ReviewProcessed cheese contamination by spore-forming bacteria: A review of sources, routes, fate during processing and control

•Processed cheese contamination by sporeforming bacteria (SB) is reviewed.•The fate of SB during processed cheese (PC) production is analysed.•Bacillus and Clostridium are the relevant genus of SB for PC shelf-life and safety.•Strategies to prevent spoilage or safety issues in PC caused by SB are discussed.•Formulation and temperature control are key to ensure PC shelf-life and safety.

BackgroundProcessed cheese is produced by blending natural cheese of different ages and degrees of maturity in the presence of emulsifying salts and other dairy and nondairy ingredients, followed by heating and continuous mixing to form a homogeneous product with an extended shelf life. However, due to the thermal processing applied and the extended shelf life, spore-forming bacteria may result in safety and stability issues.Scope and approachThe primary sources of contamination by spore-forming bacteria, routes of contamination and their fate throughout the processing and storage of processed cheese and analogues are reviewed. In addition, the main consequences of the survival and growth of these organisms in processed cheese are discussed. Lastly, aiming to ensure the quality and safety of processed cheese, strategies for controlling spore-forming bacteria from farm to processing and storage are highlighted.Key findings and conclusionsThe main bacterial genera found in processed cheese are Bacillus spp. and Clostridium spp., which is due to their wide presence in milk and the dairy farm environment as well as their abilities to form spores and withstand harsh processing conditions. Knowledge of the spore diversity in processed cheese and their responses to efforts used to increase the product's stability are critical for developing more stable formulations.

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