Food production facilities which fill beverages in PET bottles
Acetaldehyde is formed during the production of polyethylene terephthalate (PET) and is sealed into the wall of the bottles, but it is possible for the acetaldehyde to later migrate out and into the product. While low concentrations of acetaldehyde, on the order of μg/l, can have a negative influence on the quality of the product, this does not pose a health risk for consumers. Acetaldehyde is a volatile compound with a boiling point of 21 °C and is characterized by an intensely sweet, fruity aroma which is described as green apple. The olfactory sensory threshold of acetaldehyde in water ranges from 7.9 and 120 μg/. Experienced sensory panel members can detect acetaldehyde at levels between 10 and 20 μg/l. For this reason, the Genossenschaft Deutscher Mineralbrunnen (GDB) in Germany suggests a maximum value of 10 μg/l, because there is no effect on the flavor of the product at concentrations below this level. Therefore, one assumes that no perceptible effect on quality at concentrations below this reference value will be apparent.
The migration rate for acetaldehyde is dependent on the initial concentration of the compound in the PET material, the temperature and duration of storage, as well as on the weight and geometry of the bottle. A greater surface area to volume ratio also results in a higher migration rate. The migration of acetaldehyde during the production of PET bottles can be minimized through the addition of a scavenger, such as anthranilic acid amide. However, this is often not utilized in the production of disposable bottles for economic reasons. CO2 content and exposure to light also impact acetaldehyde concentrations.
This method describes the carry-over of aromas from PET containers. Returnable PET bottles should have no influence on the aroma or flavor of the beverages they contain.
Food production facilities which fill beverages in PET bottles
An increasing number of products with unique aroma formulations or very intense flavors are now being packaged in returnable PET bottles. This places new demands on the manufacturers of PET bottles and beverage producers as well as filling and packaging facilities. These bottles require more complicated cleaning procedures due to their lower heat tolerance, which in turn increases the likelihood of transferring odoriferous substances from one product to another. This phenomenon is universally referred to as the “carry-over” effect.
One source for this effect is the misuse of refillable PET bottles by customers who utilize them for storing highly odoriferous substances or chemicals. However, this effect is not limited to substances from previously used bottles but may also be attributable to adsorptive substances used in the materials of the packaging itself (seals, etc.), to inadequate cleaning or to any existing dead space in tanks, aggregates or piping systems. All of these factors are potential sources for the carryover of undesirable aroma components. Above all, filling a container with a product containing a less pronounced aroma than that of the preceding one can result in carry-over.