Use of ozone in production chain of high moisture Mozzarella cheese

- We explored the possibility to employ the ozone treatments in critical points of Mozzarella cheese processing.
- We investigate the use of ozone, as a gas or aqueous solution.
- The ozone cannot be applied for the recovery of the product if it already has high microbial load.
- The better applicability results on cooling water treatments.
- Ozone oxidant activity was ineffective in causing damage to lipids.

This work aimed to evaluate ozone effectiveness in reducing viable spoilage bacteria load throughout high moisture (HM) Mozzarella cheese-making process. At first, Mozzarella cheese samples were packaged with ozonated water (2 mg/L), stored at low temperature and monitored during shelf life. In a following phase cheese samples were put, before packaging, in direct contact with ozonated water at ozone concentrations of 2, 5 and 10 mg/L for 60 min. Then, gaseous ozone at concentrations of 10, 20 and 30 mg/m3 for different times was tested. In these experiments ozone was not effective in surface microbiological decontamination of cheeses. In all cases, there was no increase in the formation of primary and secondary lipid oxidation products.Finally, we treated only the cooling water, artificially contaminated with Pseudomonas spp. strains, obtaining a reduction of about four Log cfu/mL in the microbial load. HM Mozzarella cheeses cooled with pre-treated water were characterized by a low microbial load and an increased shelf life.We concluded that ozone can be successfully applied in Mozzarella cheese processing only to decontaminate water contaminated by potential spoilage bacteria before that it comes into contact with the product.Industrial relevanceHM Mozzarella cheese is a very popular fresh product. Microbiological contamination that occurs after the stretching step when HM Mozzarella cheese comes into contact with cooling water and preserving liquid heavily affects its shelf-life. For this reason, it was decided to investigate whether ozone applications can be extended to HM Mozzarella cheese-making process, as already occurs in other food industry sectors. This study demonstrates that water acting as carrier of spoilage microorganisms can be successfully treated with ozone in order to reduce microbial cheese contamination in each processing step after stretching and shaping.