In regions where clarified dairy fat (ghee) is a staple food, the potential for adulteration with palm oil (solid vegetable fat) is a continual concern. Analytical differentiation can be difficult.
In this study (open access) the authors experimentally compared and contrasted a range of analytical techniques that have been proposed for identifying palm oil mixed into ghee at levels down to 5 – 10% (generally considered the lower limit for economically motivated adulteration).
They concluded that both Butyro refractometer readings and iodine value analysis were not as efficient in detecting adulteration at lower level. Reichert-Meissl value analysis alone was not able to draw a conclusion regarding the purity of ghee. However, the Kirshner value analysis could be an effective parameter to detect adulteration of palm oil in ghee down to 5%. 2,2-Diphenyl-1-picrylhydrazy and ferric chloride-based chromogenic tests were very effective to detect the presence of palm oil in milk fat or ghee rapidly; thus, these tests could be used in field conditions. The use of triglyceride analysis (S-value) and plant sterol detection offered a comprehensive laboratory-based confirmation to detect palm oil adulteration in ghee at 5% levels.
