Influence of Menthol Absorption on the Mechanical Properties of PET Bottles

Interactions within a package system refer to the exchange of mass and energy inside the packaged food, the packaging material and the external environment. Absorption of flavours into packaging material causes the loss of aroma or changes in the mechanical properties of package. Therefore, it results in reduced perception of the product quality. In this research, the effect of menthol absorption by polyethylene terephthalate (PET) bottles on mechanical properties of the PET bottles was investigated through tensile test. The PET samples containing yogurt drinks with 100 ppm initial concentration of menthol were stored for about three months at 4ºC, 25ºC, and 45ºC and the mechanical properties (tensile strength, modulus of elasticity and elongation) of PET bottles were measured periodically during the storage time. A new technique, dispersive liquid-liquid microextraction (DLLME), was used before GC analysis for concentrating the acetone extraction solution containing menthol. The effect of menthol on mechanical properties of PET bottles was compared through tensile test results of the PET bottles containing yogurt drinks with 100 ppm menthol against PET bottles containing yogurt drink without initial concentration of menthol solution. Maximum effect of menthol on mechanical properties of PET bottles was observed on the samples stored at 45ºC that could be due to the high amount of absorbed menthol at higher storage temperatures. It was also found that tensile strength and modulus of elasticity of PET bottles decreased with the absorption of menthol, while the elongation increased.