Bacillus cereus hazard and control in industrial dairy processing environment

Bacillus cereus is one of the most important spoilage microorganisms in dairy environment and its growth may result in various dairy defects. Moreover, it is a great safety concern for dairy industry as it is associated with incidences of food poisoning by producing enterotoxin. Because of its outstanding ability to adhere to stainless steel surfaces of dairy plant and form biofilm, B. cereus can lead to serious hygiene problems and economic loss due to spoilage of dairy products and equipment impairment. Biofilms are more resistant to antimicrobials and cleaning regimes compared to planktonic cells, and this makes their elimination from dairy industry a big challenge. B. cereus biofilms may develop particularly in storage and piping systems that are partly filled during operation or where residual liquid has remained after a production cycle. These biofilms in pasteurizer and storage tanks can be a source of post-pasteurization recurrent contamination. Cleaning-in-place (CIP) regimes, commonly used in dairy industry, showed a varied effectiveness in eliminating B. cereus biofilms. Optimization of alkali-based CIP significantly increases B. cereus biofilm cell removal, as compared to the reference CIP usually used in dairy industry. Thus, optimization of the existing cleaning processes and development of novel and effective strategies as well are of utmost importance to the dairy industry, as these may lead to quality improvement of products and processes. This review discusses the characteristics, and spoilage and toxigenic potential of B. cereus in dairy industry, with an emphasis on biofilm development and emerging control strategies.