Comparison of the volatile composition and sensory characteristics of Spanish PDO cheeses manufactured from ewes' raw milk and animal rennet

Idiazabal, Manchego, Roncal and Zamorano varieties are the Spanish cheeses manufactured under Protected Denomination of Origin (PDO) from ewes' raw milk and coagulated with animal rennet. Two batches of each cheese variety were ripened for six months and the cheeses were compared for sensory characteristics and composition of volatile compounds. Seventy-six volatile compounds were identified by GC-MS analysis of headspaces of the cheeses. The volatile profile of the four PDO cheeses differed significantly. Acids were the most abundant volatile compounds in Idiazabal, Roncal, and Zamorano cheeses, whereas alcohols were the main volatile compounds in Manchego cheese due to the large percentage of 2-butanol. Aldehydes, ketones and esters were minor compounds in all the cheese varieties, whereas terpenes and unsaturated hydrocarbons were only found in Manchego cheese. The sensory profiles, of the four PDO cheeses also differed significantly. The highest scores for sharp, brine and rennet odours, and rancid and rennet flavours were assessed in Idiazabal and Zamorano cheeses, whereas milky and buttery odour scores were higher in Manchego, Roncal and Zamorano cheeses than in Idiazabal cheese. Principal component analysis was applied to sensory attributes and volatile composition of the cheeses. Differences in flavour and odour attributes were correlated with differences in the volatile compounds. Two principal components correlating sensory attributes and volatile compounds were defined as “strength factor” and “sweetness factor”. The “strength factor” distinguished among the four cheese varieties, except between Roncal and Manchego cheeses, and the “sweetness factor” distinguished the Zamorano cheese from the Idiazabal, Manchego and Roncal cheeses.