Water Quality and Food Safety – VII

Safety and Quality of Water

From the processor’s perspective, water quality and safety begins at the source of the raw materials and the key to good water safety and quality management is for all manufacturing facilities to have effective programs in place to control water microbiological, chemical and physical quality and to verify that the water meets specified requirements for both direct and indirect product uses. Because, water may be adulterated by a number of chemical, heavy metal, microbial and physical hazards that pose potential public health risks if they are present at high levels. The water risk management plans need to consider above risks in risk analysis process, where microbial hazards include waterborne pathogens such as E. coli, Salmonella and Listeria monocytogenes, Vibrio cholera, viruses and parasites, such as Hepatitis A virus, Giardia and Crytosporidium parvum. Chemical and heavy metal hazards in water range from the presence of lead, copper, methyl-tertiary-butyl-ether (MTBE), total trihalomethanes (TTHM), arsenic and benzene, to name a few. Physical hazards may include natural particulates, and glass and metal fragments. The potential for any one of these hazards to be present in a facility’s water supply requires, where food manufacturers to develop a solid water quality and safety management strategy.

Developing a risk-based water monitoring program, or water safety/quality assurance procedure, as part of ongoing food safety management system while considering Hazard Analysis and Critical Control Points (HACCP) requirements to comply with any national or international quality/ safety requirements is an excellent way to ensure that effective controls for water are achieved to prevent product exposure to spoilage or pathogenic microorganisms, to potential chemical contaminants and to possible physical hazards. Assessing and monitoring water quality and safety includes considering incoming water requirements, water utilities controls and treatments, and microbiological and chemical sampling and testing protocols that best meet your operation’s needs.

Water Quality Analysis

All food processors should test water in the plant from different outlets at least once each year—and preferably more often. Operators should collect water samples from the farthest faucet from the line in the facility and preferably from the cold side. This should be done even if water is obtained from a city water system. The water quality as it leaves a treatment plant and its condition when it gets to your plant may vary, which is especially true in cities where pipelines are old. If the water pipes are iron, it is quite easy to pick up that metal from the lines. High iron water, whether from old pipes or a natural source, is quite easy to detect, what necessary is to look for iron stains wherever there are leaks or drips.

Along these lines, processors should always request that the city provide them with water test results, but provided results are those obtained at the water treatment facilities. Having city water records does not preclude the processor from testing water from their own operations, however, it is your duty to test your supply. If water from multiple sources is being used (wells, city or wherever), be sure that samples from each source are tested separately. Considering the testing schedule, both microbiological and chemical parameters should be tested, because these analyses may be used to do more than just assure safety of your food and ingredients. Knowing the chemistry of the water coming into the plant will help in other areas, where microbial analyses should include total counts and coliforms. If there are concerns that the water may have been contaminated with runoff from fields or elsewhere, you may want to look for pathogens or parasites. Chemical tests should include pH, water hardness, heavy metals, pesticides, iron and nitrates. Water samples for complete chemical analyses should collected at least once a year and submitted to a recognized and accredited water testing laboratory.

Testing the microbiological quality of the water should be done more frequently, and be sure to establish documented programs for water sampling. The instructions should include how to sample, how often to sample and where to sample. The procedure should also instruct what tests should be done and the methods for doing the work as well as reference standard test and identification codes for verification purposes. If third parties are to be used for sampling and/or testing, be sure that the follow your procedures. Maintain all your records and testing procedures in a separate file or binder so that test results may be quickly and easily accessed. 

Installing sample ports on water lines is a good idea, provided they are installed properly. Don’t leave a large deadleg. It is also a good idea to allow the sample port to “run” for a short period to flush the port. If water samples are being collected for microbiological testing and the water is chlorinated, be sure that the sampling program includes a step to neutralize any residual chlorine (your sampling schedule should guide to include a thiosulfate tablet in the field sampling kit, that will meet this need). 

There are processors who have built additional safety into their systems by treating all waters entering the plant with chemicals or by UV light systems. Whether the added costs are worthwhile, only time will tell, but no effort to assure safety should be criticized.

Standard Operation Procedure for Water Safety and Quality – An Example

The following example is a generic water quality and safety procedure which might not be a very comprehensive document, but it provides the way you need to consider about your water treatment program based on your own requirements.   

1.0       SCOPE AND APPLICATION

1.1       This SOP covers the initial processing and preservation of water quality samples collected for analysis of pH, alkalinity, turbidity, apparent color, specific conductivity, total and volatile suspended solids, soluble reactive phosphorus, dissolved and total P, ammoniatot, nitrate + nitrite, dissolved and total N, dissolved and total organic carbon, major cations (Ca, Mg, Na, K), metals (e.g. Fe, Mn), and major anions (SO₄, Cl, F).

1.2       It assumes that one 1-liter sample has been collected for measurement of turbidity, apparent color, and suspended solids, 1-2 syringes have been collected for analysis of pH and alkalinity, and one 1-liter sample has been collected for the analysis of the remaining water quality parameters.

2.0       DESCRIPTION OF METHOD

A.        Definitions - N/A

B.         Health and Safety Warnings - Lab coats, gloves, and safety glasses should be worn when working with acids. Addition of strong acids to samples for preservation should be done under a hood.

C.   Interferences - Samples can be contaminated through hand contact (e.g. Na, Cl, PO₄), through contact with unclean surfaces, through aerial deposition (dust), or through dissolution of acid aerosols released from strong acids. Disposable gloves should be worn when processing samples to avoid hand contact. Samples and filters should not be touch directly; filters may be handled with forceps. Samples should not be left standing uncovered. Samples should be processed in the order described below to avoid cross-contamination from acids used in preservation. Ideally, acidification of samples with HNO₃ or H₃PO₄ should take place in a room other than that used for processing of nutrient or anion samples. Samples should be divided and filtered within 24 hours of collection. Samples must be shaken well before splitting; otherwise sample characteristics will be biased and subsequent analyses invalid. Nutrient and organic carbon samples may deteriorate (mineralize) if left at room temperature for too long; these should be kept at 4ºC until processing, and then analyzed or frozen or preserved with acid until analysis.

3.0       PERSONNEL QUALIFICATIONS  

3.1       Personnel should be familiar with general lab safety practices and steps necessary to avoid contaminating samples. Personnel preparing samples for the first time should be supervised by a staff member familiar with these procedures, and blanks samples be prepared and processed to ensure good techniques have been followed.

4.0       MATERIALS AND PROCEDURES

4.1       Materials

4.1.1         Nalgene-type filtration units (250 mL capacity), Vacuum pump, or hand pump, or lab vacuum (least desirable), Vacuum tubing or thick-walled Tygon tubing

4.1.2          Ultrex HNO₃ (or equivalent)

4.1.3          Phosphoric acid (H₃PO₄) 50%

4.1.4          Calibrated Eppendorf (or equivalent) pipettes (Repeating Eppendorf or 10-100 μL pipette)

4.1.5          Deionized water in wash bottle

4.1.6          10% HCl in wash bottle

4.1.7          10% HNO₃ in wash bottle

4.1.8          Membrane filters (Millipore) (< 0.45 μ pore diameter; 47 mm diameter) and forceps

4.1.9          Glass fiber filters as prefilters for turbid samples (47 mm diameter, e.g. GF A/E)

4.1.10        Pre-cleaned sample bottles (see pages 10-11 for volumes needed)

4.1.11        Pre-printed sample labels (corresponding to numbers on field-collected samples)

4.1.11.1  Sample numbers on the 1-L composite samples (C-nnnn) should match those on the subsamples poured off and/or filtered from the main sample

4.1.12        Sample tracking sheet

4.2       Sample filtering (for filtered sample processing)

4.2.1          Clean and soak filtration apparatus for at least one hour in deionized (DIW) water or 10% HCl or 10% HNO₃ prior to filtering samples.

4.2.2          Rinse each filtration apparatus at least 3x with DI water prior to filtering samples.

4.2.2.1    Use forceps when handling o-rings to avoid contamination.

4.2.2.2    When putting filtration apparatus back together, check to make sure that all o-rings are in place and in good condition to prevent leakage.

4.2.2.3    Using clean forceps, place filter(s) on the base of the filtration apparatus.

4.2.2.3.1    Do not touch filter or inside of filtration unit with your hands; disposable gloves should be worn.

4.2.2.3.2    Make sure filter is centered and does not overlap around edges of unit.

4.2.2.4    Replace top of filtering apparatus on bottom and tighten using the white ring around bottom of top unit, while holding down top of unit.

4.2.2.5    Wiggle the top of the unit to make sure it is screwed down snugly; if it is not, it will leak around the edges.

4.2.3          Filter cation, anion, dissolved nutrient, and dissolved organic carbon subsamples from 1-L composite sample (C-nnnn) bottle as follows:

4.2.3.1    Anion and samples will be filtered with the DI-water washed filtration apparatus.

4.2.3.2    Nutrient samples will be filtered with the HCl-washed filtration apparatus.

4.2.3.3    Cation and organic carbon samples will be filtered with the HNO₃ -washed filtration apparatus.

4.2.4          The composite sample (C-nnnn) should be shaken thoroughly before dividing into samples as to eliminate analysis bias.

4.2.5          Put approximately 20 mL of sample from composite (C-nnnn) bottle into the top of the unit, swirl, and apply suction to the filter.

4.2.5.1    The filtering apparatus is attached to the vacuum tubing and uses the vacuum pump to suction.

4.2.5.2    Release vacuum from base of unit by releasing cap on side port of filtration unit.

4.2.6          Swirl the water around the bottom of the apparatus and discard, or use to rinse out subsample bottles if only a small amount of parent sample is available.

4.2.6.1    Rinse pre-cleaned cation (M), anion (AN), nutrient (FN), or organic carbon (FC) bottle with a little filtered sample and discard before filling bottle completely

4.2.7          Fill FN bottle to just below neck to allow for sample expansion during freezing. Place FN bottle in freezer, AN bottle in refrigerator, and FC and M bottles in hood for acid additions.

4.2.8          Rinse filtering apparatus with appropriate 10% acid solution and 3X DIW between samples.

4.2.8.1    If an organic matter film builds up on the HCl-apparatus, it may need to be wiped out or scrubbed and re-soaked before additional use.

4.2.9          If sample is very turbid, a pre-filter may be needed on top of the membrane filter.

4.3       Sample splitting (for unfiltered sample processing)

4.3.1          The composite sample (C-nnnn) should be shaken thoroughly before dividing into samples as to eliminate analysis bias.

4.3.2          The composite sample for unfiltered samples will be poured into 2 sample bottles:

1) unfiltered nutrients (labeled UN-nnnn) and

2) total organic carbon (labeled UC-nnnn).

4.3.3          Fill UN bottle to just below neck to allow for sample expansion during freezing. Place UN bottle in freezer, and UC bottle in hood for acid additions.

4.4       Sample preservation

4.4.1          Freeze nutrient samples (FN, UN).

4.4.2          Refrigerate anion samples (AN).

4.4.3          Acidify cation (M) samples to pH 1-2 with Ultrex HNO₃ and refrigerate. (Start with 100 uL, check pH, add in 50 uL increments until desired pH).

4.4.3.1    Check pH on a subset of samples by pouring a small amount of sample into a beaker and testing with pH paper.

4.4.4          Acidify organic carbon samples (FC, UC) to pH 1-2 with 50% phosphoric acid (use 4 drops ~50uL then check pH) and refrigerate.

4.4.4.1    Check pH on a subset of samples by pouring a small amount of sample into a beaker and testing with pH paper.

4.5       Sample storage and tracking

4.5.1          Samples will be stored in CT rooms (refrigerated samples: UC, FC, AN, M) or in the core freezer (FN, UN) in labeled boxes by sample type.

4.5.2          Check the labels on the shelves for the proper location of different sample types for the WSDT project.

4.5.2.1    The box should be labeled with the date, batch number (corresponds to date of collection, e.g. 6/10/16 = batch 910), team, project, sample type, and holding time. Use preprinted labels provided for this purpose.

4.5.3          Fill out sample tracking sheet with each sample set processed.

5.0 DATA ACQUISITION, CALCULATIONS, AND DATA REDUCTION

A.        Computer Hardware and Software - Sample tracking sheets are generated in Paradox after sample numbers are entered from water quality sample field sheets into the R:\WATERSHD\WQ97\SAMPLES.DB file and WQTRACK.SAS is run.

B.         Data Management and Records Management - See Water Quality Information Management Plan for details. Samples are tracked by a unique sample code and batch number (corresponding to collection date).

6.0 QUALITY CONTROL AND QUALITY ASSURANCE SECTION

6.1       Field sample blanks, field bottle blanks, and field duplicate samples are all processed the same as blind samples at this point. Laboratory filter blanks are done with every filtering event. These blanks are used in analyses for background determinations.

6.2       QA sample types are recorded on field sheet sample forms and tracked through the information management system.

7.0 REFERENCES

7.1       APHA. 1992. Standard methods for the examination of water and wastewater, 18th edition. American Public Health Association, Washington, D.C.

7.2     U.S. EPA. 1983. Methods for chemical analysis of water and wastes. U.S. Environmental Protection Agency, Cincinnati, Ohio. EPA_600/4-79-020.

7.3     U.S. EPA. 1988. Chemical characteristics of streams in the Mid-Atlantic and Southeastern United States (National Stream Survey - Phase I): Volume I: Population descriptions and physico-chemical relationships. Office of Acid Deposition, Environmental Monitoring and Quality Assurance, Washington, D.C. EPA/600/3-88/021a.