GLOBAL – Mozzarella cheese-making process is dominated by Streptococcus and Lactobacillus species, DNA analysis by scientists reveals.

A team of researchers at the Department of Food and Drugs, University of Parma, Italy performed 16S rRNA amplicon gene sequencing on 19 intermediate samples of Mozzarella di Bufala Campana (MBC) production to evaluate their bacterial composition.

The research aimed to understand the dynamics of the microbial pool involved in various cheesemaking steps by comparing data from two dairies.

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

Levante and her team selected two dairies in Campania that produce mozzarella, which qualified for PDO status: one larger and using more modern technology, one smaller and using more traditional processes. 

They took samples of the dairy’s milk, natural whey starter, cheese curd before stretching, brine and mozzarella.

 This was done to analyze the role of bacteria and see if it changes with the type of technology used.

“While both dairies produced PDO Mozzarella di Bufala Campana (MBC), subtle variations, such as temperature and duration of processes, influenced the cheese’s microbial composition and potentially impacted organoleptic properties,” Levante said.

The team found that the pasteurized milk used by the more modern dairy added fewer microbes and species of microbes to the process than the thermalized milk used by the more traditional dairy. 

However, the brine samples were as rich in species as the processed cheese samples. During the curd process, a small number of species develop and take over.  

The natural whey starter from the more traditional dairy had a roughly equal abundance of both, while the more modern dairy used a natural whey starter dominated by Streptococcus.

After curdling, Lactobacillus increased and Streptococcus dropped in both sets of samples, possibly due to the removal of thermal stress caused by stretching.

Moreover, the species richness of samples from the dairy in which milk has been pasteurized was lower than that observed for the other, while similar trends were observed for the other indices.

Despite the large number of species of microbes available in the milk and the brine, the study pointed out that the natural whey starter most influences the microbial makeup of mozzarella.  

“We are planning a larger project to investigate more deeply the role of raw buffalo’s milk in defining the microbiota,” Levante noted.

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