The adoption of innovative processes, such as the automatic milking system (AMS), in the production of typical PDO cheeses, such as Parmigiano Reggiano, needs to be evaluated and tested, to verify its influence on milk quality and the typicality of the product. The present research was aimed to study the effect of the introduction of the AMS on the cheesemaking characteristics of the milk and the ripening process and the sensory properties of the Parmigiano Reggiano PDO cheese. Six cheesemaking trials were performed and, in each trial, two different separated pools of milk were submitted to the cheesemaking process in parallel, one from AMS and the other from a traditional milking parlor (TMP). AMS milk, in comparison with TMP one, showed higher content of lactose and calcium and lower contents of somatic cells, thermophilic lactic acid bacteria and chloride. Nevertheless, these changes were too small to influence the efficiency of the cheesemaking process and the cheese composition and its sensory profile. Moreover, cheeses made with AMS milk fully complied with the sensory characteristics of Parmigiano Reggiano cheese PDO, as defined by the PDO rules.

Brine soaking is one of the most important steps in the production of Parmigiano Reggiano cheese, since it determines the amount of salt in the final product. Reduction in salt in Parmigiano Reggiano cheese might be important for improving its nutritional profile, but it could affect the manufacturing processes by altering proteolysis and consequently the product quality. In this study, for the first time, salt reduction was explored at the industrial level on real cheese samples manufactured in a local dairy. In particular, 20 wheels were produced with conventional (18 days, 10 wheels) and shorter (12 days, 10 wheels) brining steps. In every group, wheels were studied at two different ripening times, 15 and 30 months. A shorter brining time resulted in an average 12% decrease in salt content. A full characterization of free amino acids and peptides was performed by LC-MS on all samples. Free amino acids and peptides, as expected, increased with ripening, due to proteolysis, with samples having low salt content showing a slightly faster increase when compared to standard ones, hinting to a slightly accelerated proteolytic process. Nonetheless, low-salt and conventional cheeses shared similar sensory profiles at both ripening times.

Natural whey starter (NWS) is an undefined and variable microbial community of starter lactic acid bacteria (SLAB), traditionally produced by back-slopping and used in the manufacture of several hard-cooked Italian cheeses, including Parmigiano Reggiano PDO. Despite its importance, the parameters influencing the microbial composition and technological performance of NWS remain poorly investigated, largely due to the lack of controlled studies that do not interfere with actual cheese production. Although the Parmigiano Reggiano PDO regulations strictly forbid the use of selected starters and require NWS to be obtained exclusively through spontaneous whey fermentation following curd extraction, we developed a freeze-dried prototypical natural starter culture (NSC) system that simulates, under laboratory conditions, the back-slopping process used in Parmigiano Reggiano dairies to ferment sweet whey into NWS. This system (referred to as NSC₀) effectively replicated fresh NWS and was successfully propagated through three consecutive rounds of laboratory-scale cheese-making. Using this validated system, we demonstrated that raw cow milk spiked with penicillin G at or below the maximum residue limits (MRL) negatively impacted NSC fermentative performance during the first round of caseification and significantly reduced microbial counts during the second round, suggesting a cumulative inhibitory effect of penicillin G, non-observable in a single back-slopping cycle. As SLAB declined, spoilage yeasts increased. qPCR analysis revealed that 2 and 4 ppb penicillin G impaired NWS biodiversity by inhibiting Lactobacillus delbrueckii and streptococci, whereas Lactobacillus helveticus remained unaffected. The validated NSC system developed in this study offers a robust platform for future investigations into the abiotic and biotic factors affecting NWS, advancing our ability to predict the behavior of undefined starter cultures under realistic cheese-making conditions.