Test Methods for Evaluating Grease and Mineral Oil Barriers

Several standard or material specific methods for grease barrier testing are being used. Results are expressed either as the time in which a test liquid has penetrated through a packaging material or as the amount of liquid which has penetrated through the material during a certain time period. However, such tests are not accurate, and there was a need for a new and more quantitative test method. A new test method developed by integrating two previous standard methods will be presented. Dyed oil or grease is placed on the food contact side of the sample under a specific weight. The reverse side is then scanned after pre-selected time intervals. This method combines visual data with a numerical result obtained by image analyses. Likewise, there are several methods for testing mineral oil hydrocarbon (MOH) barrier of packaging materials. Such mineral oil residues in food have raised concern as potential genotoxic carcinogens during the recent years, especially in Europe. These contaminants may originate from printing ink residues from recycled paperboard, certain additives, processing aids, and lubricants. A test method for MOH barrier will be presented in which the mineral oils are introduced to the test system in the gas phase. The amount of MOH diffused through a packaging material and absorbed into a food simulant is determined by gas chromatography. Focus was on compounds of relevant molecular weight, and using equipment and materials which are commercially available.