REVIEW ARTICLE Hygienic Design and Microbial Control of Refrigeration and Air Conditioning Systems for Food Processing and Packaging Plants Antonio Lo ´pez-Go ´mez • Antonio M. Castan ˜ o-Villar • Alfredo Palop • Fulgencio Marı ´n-Iniesta Received: 15 August 2012 / Accepted: 29 October 2012 / Published online: 10 November 2012 Ó Springer Science+Business Media New York 2012 Abstract The critical control points of the refrigeration and air conditioning systems serving the food processing and packaging plants are analyzed from the hygienic viewpoint. They identified the problems of hygienic design of the various components of refrigeration systems and air conditioning installations, and several solutions are described. The lack of hygienic design of air conditioning and refrigeration systems, and their inadequate cleaning and disinfection procedures, can cause significant eco- nomic losses and epidemic diseases in people, employees, or visitors, or in the final food consumers. So, the present manuscript analyses: (1) the microbial control in refriger- ation systems, including the control of Legionella, and the limitations of using biocides embedded in plastic materials (for cooling tower filling and air ducts in air conditioning systems); (2) the hygienic design of evaporative coolers (evaporative condensers and cooling towers) as a new way for controlling Legionella contamination; and (3) the microbial contamination and hygienic design of air con- ditioning systems for food processing and packaging rooms, including the microbial control in the air by means of UV lamps, essential oil aerosolization, and filtration. The interest of the clean rooms and microbiologically controlled environments for food processing and packaging is explained through a case study of slicing and packaging of ready-to-eat meat products. Keywords Hygienic design  Microbial control  Refrigeration systems  Air conditioning systems  Food processing and packaging plants Introduction The air within food factories, as in offices, hotels, hospitals, and residential buildings, should have an adequate quality (in terms of temperature, humidity, particle and microor- ganism counts, and other contaminants as volatile organic compounds). This air has to be properly renewed with fresh air, to meet established requirements of comfort and con- venience and health of people who breathe that air [142]. In addition, it is also necessary to impose controls on air quality in food processing and packaging to reduce the possibility of contamination of foods with spoilage and pathogen microorganisms. In ultraclean and aseptic pro- cessing and packaging, the quality of the process air that comes into contact with food has to be specially controlled, because these technologies pursue a very low or negligible microorganism counting in the packaged product [112]. This achievement prevents or reduces the addition of pre- servatives mainly in aseptic packaging systems, getting higher-quality products, safer, healthier, and with a longer shelf life [79]. Therefore, the use of suitable air decon- tamination systems (as filtration or other systems) and recontamination control systems is necessary to maintain the air quality [42, 79]. Air filtration is a well-known technique, but not always well applied. The need for hygienic design of different parts of refrigerating systems (especially cooling towers A. Lo ´pez-Go ´mez (&)  A. M. Castan ˜o-Villar  A. Palop Food Engineering and Agricultural Equipment Department, Universidad Polite ´cnica de Cartagena, Paseo Alfonso XIII, 48, 30203 Cartagena, Spain e-mail: antonio.lopez@upct.es F. Marı ´n-Iniesta Department of Nutrition, Bromatology and Food Technology, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain e-mail: fmarin@um.es 123 Food Eng Rev (2013) 5:18–35 DOI 10.1007/s12393-012-9060-1