Plastic in the Ice Cream
During a production line quality assurance check, the discovery of thin sheets of plastic in their ice cream caused a prominent ice cream maker to shut down the production line.
Isolation and examination of the slightly deformed plastic sheets revealed that the plastic was mostly from the ice cream process itself. McCrone scientists obtained reference samples of ten plastic films from various stages throughout the production process for comparison to the unknown contaminant.
All ten reference samples were analyzed using FTIR and identified as polyethylene. Next, using polarized light microscopy (PLM), the thicknesses of the films were measured. This helped to narrow the search and eliminated some of the reference films as suspects.
The remaining reference films were then examined by PLM for polymer strain and texture. This narrowed the search to one reference film. The contaminant film and the final suspect reference film matched in thickness, strain, texture and IR spectra. By using a combination of light and infrared microscopy, the contaminant source from the production process was isolated and identified.