Evaluation of fat-derived aroma compounds in Blue cheese by dynamic headspace GC/olfactometry-MS

The aroma compounds in Blue cheese were studied with a dynamic heads pace-GC/olfactometry (GC/O-DH) technique and evaluated by both aroma extract dilution analysis (AEDA) and the Osme technique to identify and assign importance to aroma compounds. AEDA aroma dilution values were obtained by sequential reduction of sample size, and Osme values were obtained based on aroma intensity and duration. The most important compounds contributing to Blue cheese aroma were diacetyl, 2-methylpropanal, 3-methylbutanal, ethyl butanoate, ethyl hexanoate, methional, dimethyl trisulfide, 2-heptanone, and 2-nonanone. Compounds central to the characteristic Blue cheese aroma and typically derived from milkfat included 2-heptanone, 2-nonanone, butanoic acid, hexanoic acid, and ethyl esters. Since the methyl ketones contributed the characteristic Blue cheese aroma, a flavor concentrate enriched in methyl ketones to impart characteristic Blue cheese aroma was synthesized using Penicillium roqueforti spores in a model system. A fivefold enhancement in methyl ketone production was obtained by providing aerobic conditions. The addition of sucrose and serine, compounds known to affect mold spore metabolism, did not enhance methyl ketone production but caused generation of an uncharacteristic fruity, floral aroma.