400 Chilled foods 3. The prevention of redeposition of the dispersed soil back onto the cleansed surface 4. The wetting by the disinfection solution of residual microorganisms to facilitate reaction with cell membranes and/or penetration of the microbial cell to produce a biocidal or biostatic action. Dependent on whether the disinfectant contains a surfactant and the disinfectant practice chosen (i.e with or without rinsing), this may be followed by dispersion of the microorganisms from the surface of four major factors as described below. The combinations of these four factors vary for different cleaning systems and, generally, if the use of one energy source is restricted, this short-fall may be compensated for by utilising greater nputs from the others 1. mechanical or kinetic energy 2. chemical energy 3. temperature or thermal energy Mechanical or kinetic energy is used to remove soils physically and may include craping, manual brushing and automated scrubbing(physical abrasion)and pressure jet washing(fluid abrasion). Of all four factors, physical abrasion is regarded as the most efficient in terms of energy transfer(Offiler 1990), and the efficiency of fluid abrasion and the effect of impact pressure has been described by Anon.(1973)and Holah (1991). Mechanical energy has also been demonstrated to be the most efficient for biofilm removal (Blenkinsopp and Costerton 1991. Wirtanen and Mattila Sandholm 1993.1994 Mattila-Sandholm and Wirtanen 1992 and Gibson et al. 1999) e In cleaning, chemical energy is used to break down soils to render them sier to remove and to suspend them in solution to aid rinsability. At the time of writing, no cleaning chemical has been marketed with the benefit of aiding microorganism removal. In chemical disinfection. chemicals react with microorganisms remaining on surfaces after cleaning to reduce their viability The chemical effects of cleaning and disinfection increase with temperature in a linear relationship and approximately double for every 10oC rise. For fatty and oily soils, temperatures above their melting point are used, to break down and mulsify these deposits and so aid removal. The influence of detergency in cleaning and disinfection has been described by Dunsmore(1981), Shupe et al. (1982), Mabesa et al.(1982), Anderson et al.(1985) and Middlemiss et al. (1985). For cleaning processes using mechanical, chemical and thermal energies, generally the longer the time period employed, the more efficient he process. When extended time periods can be employed in sanitation programmes, e.g. soak-tank operations, other energy inputs can be reduced(e.g reduced detergent concentration, lower temperature or less mechanical brushing3. The prevention of redeposition of the dispersed soil back onto the cleansed surface. 4. The wetting by the disinfection solution of residual microorganisms to facilitate reaction with cell membranes and/or penetration of the microbial cell to produce a biocidal or biostatic action. Dependent on whether the disinfectant contains a surfactant and the disinfectant practice chosen (i.e. with or without rinsing), this may be followed by dispersion of the microorganisms from the surface. To undertake these four stages, sanitation programmes employ a combination of four major factors as described below. The combinations of these four factors vary for different cleaning systems and, generally, if the use of one energy source is restricted, this short-fall may be compensated for by utilising greater inputs from the others. 1. mechanical or kinetic energy 2. chemical energy 3. temperature or thermal energy 4. time. Mechanical or kinetic energy is used to remove soils physically and may include scraping, manual brushing and automated scrubbing (physical abrasion) and pressure jet washing (fluid abrasion). Of all four factors, physical abrasion is regarded as the most efficient in terms of energy transfer (Offiler 1990), and the efficiency of fluid abrasion and the effect of impact pressure has been described by Anon. (1973) and Holah (1991). Mechanical energy has also been demonstrated to be the most efficient for biofilm removal (Blenkinsopp and Costerton 1991, Wirtanen and Mattila Sandholm 1993, 1994, Mattila-Sandholm and Wirtanen 1992 and Gibson et al. 1999). In cleaning, chemical energy is used to break down soils to render them easier to remove and to suspend them in solution to aid rinsability. At the time of writing, no cleaning chemical has been marketed with the benefit of aiding microorganism removal. In chemical disinfection, chemicals react with microorganisms remaining on surfaces after cleaning to reduce their viability. The chemical effects of cleaning and disinfection increase with temperature in a linear relationship and approximately double for every 10ºC rise. For fatty and oily soils, temperatures above their melting point are used, to break down and emulsify these deposits and so aid removal. The influence of detergency in cleaning and disinfection has been described by Dunsmore (1981), Shupe et al. (1982), Mabesa et al. (1982), Anderson et al. (1985) and Middlemiss et al. (1985). For cleaning processes using mechanical, chemical and thermal energies, generally the longer the time period employed, the more efficient the process. When extended time periods can be employed in sanitation programmes, e.g. soak-tank operations, other energy inputs can be reduced (e.g. reduced detergent concentration, lower temperature or less mechanical brushing). 400 Chilled foods