Thorough cleaning is essential before using a sanitizer. Sanitizers are less effective when food particles or dirt are present on equipment surfaces. Use only approved sanitizers in food processing plants. Approved sanitizers are listed in "List of proprietary substances and nonfood compounds authorized for use under USDA inspection and grading programs" (USDA, 1985). Request technical advice from a reputable sanitizer manufacturer, if you have questions on the best sanitizer to use.
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). Chlorine concentrations can be easily measured by a test kit. Chlorine solutions prepared from chlorine gas, hypochlorites, and chloramines are not compatible with quaternary ammonium compound sanitizers.
Chlorine Gas. Chlorine gas is a highly volatile compressed gas which forms hypochlorous acid (HOCl) when injected into water. It may make the pH (acidity/alkalinity) of water slightly lower (more acidic).
Hypochlorites. Sodium hypochlorite and calcium hypochlorite are formed by treating alkalis with chlorine gas. In water, they form hypochlorous acid and sodium or calcium salts. These salts can raise the pH of the water (more alkaline) and reduce the killing action of the chlorine. Hypochlorites are unstable; they lose chlorine during storage. Under controlled conditions, the germicidal action of hypochlorites equals that of chlorine gas.
Chloramines. Chloramines are formed by a reaction of chlorine with ammoniacal nitrogen in water. In solution, they slowly form hypochlorous acid and organic salts. Chloramines are more stable and less corrosive than hypochlorites, and they have a longer lasting germicidal action. Chloramines require a long contact time to be effective sanitizing agents.
The rate at which gaseous chlorine, hypochlorites, and chloramines kill bacteria is directly related to the amount of free chlorine (hypochlorous acid) in the water. In general, killing rates decrease as the pH becomes higher (more alkaline). Very acidic chlorinated water is corrosive to equipment. Very alkaline chlorinated water is also corrosive and has a reduced killing ability. A pH range of 6.0 to 7.5 is recommended for chlorine sanitizing solutions.
Organic matter will react with hypochlorous acid, leaving less free chlorine. Since it is the free chlorine that kills bacteria, large amounts of organic matter will reduce the germicidal activity of a chlorine solution.
The killing rate of chlorinated water increases with temperature, but the increased killing rate is counteracted by increased corrosiveness and vaporization (loss of chlorine). Apply chlorine-based sanitizers in cold water.
Chlorine dioxide (ClO2) is formed by reacting chlorine gas (Cl2) or hydrochloric acid (HCl) with sodium chlorite (NaClO2). In water, chlorine dioxide is the active sanitizing compound. It differs from hypochlorous acid in several significant ways.
Chlorine dioxide is uniformly active across a wide pH range, while the germicidal activity of hypochlorous acid varies with the pH of the solution. Hypochlorous acid becomes ineffective above pH 8.5, but chlorine dioxide retains some sanitizing power up to pH 10.0. Chlorine dioxide is a stronger oxidizer than other chlorine sanitizers and it is less likely to form chlorinated organic compounds. Chlorine dioxide is desirable whenever the organic load of the water is high. In addition, chlorine dioxide removes iron, manganese, odors, flavors, and colors from the water. Concentrations of chlorine dioxide can be easily measured by a test kit.
Chlorine dioxide is more expensive than chlorine gas or hypochlorites. It is highly reactive and cannot be manufactured and shipped in bulk; an on-site generating system is required. Chlorine dioxide decahydrate may be commercially prepared, but must be refrigerated because it decomposes at room temperature and can explode under certain conditions.
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.
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.
Most sanitizers are unstable, highly reactive compounds and must be handled safely. Sanitation crews should wear protective equipment and clothing including a hard hat, face shield or goggles, an apron or protective coat and pants, rubber boots, and gloves. Safety information on specific products is available from product labels, product technical sheets, and product material safety data sheets (MSDS).
Specific sanitizer safety problems include:
References
Bradley, R.L. and Bohner, H.F. 1992. Properties of chemical sanitizers. UW Dairy Pipeline, Wisconsin Center for Dairy Research. Madison, WI.
Forwalter, J. 1980. 1980 Selection guide: Cleaning and sanitizing compounds. Food Processing, Putman Publishing Co., Chicago, IL.
Haverland, H. 1978. Cleaning and sanitizing operations. In "Sanitation notebook for the seafood industry," Ed. Flick, G.J., Kassem, C.L., Huang, F., Ward, D.R., Thompson, M.J. and Fletcher, C., p. II-85. VPI-SG-78-05. Virginia Polytechnic Institute and State University, Blacksburg, VA.
Katsuyama, A.M. (ed.). 1980. Principles of food processing sanitation. The Food Processors Institute, Washington, DC.
Lentsch, S.E. 1978. Sanitizers for an effective cleaning program. In "Sanitation notebook for the seafood industry," Ed. Flick, G.J., Kassem, C.L., Huang, F., Ward, D.R., Thompson, M.J. and Fletcher, C., p. II-77. VPI-SG-78-05. Virginia Polytechnic Institute and State University, Blacksburg, VA.
USDA. 1985. List of proprietary substances and nonfood compounds authorized for use under USDA inspection and grading programs. Miscellaneous Publication No. 1419, U.S. Department of Agriculture, Washington, D.C.
York, G.K. and DeJong P. 1980. Detergents and sanitizers. University of California Cooperative Extension, Davis, CA.
Robert J. Price, Ph.D., Extension Specialist, Seafood Products Food Science & Technology, University of California, Davis, California 95616-8598
| Sanitizer Properties | Chlorine Gas | Hypochlorites: potassium, sodium or calcium hypochlorite | Chloramines: di-, tri-chloroisocyanurate | Chlorine Dioxide |
|---|---|---|---|---|
| Germicidal: | ||||
| Activity | High | High | High | High, better than chlorine |
| Specificity | Generally effective, even spores, viruses; reference sanitizer | Generally effective, even spores, viruses; reference sanitizer | Generally effective, similar to sodium hypochlorite | Generally effective against all bacteria, viruses, yeast, algai, mold |
| Speed | fastest | fastest | not as fast as hypochlorite | fast-acting |
| Sanitizer Properties | Chlorine Gas | Hypochlorites: potassium, sodium or calcium hypochlorite | Chloramines: di-, tri-chloroisocyanurate | Chlorine Dioxide |
|---|---|---|---|---|
| Form: | compressed gas | concentrated hypochlorite solution or powder | Powder | Precursors, or sodium chlorate and hypochlorite solutions |
| Stability | Good | Good as powder, fair as liquid | Good | Good |
| Toxicity | Yes | Yes | Yes | Yes |
| Irratancy | Yes | Yes | Yes | Yes |
| Sanitizer Properties | Chlorine Gas | Hypochlorites: potassium, sodium or calcium hypochlorite | Chloramines: di-, tri-chloroisocyanurate | Chlorine Dioxide |
|---|---|---|---|---|
| Dilution: | ||||
| Measurement | Easy, idometry, test its available | Easy, idometry, test its available | Easy, idometry, test its available | Difficult, titrations, interference |
| Stability | Good | Good | Good, lasts longer than hypochlorite | Moderate, decays to chloride |
| Toxicity | Low | Low | Low | Moderate |
| Irritancy | Low | Low | Low | Very irritating vapors, even at 17ppm |
| Vapors | None at correct pH | None at correct pH | None at correct pH | Typical odor, yellow-green, dangerous |
| Color | None | None | None | Yellow-green or red-brown |
| pH Range | Most active at pH of 6-7.5 | 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 | Cold water, maximum temp. 115°F | Cold water, maximum temp. 115°F | Cold water, maximum temp. 115°F | Use at low temp. To avoid vaporization |
| Conc. | 25 to 200 ppm | 25 to 200 ppm | 25 to 200 ppm | .25 to 5 ppm |
| Sanitizer Properties | Chlorine Gas | Hypochlorites: potassium, sodium or calcium hypochlorite | Chloramines: di-, tri-chloroisocyanurate | Chlorine Dioxide |
|---|---|---|---|---|
| Formation | No | No | No | No |
| Penetration | Poor | Poor | Poor | Poor |
| Sanitizer Properties | Chlorine Gas | Hypochlorites: potassium, sodium or calcium hypochlorite | Chloramines: di-, tri-chloroisocyanurate | Chlorine Dioxide |
|---|---|---|---|---|
| Effectiveness: | ||||
| Hard Water | Activity decreases in very hard water (>500 ppm) | 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 | Reacts to from chloramines | Little influence, even at high organic load |
| Sanitizer Properties | Chlorine Gas | Hypochlorites: potassium, sodium or calcium hypochlorite | Chloramines: di-, tri-chloroisocyanurate | Chlorine Dioxide |
|---|---|---|---|---|
| Corrosion: | ||||
| Solution | Slight to moderate | Slight to moderate | Low | Very Corrosive at low pH |
| Other | Very corrosive below pH 6 | Very corrosive below pH 6 | Very corrosive below pH 6 | Vapor space corrosion with high temp. |
| Sanitizer Properties | Chlorine Gas | Hypochlorites: potassium, sodium or calcium hypochlorite | Chloramines: di-, tri-chloroisocyanurate | Chlorine Dioxide |
|---|---|---|---|---|
| Used For: | All food contact surfaces, CIP | All food contact surfaces, CIP | Good sanitizer for all stainless utensils, food contact surfaces | High organic load situations: poultry, fruit, ultrafiltraion, water treatment. |
| Advantages: | Best sanitizer for clean stainless food contact surfaces; lower price than hypochlorites,organic chlorine. | Excellent sanitizer for clean stainless food contact surfaces; lower price than organic chlorine | Fast, effective; excellent for all stainless steel surfaces | Not affected by organic matter; effective against all types of organisms |
| Disadvantages: | Requires tight pH and concentration control; highly corrosive, particularly to stainless steel, when improperly used; produces corrosive gas above 115°F | Requires tight pH and concentration control; highly corrosive, particularly to stainless steel, when improperly used; produces corrosive gas above 115°F | May be corrosive if not properly used; produces corrosive gas above 115°F | Complex preparation; corrosive in acid solution; very difficult to handle unless preparation is automated |
| Sanitizer Properties | Iodine Compounds: iodophor, 12-30% iodine stabilized in surfactant and acid | Quaternary Ammonium Compounds: QUATS, QAC, benzalkonium chloride, N-alkyl dimethybenzyl ammonium chloride (ADBAC) | Acid Anionic: organic acids (formic, acetic, propionic) and anionic surfactant | Peracetic Acid Solutions: peracetic acid, acetic acid and hydrogen peroxide |
|---|---|---|---|---|
| Germicidal: | ||||
| Activity | Less effective than chlorine | Varied, poor | Good | High |
| Specificity | Good against yeasts, viruses, bacteria, algae, molds | Good against molds, ineffective with some gram-negative bacteria | Good, broad spectrum, vegetative cells | Good, particularly psychrotrophs and spores |
| Speed | Not as fast as hypochlorite | Moderate | Good at proper pH | Fast |
| Sanitizer Properties | Iodine Compounds: iodophor, 12-30% iodine stabilized in surfactant and acid | Quaternary Ammonium Compounds: QUATS, QAC, benzalkonium chloride, N-alkyl dimethybenzyl ammonium chloride (ADBAC) | Acid Anionic: organic acids (formic, acetic, propionic) and anionic surfactant | Peracetic Acid Solutions: peracetic acid, acetic acid and hydrogen peroxide |
|---|---|---|---|---|
| Form: | Solution of iodine, stabliized in surface active agent and acid. | Concentrated solution | Solution of concentrated acid and surfactant | Stablilized solution of about 25% H2O2 in acetic acid. |
| Stability | Good at room temp., avoid >120°F | Good | Good | Good |
| Toxicity | Yes, some toxic surface-active agent | Yes | relatively low | Yes |
| Irritancy | Yes | Yes, moderate | Yes | Yes, pungent smell, potent and possibly hazardous oxidizer on skin |
| Sanitizer Properties | Iodine Compounds: iodophor, 12-30% iodine stabilized in surfactant and acid | Quaternary Ammonium Compounds: QUATS, QAC, benzalkonium chloride, N-alkyl dimethybenzyl ammonium chloride (ADBAC) | Acid Anionic: organic acids (formic, acetic, propionic) and anionic surfactant | Peracetic Acid Solutions: peracetic acid, acetic acid and hydrogen peroxide |
|---|---|---|---|---|
| Dilution: | ||||
| Preparation | Easy | Easy | Easy | Easy |
| Measurements | Easy, iodometry, test kits available | Test kit | Good, pH is measured | Easy, titration of oxides |
| Stability | Stable at room temp. and below | Excellent | Excellent, even at high temperature | Good |
| Toxicity | Some wetting agents may be toxid | None | low | low |
| Irritancy | None, used for hand wash | None | Low | Irritating to nose |
| Vapors | Iodine odor, vaporizes above 120°F | None | None | Pungent |
| Color | Red-brown, used to judge concentration | None | None | None |
| pH Range | Effective at low pH, 4 or lower | Effective over broad pH range | pH 1.9-2.5 for best activity | Effective over broad pH range |
| Temperature | Maximim temp. 120°F | Broad range | Cool to Warm | |
| Conc. | 25 ppm | 200 ppm | 400 ppm | 0.20 to 0.35% |
| Sanitizer Properties | Iodine Compounds: iodophor, 12-30% iodine stabilized in surfactant and acid | Quaternary Ammonium Compounds: QUATS, QAC, benzalkonium chloride, N-alkyl dimethybenzyl ammonium chloride (ADBAC) | Acid Anionic: organic acids (formic, acetic, propionic) and anionic surfactant | Peracetic Acid Solutions: peracetic acid, acetic acid and hydrogen peroxide |
|---|---|---|---|---|
| Films: | ||||
| Formation | Slight, loses activity | Yes | Yes | Yes |
| Penetration | Good, depends on weeting agent | Very good, penetrates porous surfaces | Good, depends on wetting agent | Good |
| Sanitizer Properties | Iodine Compounds: iodophor, 12-30% iodine stabilized in surfactant and acid | Quaternary Ammonium Compounds: QUATS, QAC, benzalkonium chloride, N-alkyl dimethybenzyl ammonium chloride (ADBAC) | Acid Anionic: organic acids (formic, acetic, propionic) and anionic surfactant | Peracetic Acid Solutions: peracetic acid, acetic acid and hydrogen peroxide |
|---|---|---|---|---|
| Effectiveness: | ||||
| Hard Water | Activity decreases in water of high alkalinity (>500 ppm) | Inactivated in hard water | Slower, more sanitizer needed in hard water | Limited effect |
| Organic Matter | Somewhat more stable than chlorine | inactivate QUATS | Reacts with milkstone, low reactivity with organic matter | |
| Sanitizer Properties | Iodine Compounds: iodophor, 12-30% iodine stabilized in surfactant and acid | Quaternary Ammonium Compounds: QUATS, QAC, benzalkonium chloride, N-alkyl dimethybenzyl ammonium chloride (ADBAC) | Acid Anionic: organic acids (formic, acetic, propionic) and anionic surfactant | Peracetic Acid Solutions: peracetic acid, acetic acid and hydrogen peroxide |
|---|---|---|---|---|
| Corrosion: | ||||
| Solution | Low | None | Possible, uncommon | safe 304, 316 stainless and aluminum |
| Vapor Space | Possible, through vapor condensation | None | None | None |
| Other | Pitting with low pH, high-chloride water | None | Corrosion with high-chloride water | Do not use above 0.4% |
| Sanitizer Properties | Iodine Compounds: iodophor, 12-30% iodine stabilized in surfactant and acid | Quaternary Ammonium Compounds: QUATS, QAC, benzalkonium chloride, N-alkyl dimethybenzyl ammonium chloride (ADBAC) | Acid Anionic: organic acids (formic, acetic, propionic) and anionic surfactant | Peracetic Acid Solutions: peracetic acid, acetic acid and hydrogen peroxide |
|---|---|---|---|---|
| Used For: | Aluminum, hand sanitizer, plastics, tile, all food contact surfaces | Non-food contact, porous materials, walls, drains | Combined acid cleaning, rinsing sanitizing; ideal in CIP systems | All food-contact surfaces |
| Advantages: | Good for farm uses; effective, eliminates milkstone | Useful on non-food contact surfaces; lasting film; detergent properties; good environmental sanitizer at 1,000 ppm; persistent | Eliminates milkstone; best for hard water and CIP | Use on all food-contact surfaces |
| Disadvantages | Discolors; off-flavors at even low concentrations; less effective than chlorine | Ineffective against some organisms at 200 ppm (no rinse dilution), i.e., S. aureus, P. fluorescens, and E. coli; slows cheese cultures at 20 ppm; irritating to user if fogged | Less active against spores; may leach Cu from dairy metal; amount of foam varies with wetting agent | Odor in confined areas; store concentrated in plastic only because of metal reaction |