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2003
Journal Article
Titel
Determination of the migration of acetaldehyde from PET bottles into non-carbonated and carbonated mineral water
Abstract
The market for PET bottles for mineral water packaging is still increasing. On packaging materials very exacting levels on neutrality of odour and taste are required. In view of PET bottles the migration of acetaldehyde from the bottle wall into the mineral water is of special interest, due to the fact that acetaldehyde is noticeable in low concentrations in mineral water. Aim of this study was to monitor the acetaldehyde migration at room temperature from various commercially available PET bottles into carbonated and non-carbonated mineral water. In addition the correlation between room temperature storage and a short-term test suitable for routine testing (e.g. 10 d at 40degreesC) should be established. Within the study the acetaldehyde concentration curves of eleven PET-bottles and mineral water combinations were determined at 23 degreesC. Seven bottle/mineral water combinations fit in the migration laws similar to other organic compounds occurring in packaging materials. All these test bottles are filled with carbonated mineral water. For six bottles the diffusion coefficient of acetaldehyde in PET at 23 degreesC can be calculated from the experimental results to be in the range of 1.6 to 6.7 10(-12) cm(2) s(-1). One sample has a significantly lower diffusion coefficient of 3.6 10(-13) cm(2) s(-1). The other investigated samples, which are in most cases non-carbonated mineral water samples, show lower acetaldehyde concentrations in mineral water as expected by migration theory. In these cases most probably the acetaldehyde concentration in mineral water is influenced by additional factors. The correlation between long-term migration (23 degreesC) and short-term test (10 d at 40degreesC) was found to be not very good. Therefore the results of the short-term tests give only an orientation about the migration behaviour of the investigated PET bottles in comparison to other bottle/mineral water combinations. On the other hand if the correlation is established using the same bottle/mineral water combination short-term tests are most probably appropriate for production control. In the case of refillable bottles pre-storage of empty PET bottles before filling has a positive influence on the concentration of acetaldehyde in mineral water.