Oriented Polypropylene Research Articles

Persistence of Escherichia coli O157:H7 and Listeria monocytogenes on the exterior of three common food packaging materials

An estimated 179 million cases of acute gastroenteritis (AGE) occur each year in the United States. Escherichia coli O157:H7 and Listeria monocytogenes, common etiologic agents of AGE, both have low-infectious doses and high environmental resistance. Surfaces contaminated with either pathogen, such as the exterior surface of a food package, could serve as a vehicle for AGE transmission. The aim of this study was to determine the persistence of E. coli O157:H7 and L. monocytogenes on three common food packaging materials–oriented polyethylene terephthalate (OPET), oriented polypropylene (OPP), and nylon-6. Coupons (5 × 5 cm2) from each material were sterilized under ultraviolet light for 5 min, inoculated with ca. 7 log CFU of a three-strain-mixture of green fluorescent protein (GFP)-labeled E. coli O157:H7, then incubated according to the Technical Association of the Pulp and Paper Industry standards. Surviving E. coli O157:H7 cells were recovered in saline at 0, 0.25, 0.5, 1, 2, 3, 5, 7, 14, 15 days then enumerated on tryptic soy broth (TSB) supplemented with ampicillin using the three-tube most probable number (MPN) method. The same procedure using a three-strain mixture of rifampin-resistant (Rif)-L. monocytogenes was followed except TSB was supplemented with rifampin. E. coli O157:H7 and L. monocytogenes both survived on OPET, OPP, and nylon-6 for 15 days. The log reductions for E. coli O157:H7 were 5.7 log MPN, 5.3 log MPN, and 5.1 log MPN across the three materials respectively. The log reduction for L. monocytogenes was 6.5 log MPN, 6.3 log MPN, and 4.8 log across the same three materials. The number of surviving E. coli cells was significantly higher (P > 0.05) than L. monocytogenes at sampling times 1, 2, 3, 5, 7, 14, and 15 days. No significant difference was shown between the two bacteria between 0 and 0.5 days. Survival of both bacteria across all three materials was not significantly different (P > 0.05). These results suggest that a highly contaminated (107 CFU/coupon) exterior surface of a food package could be a potential vehicle for the transmission of bacteria associated with AGE.

Antibacterial effect and mechanisms of action of 460–470 nm light-emitting diode against Listeria monocytogenes and Pseudomonas fluorescens on the surface of packaged sliced cheese

The aim of this study was to investigate the antibacterial effect of 460–470 nm light-emitting diode (LED460–470nm) illumination against pathogens and spoilage bacteria on the surface of agar media and packaged sliced cheese. LED460–470nm illumination highly inhibited the growth of Listeria monocytogenes and Pseudomonas fluorescens on agar media covered with oriented polypropylene (OPP) film (thickness, 0.03 mm). When sliced cheeses inoculated with L. monocytogenes or P. fluorescens and packaged with OPP film were illuminated by an LED460–470 nm at 4 or 25 °C, reduction levels of L. monocytogenes and P. fluorescens on packaged slice cheese were higher at 4 °C than at 25 °C. There were no significant differences in color between non-illuminated and illuminated sliced cheese after storage for 7 d at 4 °C. LED460–470 nm illumination at 4 °C for 4 d caused cellular injury of L. monocytogenes and P. fluorescens related to RNA, protein, and peptidoglycan metabolism, and a disruption of the cell membrane and loss of cytoplasmic components were observed from TEM results. These results suggest that LED460–470 nm illumination, in combination with refrigeration temperatures, may be applied to extend the shelf-life of packaged slice cheese and minimize the risk of foodborne disease, without causing color deterioration.

Practical Notes on the Measurement and Interpretation of Thermally Stimulated Discharge Currents in Biaxially Oriented Polypropylene

The measurement and interpretation of high-field thermally stimulated depolarization current (TSDC) of capacitor-grade biaxially oriented polypropylene (BOPP) films are investigated in order to facilitate the derivation of trap parameters. Two main relaxations associable with the glass transition and detrapping of space charge from deep traps are observed, and their dependence on the polarization/depolarization conditions are studied. The complex bipolar nature of the space charge relaxation makes the derivation of trap parameters challenging. Lastly, a brief attempt is made to correlate the TSDC features with morphology and other short-term dielectric properties.

Effect of Hydrodynamic Conditions and Geometric Aspects on the Permeance of Perforated Packaging Films

Modified atmosphere packaging (MAP) is applied to extend the shelf life of fresh and minimally processed produce. Commonly used films, such as oriented polypropylene (OPP), are too impermeable to gases for successful MAP for products with moderate to high respiration rates, which has led to perforated systems. In order to design the perforation profile to ensure MAP targets for extended shelf life, it is necessary to evaluate which parameters affect the mass transfer through the perforations significantly. Perforations (270 μm, 450 μm and 750 μm diameter) were made in an OPP film under different temperatures and circulating air velocities, considering also different locations for the perforations. The results obtained showed that the perforation diameter is the most important parameter and can even be more significant than the total area of perforation (and therefore the number of perforations). Air velocity around the package and storage temperature were also relevant. Stacking during storage risks blocking perforations and therefore it is recommended to pierce trays on the sides in order to ensure better robustness. The package gas composition itself also affected mass transfer due to the interplay of oxygen flux with other gas fluxes, with particular relevance to the case of water vapour.

Chemical and physical changes during storage of differently packed biscuits formulated with sunflower oil.

Various innovative materials are already present on the market, but there is scarce knowledge on their performances when used in real food system. In this study, two innovative packaging materials were investigated for the evaluation during storage of biscuits formulated with sunflower oil and compared to a traditional one. To this aim, three different flexible and composite film containing a metalized plastic layer and a paper layer were used. The control included orientated polypropylene (OPP), while the innovative materials contained poly-lactic acid or OPP with a pro-oxidant additive, ethylene vinyl acetate. The physical (moisture, water activity, hardness/crispness) and chemical (peroxide value, conjugated dienes and trienes, and hexanal and nonanal formation) changes of biscuits were monitored during accelerated storage (35°C and 50% of relative humidity for 105days). Packaging materials did not have significant impact on textural quality of biscuits. Instead remarkable differences were observed during storage in the evolution of different lipid oxidation compounds, moisture content and water activity among differently packed biscuits. A new ecofriendly packaging showed the best performances in terms of physico-chemical quality of biscuits. The obtained results provide useful information for industrial application.

포장 필름과 저장 온도 조건에 따른 양송이버섯의 품질 변화

This study was conducted to investigate the effects of temperature and packing film with varying oxygen transmission rate (OTR) on the quality of Agaricus bisporus (mushrooms) to determine the optimum modified atmosphere package. Mushrooms were packed using 10 µm polyvinyl chloride (PVC), and 30 µm oriented polypropylene (OPP) films with the OTR ranging from 1,000 to 20,000 mL/m2/day/atm (OPP1000, OPP6000, OPP10000, and OPP20000). The quality parameters including weight loss, gas composition, cap opening rate, stipe elongation, firmness, and color of mushrooms were monitored at the following temperatures: 4℃, 8℃, 12℃, and 20℃. Overall, the mushrooms packed in OPP films showed less change in weight loss, cap opening rate, stipe elongation, and firmness than those of the control, however, these effects differed with the temperature and film OTR. Among the OPP films, OPP20000 did not exhibit any effect with respect to tissue growth inhibition. OPP1000 and OPP6000 were the most effective in suppressing the cap opening rate and stipe elongation but induced tissue damage and water soaking in the internal section. In contrast, the mushrooms packed in PVC film showed less change in weight loss, cap opening rate, and stipe elongation than those of the control, and browning of inside and outside of mushroom was less than that mushroom packed in OPP film.

Photoinduced Reactions of Benzophenone in Biaxially Oriented Polypropylene

The photoinduced reactions of benzophenone (B) in biaxially oriented polypropylene (BOPP) were studied with nanosecond laser photolysis (N2 laser, λ337.1 nm). The first observed transient was a triplet state 3B*. Decay of 3B* led to formation of a radical pair (RP) of BH• and R•, where R• is a radical formed by hydrogen abstraction from BOPP (RH) by 3B*. We studied BOPP after the preheating for a short time in a temperature range 298-423 K, which is essentially lower than its melting point of 453 K. All measurements with not-heated and with preheated (annealed) BOPP were made at 298 K. A radical pair (RP) apparently decays as a contact pair 3[BH•, R•] in nonheated BOPP. A critical phenomenon takes place: dissociation of RP with a formation of free radicals in the polymer bulk is observed at preheating temperature Tcrit ≈ 403 K and at a higher T. The physical process of heating and cooling of BOPP apparently resulted in the restructuring of crystallites, their agglomeration, shrinking of the distribution of crystallites according to their sizes in BOPP. Overall BOPP becomes softer which manifests itself in the radical kinetics. The decay kinetics of 3B* and RP in the cage fits well the first-order law. Rate constants were obtained. Radicals BH•, which exit into the polymer bulk at temperatures of preheating T ≥ 403 K, decay by cross-termination according to the second-order law. A relatively high rate constant ∼108 M-1·s-1 for this reaction was obtained due to diffusion of BH• enclosed in the soft amorphous phase of BOPP. Properties of BOPP containing B were studied with ESR, DSC, IR, and WAXD.

The variability of dynamic coefficient of friction material in flexible packaging

Labels and flexible packaging on the market today take a very important role. The possibility of printing on polymeric materials of flexible packaging is diverse from OPP (Oriented Polypropylene), PVC (Polyvinyl Chloride), OPS (Oriented Polystyrene), PET (Polyethylene Terephthalate) material and all types of self-adhesive paper and foil. Special highlight are the Shrink Sleeve labels that meet the most demanding market challenges. Its capabilities are great, and laminated materials for packaging purposes are, for their function, both as protection and as packaging. Coefficient of friction is the value that serves to meet the standard of how the flexible packaging material will glide and move on the packaging machine. This research is focused on the optimum quality of the packaging production process to meet all the preconditions for implementation of the semifinished product packaging and to avoid difficulties and possible stoppages on the packaging machine itself.

Effects of modified atmosphere packaging (MAP) on microbiological and sensory quality of ackee fruit arils (Blighia sapida Köenig) stored under refrigerated regimes

Abstract In this study, we investigated the effects of two modified atmosphere packaging films [Osmolux (Osx) and Oriented PolyPropylene (OPP)] on the microbiological and the sensory qualities of ackee fruit (Blighia sapida Köenig) arils stored during eight days under two refrigerated temperatures, 5 ±1°C and 10 ±1°C. The control samples of ackee arils were packaged in a macro-perforated highdensity polypropylene film (MP). The results showed that mesophilic aerobic bacteria (MAB), yeasts and moulds were lower under OPP, although MAB of MP was lower at 5°C. At 10°C, the pH of the ackee arils stored in Osx and OPP did not vary significantly, but the pH ofMP showed an increase from 5.32 to 5.95 and 5.83 at 5°C and 10°C, respectively. Results also showed that under OPP, weight losses were lower and averaged 0.12%and 0.19%after eight days storage at 5°C and 10°C, respectively, while the sensory quality attributes were preserved up to six days. Conclusively, OPP showed better attributes for MAP storage of ackee arils under refrigerated temperatures, although none of the two films were effective to reduce the chilling injury after the eight days storage.

The physical, microstructural, chemical and sensorial properties of spray dried full-fat white cheese powders stored in different multilayer packages

The spray-dried white cheese powder from full-fat ripened cheese was packaged in three different multilayer plastic materials such as polyethylene terephthalate/aluminum foil/low density polyethylene (PET/Al-foil/LDPE), polyethylene terephthalate/aluminum metalized polyethylene terephthalate/low density polyethylene (PET/Met-PET/LDPE) and oriented polypropylene (OPP). The density, reconstitution, microstructure, color, oxidation, non-enzymatic browning and sensory properties of powders were investigated for 12 months. There were found significant differences for almost all parameters of powders packaged in different materials. The changes in properties were negligible for samples packaged in PET/Al-foil/LDPE and acceptable in PET/Met-PET/LDPE during storage. The most evident changes in all properties were observed in powders packaged in OPP becoming easily wetted and having the highest moisture content, water activity value, oxidation and browning values with a slight oxidized flavor and slight cream color after 6 months of storage. Some powder particles seemed to merge physically, particularly in samples packaged in OPP in the 12th month of storage according to scanning electron micrographs.

Synthesized amino-functionalized porous clay heterostructure as an effective thickener in waterborne polyurethane hybrid adhesives for lamination processes

The use of waterborne polyurethane (WPU) adhesives with non-volatile organic compounds (non-VOCs) has essentially expanded in laminating adhesive applications due to stringent environmental regulations, including on the release of VOCs. To function well, the inferior properties of WPUs should be overcome with good adhesion and cohesion mechanisms. High-performance WPU adhesive was synthesized by incorporating an amino-functionalized porous clay heterostructure (APCH) into the WPU to increase its internal strength via formation of urea linkages between fillers and the polymer matrix, to yield an organic/inorganic hybrid adhesive with greater cohesion. Urea linkages, as characterized by Fourier-self deconvolution of the C=O stretching vibration region (1600−1800cm−1), increased with increasing APCH content. In addition, APCH significantly enhanced the adhesion properties of bonded joints together with an improved thermal stability of the adhesive, affirmed by the DSC analysis and higher viscosity observed by a Brookfield viscometer. The highest peel strength (126N/m) was achieved with a WPU hybrid adhesive containing 2.0wt% APCH, which can be used for application in untreated oriented polypropylene (OPP) lamination.

Paper-polymer composite devices with minimal fluorescence background

Polymer film incorporated paper-based devices show advantages in simplicity and rugged backing. However, their applications are restricted by the high fluorescence background interference of conventional laminating pouches. Herein, we report a straightforward approach for minimal fluorescence background device fabrication, in which filter paper was shaped and laminated in between two biaxially oriented polypropylene (OPP) and polyvinyl butyral (PVB) composite films. This composite film provides mechanical strength for enhanced device durability, protection from environmental contamination, and prevents reagent degradation. This approach was tested by the determination of copper ions with a fluorescent probe, while the detection of glucose was used to illustrate the improved device durability. Our results show that lamination by the polymer composite lengthens device lifetime, while allowing for fluorescence detection methods combination with greatly reduced fluorescent background widely present in commercially available lamination pouches. By the combination of rapid device prototyping with low cost materials, we believe that this composite design would further expand the potential of paper-based devices.

A novel methodology for peel strength enhancement of heat-sealed oriented polypropylene/cast polypropylene film by tensile cyclic loading

We here demonstrate a novel experimental approach by which peel strength of heat-sealed polypropylene (PP) films can be improved by a tensile cyclic loading method, without using chemical adhesive materials. Laminated films of oriented polypropylene (OPP) and cast polypropylene films (CPP) were prepared using the dry lamination method. The tensile cyclic loadings were then applied to these films, and the influence of heat sealing conditions and tensile cyclic loading on the peel strength of the films were experimentally investigated using tensile tests, optical microscopic inspection, and micro-Raman spectroscopy. As a result of the heat sealing, the peel strength was increased with increasing numbers of tensile cyclic loadings. It was noted with increasing number of cyclic loadings, the peel strength of the OPP/CPP films was enhanced and exhibited good durability after tensile cyclic loading. The result of micro-Raman spectra revealed the local variation in the heat-sealed edge part, and it was found that HWHM on line mapping correlated with the peel strength.

Synthesis and characterization of waterborne polyurethanes with alkoxy silane groups in the side chains for potential application in waterborne ink

Abstract In this study, a series of waterborne polyurethanes (WPUs) with alkoxy silane groups in the side chains were synthesized by the chain extension with diamine chain extender (3-(2-aminoethyl)aminopropyl)trimethoxysilane (AEAPTMS). The effects of AEAPTMS content on the properties of WPUs were investigated in terms of adhesion strength, mechanical property, crystallinity and thermal stability. FT-IR and 1 H NMR spectra demonstrated the successful incorporation of AEAPTMS to polyurethanes. The increase of AEAPTMS content produced a decrease in the surface tension of WPUs as well as the interfacial tension and contact angle between WPUs and oriented polypropylene (OPP) films, implying the improvement of wetting property of WPUs on OPP films. The increase of AEAPTMS content increased the hydrophobicity, tensile strength, glass transition temperature and thermostability of WPU films, and decreased the crystallinity and elongation at break of WPU films. The adhesion strength of WPUs initially increased and then decreased with the increase of AEAPTMS content, and was the highest when the AEAPTMS content was 2.0 wt%. Moreover, compared with 3-aminopropyltriethoxysilane (APTES), AEAPTMS could improve the property of WPUs more greatly. In summary, the synthesized WPU with 2.0 wt% AEAPTMS had low water absorption, high thermal stability, and good adhesion on OPP film, and could be potentially used in waterborne ink for OPP film.

나노 TiO<sub>2</sub>를 적용한 식품 포장 필름 개발 및 콩나물의 이취 제거

For testing the ultraviolet (UV)-blocking property of functional films coated with Nano-TiO₂ particles, UV-Vis spectra of oriented polypropylene (OPP) films uncoated and coated with TiO₂ of 3% and 5% in Polyurethane (PU) and polyvinyl butyral (PVB)-Cellulose binders were measured. The result of UV-Vis analyses showed that the film coated with 5% TiO₂ in PVB binders had a significant effect on UV protection of 90% compared with the film uncoated. Also The result of The photodegradation of methylene blue (MB), OPP films coated with 5% in both PU and PVB binders had a high photocatalytic activity for MB degradation. To evaluate the effect of the developed functional film coated with Nano-TiO₂ particles, fresh soybean sprouts were used. Nano-TiO₂ coated film was observed to decompose the off-flavor produced by soybean sprouts within packages during distribution, but uncoated film did not. Therefore, Nano-TiO₂ coated film package could give the greatest effect in extending the shelf life of soybean sprouts.

Influence of modified atmosphere packaging on postharvest quality of cherry tomatoes held at 20 °C

The effects of passive modified atmosphere packaging (MAP) achieved with a 30μm thick continuous oriented polypropylene (OPP) film (Film A) or by the same film either laser-perforated with increasing levels of perforation (Films B–E) or macro-perforated (Film F) on overall qualitative changes and decay was studied on cherry tomatoes cv ‘Dorotea’ and ‘Trebus’ harvested at the red-ripe stage and stored for 7, 14 or 21d at 20°C 60% RH. Respiratory activity of both cultivars decreased as permeability of macro- and laser-perforated films decreased but increased in tomatoes sealed with Film A, which led to anaerobic conditions. In laser perforated films average in-package CO2 and O2 were around 3kPa and above 15kPa, respectively, with moderate variations among Films B–E, while in Film A average CO2 and O2 were around 12kPa and 6kPa, respectively. In-package gas composition of Film F only slightly differed from air. Air composition and high in-package humidity of laser perforated films controlled water loss and delayed loss of firmness and of titratable acidity, total soluble solids, vitamin C, but increased decay of the very susceptible to cracking ‘Dorotea’ tomatoes. The high in-package CO2 of Film A reduced pathogens growth, but decay incidence was lowest in unwrapped tomatoes and packages of Film F. ‘Trebus’ tomatoes were more resistant to decay than ‘Dorotea’ ones. MAP with moderate levels of CO2 (around 3kPa), O2 not below than 12kPa and RH not higher than 90% could prolong overall quality and reduce decay of red-ripe cherry tomatoes at 20°C.

절단배추의 포장재질에 따른 단기 저장 중 품질특성

Fresh cut vegetables provide convenience and rapidity to consumers. However, they have a weakness with respect to their short shelf-life due to browning and quality degradation via increased respiration. To overcome this problem, the effect of packaging film on the short-term storage of cut kimchi cabbages was investigated. Polypropylene (PP), oriented polypropylene (OPP), and low-density polyethylene (LDPE) films were used as packaging film, and cut kimchi cabbages were stored in the packaging films at 5°C for 4 weeks. PP film packaging showed the least weight loss and soluble solids loss after 4 weeks. Titratable acidity increased during storage for all samples, however, the increase rate of titratable acidity in PP and OPP film packaging decreased, which was lower than that of LDPE film packaging. Color values decreased over time during storage. In appearance, PP film packaging was better than other films due to their high transparency. In a sensory test, there was no statistical difference among samples. Taken together, the transparent PP film packaging was more effective for short-term storage of cut kimchi cabbages. Thus, this study provides useful information for the selection of packaging materials for cut kimchi cabbage marketing.

Effect of Lemongrass Essential Oil Vapors on Microbial Dynamics and Listeria monocytogenes Survival on Rocket and Melon Stored under Different Packaging Conditions and Temperatures.

The aim of the present study was to examine the effect of lemongrass essential oil vapors on the dynamics of surface microbiota and L. monocytogenes growth on rocket and melon under different packaging conditions and storage temperature. For that purpose, rocket and melon were placed on Expanded Polystyrene (EPS) trays, sprayed with L. monocytogenes to a population of 4.5–5.0 log CFU·g−1, packaged using microperforated Oriented Polypropylene (OPP) film in either air or Microperforated Active Modified Atmosphere (MAMA) (initial atmosphere 5% O2, 10% CO2) including a Whatman paper containing the essential oil, without contact with the product, and stored at 0, 5, 10, and 15 °C. Application of lemongrass exhibited a bactericidal effect on enterococci and a fungistatic effect on yeast-mould populations but only during air storage of rocket. The former took place at all temperatures and the latter only at 10 and 15 °C. No effect on shelf life of both products was recorded. However, an important effect on the sensorial properties was observed; during the first 4–5 days of storage both products were organoleptically unacceptable. Regarding MAMA packaging, it affected only Pseudomonas spp. population resulting in a reduction of 1–2 log CFU·g−1 in both products.

Evaluation of packaging films to extend storage life of indigenous Australian vegetables and herbs

A study undertaken in Hervey Bay, Queensland, investigated the potential of creating an indigenous agribusiness opportunity based on the cultivation of indigenous Australian vegetables and herbs. Included were warrigal greens (WG) (Tetragonia tetragonioides), a green leafy vegetable and the herb sea celery (SC) (Apium prostratum); both traditional foods of the indigenous population and highly desirable to chefs wishing to add a unique, indigenous flavour to modern dishes. Packaging is important for shelf life extension and minimisation of postharvest losses in horticultural products. The ability of two packaging films to extend WG and SC shelf life was investigated. These were Antimisted Biaxial Oriented Polypropylene packaging film (BOPP) without perforations and Antifog BOPP Film with microperforations. Weight loss, packaging headspace composition, colour changes, sensory differences and microbial loads of packed WG and SC leaves were monitored to determine the impact of film oxygen transmission rate (OTR) and film water vapour transmission (WVT) on stored product quality. WG and SC were harvested, sanitised, packed and stored at 4°C for 16 days. Results indicated that the OTR and WVT rates of the package film significantly (PKLEINERDAN0.05) influenced the package headspace and weight loss, but did not affect product colour, total bacteria, yeast and mould populations during storage. There was no significant difference (PGROTERDAN0.05) in aroma, appearance, texture and flavour for WG and SC during storage. It was therefore concluded that a shelf life of 16 days at 4°C, where acceptable sensory properties were retained, was achievable for WG and SC in both packaging films.

Ultraviolet-C Light Inactivation Kinetics of E. coli on Bologna Beef Packaged in Plastic Films

This study investigated the effects of ultraviolet-C (UV-C) light as a postpackaging treatment on Escherichia coli K-12 on bologna meat packaged in polyethylene (PE), oriented polypropylene (OPP), and ClearTite® films. Findings show that PE film had the highest measured UV-C light transparency among the 15 tested films, at 76 %, followed by PP and OPP films, with 59 and 57 %, respectively. Exposure of PE film inoculated with E. coli K-12 with UV-C light resulted in a 4.6 log CFU/ml reduction after a dose of 164 mJ/cm2. Reduction of E. coli K-12 on inoculated bologna packaged in PE film was higher (1.48 log CFU/g) compared to the other films (OPP and ClearTite®) following treatment with 0.406 J/cm2 of UV-C. The surface-free energy of films was used as an indicator for changes to film surface properties. UV-C light exposure of PE, OPP, and ClearTite® films at doses in this study had no significant effect (P ≥ 0.05) on the surface properties of the treated films. This study demonstrated that treating ready-to-eat meat products, such as a bologna with UV-C light after packaging, can reduce E. coli populations by a 1.5 log cycle without negatively impacting the surface properties of plastic films.