For producers, handlers, shippers, fresh cut processors, foodservice and retailers of perishable edible horticultural commodities there should be no residual question that prevention and redundant reductions microbial food safety are critical components of a comprehensive product management plan. The selection of a sanitizer depends on the type of equipment to be sanitized, the hardness of the water, the application equipment available, the effectiveness of the sanitizer under site conditions, and cost. Sanitizing compounds which contain phenols impart strong undesirable odors and flavors to foods and should not be used.
Chlorine-based sanitizers are the most commonly used sanitizers in food plants. They are available in solid, liquid, and gas injection forms, and they are effective against all bacteria. In diluted form, chlorine-based sanitizers are colorless, relatively nontoxic, and nonstaining. They are the easiest sanitizers to prepare and apply, and they are generally the most economical. Usually, no water rinse is required if chlorine solutions do not exceed 200 parts per million (ppm). (reference)
The following table highlights the main properties of chlorine sanitizers used in the food processing industry. (reference)
|Properties||Chlorine gas||Hypochlorite (sodium or calcium)||Chlorine dioxide|
|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.|
|Solution Corrosiveness||Slight to moderate||Slight to moderate||Very Corrosive at low pH|
|Corrosive off-gassing||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.|
|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).|
|Irritancy||Low||Low||Very irritating vapors|
|Vapors||None at correct pH||None at correct pH||Typical odor, yellow-green, 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|
|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|
|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|
Iodophors are a combination of iodine and a solubilizing agent that releases free iodine when diluted with water. Iodophors are fast-acting and effective against all bacteria. In diluted form, they are nonstaining, relatively nontoxic, nonirritating to skin, and stable. Iodophors are widely used in hand sanitizing solutions. They are most effective in acidic conditions, and have minimal activity at pH 7. No water rinse is required if iodophor solutions do not exceed 25 ppm. Iodophor concentrations can be easily measured by a test kit. The color of an iodophor hand-dip solution gives a visual check on concentration. Iodophor solutions may stain porous surfaces and some plastics. (reference)
Quaternary ammonium compounds (QAC), in diluted form, are odorless, colorless, and nontoxic. They are stable at high temperatures, over a wide pH range, and in the presence of organic materials. QAC's are effective against some bacteria, but are slow-acting against some common spoilage bacteria. No water rinse is required if QAC solutions do not exceed 200 ppm. However, QAC solutions may leave objectionable films on equipment and should be rinsed off with fresh cold water. Quaternary ammonium compounds may be combined with nonionic wetting agents in detergent-sanitizer formulations. QAC are not compatible with other common detergent compounds or chlorine sanitizers.
Acid-anionic surfactants are combinations of acid, usually phosphoric acid, with surface-active agents. They are effective only below pH 2.5. These sanitizers are effective against most bacteria, and are odorless, relatively nontoxic, stable, and noncorrosive to stainless steel. They are effective in removing and controlling milkstone and water hardness films.
Peracetic acid solutions contain a mixture of peracetic acid, acetic acid and hydrogen peroxide. These sanitizers are effective against all microorganisms, including bacterial spores. They are effective over a wide pH range and are applied in cool or warm water. Peracetic acid solutions have a pungent odor and should be used in a well ventilated area. Concentrated solutions are strong oxidizers and can be corrosive to the skin.