Identification and partial characterization of lactic acid bacteria isolated from Provolone del Monaco P.D.O. cheese during manufacturing and ripening. Investigation of Biogenic Amines and Volatile Flavor compounds in aged Provolone del Monaco P.D.O. cheese.

Identification and characterization of Lactic Acid Bacteria (LAB) from Provolone del Monaco P.D.O. cheese has been carried out by the conventional microbiology followed by Pulse Field Gel Electrophoresis (PFGE) and 16S rDNA sequencing. The aim of this research was to acquire information about the different microbial groups involved in cheese making produced from raw milk. Lactobacilli dominated largely, especially casei/paracasei group, up to the end of cheeses ripening, together by Lb. delbrueckii. The dominant cocci-shaped LAB until one year of ripening were the S. macedonicus and S. lutetiensis/infantarius. Enterococci strains were also present and play a major role during manufacturing and aged cheese. Tyramine producing strains, belonging mostly to Enterococcus genus, were found by Decarboxylase Selective Medium (DSM). One strain of E. faecium tyramine positive was also enterocin A producing. Nevertheless, one strain of L. lactis was found to be Nisin A producing. Acidification capability test on selected isolates have shown Lb. delbrueckii, S. macedonicus, S. thermophilus, L. lactis and S. lutetiensis as fast acid producers. This study provided evidence that natural environments are rich in biodiversity and can be considered as proper sources of new strains and species within the LAB group. Provolone del Monaco cheeses were also analysed for their amount of biogenic amines and volatile flavor compounds using High Performance Liquid Chromatography (HPLC) and Thermal Desorption Gas Chromatography Mass Spectrometry (TD-GC/MS), respectively. All these cheeses belonged to the same batch production of the others subjected to microbiological analysis. Biogenic amines concentration was highest in sample which showed the defect of medium-sized eyes. While the other cheeses, with same typical sensorial characteristics of Provolone del Monaco P.D.O. cheese, had the lowest and similar biogenic amines levels. Ketones, esters, acids were volatile compounds associated to the analysed cheese samples. New information regarding the flavor profile of Provolone del Monaco P.D.O. cheese are provided. Moreover, sample with medium-sized eye was associated to a very high number of esters and was found to have a different profile of volatile flavor compounds than the other cheeses, which were associated mainly to ketones and acids