Laboratory antimicrobial activity of cinnamaldehyde and pomegranate‐based polycaprolactone films

Polycaprolactone (PCL) was incorporated separately with cinnamaldehyde (CNMA), pomegranate methanolic extract (PME), freeze dried arils of pomegranate (FDAP), and seed flour of pomegranate (SF) to form antimicrobial films to be used for active food packaging. PCL–CNMA films completely inactivated growth of the artificially inoculated Escherichia coli and Staphylococcus aureus, whether at 5% or 10% concentrations (wt/wt of polymer), at all studied temperatures (4, 20, and 37 °C). PCL–PME films (10% wt/wt of polymer) delayed the growth of E. coli and S. aureus for up to 7 and 6 days, respectively, at 37 °C. Two‐day delays in the growth of both bacteria were achieved with FDAP and SF films (10% wt/wt of polymer) at 20 °C. The release of CNMA was slower than the release of PME during film processing, as measured by Fourier transform infrared spectroscopy. Thus, CNMA and pomegranate‐based films perhaps should be planned further for use in controlled release food packaging. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45347.     

Development of active cassava starch cellulose nanofiber-based films incorporated with natural antimicrobial tea tree essential oil

In the present study, a cassava starch-glycerol film with reinforcement of Pinus sp. nanofibers (NFC) incorporated with tea tree (Melaleuca alternifolia) essential oil (TTO) were prepared by casting technique. The physical (barrier, mechanical, and optical), structural, and antimicrobial properties of the films were evaluated and compared with the control films. Films with 0.08% TTO exhibited a significant increase in the tensile strength (TS) while films with 1.5% TTO showed a decrease in TS, suggesting a crosslinking effect. The addition of 1.5% TTO reduced the water vapor permeability values in 43% comparing to the control films. Analysis obtained by Fourier transform infrared spectroscopy showed bands related to the interaction between TTO and matrix for films with 1.5% TTO and 0.3% NFC. This film was effective against Staphylococcus aureus and Candida albicans which could be applied for several packaging purposes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48726.     

Food compatibility and degradation properties of pro‐oxidant‐loaded LLDPE film

To avoid environmental hazards, packaging industries are aiming to produce biodegradable films for food contact safety and its degradation. LLDPE film containing 1% pro‐oxidant additive was studied for food compatibility in different simulants, at room temperature conditions as per Bureau of Indian Standards (BIS), code of federal regulations (CFR), food and drug administration USA (USFDA), and European Economic Commission directives (EEC) specifications. Overall migration values were well within the specified limits for food contact applications at room temperature filling and storing. The pro‐oxidant loaded LLDPE film was also studied for its degradation behavior with the changes in physical and mechanical properties along with thermal behavior, morphology and infrared spectroscopy. The molecular oxidations of pro‐oxidant‐loaded LLDPE films are severed which increases hydrophilicity. Evidently, the oxidation renders the material much more vulnerable to microbial attack. The combined effect of both photo and bio degradation is most effective for complete degradation of film. The results obtained from these studies revealed that the fine balance (1%) of pro‐oxidant contents in the film guarantees food contact safety and its degradation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39756.     

The influence of cinnamon and litsea cubeba essential oils on methylcellulose films

The aim of this study was to prepare active, biodegradable methylcellulose films and evaluate their properties after incorporating cinnamon (Cinnamomum cassia) and litsea cubeba (Litsea cubeba) essential oils. The properties of the methylcellulose films were modified with the addition of essential oils. The surfaces were smooth and homogeneous in all samples. The film with cinnamon oil showed higher antibacterial activity against Staphylococcus aureus and Escherichia coli and the film with litsea cubeba showed higher antioxidant activity against ABTS radical. The biodegradation time of the films in black sand and beach soil was 20 days. The films produced that presented the highest potential to become active packaging were the film with litsea cubabe oil as antioxidant packaging and the film with cinnamon oil as antibacterial packaging.     

UV-shielding antimicrobial zein films blended with essential oils for active food packaging

A comprehensive study on zein film blended with glycerol and essential oils (EOs) is presented in this work. In particular, ultra violet (UV) shielding property and antimicrobial efficacy of developed active zein films (ZF) are tested. The fabricated films show zero transmittance in the UV region as compare to commercial poly-film which shows 40%–80% of UV transmittance. Results show that films are effective against spoilage microorganisms. The incorporation of EOs in ZF significantly reduces the growth of microbes over fruit samples since day 3. Physical interactions existing between EOs along with glycerol and zein provide considerable barrier properties. The glass transition temperature of the film comes out to be 47.7°C having the tensile strength of 1.21 ± 0.05 MPa. TGA curves show major weight loss in the range of 220–375°C. In conclusion, edible active ZF can be used as healthy packages over food and drug to increase their shelf life.     

Influence of Syzygium cumini leaves extract on morphological,thermal, mechanical,and antimicrobial properties of PVA and PVA/chitosan blend films

In the present work, poly(vinyl alcohol)/Syzygium cumini leaves extract (PSN) and poly(vinyl alcohol)/chitosan/S. cumini leaves extract blend films were prepared by solution casting technique. The films were characterized by using scanning electron microscopy, atomic force microscopy, X‐ray diffraction study, Fourier transform infrared spectroscopy, thermogravimetric analysis, and universal testing machine. The results indicated that the appreciable physical interaction at lower concentrations of S. cumini leaves extract in the PVA and PVA/chitosan films contribute to the smooth uniform morphology, increased the degree of crystallinity, degradation temperature, and improved mechanical properties. Further, films were analyzed with water contact angle analyzer which illustrates that blend films were hydrophilic (PSN‐1) and hydrophobic (PCS‐1) in nature. However, blend films were also subjected to the antimicrobial study, which revealed that inclusion of S. cumini leaves extracts significantly enhanced the antibacterial activity in the PVA and PVA/chitosan film. With all of these results, fabricated blends can find potential applications in packaging material to extend the shelf life of foodstuffs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46188.     

Mechanical and antimicrobial properties of multilayer films with a polyethylene/silver nanocomposite layer

A layer of a polyethylene–silver nanoparticles composite was deposited on a five layer barrier film structure. Different methods were used for the nanocomposite layer deposition: laminating, casting, and spraying over the multilayer structure. For the casting and spraying methods, the silver nanoparticles were previously dispersed in the polymer solution, with the assistance of ultrasound energy. The effect of silver nanoparticles and deposition method on the barrier, mechanical, and optical properties of the multilayer films was evaluated. The efficiency of silver ion release from the PE‐Silver nanocomposite deposited on the multilayer films and their antimicrobial characteristics were investigated and discussed. The silver ion release and biocide effect of the multilayer films was found to be dependant on the silver nanoparticle content and on the deposition method used. The observed results could be helpful in the design of industrial films for packaging. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Development of antifungal films based on low‐density polyethylene and thyme oil for avocado packaging

Trilayer low‐density polyethylene (LDPE) films were prepared by incorporating varying concentrations of thyme oil, as the antifungal active additive for avocado packaging. A comprehensive thermal, structural, mechanical, and functional characterization of the prepared films was carried out. Thermal stability of the film reduced with the addition of thyme oil in higher concentration, whereas the degree of crystallinity increased upto 2.5 wt % thyme oil loading. The elastic modulus and elongation at break of the films decreased in presence of thyme oil. However, the incorporation of thyme oil did not change the water vapor transmission characteristics of the original film. The antifungal activity of the films was tested against Colletotrichum gloeosporioides causal organism of “anthracnose” postharvest disease in avocados. The results indicated that the films have great potential as antifungal packaging materials for avocado fruits. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43045.     

Physical properties of fish gelatin-based bio-nanocomposite films incorporated with ZnO nanorods

Well-dispersed fish gelatin-based nanocomposites were prepared by adding ZnO nanorods (NRs) as fillers to aqueous gelatin. The effects of ZnO NR fillers on the mechanical, optical, and electrical properties of fish gelatin bio-nanocomposite films were investigated. Results showed an increase in Young''s modulus and tensile strength of 42% and 25% for nanocomposites incorporated with 5% ZnO NRs, respectively, compared with unfilled gelatin-based films. UV transmission decreased to zero with the addition of a small amount of ZnO NRs in the biopolymer matrix. X-ray diffraction showed an increase in the intensity of the crystal facets of (10^ī1) and (0002) with the addition of ZnO NRs in the biocomposite matrix. The surface topography of the fish gelatin films indicated an increase in surface roughness with increasing ZnO NR concentrations. The conductivity of the films also significantly increased with the addition of ZnO NRs. These results indicated that bio-nanocomposites based on ZnO NRs had great potentials for applications in packaging technology, food preservation, and UV-shielding systems.     

Development of active cassava starch films reinforced with waste from industrial wine production and enriched with pink pepper extract

This study investigated the influence of grape stalk (GS) from the Bordo grape variety (Vittis labrusca L.) as a reinforcing agent, and pink pepper (Schinus terebinthifolius Raddi) extract (PPE) as an antioxidant, in cassava starch (CS)-glycerol (GLY) films. The developed biodegradable films were characterized according to structural, barrier, mechanical, antioxidant and optical properties, as well as biodegradability and compared to both the control and blank films. Films containing a high GS content exhibited a significant increase in tensile strength (TS) values by 73%, whereas the films containing a high PPE content exhibited an important increase elongation (ELO) values by 20%, comparing to the control film (CO). The films containing 5.52% v/v of PPE presented an improving on antioxidant activity and barrier properties, leading DPPH and ABTS percentual radical scavenging activity by 51.79% and 58.18%, and decreasing water vapor permeability and solubility by expressive values of 34.11% and 79.43%, respectively. According to the results obtained in this study, the films using GS and PPE exhibited valuable characteristics and are an alternative for applications as a promising biodegradable packaging material.     

Barrier and mechanical properties of biodegradable poly(ε‐caprolactone)/cellophane multilayer film

In this study, cellophane (PT) multilayer films were prepared by coating with different thickness of poly(ε‐caprolactone) (PCL) and chitosan (CH), and its effects on barrier and mechanical properties were evaluated. It was shown that the PCL/PT/PCL and PCL/CH/PT/CH/PCL multilayer films exhibit much better water vapor barrier than PT, and these films still keep the high oxygen barrier. And the barrier properties of multilayer film were improved with the increase of the thickness of coating materials. The Young's modulus and tensile strength of PT multilayer film were slightly decreased, and their elongations at break were increased by coating. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1805–1811, 2013     

Improved properties of poly(butylene adipate-co-terephthalate)/calcium carbonate films through silane modification

One of the most used inorganic fillers is calcium carbonate which quite efficiently enhances the mechanical characteristics while simultaneously lower the cost of thermoplastics, particularly for biodegradable polyester. Virtually, all studies so far have focused on the quest for the filling and modification of nano-sized calcium carbonates. However, the quantity of nano-sized CaCO₃ added in the polymer is usually lower than 10%, owing to its high-surface energy and high-surface area and makes powder easier to agglomerate. In this work, we prepared poly(butylene adipate-co-terephthalate) (PBAT)/calcium carbonate composite films by extrusion-blown films with up to 40 wt% micro-sized CaCO₃ content. The influence of particle size (5–12 μm) and modification of the particles (with and without silane coupling agents) on the rheological and mechanical properties was thoroughly investigated. Of all the particle sizes employed in this study, the 5 μm (3000 mesh) particles with 30 wt% content coated with 2 wt% aliphatic silane coupling (CA1) agent was observed to furnish the optimum combination of characteristics. The mechanical properties of P7C3/CA1-2 film even better than that of neat PBAT film. These results provided a simple approach for PBAT/CaCO₃ films manufacture with low-cost and simultaneously with sound mechanical properties, which can be good candidate for mulching films and packaging applications.     

Novel cross‐linked sericin films: Characterization and properties

In the present study, an attempt has been made to convert sericin into film form and further make it insoluble by forming sericin–aluminum metal complex using alum salt, which may lead to some extent of cross‐linking. After complex formation sericin becomes insoluble in warm water as well as thermal stability and tensile strength improves significantly with increasing alum content. Metal complexed sericin films show good antimicrobial property and both the pure and alum modified sericin (AM‐Sericin) films show a very good oil barrier property. But after complex formation moisture content and swelling percentage of sericin film decreases quite significantly with increasing aluminum concentration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41400.     

Utilization of lentil flour as a biopolymer source for the development of edible films

Lentils are one of the cheapest and most nutritional protein sources for vegetarians. Our objective in this study was to evaluate the feasibility of using lentil flour as a raw material for the development of edible films and to investigate the effects of the glycerol concentration (C_g = 1%, 1.5%, and 2%) and process temperature (T_p; 70 and 90 °C) on the physical properties of these films. The films were characterized via their density; water solubility; thermal, morphological, and chemical characteristics; water vapor permeability (WVP); and tensile and optical properties. The lentil flour films were highly transparent and had lower water solubility values yet similar WVPs and mechanical properties compared to most other biodegradable films. An increase in C_g led to the formation of more flexible films with increased hydrophilicity. A T_p of 90 °C resulted in yellower, more transparent films with increased stiffness compared to a T_p of 70 °C. In this study, lentil flour was shown to be an ideal source for edible film production. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46356.     

Effects of nano‐tio2 on the performance of high‐amylose starch based antibacterial films

The purpose of this article is to investigate the effects of nano‐tianium dioxide (nano‐TiO₂) on the high‐amylose starch/polyvingl alcohol (PVA) blend films prepared by a solution casting method. The results show that at the concentration of 0.6% of nano‐TiO₂, the film demonstrated the best tensile strength at 9.53 MPa, and the elongation at break was noted as 49.50%. The optical transmittance of the film was decreased and the water resistance was improved with further increase of the concentration of nano‐TiO₂. Using the techniques of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and field‐emission scanning electron microscopy (SEM), the molecular and the crystal structures of the films were characterized. The results indicate that the miscibility and compatibility between high‐amylose starch and PVA were increased with the addition of nano‐TiO₂ into the films due to the formation of hydrogen and C? O? Ti bonds. The antimicrobial activities of the blend films were also explored. The results show that there were inhibitory zones around the circular film disc, which is attributable to the addition of nano‐TiO₂. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42339.     

Development of protein‐based bioplastics modified with different additives

Proteins have been postulated as a feasible source for manufacturing biodegradable polymeric materials. The aim of this study is the development of bioplastic materials from two different protein sources: albumen protein isolated (API), which consists of globular proteins, and crayfish flour (CF), mostly composed of myofibrillar proteins. In order to explore the effect of some chemical reagents on the mechanical properties of the blends and bioplastic materials, two different additives have been used: sodium sulfite (SS) and urea (U). The first one is a reducing agent, and the second one is considered a denaturing agent. The addition of chemical agents induces changes not only in mechanical properties but also in the most suitable processing conditions, which strongly depends on the protein used. Thus, the denaturation of globular proteins seems to lead to a more consistent blend before the injection‐molding process. However, when myofibrillar proteins are used, the processability of the dough‐like material increases after using either SS or U additives. This work illustrates the feasibility of producing animal‐based biodegradable bioplastic materials with different properties and, consequently, different applications, which contribute to adding a high value to two different byproducts from the food industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45430.     

Impact of the starch source on the physicochemical properties and biodegradability of different starch‐based films

Concern about environmental issues has motivated research into the development of biodegradable packaging from renewable sources. Natural polymers such as starch constitute a good alternative for diminishing the use of nonbiodegradable and nonrenewable components in the packaging industry. However, depending on the botanical source, films with different properties are formed. The aim of this study was to evaluate the film‐forming capacity of different starch sources (cassava, corn, potato, and wheat) by casting with starch contents from 2 to 6%. Principal component analysis methodology was used to evaluate the correlation between the formulations and their physicochemical and mechanical properties. It was not possible to produce continuous films based on potato starch, probably because of its very low amylose content (10%). The corn‐, cassava‐, and wheat‐starch‐based films were characterized by their thicknesses (0.06–0.22 mm), moisture contents (19–26%), water solubilities (13.7–26.5%), water‐vapor permeabilities (WVPs; 0.19–0.48 g mm h^?1 m^?2 kPa^?1), wettabilities (35–106°), biodegradabilities in soil, and thermal and mechanical properties (tensile strength = 1.9–6.7 MPa, elongation = 41–166%, and Young's modulus = 8–127 MPa). The wheat starch films presented higher WVPs and lower mechanical properties. The cassava starch films presented lower wettabilities and good mechanical properties; this suggested that their use in packaging for products, such as fruits and vegetables, with higher water activities could be feasible. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46564.     

Antioxidant and physicochemical properties of blended films based on gelatin‐sodium caseinate activated with natural extracts

Blend films of pigskin gelatin (GEL) and sodium caseinate (SCas) with boldo (B), guarana (G), cinnamon (C), or rosemary (R) extracts added were studied. SCas and extracts addition in blend films significantly increased the gloss and better UV barrier of GEL100 films. Extracts incorporation significantly decreased the rigidity and elongation of GEL100 films, which were significantly improved in GEL75:SCas25 blend films with extracts (EM = 295.69 ± 21.75 MPa and EB = 11.60 ± 3.43%). SCas addition not affected the TS parameter. The water vapor permeability of GEL100 films was reduced in blended films with extracts, showing the lowest value for GEL75:SCas25 + R (0.99 ± 0.07 × 10¹⁰ g s^?1 m^?1 Pa^?1). FTIR and microstructure analyses showed good compatibility for all components. The antioxidant activity of GEL100 was significantly increased with SCas and extracts addition (GEL50:SCas50 + R = 4.31 ± 0.11 mM ), suggesting the application of these films as an active food packaging material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44467.     

Biodegradability and mechanical properties of agro‐flour–filled polybutylene succinate biocomposites

The objective of this study was the production of rice husk flour (RHF) and wood flour (WF) filled polybutylene succinate (PBS) biocomposites as alternatives to cellulosic material filled conventional plastic (polyolefins) composites. PBS is one of the biodegradable polymers, made from the condensation reaction of 1,4‐butanediol and succinic acid that can be naturally degraded in the natural environment. We compared the mechanical properties between conventional plastics and agro‐flour–filled PBS biocomposites. We evaluated the biodegradability and mechanical properties of agro‐flour–filled PBS biocomposites according to the content and filler particle size of agro‐flour. As the agro‐flour loading was increased, the tensile and impact strength of the biocomposites decreased. As the filler particle size decreased, the tensile strength of the biocomposites increased but the impact strength decreased. The addition of agro‐flour to PBS produced a more rapid decrease in the tensile strength, notched Izod impact strength, and percentage weight loss of the biocomposites during the natural soil burial test. These results support the application of biocomposites as environmentally friendly materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1513–1521, 2005     

Polyhydroxyalkanoate coatings restrict moisture uptake and associated loss of barrier properties of thermoplastic starch films

This work investigates the use of polyhydroxyalkanoate (PHA) films as moisture barriers for thermoplastic starch (TPS) films, to produce biodegradable, multi‐layer materials with high gas barrier properties. This is a necessary extension to the limited work available on this topic and confirms that PHAs are suitable coating materials for TPS films intended for use in food packaging. Under storage conditions of up to 75% relative humidity (RH) for 2 weeks, a PHA coating maintained the moisture content (MC) of the TPS below the point at which its barrier properties were detrimentally affected. Furthermore, for PHBV coating thicknesses of 91–115 μm, the MC of the TPS remains significantly lower than uncoated TPS for the duration of the experiment (>25 days). The flux of water into the coated TPS fit to a model based on Fick's law. However, when the multi‐layered films were stored at 95% RH delamination occurred within 24 h. Preliminary investigation into possible material design improvements showed that the addition of a small amount of PHA to the TPS layer prolonged the time to delamination. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46379.