N.Y. Comp. Codes R. & Regs. tit. 1, Appendices, app 6
SANITIZATION
(cf. Part 3)
I. Methods of Sanitization
CHEMICAL
Certain chemical compounds are effective for the sanitization of utensils, containers, and equipment. The bactericidal activity of such compounds is influenced by temperature, hydrogen-ion concentration (pH), and, in some instances, by interfering substances in the water in which they are used.
The activity of chemical sanitizers may also be adversely affected by ingredients in washing compounds and organic matter carried over from the wash solution. Consequently, a rinse between washing and bactericidal treatment is important in maintaining the strength of solutions. Similarly, deposits of milk solids on utensil surfaces interfere with bactericidal activity, and chemical sanitizers cannot be relied upon unless the surfaces to be treated are clean.
Temperature, pH and exposure time also influence the corrosive action of the chemical bactericides and sanitizers on materials used for product-contact surfaces of equipment, containers, utensils, and pipelines. Minimum treatment consistent with sanitizing requirements will aid in preserving the sanitary finish of surfaces.
Hypochlorites.--Either calcium or sodium hypochlorite (stock powder or solution) is a satisfactory chemical sanitizer.
An exposure period of at least 1 minute to at least 50 ppm available chlorine should be maintained when the temperature is at least 75° F (24° C). Under these conditions, an exposure of 1 minute is considered adequate for all hypochlorites, including the slower, more alkaline compounds. Lower solution temperatures result in slower action; for each 18° F (10° C) drop in temperature, approximately double the exposure time is needed to achieve equivalent bactericidal action with the same strength of solution. It is also possible to compensate for lower temperatures by increasing the concentration of the bactericide.
Hypochlorite bactericides cannot be relied upon in the presence of large amounts of milk or other organic matter. A sharp decline in the available chlorine content of a sanitizer following circulation through processing equipment is usually regarded as evidence of inadequate cleaning and should be promptly investigated. When a spray is used in lieu of circulation or immersion, the above specified concentrations of available chlorine should be doubled.
Organic Chlorine Compounds.--The bactericidal action of chloramine T, the chlorinated hydantoins, the chlorinated isocyanurates and other organic forms of chlorine are significantly affected by pH.A
Note.--Trichloromelamine, an organic chlorine, may not be used to sanitize product containers and equipment.
For example, with chloramine T solutions, the maximum pH which can be tolerated and still provide satisfactory results at 200 ppm available chlorine is 7.2; at 100 ppm concentration it is 6.8; and at the 50 ppm level, 6.4. Thus, satisfactory results with formulations of the chemical based on the above equivalent germicidal activities cannot be expected with products which ionize in solutions to give pH values higher than 6.4. The practical value of chloramine T is limited to situations where long exposure periods are practicable, or where a low pH can be provided.
Chlorinated hydantoin formulations giving solutions of pH 7.0 and below should be satisfactory.
Satisfactory results in chlorinated isocyanuric acid solutions of pH values up to 9.5 can be expected.
The marked differences found in bactericidal activity of organic chlorine compounds over the pH range illustrate the necessity of establishing the conditions of use, including concentration, from experimental data.
Quaternary Ammonium Compounds.--Continued field use has established that certain quaternary ammonium compounds are effective bactericides for the treatment of utensils, containers, and equipment. The bactericidal effectiveness of specific quaternary ammonium compounds varies and is influenced by the chemical nature and concentration of active agent, temperature, pH, exposure time, and by interfering substances present in natural waters. It has been established that the interference of natural waters is due principally to bicarbonates, sulphates, and chlorides of calcium and magnesium. B Ferrous bicarbonate may also interfere to a lesser degree but its interference is minimized when the iron is oxidized. Any treatment which tends to precipitate, remove or inactivate calcium or magnesium reduces this interference as do increased pH and temperature.
Products containing n-alkyl (C 8-C 18 dimethyl benzyl ammonium chlorides, n-alkyl (C14-C18) dimethyl benzyl ammonium chlorides, alkyl dimethyl dichlorobenzyl ammonium chlorides and n-alkyl (C 12-C 18) dimethyl ethylbenzyl ammonium chlorides are effective in waters ranging from 550 to 1,100 ppm hardness without added sequestering agents. Other quaternary products such as diisobutyl phenoxy ethoxy ethyl dimethyl benzyl ammonium chloride and methyl dodecyl benzyl trimethyl ammonium chloride-methyl dodecyl xylene bis (trimethyl ammonium chloride) require compounding with sufficient sodium tripolyphosphate to raise their hard water ceiling levels to a minimum of 500 ppm hardness at use concentrations. By proper formulation, however, levels up to 1,200 ppm are possible. The above products have been found to be bactericidally effective when used:
1. At concentrations of 200 ppm or more;
2. At pH levels of 5.0 or higher;
3. At temperatures of 75° F (24° C) or higher; and
4. For a 30-second exposure period.
The above-named compounds without sequestering agents are also effective within certain limits of water hardness under the conditions of use enumerated above however, the level of hardness at which bactericidal activity is reduced below that necessary for effective treatment, varies among the four named compounds and may be influenced by other ingredients in a proprietary formulation. Accordingly, the limiting hardness should be established for the use of each quaternary ammonium product. Unless stated on the label,c the regulatory agency should request such information from the manufacturer.
Bacteriological data should be used to establish the usefulness of the above named quaternary ammonium compounds and sequestering agents and any others:
1. At temperatures less than 75° F (24° C); or
2. At a pH below 6.0; or
3. When combined with a compatible sequestering agent in waters above 500 ppm of hardness; or
4. Without, or with less than, the specified amount of sequestering agent. Suggested methods and criteria are given in a following subsection on Other Chemical Sanitizers.
Iodine Compounds.--Another type of halogen sanitizer that has been found effective consists of a combination of iodine with certain nonionic substances. Although iodine is only slightly soluble in water and is volatile; in combination with nonionic wetting agents as an iodophor, it is readily soluble in water and is less volatile. When diluted for use, iodophors have a low pH which enhances their germicidal qualities. Increasing the temperatures of a sanitizing solution containing iodophors also increases its effectiveness, but above 120° F (49° C) iodine volatilizes, resulting in a decrease in solution strength.
In solution, iodophors are yellow or amber in color and the intensity is proportional to the concentration of iodine. Concentrations of 12.5 ppm when used as a bactericide only and 25 ppm when used as a detergent-sanitizer have been found effective. The concentration of iodine can be determined by titration with sodium thiosulfate, and color tests for field use are available. Since the bactericidal properties of different proprietary formulations may vary because of differences in ingredients and pH, their effectiveness may be evaluated by the use of a bacteriological test procedure such as that proposed by Weber and Black D or the Chambers modification thereofE.
Detergent-Sanitizers. --Bactericides are sometimes combined with detergents in proprietary formulations for the cleaning and bactericidal treatment of containers, utensils, and equipment in a single operation. Such use has been reported to be effective under certain conditions for the cleaning and bactericidal treatment of dairy farm equipment, milk tank trucks, and similar equipment.
The limitations of detergent-sanitizer combinations should be understood if they are to be used effectively. Certain sanitizers and detergents cannot be combined in solution without impairment of bactericidal properties, cleaning properties, or both. In addition, the activity of a detergent-sanitizer is likely to be reduced more rapidly by the presence of milk solids and other organic matter in a combined operation than when bactericidal treatment is a separate process which follows cleaning.
These factors tend to point up the fact that the usefulness of a detergent- sanitizer for the combined cleaning and sanitizing treatment of product-contact surfaces is dependent on both the composition of the product and its intended use.
"Single-step" operations are actually considered most dependable when the amount of detergent-sanitizer can be carefully proportioned to the exact needs of the equipment involved, assuring effective cleaning and sanitizing, while minimizing the chance of residual chemical deposits on the equipment treated.
Further, and of equal importance to the above, is the need for the protection between treatment and use of all product-contact surfaces so sanitized. The application of untreated rinse water; the handling of equipment, as in the assembly of milking machines on farms or piping systems in milk plants; and the exposure of treated surfaces to airborne contamination through extended storage periods all tend to downgrade the values suggested for detergent-sanitizers.
These precautions are suggested where detergent-sanitizers are used:
1. Equipment to be treated should be thoroughly prerinsed.
2. Solutions should be prepared and used according to manufacturer's directions.
3. Treated equipment which is exposed to any of the hazards of contamination described above should be resanitized prior to use.
Other Chemical Sanitizers. --Bactericides other than those described in the previous sections are also available which are suitable for use on milk equipment. Compounds containing bromine and iodine have been found to be effective for bactericidal treatment. In addition, other types of chemical agents are being compounded into proprietary formulations for the bactericidal treatment of milk equipment; however, their bactericidal effectiveness varies with specific formulations. Such compounds should be safe, and the recommended conditions of usage should provide bactericidal treatment at least equal to that given by 50 ppm of chlorine as hypochlorite at pH 10.0, at a temperature of 75° F (24° C), and with an exposure period of 1 minute.F
Sanitizing solutions should be prepared at a concentration such as to provide bactericidal effectiveness (for circulation and immersion applications) equivalent to that of hypochlorite solutions at a concentration of 50 ppm of available chlorine.
The bactericidal efficiency of chemical compounds may be evaluated without direct comparison to chlorine. Suitable data may be obtained by use of a bacteriological test procedure such as that proposed by Weber and BlackD, or the Chambers modification thereof E. These tests provide better comparative data at an endpoint somewhat less than total kill of the test cultures. Therefore, the test time is less than 1-minute exposure period prescribed in Section 7 of this Ordinance. Bactericides which, in recommended concentration, produce a 99.999-percent kill of 75-125 million E. coli ATTC 11229 and of 75- 125 million M. pyogenes var. aureus ATCC 6538, within 30, seconds at 70°-75° F (22°-24° C), should be considered satisfactory. Swab tests of treated equipment do not furnish sufficient data for this purpose. Valid data can be obtained only when stock cultures and suspensions of the test organisms are prepared in a manner that uniformly maintains their normal level of resistance to germicidal action. Periodic checks to determine the consistency of test results, using a well known chemical such as phenol, are helpful in this regard. The importance of adhering strictly to the composition of mediums and manner of transplanting cultures specified in the test procedures cannot be overemphasized.
II. Sanitization of Assembled Equipment
STEAM
When steam is used, each group of assembled piping shall be treated separately by inserting the steam hose into the inlet and maintaining steam flow from the outlet for at least 5 minutes after the temperature of the drainage at the outlet has reached 200° F (94° C). (The period of exposure required here is longer than that required for individual cans, etc., because of the heat lost through the large surface exposed to the air.) Covers must be in place during treatment.
HOT WATER
Hot water may be used by pumping it through the inlet if the temperature at outlet end of the assembly is maintained to at least 170° F (77° C) for at least 5 minutes.
CHEMICALS
When chlorine or another chemical solution is used, the solution appearing at the outlet end shall show in excess of the minimum required strength. The chemical solution shall be pumped through the entire equipment for at least 1 minute. Unions and other connectors should be slightly loosened to permit treatment of gaskets and threads, except on lines cleaned-in-place. Surfaces which are not reached by the chemical solution shall be treated with steam as previously described, spray application of chemical solution or by other acceptable means. Header ends and connecting piping of cabinet coolers should not be overlooked, since condensation from them may enter the collecting trough. Chemical sanitizing solutions should be prepared fresh for each use.
TREATMENT OF EQUIPMENT
The treatment of milk cans, coolers, packaging machines, other equipment, and all parts thereof, requires special consideration. Large equipment may be treated by thorough swabbing with a bactericidal solution of adequate strength, allowing the solution film to remain at least one minute.
III. Sanitizer Strength and Water Hardness Tests
TESTS FOR CHLORINE CONCENTRATION
Three types of field tests are satisfactory for chlorine concentration determinations:
Starch-Iodide Method (iodometric).--This test makes use of the fact that chlorine displaces iodine from potassium iodide in an acid solution (low pH). See general discussions in the latest edition of Standard Methods for the Examination of Water and Wastewater, published by the American Public Health Association. Iodine, plus starch, forms a blue color which is removed (decolorized) by the addition of standard sodium thiosulphate. The quantity of standard sodium thiosulphate required to remove the starch-iodine color is a measure of the chlorine present.
Field kits are available which give satisfactorily accurate readings of available chlorine. In some of these kits, the starch and potassium iodide are mixed in dry form for convenience of handling. Some use a liquid acid while others employ, for convenience, a crystalline one, such as sulphamic acid. The sodium thiosulphate is unstable unless a preservative is added. Some test kits make use of a preserved standardized sodium thiosulphate so that one drop of solution is equivalent to 10 ppm of available chlorine. Test kits should be checked periodically against standardized chlorine solutions.
Orthotolidine Colorimetric Comparison.--This test is based on the fact that orthotolidine, which is colorless, forms an orange-brown colored compound when added to chlorine. The depth of color is a measure of the amount of chlorine present. A concentration of 20 ppm of available chlorine causes a precipitate. Consequently, solutions which are concentrated must be diluted, usually at least 1:10 with chlorine-free water. Specific directions and color standards for comparison are included in test kits. Such test kits are available commercially. Color develops more slowly with alkaline hypochlorites than with the less alkaline compounds. Chloramines are considerably slower than alkaline hypochlorites in color formation, usually requiring at least 5 minutes.
Indicator Paper Test.--The indicator paper test is widely used in situations where a high degree of accuracy is not required. It is a convenient, rapid, and generally a useful screening device. Ranges of chlorine concentration are indicated by the color developed on the test paper (usually starch-iodide impregnated) as it is immersed in the solution being tested.
Indicator papers are subject to rather rapid deterioration, especially if they are stored in a damp or chemically adverse environment. Their accuracy also suffers when they are handled excessively, especially if the operator's hands have been exposed to detergents, sanitizers, or other chemically active substances.
TESTS FOR QUATERNARY AMMONIUM COMPOUNDS
Test kits are available which give satisfactory accurate readings within the range of recommended quaternary ammonium compound concentrations.
In some, the reagents are tableted for convenience of handling; others make use of test papers. Where the sanitizing solution is essentially clear and free from organic contamination, the above chemical test procedures will measure the amount of bactericidally active quaternary ammonium compound present during or after use. Where organic contamination is apparent, as evidenced by cloudiness in the sanitizing solution, the test sample should be heated to boiling for at least 5 minutes, and the supernatant liquid made up to volume with water and then removed for testing by pipetting or decantation in order to differentiate between the total amount of quarternary ammonium compound present and the amount bactericidally active G. If there is reason to verify the concentration of the stock quaternary ammonium compound solution from which the standardized solutions are made, a laboratory procedure such as that of Furlong and Elliker may be used.H
TESTS FOR WATER HARDNESS
The water to be used for preparing solutions should, if pertinent, be within the range of hardness in which the proprietary formulation to be used is effective. Hardness may be determined by either the Hardness by Calculation Method or the Versenate Test (EDTA, titration method, ammonium buffer procedure), as described in the latest edition of Standard Methods for the Examination of Water and Wastewater, published by the American Public Health Association.
TESTS FOR HYDROGEN-ION CONCENTRATION
Hydrogen-ion concentration (pH) has a pronounced effect on the activity of sanitizing solutions. Consequently, solutions must be maintained in the pH range within which the bactericidal agent is effective. In most cases, the pH of the solution is dependent upon the buffering action of the compound used. The pH of bactericide solutions can best be determined electrometrically, using the glass electrode. However, for a field test, colorimetric methods are more applicable. Two types of test kits for such determinations are available commercially. Colorimetric readings should be made immediately, because of the tendency toward oxidation and decolorization of the indicator. Such indicators as bromthymol blue, cresol red, thymol blue, or others are satisfactory, depending upon the pH range desired.
References
A Ortenzio, L. F., and Stuart, L. S., The Behavior of Chlorine-Bearing Organic Compounds in the AOAC Available Chlorine Germicidal Equivalent Concentration Test. Journal of the Association of Official Agricultural Chemists. August 1959.
B Chambers, Kabler, Bryant, Chambers, and Ettinger, Bacterial Efficiency of Q.A.C in Different Waters. Public Health Reports, 70:545-554. June 1955.
C Bactericides shipped interstate are subject to the provisions of the Federal Insecticide, Fungicide, and Rodenticide Act and their labels must be registered with the U. S. Environmental Protection Agency.
D American Journal of Public Health, 38:1405-17, 1948.
E Chambers C. W., A Procedure for Evaluating the Efficiency of Bactericidal Agents, Journal of Milk and Food Technology, 19:183-187, July 1990.
F Criteria for the Selection of Germicides, American Journal of Public Health, 51:1054-60, July 1961.
G Law, McNulty and Rakus, Development of a Procedure for Chemical Assay of the Bacterially Active Ingredient in Quaternary Ammonium Sanitizing Solutions, Manufacturing Chemist and Aerosol News. November 1964. Lautier Fils Ltd., London.
H Journal of Dairy Science, 36:225-234, March 1953.
N.Y. Comp. Codes R. & Regs. tit. 1, Appendices, app 6