Serpa PDO cheese: towards identification of chemical markers involved in organoleptic attributes

Serpa is a PDO cheese manufactured using raw ovine milk and extracts of C. cardunculus L. as rennet, without addition of starter cultures and followed by a minimum (but safe) ripening period. Both the processing technology and ingredients used result in a high microbial biodiversity that allows the development of a unique flavor. Variations in the manufacture process and distinct milk composition among producers result in a considerably heterogeneous cheese. The present study aimed at screening some groups of sensorial related compounds during two consecutive months of production, towards the identification of chemical markers involved in the specificity of Serpa cheese. The results suggested a high diversity and heterogenous chemical composition according to the producer and month. The free amino acids (FAAs) profile suggested the presence of almost all amino acids in the analyzed cheeses, being glutamic acid, alanine, leucine, valine and phenylalanine the most prevalent ones. Regarding the organic acid profile, lactic and acetic acids were the dominant groups. The volatile analysis suggested a high diversity and variability of volatile composition between cheeses, including several chemical groups, namely, ethyl esters, aldehydes and alcohols. The identification of sensorial chemical markers will be crucial to guide the selection and development of an autochthonous starter culture to improve Serpa’s quality and safety.