Pseudomonas fluorescens and Escherichia coli in Fresh Mozzarella Cheese: Effect of Cellobiose Oxidase on Microbiological Stability during Refrigerated Shelf Life

Abstract

Background: Mozzarella cheese possesses a high moisture content (50–60%) and a relatively high pH (around 5.5) and is therefore considered a perishable food product characterized by high quality deterioration and the potential risk of microbial contamination. Moreover, it can be spoiled by Pseudomonas spp. and coliform bacteria, which may be involved in different negative phenomena, such as proteolysis, discolorations, pigmentation, and off-flavors. To prevent these, different methods were investigated. In this context, the present study aims to assess the antimicrobial effect of cellobiose oxidase on Pseudomonas fluorescens (5026) and Escherichia coli (k88, k99) in mozzarella cheese during refrigerated shelf life. Methods: microbiological challenge tests were designed by contaminating the mozzarella covering liquid containing different cellobiose oxidase concentrations with P. fluorescens (5026) and E. coli (k88, k99). The behavior of these microorganisms and the variation of hydrogen peroxide concentrations were then tested under refrigerated conditions for 20 days to simulate the mozzarella cheese shelf life. Results and Conclusions: The data obtained demonstrated the effect of cellobiose oxidase on microbial growth. In particular, E. coli (k88, k99) was inhibited over the entire shelf life, while P. fluorescens (5026) was only partially affected after a few days of refrigerated storage.

Identification and Genetic Analysis of Pseudomonas fluorescence in Milk and Milk Products in Mosul City

“…Various preservation methods, such as the direct addition of the preservative to the food product composition or the packaging material, have been suggested to prevent the growth of spoilage microorganisms [43]. Variations in geographical locations and techniques for isolation participate as other factors affecting the level of contamination of milk and cheese with P.flouresence whereas the development of molecular methods [44]. The risk associated with a lack of clearly defined and regulated sanitization measures is demonstrated by the pseudomonas fast environmental proliferation as biofilm communities [45].…”