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Table 1. Strength of chlorine sanitizing wash recommended for various types of produce. Type of Produce Apples, pears, squash, cucumbers Leafy greens, peaches, peppers, tomatoes, asparagus, broccoli, carrots Melons, citrus, root crops Berries (strawberries, blueberries, blackberries, raspberries, etc) Recommended PPM Chlorine 65 PPM 130 PPM Bleach/gallon of water 1 1 tsp/gal 2 tsp/gal 400 PPM2 No washing 2 tblsp/gal 1 Bleach/gallon of water based on using household bleasch containing no fragrances or thickeners with a base concentration of 5.25% sodium hypochlorite. 2 Sanitizing wash should be followed by a potable water rinse. Table 2. Common Types of Sanitizers and Their Characteristics Sanitizer Uses Recommended Contact Concentrations Time Required Advantages Disadvantages Chlorine Based Produce wash water, equipment, facilities Hands, facilities, food contact surfaces & equipment Facilities, food contactsurfaces & equipment <200 ppm without rinsing <2,000 ppm with potable water rinse 1 to 5 minutes at 200 ppm *Inexpensive *Available * Wide range of effectiveness * Corrosive * Irritating fumes * Rapid loss of effectiveness <200 ppm without rinsing *200-500 ppm with potable water rinse > 1 minute *Non-corrosive *Relatively nonirritating * Good residual activity/stability * Less effective than others for control of E coli *12.5- 25 ppm without rinsing >25 ppm with potable water rinse > 1 minute * Effective at; - Low conc - Wide pH range - Hard water -8 Non-irritating * Good Penetration * Prevents biofilm formation * Good residual * Expensive * May stain * Not a cleaner Quaternary Ammonia “Quats” Iodophors “Iodinebased” Table 3. Efficacy of Various Chloride Sanitizers COMMON DISINFECTANT PROPERTIES CHLORINE GAS SODIUM OR CALCIUM HYPOCHLORITE CHLORINE DIOXIDE Disinfection Action High High High, better than chlorine Specificity Generally effective, including, viruses; reference sanitizer. Limited practical effect on parasitic spores (i.e. Crytosporidium). Oxidizer and metabolic poison. Generally effective, including viruses; reference sanitizer. Limited practical effect on parasitic spores (i.e. Crytosporidium). Oxidizer and metabolic poison. Generally effective. Recognized for biofilm penetration. Oxidizer. Speed fastest fastest fast-acting Form Compressed gas. On-site injection. Concentrated hypochlorite solution or powder On-site generation from precursors, or sodium chlorate and hypochlorite solutions. Some stabilized forms released on acidification. Stability Good Good as powder, fair as liquid Good Preparation Easy Easy Complex equipment or procedure Measurement Easy. Functional relation to redox potential (ORP). Easy. Functional relation to redox potential (ORP). More difficult. Moderately functional relation to redox potential (ORP). Stability Good Good Moderate Irritancy Low Low Very irritating vapors Vapors None at correct pH None at correct pH Typical odor, yellowgreen, dangerous pH impact Most active at pH of 6-7.5 Most active at pH of 6-7.5 Effective at broad pH, best at 8.5 Temperature For produce, generally cold water, but heated water up to 52oC in use For produce, generally cold water, but heated water up to 52oC in use Use at low temp to minimize vaporization. Some use of gaseous forms on produce. Conc. 25 to 200 ppm 25 to 200 ppm, 20,000 ppm limited approval for sprout seed disinfection 3 to 5 ppm Penetration Poor Poor Poor Hard Water Activity decreases in very hard water(>500 ppm) Activity decreases in very hard water(>500 ppm) No effect Organic Matter Reacts to from chloramines Reacts to from chloramines Little influence, even at high organic load Solution Corrosiveness Slight to moderate Slight to moderate Very Corrosive at low pH Corrosive offgassing Possible, through condensation Possible, through condensation Slight corrosion Other Very corrosive below pH 6 Very corrosive below pH 6 Vapor space corrosion with high temp. Best use Food contact surfaces, water disinfection, smooth produce surfaces Food contact surfaces, water disinfection, smooth produce surfaces High organic load situations, smooth or complex produce surfaces, flume water disinfection Disadvantages: Requires tight pH and concentration control; highly corrosive, when improperly used; produces corrosive gas above 46oC. Requires tight pH and concentration control; highly corrosive, when improperly used; produces corrosive gas above 46oC. Complex preparation; corrosive in acid solution; very difficult to handle unless preparation is automated