Screening of indoles in cheese

 Indole and skatole (3-methylindole) are formed from tryptophan by microbial activity. Depending on their concentration, they may either contribute to an unpleasant odour, as described for pig meat, or alternatively to a positive aroma profile, as during ripening of cheese. In a screening study, the two indoles in various types of cheese were determined, by both HPLC and GC. It was found that the two compounds mainly occur in mould cheese, such as Camembert and are even more pronounced in blue-veined cheese. The concentrations in unripened cheese were up to 700 ng/g fat for indole and 50 ng/g fat for skatole. The formation of the two indoles increases when proteolysis during ripening provides more tryptophan. Skatole formation appears to be specifically favoured by a low pH and anaerobic conditions. Received: 14 May 1997