conductivity emulsification saponification wetting peptizing dispersion rinsability controlling mineral deposits Sequestration chelation

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1 ENVH 441 FOOD PROTECTION DETERGENTS AND SANITIZERS Cleaning and sanitizing must both occur for dishware to be safe. These are accomplished by use of a (1) detergent to clean utensil surfaces (remove the soil) and allow the (2) sanitizer to reduce microorganism numbers to below the point of health significance. Soil is unwanted material on an object, e.g., food residues on a plate, lipstick on a coffee cup, or a film of water hardness minerals on a glass (a combination of carbohydrates [sugars], proteins, fats and oils. General soils encountered in food service operations are countered by cleaning agents detergents which have been developed for food service use--that will be most effective in their removal. Detergents are also important for conditioning water so that water hardness chemicals are not left as a soil on tableware and kitchenware being cleaned. Soils in a food service establishment are usually a combination of: Water Alkali/Acid Soluble Soluble A. Carbohydrates (sugars) Yes Alkali (starches) B. Proteins No Alkali C. Fats and oils No Alkali (saponification) D. Minerals Slight Acid Water is the major solvent in cleaning kitchenware. DETERGENTS Cleaning agents (detergents) are a combination of chemicals designed to remove a specific soil or blend of soils taking into consideration: A. The surface being cleaned and its susceptibility to damage by the cleaning agent. B. The method of applying the cleaning agent: by hand or machine. The major chemical groups used in detergents are: A. alkalis (usually caustic in nature) B. complex phosphates C. organic compounds D. mineral acids 1

2 Detergents blended for machine washing operations generally contain highly caustic alkalis (caustic soda [NAOH] or soda ash (Ca[OH] 2 ) and phosphates (trisodium phosphate or sodium tripolyphosphate). They may contain 1% or 2% organic compounds, commonly a combination of a non-foaming wetting agent and a chelating agent with ph between 13 and 14. The detergent concentration in a wash solution is normally 0.25% to 0.30% ( ppm). Most dishwashing machines have automated detergent dispensers activated by a monitor continuously measuring wash water conductivity. Detergent is automatically added as needed to maintain the desired conductivity which directly corresponds to the detergent concentration present. Low causticity complex phosphates plus a wetting agent are the major chemicals in a detergent formulated for a hand washing operation. Other chemicals may be used to give the detergent color, viscosity and a pleasant odor. Detergents used in hand washing operations are usually a liquid formulation containing >50% water with ph <10. This blend of chemicals is much more expensive than the caustic alkalis and phosphates in detergents used in machine washing. When formulating a detergent, after considering the characteristics of the types of soils that will be encountered, chemicals are selected because of their specific cleaning properties. Cleaning actions include: emulsification and saponification to control fats and oils (wetting agents and alkalis); wetting to enhance penetration of water and other chemicals between the soil and the surface being cleaned and between soil particles; and peptizing and dispersion to reduce the size of soil particles or clumps of protein and carbohydrate soils (phosphates) so they will be suspended in the cleaning solution. Chemicals are also selected for their rinsability so they do not leave a chemical film on the surface being cleaned and rinsed with clean water. Preparing the water so that water hardness chemicals don't interfere with the cleaning operation is an important part of the cleaning operation. Thus, controlling mineral deposits from water hardness chemicals e.g. calcium salts, is also an important cleaning action. Sequestration or chelation is the preferred method for controlling or removing water hardness chemicals, and is the combining of the hardness ions so they cannot precipitate and leave a film on the materials being cleaned. Other properties considered in selecting chemicals used in a detergent are suds formation (or reduction), irritation to skin and corrosion of metals. The "Common Detergent Ingredients" table shows a few of the specific chemicals used in detergents and their relative cleaning properties. See page 7 of this handout. Wetting agents have had the greatest impact in detergent formulation. They have been the "miracle" chemicals in cleaning just as antibiotics were to controlling bacterial infections or DDT and subsequent insecticides to insect control. There are three major groups of wetting agents: anionic, cationic, and non-ionic. Anionic wetting agents are the cheapest, most heavily used and characterized as generally having high sudsforming properties. Cationic wetting agents have disinfecting and wetting properties 2

3 and are primarily used for disinfecting properties. Non-ionic wetting agents and amphoteric wetting agents are low- or non-sudsing and more expensive than anionic compounds. Wetting agents and chelating agents are the most expensive chemicals used in detergents, while complex phosphates are cheaper, and the basic alkalis are cheapest. The most common anionic wetting agents are the linear alkyl sulfonates (LAS) (anion) R-CH 2 -SO 3 - (lipophilic) Na + (cation) (hydrophilic) Quaternary ammonium compounds (quats) are a common group of cationic wetting agents and disinfectants R R + \ / N -- Cl - / \ R R Buying the proper detergent can be a problem. Detergent formulators and distributors market products most suitable for the geographical area after considering water hardness properties and the types of soils most commonly encountered in food service operations. The best test for selecting a detergent is to use a specific product for a period of time, e.g., a month or more, to see if it is achieving the required cleaning. Large organizations may do laboratory tests on the products they buy: testing for wetting, chelation, ph, and free alkali, causticity or acid. The bottom line is the visual test: does it look clean and feel clean? 1. The salt test is simple: wet a clean glass and then sprinkle it with table salt. The salt should stick to the film of water covering the glass surface. If there are drops of water on the glass to which the salt sticks, it suggests there is a grease film on the other glass surface areas; thus it is not clean. 2. The beer glass test (very popular with college students) is done by filling a glass with beer and seeing whether bubbles rise to the surface. A clean glass will show only the clear liquid within the glass, while a dirty glass will produce steady bubble streams arising from the soils adhering to the unclean glass sides. 3

4 SANITIZERS A. Definitions 1. Sanitizing--reducing the bacterial load to a level sufficiently low so no threat to health exists 2. Disinfecting--destroying all pathogens but not necessarily all microorganisms 3. Commercially sterile: destruction of all pathogens and sufficient spoilage microorganisms so that no microbial growth inside a container occurs 4. Sterilizing--destroying all viable microorganisms To sanitize or disinfect you must start with a clean (soil free) surface. B. To sanitize: 1. HEAT a. hot water--immersion 1. minimum temperature = 170 o F 2. minimum exposure time = 30 seconds b. hot water spray This method is preceded by a minimum 150 o F wash temperature 1. minimum spray temperature = 180 o F 2. minimum exposure time = 10 seconds c. Flowing steam--in enclosed chamber 1. achieve temperatures >170 o F for 15 minutes or >200 o F for 5 minutes d. Steam jet 1. exposure for > one minute e. Hot air 1. achieve temperature > 180 o F for 20 minutes 2. CHEMICAL 1. Free chlorine NaOCl sodium hypochlorite liquid Ca(OCl) 2 calcium hypochlorite powder a. Properties 1. Use concentration: ppm for 1 minute 2. Stability: poor, dissociates and breaks down upon exposure to light and organic compounds 3. Odor of chlorine or bleach 4

5 Free chlorine (continued) b. Field test 1. Starch-Iodide I - + Cl 2 I 2 + Cl - ; I 2 + starch = purple (colorless) Iodide and starch are colorless when mixed together, but in the presence of free chlorine, the iodide is converted to iodine and reacts with the starch to give a deep purple color. 2. Combined or Organic Chlorine a. Products 1) Dichloroisocyanurate 2) Dichlorotrimethyl hydantoin 3) Chloramine T b. Properties of combined or organic chlorine compounds 1) Use concentration: ppm for 1 minute 2) More stable than free chlorine but slower acting 3) Lacks the "chlorine" odor 3. Quaternary Ammonium Compounds "Quats" a. Products 1) There are a vast number of "quats" because the H + on the ammonium compound may be replaced by a number of organic radicals. Therefore: there is no single test for product concentration or an ideal ph or temperature for maximum efficiency. The FDA has identified a long list of effective products allowed for food service use. b. Properties 1) Use concentration: ppm for 1 minute 2) Stable 3) No odor 4) A film will gradually accumulate on glasses 5) May be selective for Gram+ organisms and therefore less effective on Gram organisms. 6) Not compatible with anionic compounds but unreactive with organic compounds 5

6 4. Iodophors a. Products 1) Iodine bound with organic wetting agents There are several different formulations of "tamed iodine." b. Properties 1) Use concentration: ppm for 1 minute 2) Reddish-rust color in the water at use concentrations 3) Volatile; stains walls above sinks if hot water used 3) Most effective at ~4.5 ph 4) Non-selective 5) Iodophor test kit available 5. Other chemicals There are a variety of "other" chemicals that have sanitizing or disinfecting properties but most are not acceptable for use on food contact surfaces, tableware, etc., e.g., chlorinated phenols. C. PHYSICAL 1. Ultraviolet light a. Used in an enclosed cabinet providing a 2-minute exposure of glasses to the radiation. b. Uncommon; most frequently in bars and taverns. D. DETERGENT-SANITIZERS 1. Non-ionic based detergent plus chlorine (powder form) A synergistic affect is achieved enhancing removal of protein soils and sanitizing too. Used in many food processing plants, e.g., fish processing plant clean-up. 2. Quats may also be formulated and used as described for iodophors. 3. Iodophors, when used at increased concentrations, will function as a cleaning agent and sanitizer simultaneously. A final sanitizing rinse is still required. 24 Detergents-Sanitizers Comprehensive HO 12/11/07 6