Protein‐based bioplastics and their antibacterial potential

The use of conventional petroleum‐based plastics in many applications poses the risk of contamination, potentially causing infection when used in medical applications, and contamination when used in food packaging. Nontraditional materials such as protein are being examined for their potential use in the production of bioplastics for applications that require uncontaminated materials. The proteins of albumin, soy, and whey provide possible sources of raw material for bioplastic production, as they have already been utilized in the area of edible films and low‐stress applications. We conducted this study to investigate the thermal, viscoelastic, and antibacterial properties of the albumin, soy, and whey bioplastics with the use of three plasticizers—water, glycerol, and natural rubber latex (NRL). Bacillus subtilis and Escherichia coli were utilized as Gram (+) and Gram (?) species, respectively, for antimicrobial analysis. Albumin and whey bioplastics exhibited similar thermal and viscoelastic properties, whereas soy bioplastics had varied viscoelastic properties based on the plasticizer used. In terms of antibacterial activity, the albumin–glycerol and whey–glycerol were the best bioplastics, as no bacterial growth was observed on the plastics after 24 h of inoculation. In terms of the future impact of this research, the aim will be to scale up production of the bioplastics for use in food packaging as well as biomedical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41931.     

Effect of lignin removal on mechanical,thermal, and morphological properties of polylactide/starch/rice husk blend used in food packaging

The aim of this work was to investigate the possibility of using cost‐effective natural filler in a biodegradable polymer and find new set of materials for green biocomposites to be used in food packaging. In this regard, rice husk (RH) and bleached rice husk (BRH) have been used in the form of powder and the effect of lignin removal on mechanical and thermal properties of prepared composites with poly(l ‐lactide) and starch were studied. Using FTIR technique, the lignin removal from RH has been approved. The tensile, charpy impact, and hardness tests were implemented to investigate the mechanical properties. It was concluded that filler caused increase both in the toughness and the Young modulus of samples. It was also found that the lack of lignin in BRH samples improves the mechanical properties. It was clearly observed that the BRH samples show larger modulus, charpy impact strength, and hardness compared to those filled with RH. Despite larger values for the elongations at break of RH samples, the mechanical properties showed a significant improvement (between 25 and 50% improvements) on lignin removal. The differential scanning calorimetry thermograms revealed an improvement in crystallization behavior and reduction of T_g from 47 to 31°C in the case of BRH‐filled samples. Finally, due to the removal of toxic lignin in the samples and modification of mechanical properties by this method, the BRH could have the ability of wide use in the bioplastics and food packaging industries. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41095.     

Surface and degradation properties of thermoplastic blends from albumin and zein‐based plastics

The use of traditional petroleum‐based thermoplastics in food packaging applications pose an environmental hazard, as their lack of biodegradability creates waste that environmental systems are unable to cope with. To address this issue, the investigation of surface, biodegradation, and water solubility properties of the albumin and zein thermoplastic blends plasticized with glycerol and mixed with varying amounts of low‐density polyethylene (LDPE) is conducted. When subjected to soil burial, albumin as a bioplastic completely biodegrades within two months, while a zein‐based bioplastic is more resilient to attacks from microbes within the soil (4.34% of intial mass remains). If albumin and zein proteins are used in the production of thermoplastics in tandem with LDPE, it could be possible to produce a plastic that will naturally biodegrade over time, decreasing the environmental impact of the use of thermoplastics in medical and food packaging applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44646.     

Zein‐based ultrathin fibers containing ceramic nanofillers obtained by electrospinning. II. Mechanical properties,gas barrier,and sustained release capacity of biocide thymol in multilayer polylactide films

The combination of electrospinning technology and nanomaterials such as nanoclays can synergistically lead to novel materials with enhanced properties and functionalities for their usage in passive and active packaging applications. Part I of this work was focused on the development of ultrathin zein fibers containing nanoclays, which were oriented along the fiber axis and increased the thermal properties. Part II presents the use of the hybrid fibers as passive and active components in multilayer packaging structures. The hybrid fibers are incorporated in poly(lactic acid) films via a two‐step process: Electrospinning and compression molding. The composites thus produced presented improved mechanical and barrier properties than the unfilled material. The natural biocide extract thymol is then incorporated in the coating, and its sustained release properties are shown. The antimicrobial capacity of the hybrid fibers was also determined against foodborne bacteria. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40768.     

Engineering of Poly Lactic Acids (PLAs) for melt processing: Material structure and thermal properties

Bottles and other packaging account for approximately 70% of the global market of biopolymers, which include both biodegradable and durable materials. Durable materials account for the vast majority of the market, especially the bottles. Degradable polymers are instead refrained by the often‐insufficient mechanical and thermal properties, which limit their usage to single‐use packaging items at ambient temperature and in dry conditions. In this respect, the present work deals with the development and manufacturing of innovative and custom‐built Poly Lactic Acids (PLAs) for injection and compression molding, which are designed to be compostable, suitable for food contact and characterized by a good compromise of mechanical properties and thermal stability. A commercial grade PLA was, therefore, compounded in a twin‐screw co‐rotating extruder by the addition of maleated and glycidyl methacrylate PLAs as chain extenders and micro‐lamellar talc as mineral filler and nucleation promoter. Compatibilization between PLA, chain extenders and mineral filler was, therefore, investigated. Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) were performed to evaluate the material structure and thermal response of the pellets after reactive compounding extrusion. The experimental findings show that material structure and, especially, crystallization of the PLA can be controlled by fine‐tuning the compound formulation as well as by setting of the operational parameters. In addition, achievement of the appropriate crystallization degree in the polymer is found to lead to composite materials, which can boast very good thermal stability. Accordingly, the custom‐built PLA formulations feature the potential to expand significantly the fields of application of non‐durable polymers, thus posing a valid alternative to both durable biopolymers and conventional plastics in injection and compression molding process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44504.     

Recent advances in molecularly imprinted polymers in food analysis

Food security as a world issue has received increasing concern, and therefore, effective analytical methods and technologies have been continuously developed. However, the matrix complexity of food samples and the trace/ultratrace presence of targeted analytes require highly efficient cleanup and enrichment materials and procedures. Molecularly imprinted polymers (MIPs) with specific recognition abilities as versatile materials are being increasingly developed for diverse species in various fields, especially in food analysis. In this review, we mainly summarize the recent advances in MIPs used for food matrices over the last 5 years. We focus on toxic and harmful substances, such as pesticide/drug residues, heavy metals, microbial toxins, and additives. Some relatively new preparation methods involving surface imprinting, composites, and stimuli responsiveness are reviewed. Different MIPs as solid‐phase adsorbents in solid‐phase extraction, solid‐phase microextraction, matrix solid‐phase dispersion, stirring bar sorptive extraction, and magnetic material extraction and as stationary phases in chromatographic separation for foodstuff have been comprehensively summarized. MIP‐based biomimetic sensing and enzymelike catalysis receive special attention. Moreover, some limitations and comparisons related to MIPs performances are also discussed. Finally, some significant attempts to further promote MIP properties and applications to ensure food safety are discussed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40766.     

Fabrication and improved performance of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) for packaging by addition of high molecular weight natural rubber

The packaging industry is searching for alternative materials to attain environmental sustainability. Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) is a semicrystalline polymer that meets this sustainability goal since it is bioderived and biodegradable. However, its brittle nature and relatively high water permeation and transmission rates make it unsuitable for packaging applications. In addition, PHBV has poor mechanical, thermal, and rheological properties above 160 °C, limiting its use in cast sheets and thermo‐formed packaging applications. To improve these properties, new blends of PHBV with high molecular weight natural rubber at 5, 10, 15, and 25% by weight were fabricated, and physico‐chemical properties of the blends were characterized. The rubber in the blends aided in the following: increased thermal stability since the complex viscosities of the blends were improved by one log over pure PHBV at 170 °C, created more uniform melting peaks attesting to improved homogeneity, decreased water permeation to a level similar to that of traditional thermoplastics; increased the elongation at break, and stabilized the Young's modulus. Therefore, these blends can potentially be used in‐place of traditional, petroleum‐based thermoplastics in cast sheets and thermoforms. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43937.     

Development of vegetable‐oil‐based polymers

The utilization of renewable resources for the preparation of new materials is an alternative option for reducing the high demand of fossil feedstocks. Vegetable oils are potential bioresources that are renewable and abundantly available. Triglyceride‐based vegetable oils, such as soybean, jatropha, linseed, sunflower, palm, castor, nahar seed, and canola oil, are being considered as precursors in the production of polymers. In this article, we attempt to summarize advancements in processes and technologies for the synthesis of polymers from various kinds of vegetable oils. The advantages and disadvantages of these biobased polymers with respect to traditional monomer‐based ones are also highlighted. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40787.     

Zein film: Effects of dielectric barrier discharge atmospheric cold plasma

Dielectric barrier discharge atmospheric plasma is a novel nonthermal technology for the food and packaging industry. The effects of dielectric barrier discharge plasma on the surface, structural, thermal, and moisture sorption properties of edible zein films have been examined. Plasma treatment increased the surface roughness and equillibrium moisture content of the zein film in a direct relationship with the applied voltage level. No significant difference in the thermal stability of the zein film is also observed after plasma treatment. Dielectric barrier discharge plasma treatments of zein film lead to a change in the protein conformation which is confirmed by X‐ray diffraction and Fourier transform Infrared spectroscopy. The evaluation of films modifications by plasma discharge will contribute to enhance the in‐package decontamination studies of food products by plasma. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40803.     

Cellulose nanofibrils in biobased multilayer films for food packaging

The aim of this study was to evaluate a thin, TEMPO‐oxidized (2,2,6,6‐tetramethylpiperidine‐1‐oxyl–mediated oxidation) cellulose nanofibril (CNF) coating as a barrier layer in multilayer packaging films together with biobased polyethylenes. The purpose was also to explore the possible interactions between food products and the biobased films, and to evaluate the feasibility of these films for packaging of dry foods. CNF provided the biobased multilayer films with an oxygen barrier suitable for both demanding food products and modified atmosphere packaging (MAP). The MAP pouches made of these multilayer films retained their atmosphere and shape and protected ground hazelnuts from further oxidation for the storage time used in this study. However, irradiation used to sterilize packed foods and aroma compounds from clove in particular impaired the oxygen barrier property of the CNF layer, while the water vapor barrier property of the multilayer films remained unaffected. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44830.     

Thermal properties and crystallization behavior of fractionated blocky and random polyhydroxyalkanoate copolymers from mixed microbial cultures

This study represents the first detailed analysis of the thermal, morphological, and crystallization properties of the blend components within a range of mixed‐culture polyhydroxyalkanoates (PHAs), with 3‐hydroxyvalerate content in the as‐produced materials and in the fractions ranging from low (12 mol %) to high (91 mol %). Both coarse and fine fractionation of the as‐produced copolymers confirmed that they were blends of nominally blocky and/or random copolymers of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate), with very broad compositional distributions as governed by the PHA accumulation strategy. The crystallization kinetics and thermal properties of the fractions were found to be very significantly different from each other, consistent with the hypothesis that the overall mechanical properties were primarily controlled by the more rapidly crystallizing components. Two materials produced using an alternating feeding strategy demonstrated unique crystallization and thermal properties in their fractions, which are considered to have contributed to distinctly more elastic mechanical properties in these particular samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40836.     

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.     

Development of antibacterial silver treatments on HDPE nets for agriculture

The defense mechanism of crops associated with the use of polymeric nets and fabrics is only physical and, hence, ineffective against the bacterial contaminations. The presence of an antibacterial agent associated with the use of conventional agro‐textiles can represent a great advantage in the prevention of plant diseases and for food safety. The aim of this work was the development of antibacterial silver‐coated HDPE nets for an innovative application such as agriculture. Antibacterial coatings on high‐density polyethylene nets were obtained by a patented nanosilver deposition technique based on the in situ photo‐reduction of a silver solution. The concentration of silver deposited was defined by testing different silver solutions from a biological point of view. Moreover, in order to improve the adhesion of the silver coating to the substrate, the nets underwent low‐pressure plasma treatment before the silver deposition. The materials were characterized in terms of quality of the coating through scanning electron microscopy, and in terms of antibacterial capability on Gram positive and Gram negative bacteria through qualitative and quantitative microbiological tests. The most effective process parameters were defined and the importance of performing plasma pretreatment on this specific substrate was assessed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41623.     

Photoresponsive nanogels synthesized using spiropyrane‐modified pullulan as potential drug carriers

Reversible light‐responsive nanogels were constructed from an amphiphilic spiropyrane‐modified pullulan (SpP). The polymer was synthesized by modifying a biodegradable pullulan with carboxyl‐containing spiropyrane (Sp) molecules. The SpP structure was confirmed by the appearance of a carbonyl signal in the FT‐IR and ¹H NMR spectra. The nanogels can be controlled by photostimulation, which results in the reversible structural transformation of the hydrophobic Sp to the hydrophilic merocyanine. The physical properties of the nanogels were confirmed to change dramatically after being irradiated with different wavelengths of light. Drug delivery tests showed that the model drug pyrene was completely captured by the nanogels and then released from the SpP nanogels in a light‐dependent manner. This study provides an alternative approach to constructing light‐responsive nanocarriers with excellent biocompatibility for drug uptake and release. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40288.     

Fabrication and characterization of sucrose palmitate reinforced poly(lactic acid) bionanocomposite films

Environmental issues concerning petroleum‐based polymers have begun a growing emphasis to utilize sustainable poly(lactic acid) (PLA) based packaging. However, PLA has its own limitations such as brittleness, high gas permeabilities and slow crystallization rate. With the aim to alleviate these limitations, we made a maiden effort to use a food additive, sucrose palmitate (SP) as eco‐friendly filler for fabrication of PLA based bionanocomposites. FTIR analysis elucidated the presence of hydrogen bonding and intermolecular interaction between PLA and reinforcement. Ordered orientation of the SP in the PLA matrix visualized by TEM analysis revealed uniform dispersion of SP filler into PLA matrix. DSC and XRD results confirmed that the incorporated bio‐filler acted as a nucleating agent and thus partially contributed towards the crystallinity of PLA‐SP bionanocomposites. Enhancement in the tensile strength and elongation at break up to 83 and 56% respectively is obtained. The best positive influence for the oxygen barrier was confirmed for the PLA‐SP bionanocomposite film where the reduction in oxygen permeability by 69% is achieved in comparison to pure PLA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41320.     

Production and isolation of chitosan from Aspergillus terreus and application in tin(II) adsorption

Fed‐batch fermentation was used for biomass and fungal chitosan production by Aspergillus terreus (BCRC 32068) grown in a potato dextrose agar medium. The polysaccharides were extracted by an alkali–acid treatment, and structural investigations by X‐ray diffraction, Fourier transform infrared analysis, and viscosity and thermal analysis were done. A high level of chitosan was extracted from A. terreus; this implied that it was feasible to produce chitosan from industrial waste mycelia. Fungal chitosan derived from A. terreus showed the highest adsorption capacity for Sn(II). The order of Sn(II) adsorption capacity for these chitosanaceous materials was Fungal chitosan > Chitin > Biomass. Fungal chitosan derived from A. terreus was well correlated with Langmuir's isotherm model. The maximum capacity for Sn(II) sorption deduced from the use of the Langmuir isotherm equation was 303 mg/g; this was significantly higher than that of A. terreus. Fungal chitosan is an easy and cost‐effective material for the abatement of pollution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40436.     

Characterization of mouthguard materials: A comparison of a commercial material to a novel thiolene family

The goal of this study is to compare the thermal and mechanical properties of a commercial mouthguard material with a novel class of thermoset polymers based on thiolene “click” chemistry. Ternary thiolene systems modified with urethane or acrylate [urethane‐modified thiolene network (UMTEN) and acrylate‐modified thiolene network (AMTEN), respectively] were synthesized and their properties compared with commercially available Polyshok™. Durometer hardness (ASTM D2240‐05), water absorption [ASTM D570‐98 (2005)], tear strength (ASTM D624‐00), and impact attenuation [ASTM D6110‐06f (modified)] were measured for physical property comparison. Differential scanning calorimetry and dynamic mechanical analysis were used as a means to compare thermal properties. One‐way analysis of variance and independent t tests were used to test for differences between Polyshok™, AMTEN and UMTEN samples. It was found that the novel thiolene networks exhibit higher impact attenuation at intraoral temperature compared with Polyshok™, although Polyshok™ demonstrates lower water absorption and hardness, as well as higher tear strength. With further modification, this family of thiolene materials may provide a platform for developing next‐generation mouthguard materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40402.     

Morphology,physical properties,silver release,and antimicrobial capacity of ionic silver‐loaded poly(l‐lactide) films of interest in food‐coating applications

In the present study, silver ions were incorporated into a poly‐(l ‐lactide) (PLA) matrix by a solvent casting technique using different solvents and glycerol as plasticizer. The effect of the different formulations on the morphology, thermal, mechanical and color properties were first evaluated. Additionally, a thorough study of the silver ions release to an aqueous environment was also monitored over time by anodic stripping voltammetry and correlated with the antimicrobial performance against S. enterica. The incorporation of silver contents of up to 1 wt % did not affect morphology, thermal or mechanical properties of the films. A sustainable, antibacterial effectiveness was found for the films in liquid medium and a breakpoint of 10–20 μg L^?1 silver was established under the stated conditions, evincing silver ion releasing technologies may be applied to liquid environments while complying with current legislation. This study provides insight into the structure properties relationship of these antibacterial polylactide materials of significant potential in coating applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41001.     

Hyperbranched polyglycerols,obtained from environmentally benign monomer,as reactive clays inhibitors for water‐based drilling fluids

To prevent the degradation of the borehole and also the disintegration and dispersion of drilled cuttings, different shale stabilizing additives are used in water‐based drilling fluids (WBFs). Glycols, poly(ethylene glycol), glycerols, and polyglycerol derivatives, also called polyols, have been used to inhibit shales containing reactive clays in WBF. These additives are normally used in conjunction with KCl to reduce clay swelling and dispersion of drilled cuttings. Highly branched polymers have become an important field in current polymer science. Such materials typically exhibit compact, globular structures in combination with an exceptionally high number of sites with functional groups. They have unique properties that differ significantly from their linear counterparts, and the hyperbranched polyglycerol (hPG) is an important hyperbranched polymer that can be produced from an environmentally benign monomer, the glycerol carbonate. In this article, the clay inhibitive properties of hPG were evaluated by different test methods including bentonite inhibition test, cuttings recovery, and X‐ray diffraction measurements. The results show that the hPG has a great potential to be used as an environmental friendly inhibitor additive in WBFs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40384.     

Poly(lactic acid) biocomposites with mango waste and organo-montmorillonite for packaging

Poly(lactic acid) (PLA) is a biodegradable polymer used in packaging, but its properties can be improved by manufacturing composite matrixes. The combination of PLA, starch, and nano-montmorillonite leads to materials with superior mechanical properties. Mango lump is rich in cellulose and starch. The goal of this study is to develop and characterize biocomposites based on PLA, mango waste, and nano-organo-montmorillonite for packaging. The samples were microstructurally, morphologically, and mechanically characterized. Physical interaction between the phases was observed. The mango components displaced the PLA X-ray diffraction peaks and the clays altered their intensity, by interfering with chain packing. The addition of single components to PLA increased the samples’ transition temperatures, but the addition of multiple components diminished them. PLA showed adhesiveness to cellulose fibers and nonadhesiveness to starch granules. Thicker samples presented better mechanical properties. PLA–mango–“chocolate clay” samples are relatively stable materials, while PLA–mango–“bofe clay” samples could represent promising highly biodegradable materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47512.