3-Mercapto-2-butanone is a sulfur-containing flavor compound mainly found in meat and meat products.It is formed by the Maillard reaction between sugars and cysteine or thiamin, which are known precursors for meat-like flavorings. 3-Mercapto-2-butanone is a sulfur-containing flavor compound mainly found in meat and meat products.It is formed by the Maillard reaction between sugars and cysteine or thiamin, which are known precursors for meat-like flavorings.