Food Protection Trends - March 2010 - 166

Water supplies vary from place to place; some supplies are more corrosive than others, and pH values vary, as does mineral content (soft vs. hard water). Therefore, the disinfectant level necessary to achieve and maintain recommended minimum residual concentration and the maximum level that can be tolerated (e.g., to maximize employee safety and minimize corrosivity) must be determined for each individual system. Whatever verification system is employed should include monitoring the bacterial quality of the water. Simply targeting for a residual disinfectant level alone may not be adequate. cooling water feed to retorts. Residual disinfectant levels reported ranged from 0.1 to 1.5 ppm; however, the chemical type was not specified, making the differentiation between various forms of chlorine, bromine, or other disinfectants impossible. A number of processors noted the use of alarms, and one reported the use of an automated chemical injection system (with a manual check backup). Three of the respondents reported a product hold and review process following a chemical residual alarm. RECOMMENDATIONS Many factors ultimately contribute to the assurance of bacteriological quality in food plant cooling water systems. As seen from surveys of cannery cooling water systems, bacteriological loads can be significant. While container integrity plays an important role in the final spoilage rate for the end product, it is important to understand and control as many risk factors as possible to insure against rare events, such as suboptimal seams/seals. For the purposes of this paper, adequate seam/seal integrity will be assumed relative to any cooling water system recommendations. As discussed earlier, APCs have been shown to be significant indicators of specific spoilage organisms and rates of product contamination. Several sources have suggested that containers may be sufficiently protected against leaker spoilage only if the bacterial count (APC) of the cooling water is < 100 CFU/ml (5, 7, 8, 9, 20, 30). Put et al. (20) found that reinfection of containers could be minimized if cooling water had less than 100 bacteria/ml and if the number of bacteria in the water on the double seam at the end of container handling was less than 10,000/ml. Herbert (9) reported that there was little or no recontamination of cans at the cooling stage when cooling water counts were less than 100 bacteria per ml. Williams (30) considered 100 bacteria per ml to be an acceptable contamination level for cooling water. Consequently, it is a good practice to monitor the bacterial level of cooling water on a periodic basis. This includes both the microbial quality of incoming water, and the microbial quality of the cooling water system. GMA SURVEy Results of a survey by GMA, conducted in the summer of 2008, requesting specific cooling water system information from low-acid canned food facilities are summarized in Table 4. Respondents represent small to large canning companies with various system approaches. A total of 10 facilities, representing 15 separate systems, responded to the survey. Some of these facilities used multiple water sources (city water treated/untreated and well water treated/ untreated) and cooling water systems (single pass and recirculating systems). Most of the respondents (90%) indicated that source water is treated (with disinfectants) prior to entering the facility, and 60% of the facilities further treat incoming water regardless of the source. Routine microbial testing on the source water was performed on 70% of the cooling water systems. Additional microbial testing of cooling water systems was performed in 80% of the facilities responding to the survey. More than half (53%) of the systems reported are singlepass systems with recirculating systems making up the balance. For recirculating systems, all plants indicated replenishment with fresh water, chemical treatment, and testing for chemical residual. One facility noted the use of carbon filters and oil skimming. Half (50%) of all respondents treating their systems checked for chemical residuals of disinfectants at the cooling water or retort discharge. Respondents indicated that chemical residuals were predominantly checked at cooling water sumps and can discharge locations, and in one instance a respondent indicated checking the Disinfection of all cooling water, regardless of source, is a dependable means of maintaining microbial counts of cooling water at low levels. As mentioned above, various canning regulations require chlorination, or other methods of sanitation, for cooling canals and recirculated cooling water and stipulate a measurable residual level of sanitizer at the discharge point of the container cooler section. When single pass systems have APC loads of 100 CFU/ml or above as the water enters the cooling system, these systems should be monitored and treated in the same manner as recirculating systems. As seen from the GMA survey (above), chemical residual levels may vary by chemical and by facility. It is important for each facility to document and maintain chemical treatment protocols that are sufficient for their product, container and historical incidence of spoilage. It is recommended that processors take advantage of the expertise and services of water treatment professionals in the food industry and/or their local area. Combining microbial testing and cooling water treatment into an operational protocol, or standard operational procedure, would allow the processor to better evaluate and control risks associated with the cooling of thermally processed food containers in their facilities. In view of the fact that there is no one solution that works for every producer, it is important that companies include basic testing, monitoring and treatment protocols in their cooling water systems in a structured and documented program, such as an Standard Operating Procedure (SOP), with clear plans of corrective actions and verification procedures should non-optimal conditions exist. ACKNOWLEDGMENTS The authors gratefully acknowledge the valuable assistance of Virginia N. Scott (GMA, currently with FDA), Bradley Shafer (GMA), Chris Balestrini (GMA), Keith A. Ito (UCLRFP), Ray Carroll (Campbell Soup Co.) and David Anderson (Del Monte Co.). REFERENCES 1. Association of Official Analytical Chemists. 2008. 18 ed. AOAC, 166 FOOD PROTECTION TRENDS | MARCH 2010

Food Protection Trends - March 2010

Table of Contents for the Digital Edition of Food Protection Trends - March 2010