Effects of the Cooling Temperature at the Farm on Milk Maturation and Cheesemaking Process in the Manufacture of Parmigiano Reggiano PDO Cheese.

Abstract

Simple SummaryCurrently, the official protocol of Parmigiano Reggiano, a hard, cooked Italian PDO cheese, prohibits cooling the milk at the farm below 18 °C. As Parmigiano is made from raw milk, the microbiological characteristics of the raw matter have a strong impact both on the cheesemaking process and cheese quality. A lower cooling temperature, i.e., 9 °C, could better keep under control the microbial growth rate, which affects both the total bacterial count and specific species that are detrimental for dairy products. In this research, the impact of keeping milk at the farm at 9 °C on milk quality and cheese characteristics was investigated. The outcomes of the study showed that while the microbiological aspects benefited from the lower temperature, the coagulation properties of milk tended to worsen and caused slightly higher losses of macroconstituents in the whey. Nevertheless, the cheesemaking process and cheese features were not substantially modified, suggesting that the improvement of the microbiological aspects largely offsets the worsening of coagulation properties. The results of this research represent a scientific contribution to get to a formal request for modification of the Parmigiano Reggiano regulation, which, once accepted, could improve the hygienic characteristics of milk and, possibly, the final quality of Parmigiano Reggiano cheese.Parmigiano Reggiano is a hard PDO cheese made from bovine raw milk, whose microbiological characteristics have important repercussions on cheese quality. According to the EU official production protocol, milk temperature at the farm must not drop below 18 °C. The present research aimed to study the effect of cooling milk at the farm at 9 °C on the characteristics of milk and on the cheesemaking process and losses during manufacture. Six cheesemaking trials were performed in two different dairies. In each of them, two cheesemakings were made in parallel: one with milk kept at 9 °C (TM9) and the other with milk kept at 20 °C (TM20). TM9 milk, in comparison with TM20, showed after the creaming process a significant reduction not only of total bacterial count but also of psychrotrophic and lipolytic bacteria. At the same time, TM9 milk showed a higher creaming capacity and, consequently, a lower fat content than TM20. TM9 vat milk had worst coagulation properties than TM20, which caused slightly higher loss of fat and curd fines into the whey. Nevertheless, these changes were too small to influence the efficiency of the cheesemaking process; conversely, maintaining milk at the farm at 9 °C led to a reduction of the number of spoilage bacteria.