Review Use of ozone in food industries for reducing the environmental impact of cleaning and disinfection activities A. Pascual * , I. Llorca and A. Canut Parque Tecnolo´ gico de Valencia, Benjamin Franklin, 5-11, 46980 Paterna, Valencia, Spain (Tel.: D34961366090; fax: D34961318008; e-mail: apascual@ainia.es) Introduction The interest in ozone as an alternative to chlorine and other chemical disinfectants in cleaning and disinfection operations is based on its high biocidal efficacy, wide anti- microbial spectrum, absence of by-products that are detri- mental to health and the ability to generate it on demand, ‘in situ’, without needing to store it for later use. It also has the significant advantage of being an environ- mentally friendly technology that reduces the company’s environmental costs and facilitates their compliance with statutory obligations. This advantage is usually underestimated by food com- panies, but the new environmental legislation emerging in Europe, especially the IPPC Directive 96/61/EC, will drive a change in the food industry in the next years that will in- crease the interest in the use of ozone. It should be taken into account that cleaning and disinfection operations are responsible for the greatest environmental impacts (water and energy consumption, wastewater, etc.) in a number of food processing plants. The Spanish technological centre ainia is the leader of the OZONECIP project which has been recently funded by the EU LIFE Programme (LIFE 05 ENV/E/000251). This project will not only evaluate the use of ozone as a powerful disinfectant for machinery and equipment, and sanitisable surfaces in general, but also analyse the environ- mental advantages of ozone and its potential consideration as a Best Available Technology (BAT) for cleaning and dis- infection in food processing plants. Ozone as a disinfectant agent Effect of the medium on the bactericidal efficacy of ozone Ozone effectiveness against micro-organisms depends not only on the amount applied, but also on the residual ozone in the medium. Residual ozone is the concentration of ozone that can be detected in the medium after application to the target surface. Both the instability of ozone under certain conditions and the presence of ozone-consuming materials affect the level of residual ozone available in the medium. It is important, therefore, to distinguish between the concen- tration of applied ozone and residual ozone necessary for effective disinfection. It is advisable to monitor ozone availability during treatment. Pure water has the lowest ozone demand. Impurities react with and consume the applied ozone. Depending on the type of substance, the demand will be greater or less. For example, according to one study, the residual ozone in ozonated water containing 20 ppm of Bovine Serum Albumin (BSA) was sig- nificantly lower than in deionised water or water with 20 ppm of soluble starch. As a result, the biocidal efficacy of ozone was not affected by the starch but was significantly reduced by the BSA (Restaino, Frampton, Hemphill, & Palnikar, 1995). There is no consensus on the effect of temperature on the biocidal efficacy of ozone. A fall in the temperature of the aqueous medium increases ozone solubility and stability, augmenting its availability in the medium and, conse- quently, its efficacy. A rise in temperature, on the other hand, increases the proportion of micro-organisms de- stroyed by disinfectants. Consequently, the simultaneous contribution of these two factors (solubility/stability and reactivity) to ozone efficacy can vary with experimental conditions, making it difficult to predict the influence of temperature on a particular application. High relative humidity is required for micro-organisms to be inactivated by ozone gas. The optimum level is * Corresponding author. 0924-2244/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.tifs.2006.10.006 Trends in Food Science & Technology 18 (2007) S29eS35