Polymeric Packaging Materials Research Articles

Retention of α‐tocopherol in low‐density polyethylene (LDPE) and polypropylene (PP) in contact with foodstuffs and food‐simulating liquids

Alpha-tocopherol occurs as a natural antioxidant in many foods and has also found use as a stabiliser in polymeric packaging materials. During storage of a food in contact with a plastic material, α-tocopherol may be released from the packaging material and transferred into the food. An active packaging application with the transfer of a substance, such as an antioxidant, from a packaging material to a food may help to prolong the shelf-life of the food. In this study, the retention of α-tocopherol in low-density polyethylene (LDPE) and polypropylene (PP) was investigated for contact with liquid foods with different fat contents and food simulants with different ethanol contents. The PP film exhibited excellent retention of α-tocopherol when in contact with all media, whereas some losses were observed from the LDPE film. A number of factors including fat, alcohol and organic acid contents of the various foodstuffs seemed to influence the loss of α-tocopherol from the LDPE film. © 1999 Society of Chemical Industry

Development of an analytical method for the determination of congener specific PCBs in selected polymeric packaging materials.

at least 18 and perhaps up to 36 of the 209 congeners have potential for toxicity due to their abundance in fish/animal tissue and their demonstrated enzyme induction effects (McFarland & Clark 1989, Tanabe 1988). Recent research has focused on the use of polymeric materials as cleanup and bioconcentration tools and for the analysis of PCBs and other organic chemicals from water, soil and lipophilic media (Huckins et al. 1990, Zabik et al. 1992). In food packaging, there is a need for research on issues such as the migration of PCBs from packaging materials to packaged foods or the reverse case, the sorption of PCBs from contaminated foods by the packaging material. The purpose of this study was to develop the methodology for the determination of specific PCB congeners in selected polymeric packaging materials used for the packaging of foods. Once the method is developed, it will be possible to investigate the effect of the chemical composition and physical characteristics of food polymers on the potential sorption of selected PCB congeners ranging from tri to deca chlorinated PCBs.

FE-simulation for polymeric packaging materials

Finite element (FE) simulations represent a useful tool to evaluate the thermomechanical behaviour of electronic packages. However, the use of the FE-method generates special difficulties, with particular regard to the proper constitutive modelling of materials used in the assembly. One more general problem in the numerical investigations of encapsulated silicon chips is the occurrence of interfaces between the dissimilar materials. Due to the assumption of sharp interface edges and interface crack tips, stress singularities arise which might be accounted for only approximately in the FE-calculation. The paper intends to show solutions of these simulation difficulties, also by means of materials testing. The complex material behaviour is discussed for different filled epoxy materials, with particular regard to the influence of filler content. A new solution method for the interfacial edge problem is briefly introduced. As an example, the pull strength test is used and the asymptotic solution for an interface edge is presented.

Migration and sorption phenomena in packaged foods

Rapidly developing analytical capabilities and continuously evolving stringent regulations have made food/package interactions a subject of intense research. This article focusses on: (1) the migration of package components such as oligomers and monomers, processing aids, additives, and residual reactants in to packaged foods, and (2) sorption of food components such as flavors, lipids, and moisture into packages. Principles of diffusion and thermodynamics are utilized to describe the mathematics of migration and sorption. Mathematical models are developed from first principles, and their applicability is illustrated using numerical simulations and published data. Simulations indicate that available models are system (polymer‐penetrant) specific. Furthermore, some models best describe the early stages of migration/sorption, whereas others should be used for the late stages of these phenomena. Migration‐ and/or sorption‐related problems with respect to glass, metal, paper‐based and polymeric packaging materials are discussed, and their importance is illustrated using published examples. The effects of migrating and absorbed components on food safety, quality, and the environment are presented for various foods and packaging materials. The impact of currently popular packaging techniques such as microwavable, ovenable, and retortable packaging on migration and sorption are discussed with examples. Analytical techniques for investigating migration and sorption phenomena in food packaging are critically reviewed, with special emphasis on the use and characteristics of food‐simulating liquids (FSLs). Finally, domestic and international regulations concerning migration in packaged foods, and their impact on food packaging is briefly presented.

Absorption of Maillard Reaction Volatiles by Polymers

The antioxidant properties of Maillard reaction volatiles (MRV) have been demonstrated in previous studies; in particular a significant antioxidant activity of MRV on the oxidation of heat-treated soybean oil was found. These findings offer an opportunity to use MRV to protect foods susceptible to oxidative deterioration. Polymeric packaging materials may be a suitable vehicle to deliver M RV to foods in a controlled manner. The object of this study was to gain information on MRV sorption by commercially available films used for packaging. The absorption of these volatiles by polymeric films was found to follow the solvent properties of commonly used polymers. Polymeric films were found to absorb some compounds when they were suspended above a glucose-glycine solution during heating. The absorption of these volatiles by polymeric films demonstrated the solvent properties of commonly available polymers.

食品と高分子 美味しさを包む高分子 食品包装と高分子包装材料

食品と高分子 美味しさを包む高分子 食品包装と高分子包装材料

95/05573 Reuse of coal mining wastes in civil engineering - Part 1: Properties of minestone

The barrier characteristics of polymeric packaging materials are measured by the intensity of the molecular exchange between the packaged product and its external environment. The exchange of penetrant molecules through polymeric materials is determined by the capacity of a polymer matrix to sorb the penetrant molecules, and the ability of the penetrant to diffuse through the polymeric material according to Fick's laws. However, the presence of other small relative molecular mass compounds present in the polymer matrix may change the way in which the permeant is sorbed and diffused. The case is such when water molecules are present in hydrophilic polymers affecting barrier characteristics of those polymers to penetrants such as oxygen or organic compounds. The oxygen barrier properties of hydrophilic polyamides change as a function of the amount of water in the polymer matrix. In addition, polymer morphology plays an important role in controlling the mode in which water molecules affect the transport of the penetrant. The change in oxygen barrier properties is then a function of the polymer water activity and morphology. A dual mode sorption model based on the Flory-Huggins and Langmuir equations is applied to the sorption of water by an amorphous and a semicrystalline polyamide, at three temperatures. The model provides the basis for the interpretation of the effect of water on the permeability, solubility and diffusion of oxygen within the polyamides. Different interaction mechanisms of water and oxygen within the polymers, to include self-association of water molecules and oxygen-water molecular competition, are discussed at different water activity values for both polyamides.

Influence of sorbed vegetable oil and relative humidity on the oxygen transmission rate through various polymer packaging films

AbstractIn this study, the effect of a vegetable oil on the oxygen barrier properties of different polymer packaging materials [i.e. amorphous polyethylene terephtalate (APET), polypropylene (PP) and high density polyethylene (HDPE)] was investigated. The influence of both relative humidity and the combination of relative humidity and sorbed oil on the oxygen transmission rate (OTR) was studied. Regardless of the relative humidity, the APET film remained an excellent oxygen barrier even after storage in rapeseed oil for 40 days. An increased OTR was observed in both the PP and HDPE films stored for 40 days in rapeseed oil. The OTR of the HDPE films was altered to a much greater extent than the OTR of the PP film. The OTR of the HDPE film was also significantly increased for films stored for 20 days in rapeseed oil. The increase in OTR of an HDPE film stored for 40 days in rapeseed oil was between 36 and 44%, depending on the relative humidity, compared to the OTR through the virginal polymer. The amount of oil sorbed by the polymer films used decreased in the following order: HDPE ≫ APET > PP.

Interaction of food packaging material and selected food components under high pressure

Abstract Interactions between ethanolic solutions of p-cymene and acetophenone and different polymer packaging materials. were studied at 500 MPa and 25° C. p-Cymene solution, filled into low-density polyethylene bags, lost 30% of its aroma concentration after 24 h at 500 MPa compared to a 60% loss at atmospheric pressure. The decrease was strongest within the first 15 min. Using LDPE/HDPE/LDPE bags, losses were 20% and 30%, resp. Applying the “bag in the bag” method, p-cymene concentrations measured inside and outside the inner bag has shown sorption by the pressurized film to be one third of that by the non-pressurized. In PET/AI/LDPE bags impermeable to p-cymene, sorption was confined to the inner LDPE layer and caused higher loss in the non-pressurized sample. Acetophenone has not been found to interact with the polymer during pressure treatment, while at atmospheric pressure sorption loss in aroma concentration was nearly 70% after 60 h.

Effect of water vapor on the transport properties of oxygen through polyamide packaging materials

The barrier characteristics of polymeric packaging materials are measured by the intensity of the molecular exchange between the packaged product and its external environment. The exchange of penetrant molecules through polymeric materials is determined by the capacity of a polymer matrix to sorb the penetrant molecules, and the ability of the penetrant to diffuse through the polymeric material according to Fick's laws. However, the presence of other small relative molecular mass compounds present in the polymer matrix may change the way in which the permeant is sorbed and diffused. The case is such when water molecules are present in hydrophilic polymers affecting barrier characteristics of those polymers to penetrants such as oxygen or organic compounds. The oxygen barrier properties of hydrophilic polyamides change as a function of the amount of water in the polymer matrix. In addition, polymer morphology plays an important role in controlling the mode in which water molecules affect the transport of the penetrant. The change in oxygen barrier properties is then a function of the polymer water activity and morphology. A dual mode sorption model based on the Flory-Huggins and Langmuir equations is applied to the sorption of water by an amorphous and a semicrystalline polyamide, at three temperatures. The model provides the basis for the interpretation of the effect of water on the permeability, solubility and diffusion of oxygen within the polyamides. Different interaction mechanisms of water and oxygen within the polymers, to include self-association of water molecules and oxygen-water molecular competition, are discussed at different water activity values for both polyamides.

Application of regular solution theory in predicting equilibrium sorption of flavor compounds by packaging polymers

Equilibrium sorption values of model flavor compounds and polymers used in packaging were determined by immersing polymer samples in liquid flavor compounds. The equilibrium sorption values were normalized for crystallinity and concentration differences. The plot of ln S vs the squared difference between the solubility parameter of polymer and solvents (δ 1 -δ 2 ) 2 resulted in poor correlation. This seems to indicate that modifications are required in applying the Hildebrand-Scatchard concept of solution for the prediction of flavor sorption by polymer packaging materials. Results indicate that the consideration of polymer chain configurations and more reliable δ values for polymers may improve the prediction

Aroma Sorption Evaluation of Aseptic Packaging

ABSTRACTA headspace method was developed for evaluating aroma sorption by polymeric packaging materials. Partition coefficients for ethyl acetate, n‐hexanal, d‐limonene and α‐terpineol at vapor activities of 0.2 were measured between air and the materials at 25°C and 40°C. Four different flexible aseptic packaging materials with barrier layers of aluminum foil, polyvinylidene chloride (SARAN), metallized polyester (MPET) and ethylene vinyl alcohol (EVOH) were evaluated. Temperature and aroma type had significant effects on partition coefficients. No significant interactions between aromas were observed in partition coefficients. The inner polyolefin sealing layer determined the aroma sorption behavior.

Compatibility of polymeric packaging materials with pharmaceutical products: Estimation at migration levels

Compatibility of polymeric packaging materials with pharmaceutical products: Estimation at migration levels

Indirect food additive migration from polymeric food packaging materials.

Many foods contact polymeric packaging materials which contain residues of the polymerization process or additives employed to facilitate processing. The extent of migration of such materials from the packaging to foods is the focus of the present article. A major experimental program using eight polymer-migrant systems is described. Migration was measured to food-simulating liquids (FSL) and to foods. Accelerated tests were conducted with FSL under FDA guidelines conditions so as to develop correlations between such data and those found using foods under normal storage temperatures and shelf lives. In the majority of tests, the migration was found to be approximately proportional to the square root of time, to increase significantly with a rise in temperature, and to be proportional to the initial concentration of migrant in the polymer. Stirring in the FSL or food phase was generally not important except for the system involving dioctyl adipate migrating from polyvinyl chloride film. In some instances, after a period of time, migration rates became very low, and this effect was attributed to saturating the FSL or food phase with migrant. The foods comprised a variety of types, including liquid, semisolid, solid, and dry; both oily and aqueous foods were included. The physical steps involved in migration include the diffusion of the migrant from the interior of the film to the surface, where it can dissolve in the external FSL or food phase. The nature of the FSL or food is shown to be very important in that components can penetrate the polymer and dramatically increase migration rates. Consistent with the FDA guidelines in effect at the time of this study, testing was performed with five FSL (water, 3% acetic acid, 8% and 50% ethanol, and n-heptane) at 49 degrees C. Detailed comparisons were made between the migrations to foods and to FSL; following are the more relevant conclusions. (1) Three percent acetic acid showed no advantage over water as a food simulant even in those cases where the food could be considered acidic in nature. (2) Water, when used as an FSL at 49 degrees C for 5 days, overestimated migration in aqueous foods in about 75% of the cases. In some instances, however, the water phase became saturated with migrant. In other situations, this test protocol underpredicted migration--especially in those cases where there were components in the food that were able to penetrate into the polymer and enhance migration (such as orange juice).(ABSTRACT TRUNCATED AT 400 WORDS)

Analytical Measurements of Package Components for Unintentional Migrants

The results of selected studies dealing with the transfer or migration of indirect additives from food contact materials to foodstuffs and/or their appropriate simulants have been reviewed in terms of the polymeric packaging material or packaging article, specific migrant, nature of the contact phase, level of migrant transferred under the conditions of test, and the analytical method employed to monitor com positional changes. The references presented on the analytical procedures developed for quantitation of migrated species are intended as a guide to the literature, where only representative studies have been reviewed.

TRANSPORT CONSIDERATIONS OF POTENTIAL MIGRANTS FROM FOOD PACKAGING MATERIALS

Migration from polymeric packaging materials to containd foods is essentially a desorption process involving low molecular weight species in a polymeric matrix. Such desorption can affect both intrinsic quality and safety of ingested packaged food. A legalistic problem also exists because of present regulations of “zero tolerance” where a possible migrant is a potential carcinogen. The precise elucidation of desorption, at extremely low levels of initial migrant concentration, has thus become a major issue. However, desorption at such levels has not been adequately studied. Sorption/desorption studies conducted with food simulating solvents and foods in classical phase distribution systems shows marked concentration dependence for certain poly (vinyl chloride) resins. The thermodynamic relations between selected monomer/polymer systems have been further studied by inverse phase gas chromatography for both poly (vinyl chloride) and poly (acrylonitrile) and some of its copolymers. Results from these studies suggest that entropic relations are dominant at such low levels for transport.