A rapid and sensitive method to determine potassium permanganate in meat

In some countries, potassium permanganate is illegally added to meat to improve the colour and mask the smell of spoiled meat. In this study, we developed a method for rapidly detecting and quantifying potassium permanganate in beef, horse, lamb and pork meats. First, the surface of meat was treated with 0.2% ethanolic benzidine. In meat containing potassium permanganate, the spots treated with ethanolic benzidine developed a dark green colour within 1–2 s, turning rapidly to black. The changes in colour were similar in potassium permanganate-containing meat of different types (beef, horse, lamb, pork), suggesting that the proposed method can be applied to determine the presence of potassium permanganate irrespective of animal species. We also prepared filter paper strips impregnated with 0.2% ethanolic benzidine, which developed a dark blue-green colour when applied to meat treated with potassium permanganate. The intensity of colour developed was directly related to the concentration of potassium permanganate used in the meat. Analysis of the same samples by spectrophotometer at 450 nm confirmed the results. Using the paper strip method, we were able to non-invasively analyse 37,000 retail meat samples from cattle, horses, lambs and pigs for their content of potassium permanganate. We believe that this method has considerable potential for use by food safety regulatory bodies and consumers at the point of sale.