Frying oil can go rancid due to many factors including overheating, prolonged use, and contamination from foods. There are many tests available to measure the degradation of cooking oils including total polar materials, pH, viscosity, fatty acid composition and others as described by the American Oil Chemists' Society. Several instruments are available to provide these results on a timely basis as well as dipstick assays which give qualitative results. Of these methods oil polarity is the best indicator of oil quality but has required expensive equipment and expertise to measure.
OBR has designed this kit to quickly measure the change in polarity of a cooking oil. It is based on the properties of a mercyanine dye that undergoes a significant color change related to the oil polarity. This assay is more accurate and less costly than other methods available.