Fouling of food process plant surfaces and the subsequent cleaning needed is a significant industrial problem, and as the cost of water and chemical disposal increases, the problem is becoming more significant. Current literature on water-based cleaning is reviewed here according to the classification of 3 types of cleaning problems. By doing this, it is hoped that new knowledge can be highlighted applicable to improving industrial cleaning. (i) For type 1 deposits (that can be cleaned with water alone)—Cleaning time appears related to Reynolds number and surface shear stress. An increase in Reynolds number seems to decrease cleaning time. Cleaning temperatures greater than 50 °C do not appear beneficial. (ii) For type 2 deposits (biofilms)—Removal behavior of biofilms seems to be dependent on the microbial aging time on the surface. Keeping a material hydrated on a surface enables easier removal of it with water. a. Water rinsing: Temperature and wall shear stress have varied effects on removal. b. Chemical rinsing: Flow and temperature were seen to have the biggest effect at the start of cleaning, but contact time was more important as cleaning progressed at a given sodium hydroxide solution flow and temperature. (iii) For type 3 deposits (that require a cleaning chemical)—For specifically, protein-based systems excessive chemical forms a deposit difficult to remove. Increasing wall shear stress and temperature was most beneficial to cleaning rather than concentration. The action of temperature can reduce the use of a chemical for type 2 and type 3 soils. The findings suggest that the right combination of flow characteristics at a given temperature and concentration is crucial to achieving fast cleaning in all cases. There are a number of cleaning monitoring methods at various stages of commercialization that may be capable of monitoring bulk cleaning and cleaning at the surface. To optimize cleaning will require integration of measurement methods into the cleaning process.
|Journal||Comprehensive Reviews in Food Science and Food Safety|
|Publication status||Published - Mar 2013|