Evolution of the volatile components of ewe raw milk La Serena cheese during ripening. Correlation with flavour characteristics

Abstract

La Serena cheese is a soft to semi-soft Spanish variety manufactured from Merino ewe raw milk coagulated with an extract of Cynara cardunculus. In the present work a purge and trap extraction procedure coupled to gas chromatography mass spectrometry was used to study the volatile fraction evolution during ripening of La Serena cheese. A total of 112 compounds were identified. Alcohols were quantitatively the main chemical family in the volatile fraction, increasing significantly during ripening. Ethanol, 1-propanol, 2-propenol, 2-propanol, 2-butanol, 2-pentanol and the branched chain 2-methyl-1-propanol and 3-methyl-1-butanol, were abundant at the end of ripening. Esters, especially ethyl esters of acetic, butanoic, hexanoic and octanoic acids and 3-methyl-1-butanol acetate, were found at high levels in the headspace of La Serena cheese. Concentrations of most esters increased dramatically during ripening, and, given their low perception thresholds, may be considered as key constituents of the aroma of this cheese variety. The principal component analysis of sensory attributes and volatile compounds extracted 3 functions. Linear aldehydes and alcohols, 2-alkanols, branched-chain alcohols, 2-methyl-ketones, alkanes, terpenes and esters other than ethyl esters correlated positively with function 1 (25.8% of the variance explained). Odour and aroma quality, along with the sensory attributes lactic, fruits-flowers, and clean cheese flavour, and the volatiles ethanol and ethyl esters, had a high correlation coefficient with function 2 (14.8% of the variance explained). 2-Butanone and the sensory attributes fishy and putrid had a negative correlation coefficient with this function. Odour and aroma intensity, along with the sensory attributes animal, pungent and fishy, and the volatile compounds branched chain aldehydes, n-alkanols, 2-butanol and esters, were positively correlated with function 3 (11.0% of the variance explained). Terpenes had a negative correlation coefficient with this function.