Changes of Volatile Compounds in PET Bottle during Storage

Abstract

Sample solution containing various volatile compounds was aseptically filled into polyethylene terephthalate (PET) bottles with a volume of 300ml. The loss of volatile compounds due to sorption into PET bottle and the chemical changes of volatile compounds during storage were investigated by comparing with glass- and flexible pouch-packaged samples. (1) The distribution ratios (quantity of a compound recovered from PET bottle/quantity from sample solution) of volatile compounds after storage for 2 months were less than 0.7, thus the flavor deterioration due to sorption was not significant. (2) The aliphatic aldehydes were oxidized to carboxylic acids by dissolved oxygen during storage. On the other hand, the cyclic aldehydes were not oxidized. (3) The ethyl alkanoates were hydrolyzed to result in the production of carboxylic acids in PET or glass bottle. However, in pouch lined with middle-density polyethylene film, since the ethyl alkanoates sorbed into the liner predominantly, the extent of the hydrolysis was much smaller. (4) The interconversions of terpene alcohols led to the productions of 2, 6, 6-trimethyl-2-vinyl tetrahydropyran, terpin hydrate and α-terpineol in any type of container. The flavor deterioration in PET bottle during storage was not due to sorption of volatile compounds, but due to chemical changes of volatile compounds.