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Abstract: Mass transfer and related shelf life assessment is an important issue in the beverage industry. Product change due to mass transfer is at stake and, with it, its consumer value and consideration. Carbonation loss takes place at the product/package interface, and to the environment through the package itself. In this paper a joint experimental/computational approach has been exploited: the loss through the polyethylene terephthalate barrier has been computed by means of a multidimensional finite element code, while actual measurements have been carried out to validate the computations. Residual carbonation histories are validated and presented for a variety of thermal regimes and for two different bottles carrying the same capacity. The paper highlights on the combination of bottle weight, initial carbonation and storage temperature, indicating the operational set for the longest shelf life within the explored cases. Lighter bottles can be used with no inference on shelf life, while the carbonic loss depends non-linearly on initial carbonation and temperature increment. The associated concentration maps help infer on the importance of polyethylene terephthalate thickness uniformity. It is then demonstrated that the model carries the flexibility of a general tool, applicable to any carbonated beverage at any storage condition. [Copyright &y& Elsevier]

Abstract: We present a material flow analysis (MFA) for polyethylene terephthalate (PET), a synthetic polymer, in the United States for the years 1996–2007. We model the industrial metabolism of PET as a network of flows linking stocks and processes. The most common worldwide use of PET is in textile production, but in the US it is increasingly used to make disposable beverage containers for transporting water, carbonated soda, and other beverages. Bottles made from PET are the most-recycled plastic product in the US by mass and by recovery rate, and thus the PET material flow system constitutes an ideal case study of polymer recycling. We find that total consumption of PET resin grew at 2.7% per year over the period of the study, reaching 5.01 million metric tons in 2007. This growth was driven largely by the beverage packaging market, which accounted for 55% of consumption in 2007. About a quarter of PET bottles are collected for recycling, a number that has fluctuated widely but kept pace with consumption. However, domestic capacity for reclamation of post-consumer PET has not grown as quickly, leading recyclers to export increasing amounts of post-consumer material. Manufacturers have also imported secondary PET in increasing amounts. Reclaimed PET accounted for 6–9% of total resin demand throughout the study. While polymer recycling appears to be viable, efforts to improve material efficiency are confounded by low collection rates and a lack of reclamation infrastructure. [ABSTRACT FROM AUTHOR]

Abstract: A recently described bottle test method was used to evaluate the dependence of stress crack failure of poly(ethylene terephthalate) (PET) carbonated soft drink bottles on water hardness. Although the industry belief is that water hardness is irrelevant to stress cracking, it was found that hardness ions exert a tremendous positive impact by deactivating water alkalinity through precipitation as harmless carbonate minerals. This mitigating effect of hardness means that no complete understanding of stress cracking as a function of alkalinity is possible without also considering water hardness. A useful concept is that of excess alkalinity, which is defined as alkalinity that is not precipitated during solution evaporation. Limiting excess alkalinity by using water with sufficient hardness is an effective means of stress crack prevention in PET soft drink bottles. Evaluation of compositions which are typical of those used for lubricating PET bottles on production conveyors showed that the role of these compositions in stress cracking was that of spectators, that is, they neither cause failure if water does not otherwise cause it, nor stop failure if water otherwise causes it. [Copyright &y& Elsevier]

A contamination of soft drinks in sealed bottles by organic solvents is reported: closed bottles full of soft drinks were accidentally placed on a cardboard soaked with thinner and the organic fluid subsequently fissured the bottom of the bottles and penetrated into the soft drinks without any apparent leakage of the soft drinks. Experiments were carried out to simulate the process: the penetration of different organic solvents into soft drinks through the bottom of closed bottles was tested. The penetration occurred only when the closed bottles contained carbonated soft drinks (CSD), indicating that inner pressure is a necessary condition for the fissuring of the bottles. This paper discusses environmental stress cracking of polyethylene terephthalate (PET) bottles by organic solvents and migration of chemicals to CSD. Experiments were conducted to determine the conditions in which PET can be permeable to poisoning organic products. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) is one of the packaging materials that is widely used for packaging of soft drinks. PET may contain acetaldehyde which is a thermal degradation product, and hence acetaldehyde may migrate into the product in the package. In this study, the migration of acetaldehyde from PET bottles into soft drinks containing carbonic acid was determined by gas chromatography without headspace instrument. Carbonated beverage samples obtained from four different firms following the filling process were stored at 5, 20 and 40 °C for 6 months and analysed periodically at 0 day, 2, 4 and 6 months. As a result, it was seen that the acetaldehyde concentrations of all samples were quite different from each other and also related to the storage temperature, and an increase in storage time raised acetaldehyde concentrations in beverages. Especially, storages at 40 °C had very serious effect on acetaldehyde concentrations in the beverages. [ABSTRACT FROM AUTHOR]