Selection Of Packaging Materials Research Articles

Food‐packaging interactions influencing quality and safety

Interactions between foods and packaging can be detrimental to quality and/or safety. Changes in product flavour due to aroma sorption and the transfer of undesirable flavours from packaging to foods are important mechanisms of deterioration when foods are packaged in polymer‐based materials. Careful consideration must be given to those factors affecting such interactions when selecting packaging materials in order to maximize product quality, safety, and shelf‐life while minimizing undesirable changes. Product considerations include sensitivity to flavour and related deteriorations, colour changes, vitamin loss, microbial activity, and amount of flavour available. Storage considerations include temperature, time, and processing method. Polymer considerations include type of polymer and processing method, volume or mass of polymer to product ratio, and whether the interaction is Fickian or non‐Fickian. Methodology to determine the extent of such interactions must be developed. Direct interactions between food and packaging are not necessarily detrimental. The same principles governing undesirable interactions can be used to affect desirable outcomes. Examples include films which directly intercept or absorb oxygen, inhibit microorganisms, remove undesirable flavours by sorption, or indicate safety and product shelf‐life.

In-situ measurements of surface mount IC package deformations during reflow soldering

In this study, a real-time probe was developed for in-process measurement and recording of package deformations during simulated solder reflow. The objective was to obtain fundamental insights into the stresses seen by the package during reflow, to guide package design, modeling, material selection, and process improvement efforts. Experiments were conducted to obtain temperature and time resolved deformation signatures of packages due to the applied reflow profile. The occurrence of delamination and cracking and the reflow parameters associated with its initiation were identified using the deformation plots and the observations were verified by post-reflow inspection using scanning acoustic microscopy. Absorbed moisture in the package was found to play a role in package deformations beyond 90/spl deg/C, with an increased rate of deformations beyond approximately 138/spl deg/C. Partial reflow simulation experiments revealed that these deformations were not caused by the initiation and growth of interfacial delaminations, but rather to moisture-induced swelling and thermal expansion effects.

Moisture absorption and desorption predictions for plastic ball grid array packages

Plastic electronic packages are known to absorb moisture when exposed to humid ambient conditions during storage in tape and reel in the factory. Reliability becomes a concern when packages are exposed to a humid environment for a prolonged time and then processed through a reflow oven. Thermo-mechanical and moisture induced interfacial stresses generated between the die attach and die may lead to die delamination and package cracking. Current package level moisture evaluation methods are based on experimental weight gain measurements and visual inspection after reflow for cracking or delamination. This study presents a finite element analysis (FEA) simulation of the moisture weight gain or loss in plastic ball grid array (PBGA) packages as a function of time including the effects of package geometry and material selection. Experimental weight gain and bakeout data for a 68 I/O PBGA package are shown to closely match FEA model predictions. Diffusivity and solubility property data for common packaging materials are given as a function of temperature ranging from 23/spl deg/C to 150/spl deg/C. Solder pot dip tests performed at 230/spl deg/C indicate that popcorn failures result when the moisture concentration in the die attach region exceeds 0.0048 g/cm/sup 3/ for the specific package tested.

Thermal fatigue behavior of J-lead solder joints

Thermal cycling environments were applied to test specimens with J-lead eutectic Sn-Pb solder joints to assess the effect of lead and package material selection. Metallographic examination and finite element analysis were used to evaluate the effect of thermal cycling environments on solder joints. Matching the coefficient of thermal expansion (CTE) of the lead and solder was found to be crucial to reducing thermal cycling damage for the J-lead solder joints examined. Matching the CTE of the package and the board was substantially less important. The number of thermal cycles 1.9 nucleate cracks in the J-lead solder joints correlated reasonably well with the number of cycles to produce a 50% drop in the load range in isothermal strain controlled mechanical fatigue tests on Sn/Pb solder.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Recyclability and the selection of packaging materials

Costs of solid-waste disposal, concern for environmental impact, and “green” marketing opportunities have placed more attention on recyclability of packaging materials. Recyclability is determined not only by the characteristics of materials themselves, but also by the presence or absence of collection facilities, ease of separation, technology for reprocessing, and markets for recovered materials. By these measures, packaging materials are becoming more recyclable and recyclability is growing in importance as a factor in material selection.

Water sorption and water vapour diffusion in food‐grade plastics packaging materials: Effect of a polymeric plasticizer

AbstractIt is recognized that packaging has a profound effect on the ultimate quality of food products reaching the consumer. So, the selection of proper packaging materials has become one of the major problems of the food technologist. In the field of flexible packaging one of the most important properties is water vapour/package interaction. Inverse gas chromatography has been used to study water sorption of polyvinylchlor‐ide and poly(vinylidene chloride‐vinylchloride) plasticized with different amounts of a polymeric plasticizer (poly(adipate ester)) at temperatures between 25°C and 50°C. It was found that the specific retention volume of water increases with decreasing temperature and increasing amount of plasticizer into the polymeric mixtures. The effect of temperature on water sorption behaviour is more pronounced compared with that of plasticizer addition. The thermodynamic parameters of water/polymer interaction, namely free energy, entropy, enthalpy and activity coefficient were calculated. Values were interpreted on the basis of an active‐site absorption model. The Van Deemter equation was found to be applicable to these systems and was used to determine diffusion coefficients and activation energies for diffusion. Diffusion coefficient values increase with increasing amounts of plasticizer and this increase is accompanied by a decrease in the activation energy for diffusion.

Accelerated physical stability testing and long-term predictions of changes in the crushing strength of tablets stored in blister packages

A physical model is presented which permits the amount of sorbed moisture and the crushing strength of compressed tablets stored in blister packages to be predicted based on a knowledge of: (1) tablet moisture sensitivity; (2) package moisture permeability; and (3) relative humidity storage conditions. The tendency of tablets to sorb water can be characterized in approximately one week by storing unprotected tablets at several relative humidities. This information, in combination with package moisture permeability data, permits changes in tablet crushing strength and sorbed moisture to be made under a variety of storage and packaging conditions. These predictions are useful in establishing long-term stability testing protocols. They are also useful in predicting what tablets stored in blister packages might reasonably be expected to experience in the market place where short-term and long-term oscillating conditions are likely to occur. Theoretical predictions based on the physical model indicate that, in general, tablets stored in relatively permeable blister packaging materials will be protected from large, short-term humidity fluctuations of several hours or days. Long-term fluctuations due to monthly and seasonal variations in humidity will be important. Tablets stored in relatively permeable blister packages at relative humidities representative of marketplace conditions can be expected to experience humidities varying between 30% and 70% while less permeable packages will show less variation. This suggests that oscillating unprotected tablets between 30% and 70% relative humidity every 2–3 days for a 2–3-week period may produce changes similar to those observed for tablets stored in marketed blister packages. Tablets tested using these conditions showed changes in crushing strength similar to those packaged in blister packages and used in a 3-year field study. The theoretical predictions and experimental results emphasize the importance of matching the dosage formulation characteristics to the package material and testing conditions. In this way, a more rational selection of packaging material and testing protocols can be made.

Developing criteria for the selection of packaging materials.

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EVALUATION OF PLASTICS PACKAGING MATERIALS FOR FOOD PACKAGING APPLICATIONS: FOOD SAFETY CONSIDERATIONS

In evaluating a packaging system for food packaging applications, consideration must be given to the physical properties, chemical composition and extractivity of the packaging material. The last point, extractivity, or migration from the packaging material to a food contact phase, is of major concern in the selection and use of plastics packaging materials for food packaging.The present article deals specifically with migration of indirect food additives from plastics packaging materials and the scientific principles related to migrant transport or diffusion, as they apply to food safety. These principles and their experimental basis are discussed.

Toxicological Considerations in the Selection of Flexible Packaging Materials for Foodstuffs

High molecular weight polymers are the “backbone” of the flexible packaging industry, although a variety of papers, fabrics, and metallic foils are also employed. Almost without exception, high molecular weight polymers are physiologically inert and, therefore, pose no toxicological problems in themselves. However, monomers and low molecular weight fractions that may be incorporated in certain commercial polymers can be a source of concern, as can be other low molecular weight chemicals purposely added to commercial polymers, in some instances, to modify their processing or functioning characteristics. Conditions of use must also be considered when employing polymeric films (with or without additives) as the food contact components of packages. A polymer may be completely nontoxic and an adequate barrier to other package constituents when used to contain foodstuffs if the resultant package is subsequently stored at room temperature, under refrigeration, or frozen. However, when used as the inner ply of a boil-in pouch, a retortable pouch, or an oven bag, it must be determined that it is not subject to some degree of thermal breakdown or allows permeation of adhesive or ink components not approved for direct contact with food. Finally, if there is a requirement to sterilize packages before filling, as in aseptic packaging, the effect of the sterilizing medium on the packaging material must be fully understood.

Palatability of Ground Beef Home Frozen and Stored in Selected Wraps1

A survey of household practices in wrapping, freezing, and storing ground beef was used as the basis for planning a laboratory study of the effects of packaging materials on palatability and weight loss of ground beef patties frozen and stored at ‐18°C. (0°F.) and at −9°C. (15°F.). Quality was monitored at 0‐, 1‐, 2‐, 3‐, 4‐, 6‐, and 12‐week intervals.Palatability of ground beef was affected less by storage temperature when packaged in aluminum foil than when wrapped in freezer paper, polyvinylchloride‐1 film, or wax paper. Storage at −18°C. (0°F.) was more effective than ‐9°C. (15°F.) in protecting flavor and aroma. Palatability of ground beef declined significantly between 6 and 12 weeks when stored at the high temperature. Wax paper permitted significantly more loss in weight in ground beef patties during freezer storage than did any of the other selected packaging materials.