The Azeitão and Nisa PDO cheeses are protected designation of origin (PDO) Portuguese cheeses produced with raw ewe’s milk and Cardoon flower (Cynara Cardunculus L.) as a coagulant. Both cheeses are highly valued and easily recognized by their distinctive features. The quality and unique characteristics of these traditional cheeses should be maintained and protected, thus distinctive features for each type of cheese need to be searched, to be further used as fingerprints of their authenticity.
This work will explore the potential of fatty acids (FA) as markers of both PDO cheeses. For that, samples were obtained from 2016 to 2022 (n=7) from all the available certified traditional cheesemaking factories (Azeitão=5 and Nisa=2) manufacturing according to PDO specifications. Fatty acids were analysed by gas chromatography with flame ionization detection as their FA methyl ester derivatives. Data were analysed in SAS9.4 and MetaboAnalyst5.0 for statistical and multivariate analysis, respectively. The results showed that the 16:0, 18:1c9, 14:0 and 18:0 were the main FA detected in both types of cheeses, comprising together 62.9% of total FA. Comparing the FA composition between origins, only 9 FA varied (P<0.05), being the branched-chain FA (BCFA), i-15:0, a-15:0, i-16:0, i-17, and also the 16:1c7, 18:1t11 and 18:2c9t11 (CLA) higher in Nisa than in Azeitão, and the 18:2n-6 and 20:4n-6 were highest in Azeitão.
When exploring possible cheese biomarkers using multivariate analysis, it was possible to observe by orthogonal partial least squares discriminant analysis (OPLS-DA) that BCFA could be used to distinguish the Nisa cheeses from Azeitão. This work demonstrates the potential of FA to discriminate the PDO traditional cheeses according to their origin.
Financial support was provided by Fundação para a Ciência e a Tecnologia (FCT) through the research projects PTDC/OCE-ETA/1785/2020 (EMOTION), UIDB/ 00276/2020 and LA/P/0059/2020.