physicochemical and functional parameters of untreated and cold plasma treated gelatin. An increase in porosity and angle of repose, and decrease in flow characteristics were observed. The etching phenomenon of cold plasma enhanced surface area, and hence increased viscosity. An increase in the elastic behaviour of gelatin was detected from G' (Storage Modulus) and G" (Loss Modulus). The relative crystallinity dropped to 39.45% in the control sample and 36.9% in the treated samples on XRD as an effect of active plasma species. FTIR revealed minor differences in peak intensity, without a new chemical group. Gelatin's microstructure and surface topography were revealed via SEM investigation. The DSC analysis demonstrated an increase in glass transition (Tg) temperature of gelatin molecules due to alteration in chain dynamics and intermolecular interactions. Moreover, gelatin films prepared from cold plasma treated gelatin showed significant improvement in their tensile strength and mechanical properties suitable for development of packaging films.

Preparation and Characterization of Chitosan-Gelatin Film for Wound Dressing

This study aims to explore the effect of various components of chitosan gelatin on its characteristics. The method used was drying at room temperature using petridish for 2-3 days, by mixing all raw materials with chitosan : gelatin weight ratio of 1:0, 0:1, 1:1, 1:2, and 2:1. The dried film was taken and tested for film characteristics. The analysis conducted was FTIR analysis, swelling analysis, and degradation analysis. The results of the swelling analysis showed that the more the addition of gelatin composition, the percentage of swelling increased as shown in the ratio of 1:2, namely 85.178%, 144.072%, 102.068%, 184.660%, 135.272%. Meanwhile, the degradation test results showed that the chitosan and gelatin films with various composition variations increased as the test time progressed. FTIR analysis revealed that gelatin (Ge), chitosan (Ch), and chitosan-gelatin mixture (Ch-Ge) with 1:1 ratio had similar absorption peaks.

Anthocyanin modified by chondroitin sulphate and tannic acid improved the quality-indicating properties of gelatin-based intelligent film

A highly pH-responsive gelatin film incorporating purple cabbage anthocyanin (PCA) and chondroitin sulphate (CS)/tannic acid (TA) was developed. Co-pigmentation of PCA via CS/TA improved its photothermal stability and visibility of color change in gelatin film. The morphological and structural properties of CS-PCA and TA-PCA films revealed that a more stable network was formed as new hydrogen bonds were generated by the co-pigmentation. Meanwhile, the co-pigmentation improved film's mechanical and hydrophobic properties, expressed as higher tensile strength (16.65 and 17.97 Mpa) and lower water vapor permeability (1.45 and 1.41) in CS-PCA and TA-PCA films, compared to PCA film. CS-PCA and TA-PCA films showed distinct color transitions for chilled fish fillets during storage. Total color difference (ΔE) of CS-PCA and TA-PCA films correlated well with the deterioration indexes of total volatile base nitrogen (TVB-N). All the results provided a novel pH-sensitive intelligent packaging strategy by co-pigmenting CS/TA with PCA for freshness monitoring.

Enhancement of the hygrothermal ageing properties of gelatine films by ethylene glycol diglycidyl ether

Owing to the instability of gelatine in hygrothermal environments, gelatine-based cultural heritage undergo various deterioration processes, such as cracking, peeling, warping, curling and fracture, posing significant threats to its long-term preservation. Building on previous research, this study investigates the stability of polyol glycidyl ether–gelatine composite films under high-humidity and high-temperature conditions using ethylene glycol diglycidyl ether (EGDE) as a model compound. The hygrothermal ageing properties of EGDE–gelatine composite films are evaluated in terms of macrosize, mesoscopic structure, surface properties and mechanical properties. Results indicate that EGDE enhances the dimensional stability and swelling ratios of the composite films, stabilizes the pore structure and distribution and maintains the hydrophilicity and molecular structural stability under hygrothermal ageing conditions. Furthermore, the incorporation of EGDE leads to superior stress–strain properties of the composite films in such challenging environments. This study provides valuable experimental data for the preparation and conservation applications of gelatine-based cultural heritage materials.

Fish Scales for Wearable Patches: Tailoring Films Assembled From Fish Waste Gelatin, Carbon Dots and Chitin Nanocrystals

AbstractThe properties of gelatin and collagen extracted from fishery wastes, specifically from mullet (Mugil Cephalus) scales, are modified with the aim to achieve biocompatible films with tunable characteristics to design sustainable UV protection solutions in the healthcare sector. Different additives are used to the scope including plasticizers, cross‐linkers, surfactants and optical modifiers. Carbon dots (CDs) obtained from seabass (Dicentrarchus labrax) scales combined with polysorbate‐20 (PS) as a dispersant agent, enable the fabrication of materials capable of blocking UV radiation almost completely, a crucial feature for dermal contact applications. The addition of hydrophobic surfactants and crosslinkers as citric acid, chitosan and surface deacetylated chitin nanocrystals (CsNCs) allowed to modulate the water adsorption of the films in the range 3–30% and to reach a twofold and 4.5‐fold increase of tensile strength and elastic modulus, respectively, as compared to the neat gelatin film. Moreover, film thickness is shown to be another adjustable parameter to enhance optic, mechanical, and permeation properties: the higher the thickness, the greater the UV‐blocking properties, elongation‐at‐break and water vapor permeability, leading to films with attractive characteristics as wearable patches.

A novel biodegradable film based on chicken gelatin and κ-carrageenan cross-linked with oxidized phenolic compounds.

Natural and renewable polymers are gradually replacing petroleum-based plastics, mostly as a result of environmental concerns. Moreover, upcycling industrial food waste into new added-value products is a creative approach that is crucial for cleaner and more sustainable manufacturing. The aim of this study was to obtain an environmentally friendly biodegradable film using a combination of k-carrageenan (KCAR) and chicken gelatin (CGEL), which obtained from poultry by-products. The effects of varying concentrations of KCAR (0-2%) on the physical, permeability, textural, thermal, and microstructural properties of CGEL/KCAR composite films were evaluated. The findings demonstrated that an increase in KCAR enhanced the lightness and opacity levels of the films. Water vapor permeability (WVP) values reduced as the KCAR concentration increased. The lowest WVP value (0.0012g.mm/h.m2.kpa) was seen in the treatment with 2% KCAR. Tensile strength (TS) values increased with increasing KCAR. The films' thermal stability was increased by the addition of KCAR. Microstructure assessments revealed a more compact and smooth structure in the KCAR-containing treatments, indicating improvements in WVP, thermal stability, and TS. Compared to the commercial cattle gelatin film, the CGEL film had higher TS and lower water solubility (WS). Overall, this study showed that the physical, mechanical, barrier and thermal and microstructural qualities of gelatin-based films may be enhanced by combining CGEL and KCAR to create an effective biodegradable film. Moreover, the comparison study between commercial cattle and chicken gelatin films revealed that cross-linked chicken gelatin films would be a suitable alternative for bovine gelatin films in the production of biodegradable film.

Vaccinium corymbosum–Derived Carbon Dots and Anthocyanin‐Infused Gelatin Multifunctional Films for Smart Packaging Applications

ABSTRACTConsumers and food industry stakeholders have expressed great interest in using simple, non‐destructive and inexpensive methods to control/maintain or monitor the freshness of perishable foods. The idea of smart packaging has been introduced to address these requirements satisfactorily, revolutionizing conventional food packaging. Vaccinium corymbosum (VC)–based carbon dots (CDs) and anthocyanin were matrixed on gelatin (GEL) to fabricate smart packaging film. The VC biowaste–derived carbon dots (VC‐CDs) were characterized using photoluminescence, fluorescence spectrometry, FTIR, antibacterial/antioxidant potential, TEM and XPS analysis. Fabricated films were subjected to physico‐chemical, antioxidant and optical properties, SEM, TGA simulation and in vivo food model system. The VC‐CDs exhibited excellent functional properties like ultraviolet (UV) blocking and antibacterial properties. The reinforcement with 1.5% VC‐CDs and 6% VC anthocyanins (VCA) in the GEL polymer matrix improved UV blocking (&gt; 189%) properties and showed potent antioxidant potential (&gt; 164%) compared to the neat GEL film. In vivo food packaging (minced pork, fish and shrimp) with films has shown that indicator films work efficiently and non‐destructively and monitor real‐time freshness. The GEL/VC‐CDs/VCA‐based active and intelligent films are expected to be applied as multifunctional nanocomposite packaging materials that can indicate quality changes in real time, maintain quality and prolong the shelf life of packaged foods.

Utilization of Butterfly Pea Flower as Shelf-Life Colour Indicator for Keropok Lekor Smart Packaging

Studying the feasibility of using Clitoria ternatea or butterfly pea extract (BPE) as a colorimetric indicator to determine the shelf life of Keropok Lekor would aid in monitoring storage conditions, emphasizing its potential contribution to the smart packaging industry. The objective of this research is to develop pH-sensitive packaging using gelatine film infused with butterfly pea extract (BPE) along with ultrasonic-assisted extraction methods. The investigation involves quantifying the physicochemical attributes of the extracted butterfly pea and ascertaining the colour alterations during the storage of Keropok Lekor over a duration of six days. The determination of total anthocyanin content in BPE, conducted through a pH differential assay, yielded a value of 1.08 mg/g. Texture analysis revealed that the film with 10% BPE exhibited elevated tensile strength (0.11±0.01) and toughness (0.03±0.01). Total phenolic compound analysis indicated that the film containing 30% BPE possessed the highest value at 0.16±0.02. Notably, the film with 30% BPE demonstrated the highest colour change in Keropok Lekor storage from dark blue (-22.5±80.95) to dark green (6.34±1.85) over the course of six days. The film incorporated with 30% BPE stands as a viable colour indicator, demonstrating the potential for monitoring the freshness and quality of Keropok Lekor.

Development and characterization of multifunctional fish gelatin composite films reinforced with ε‐polylysine and zinc oxide nanoparticles

AbstractActive compounds were usually incorporated into biopolymer films to enhance their properties. The tensile strength (TS) and elongation at break (EAB) of the gelatin composite films increased along with the addition of ε‐polylysine (ε‐PL) and zinc oxide nanoparticles (nano‐ZnO). When the concentrations of ε‐PL and nano‐ZnO were 4% and 0.5%, TS and EAB reached to the maximum which were 53.98 ± 2.61 MPa and 16.05 ± 1.76%. The water vapor permeability, water solubility, and water content of the composite films decreased from 2.01 ± 0.04 10−10 g m−1 Pa−1 s−1 to 1.56 ± 0.07 × 10−10 g m−1 Pa−1 s−1, from 45.23 ± 1.54% to 31.39 ± 1.24% and from 23.89 ± 1.41% to 17.34 ± 2.61%, respectively, compared with gelatin film. The light barrier capacity of the composite film was improved. The surface of the film was relatively smooth, and the cross‐section was overall flat. FTIR results indicated that no chemical reaction occurred among ε‐PL, nano‐ZnO and gelatin. The chemical structure of the films remained unchanged throughout the heat‐sealing process. Moreover, the gelatin films containing ε‐PL and nano‐ZnO showed excellent antibacterial activity. Our findings suggest that the gelatin composite films with antibacterial property hold promise for the application in food packaging materials.

Development of crosslinked gelatin films through Maillard reaction and reinforced with poly(vinyl alcohol) for active food packaging

In order to improve the functionality of natural gelatin films for active food packaging applications, a combined strategy of crosslinking via Maillard reaction and blending enhancement incorporated with poly(vinyl alcohol) (PVA) was explored. In this study, when the mass ratio of gelatin to glucose was 10:1, Maillard reaction of crosslinked gelatin films was the highest, UV absorption and browning index reached the maximum. Infrared analysis showed that PVA could form strong interfacial interactions with gelatin matrix. The presence of PVA could significantly improve the toughness, water absorption, transparency, and oxygen barrier properties of crosslinked gelatin films. When the amount of PVA reached 5 %, elongation at break and oxygen barrier properties of crosslinked gelatin films were improved by 76.7 % and 47.9 % compared with pure crosslinked gelatin film. Even when the amount of PVA reached 10 %, UV absorption (at 315 nm) of crosslinked gelatin films still exceeded 98.7 %. The addition of PVA could accelerate the dissolution and swelling of crosslinked gelatin films, promoting the migration and release of active substances (Maillard reaction products (MRPs)). The two antioxidant activities tests (DPPH and ABTS method) achieved the highest radical scavenging rates of 71.6 % and 91.2 %, respectively, with corresponding PVA addition of 5 % and 7.5 %. After continuing to add PVA, antioxidant activities began to significantly decrease, which was directly related to the decrease in the generation of MRPs. Therefore, crosslinked gelatin films reinforced with appropriate amount of PVA can be considerable potential as active films for renewable food packaging applications.