Migration studies and chemical characterization of short chain cyclic polyester oligomers from food packaging laminate adhesives

Laminates are extensively used for food packaging applications such as retort pouches and retort packaging, boil in the bag, microwavable packaging, military meals ready to eat (MRE’s), single serving dispensers, etc. Laminates are manufactured by bonding multiple layers of films together using adhesives, where each layer acts as a functional component and contributes to overall integrity of the package. Polyurethane adhesive, the most common choice of adhesive for flexible packaging, is the reaction product of polyurethane pre-polymer and/or diisocyanate with polyester. The polyester component reacts with isocyanate, forming urethane bonds and introduces soft chain segments into the final, cured polyurethane. During the formation of polyester, low molecular weight cyclic diesters and oligoesters are formed as unwanted byproducts. These low molecular weight species often migrate out of packaging into the contents of the package. Since these species are novel compounds, the safety and toxicological properties have not been investigated. Our research focused on studying the chemistry and migratory properties of these compounds. We conducted migration testing of laminates using USFDA recommended food simulants such as 10% Ethanol for aqueous and acid foods and 95% Ethanol for the fatty foods. Single side extraction cell assembly was used for the purpose of extraction which was conditioned at 100 °C for 30 min. In our research GC-MS analysis was used to determine chemical structures, gas chromatography retention time indices and the average migratory concentration levels of ten short chain cyclic diesters and oligoesters. The chemical structures were deduced by analyzing the characteristic fragmentation pattern. Also to investigate the predicted metabolic fate of short chain cyclic diesters and oligoesters after their ingestion and potential absorption into the bloodstream, they were treated with non-specific porcine esterase enzyme at 37 °C for 1 h. In our research it was also shown that the enzyme treatment metabolized the short chain cyclic diesters and oligoesters back into their original corresponding diol and dicarboxylic acid precursors.M.S.Includes bibliographical referencesby Aditi Shrikhand