Sorption Behavior of an Aliphatic Series of Aldehydes in the Presence of Poly(ethylene terephthalate) Blends Containing Aldehyde Scavenging Agents

Abstract

The quality of many beverages and food products is compromised by the presence of low molecular weight aldehydes. Aldehydes are commonly formed during storage by the oxidation of lipids or are introduced as migrants from polymeric packaging material. The objective of this project was to evaluate the effectiveness of three aldehyde scavenging agents, blended into poly(ethylene terephthalate) (PET) films, in removing an aliphatic series of aldehydes from an acidified aqueous model solution (pH 3.6) during storage. Aldehyde concentration in solution was determined by an improved high performance liquid chromatography method involving the formation of aldehyde-hydrazine complexes by 2,4-dinitrophenylhydrazine. Storage of 25 μM mixtures of acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, and caproaldehyde in contact with PET films blended with 5% poly(m-xylylene adipamide) (nylon MXD6), D-sorbitol, or alpha-cyclodextrin reduced the concentration of each aldehyde in solution by 21 to 90% after 14 days of exposure. D-sorbitol and alpha-cyclodextrin aldehyde scavenging PET films were the most effective treatments for the reduction of aldehydes from solution showing similar average reductions for the five aldehyde species of 11.4 and 13.8 μM, respectively. PET films blended with nylon MXD6 were less effective in removing aldehydes from solution showing an average reduction of 8.4 μM for the five aldehyde species. However, nylon MXD6 proved to the most efficient aldehyde scavenging agent tested. D-sorbitol and alpha-cyclodextrin blends include 45 and 17 times more aldehyde scavenging sites then nylon MXD6 blends, but only showed 26 and 39% improvements in aldehyde scavenging ability when compared to nylon MXD6 blends. Aldehyde scavenging films demonstrated selective scalping preferring smaller molecular weight aldehydes, such as acetaldehyde, propionaldehyde, and butyraldehyde, more than larger aldehydes, valeraldehyde and caproaldehyde. Partition coefficients for smaller aldehydes were 3 to 6 times greater for aldehyde scavenging films then control film.