Crosslinking Treatment of EVA Film To Improve Flavor Preservation

Surface cross-linking treatment of ethylene—vinyl acetate copolymer (EVA) film was performed by formalization in a moderate condition. This treatment led to a marked depression of flavor sorptions. Maximal sorption depression was observed for 18.8 mmol % formalized film, and the maximal depression ratio of solubility coefficient against the unformalized one was about 54% for decane. To elucidate this phenomenon, sorption depression ratios against molecular size were plotted. The sorption of flavors was linearly depressed with an increase in the molecular sizes of the compounds, and the plots for ethyl esters, aldehydes, and alcohols were on the same line (r = 0.842). According to the SEM analysis, which revealed the formation of cross-linkage in the formalized film, the depression effect may be attributed to a restriction of the chain mobility in amorphous regions.