A large factory-scale application of selected autochthonous lactic acid bacteria for PDO Pecorino Siciliano cheese production

The main hypothesis of this study was that the autochthonous lactic acid bacteria (LAB) selected for theirdairy traits are able to stabilize the production of PDO (Protected Denomination of Origin) PecorinoSiciliano cheese, preserving its typicality. The experimental plan included the application of a multistrainlactic acid bacteria (LAB) culture, composed of starter (Lactococcus lactis subsp. lactis CAG4 andCAG37) and non starter (Enterococcus faecalis PSL71, Lactococcus garviae PSL67 and Streptococcus macedonicusPSL72) strains, during the traditional production of cheese at large scale level in six factorieslocated in different areas of Sicily. The cheese making processes were followed from milk to ripenedcheeses and the effects of the added LAB were evaluated on the microbiological, chemico-physical andsensorial characteristics of the final products. Results highlighted a high variability for all investigatedparameters and the dominance of LAB cocci in bulk milk samples. The experimental curds showed afaster pH drop than control curds and the levels of LAB estimated in 5-month ripened experimentalcheeses (7.59 and 7.27 Log CFU/g for rods and cocci, respectively) were higher than those of controlcheeses (7.02 and 6.61 Log CFU/g for rods and cocci, respectively). The comparison of the bacterial isolatesby randomly amplified polymorphic DNA (RAPD)-PCR evidenced the dominance of the addedstarter lactococci over native milk and vat LAB, while the added non starter LAB were found at almost thesame levels of the indigenous strains. The sensory evaluation showed that the mixed LAB culture did notinfluence the majority of the sensory attributes of the cheeses and that each factory produced cheeseswith unique characteristics. Finally, the multivariate statistical analysis based on all parameters evaluatedon the ripened cheeses showed the dissimilarities and the relationships among cheeses. Thus, the mainhypothesis of the work was accepted since the quality parameters of the final cheeses were stabilized,but all cheeses maintained their local typicality.