Changes in proteolysis and volatile fraction during ripening of Darfiyeh, a Lebanese artisanal raw goat's milk cheese

Abstract

In order to contribute for the preservation of the Lebanese dairy heritage, the aim of this study was to characterize Darfiyeh cheese, a traditional variety made from raw goats milk and ripened in goat's skin. This research effort focused on following the changes in the physicochemical parameters of Darfiyeh throughout its ripening, with specific reference to the cheese-making procedure and ripening conditions. Three independent batches of Darfiyeh production, were processed at small scale cheese farming in Northern Lebanese mountains and were analysed after 20, 40 and 60 days of ripening. Compositional parameters such as moisture, fat in dry matter and chloride content were performed. Proteolysis was followed by determining soluble nitrogen at pH 4.6 and in 12% trichloroacetic acid. The results showed that Darfiyeh is a semi-hard goat cheese that undergoes a moderate proteolysis during ripening. Acidity index and fatty acid (FA) profile were also performed. The average acidity index of fat values increases continuously up to 60 days of ripening. The FA profile was similar to that reported for other goat cheeses in the literature. Short- and long-chain FAs groups were the variables that most contributed to sample differentiation, unexpectedly through their un-uniform behaviour. Solid-phase microextraction (SPME) was applied to study the volatile compounds in Darfiyeh. 16 volatile compounds (2 aldehydes, 8 alcohols, and 6 ketones) were identified. Our findings may be of possible concern for the dairy industry in imitating the peculiarities of artisanal cheeses made from raw milk.