Scientists pinpoint the microbes essential to making traditional mozzarella

The use of mozzarella extends well beyond pizza toppings. Buffalo mozzarella from Campania is a distinctive Italian cheese that has been declared a delicacy and is protected by EU legislation for almost 30 years. What, though, makes this mozzarella so unique? The components are straightforward: fresh water and brine were used to process the water buffalo milk, rennet, and natural whey starter.

However, the natural whey starter has microorganisms that are essential for producing mozzarella. High-throughput 16S rRNA amplicon sequencing, which provides a thorough image of what microorganisms are present and in what proportions, was employed by Italian researchers to gain an understanding of how microbes produce mozzarella.

Dr. Alessia Levante of the University of Parma, the study's lead author, said, "This study fosters a deeper understanding of the craftsmanship behind this esteemed Italian cheese and sheds light on the intricate interactions of microorganisms throughout the manufacturing process."

Under the microscope, mozzarella

Buffalo mozzarella must be produced in accordance with a precise formula to be eligible for protected designation of origin (PDO) certification. Heat, rennet, and natural whey starter are added to heated raw or pasteurized water buffalo milk. With the help of this starter, the curd soon becomes acidified, reaching the proper pH and becoming elastic enough to be shaped.

The resulting curds are allowed to mature for around four hours until they reach the proper pH level, at which point they become elastic and may be stretched and shaped in boiling water. The curds are then brined and hardened under running water. This process, with a few minor modifications, distinguishes between the products of various dairy farms.

Levante and her team chose two dairies in Campania that produce mozzarella that is eligible for PDO status: one larger and using more modern technology, and one smaller and using more traditional processes. They did this to examine the role of bacteria and see if it differs between traditional dairies and more modern ones. They sampled the milk, natural whey starter, curds before stretching, brine, and mozzarella from the dairies.

While both farms produced PDO mozzarella di bufala Campana, there were slight differences in the cheese's microbiological makeup and possible organoleptic qualities due to factors including temperature and processing time, according to Levante.

Bacteria take action and order a pizza.

The concentration of 19 samples was sufficient for 16S rRNA amplicon gene sequencing. This method identifies the microorganism species present and the amounts they occur in by sequencing the DNA of a sample and amplifying certain sections of a highly variable gene.

The researchers discovered that although the more traditional dairy utilized thermized milk, which introduced more bacteria and species to the process, the more contemporary dairy used pasteurized milk. However, the brine samples were just as rich in species as the processed cheese samples. During the curd-making process, a few species emerge and take control.

Microorganisms from the Lactobacillus and Streptococcus genera dominated both samples. While the more contemporary dairy employed a natural whey starting dominated by Streptococcus, the more traditional dairy's starter had nearly equal amounts of both. Each genus had species that were unique to that dairy. After curdling, Lactobacillus rises and Streptococcus falls in both sets of samples, probably as a result of the removal of the heat stress brought on by the stretching procedure.

Additionally, the brine provides a source of microbial variety by introducing fresh bacteria to the cheese's outer layer when it comes into contact with it. Not all of the bacteria in the brine, nevertheless, transfer to the cheese. This could be the case either because they cannot survive on cheese or because they appear later in the cheese's shelf life, after the cheese samples were obtained. Despite the enormous variety of microbe species present in the milk and brine, it appears that the natural whey starter has the greatest impact on the microbial composition of mozzarella.

Levante stated, "We are preparing a larger experiment to explore more thoroughly the function of raw buffalo milk in defining the microbiota. The scope of this investigation was constrained to two dairies and a certain sample size. Future research seeks to include a greater number of producers and manufacturing days to give more thorough insights into the microbiological complexities of traditional food production.

Provided by Frontiers