Formation of Ketones from Fatty Acids by Spores of Penicillium roqueforti

Abstract

FROM time to time during the past decade attempts have been made in this laboratory to determine the mechanism by which the mould Penicillium roqueforti produces the flavouring and aromatic compounds characteristic of the blue-veined cheeses, Roquefort, Stilton, Gorgonzola and ‘Bleu’. These aromatic compounds are a family of ketones, each one produced from a specific fatty acid which is one carbon longer, the carboxyl carbon, than the ketone. Thus the mould converts caprylic (octanoic) acid to 2-heptanone, caproic (hexanoic) acid to 2-pentanone, and so on. The overall kinetics for the conversion of fatty acids to ketones by P. roqueforti was published in 1955¹; however, the individual steps in the conversion were not known. Until recently, the occurrence of the reaction under controlled conditions in the laboratory has been most erratic and unpredictable, not at all commensurate with the apparent reliability of the reaction in the manufacture of blue-veined cheese.