Volatile compounds of Croatian cheese in a lamb skin sack prepared from a mixture of goat's and cow's milk

Volatile aroma compounds are one of the main parameters in consumer choice and acceptance of cheese. The traditional way of making cheese, still preserved in Croatia, is the anaerobic ripening of curds in a lamb or goat sack. Cheeses produced in such a way have a specific aroma. The objective of this study was to determine the volatile compounds of Croatian cheese in a lamb skin sack prepared from a mixture of goat's and cow's milk and relate them with the aroma of this traditional cheese. The cheese extracts were obtained by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) and analysed by gas chromatography-mass spectrometry (GCMS). HS-SPME was performed at different temperatures (40, 50 and 60°C) using 2 fibres, divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibre and carboxen/ polydimethylsiloxane (CAR/PDMS) fibre. Increasing the extraction temperature resulted in higher sorption of fatty acids on both fibres. A total of 28 volatile compounds were identified in the cheese samples including 13 acids, 10 esters, 2 alcohols, 2 hydrocarbons and 1 ketone. Results revealed that fatty acids were the predominant group of volatile compounds in all samples. In samples obtained by HS-SPME, the most abundant were hexanoic, octanoic, butanoic, acetic and decanoic acid while (Z)-octadec-9-enoic, hexadecanoic, decanoic and tetradecanoic acid were the most abundant in the sample obtained by USE.