Serpa is a protected designation of origin (PDO) cheese produced with raw ewes' milk and coagulated with Cynara cardunculus. Legislation does not allow for milk pasteurization and starter culture inoculation. Although natural Serpa's rich microbiota allows for the development of a unique organoleptic profile, it also suggests high heterogeneity. This raises issues in the final sensory and safety properties, leading to several losses in the sector. A possible solution to overcoming these issues is the development of an autochthonous starter culture. In the present work, some Serpa cheese Lactic acid bacteria (LAB)-isolated microorganisms, previously selected based on their safety, technological and protective performance, were tested in laboratory-scale cheeses. Their acidification, proteolysis (protein and peptide profile, nitrogen fractions, free amino acids (FAA)), and volatiles generation (volatile fatty acids (VFA) and esters) potential was investigated. Significant differences were found in all parameters analyzed, showing a considerable strain effect. Successive statistical analyses were performed to compare cheese models and Serpa PDO cheese. The strains L. plantarum PL1 and PL2 and the PL1 and L. paracasei PC mix were selected as the most promising, resulting in a closer lipolytic and proteolytic profile of Serpa PDO cheese. In future work, these inocula will be produced at a pilot scale and tested at the cheese level to validate their application.
Keywords: Lactic acid bacteria; Serpa PDO cheese; autochthonous starter culture; cheese models; lipolysis; proteolysis.