Odour-impact compounds of Gorgonzola cheese

Abstract

Volatile concentrates were obtained by vacuum distillation from both natural and creamy Gorgonzola cheese and isolated by continuous liquid–liquid extraction. Both were analysed by high resolution gas chromatography (HRGC), HRGC–mass spectrometry and HRGC–olfactometry. A total of 63 components were identified in the neutral extract of the natural type (21 esters, 13 ketones, 14 alcohols, 5 aldehydes, 1 sulphur compound, 7 aromatic compounds and 2 terpenes) and 52 in the creamy type (17 esters, 12 ketones, 10 alcohols, 5 aldehydes, 1 sulphur compound, 5 aromatic compounds and 2 terpenes). Ketones, whose major components were 2-nonanone and 2-heptanone, were the predominant constituents of the neutral fraction. By olfactometric analysis of the neutral extracts, 23 odour-impact compounds were found in the natural and 21 in the creamy Gorgonzola cheese. 1-Octen-3-ol, ethyl hexanoate, 2-nonanone, 2-heptanone, 2-heptanol, ethyl butanoate, 2-nonanol and 4-methylanisole were the key odorants of the natural cheese, whereas 2-heptanone, 2-heptanol, ethyl butanoate, 3-methyl thiopropanal and an unidentified constituent with a fruity odour were characteristic of the creamy Gorgonzola cheese. On the basis of high odour unity values, 2-nonanone, 1-octen-3-ol, 2-heptanol, ethyl hexanoate, methylanisole and 2-heptanone were the most important odorants of natural and creamy Gorgonzola cheese aroma.