• About Dr. Bob Whitaker
  • About this blog
  • @@post_notification_header
  • Archive for the ‘Microbial Testing’ Category

    Wash Water Sanitation

    Tuesday, December 20th, 2011

    In recent years, advancements in wash water sanitation have created questions as well as answers. New developments have occurred both in the field and in research findings, leaving some companies to wonder how to decide which technology is best for them. I’ve increasingly fielded questions from buying companies as they consider rewriting product specifications to require use of one sanitizer over another. I’ve also received several calls from producers wanting to understand how to determine if they should change their systems. My purpose in this post is to highlight a few of the factors each company should consider in evaluating their wash water system.

    The first step in evaluating any wash water scheme is to test the products in your system and validate what works in your specific operation. Validation is an extremely important concept. Past measures have often revolved around adding a sanitizer to water and then measuring the level of sanitizer at some time interval that meets a specific HACCP requirement. But, indirect measures of sanitizer (such as oxidation reduction potential) while convenient and continuous do not accurately reflect actual sanitizer levels, especially when organic loads accumulate during the production run.

    In today’s world we must understand how effective a particular wash water system is in controlling the bacteria that could accumulate in wash water over a wide variety of treatment conditions and time. In evaluating whether new technologies will work for a specific operation, it’s crucial to conduct experiments on each possible technology. An operation must validate that the practices used for wash water sanitation actually achieve microbial control or reduce the risk of cross-contamination under the conditions typically encountered in their production environment. A generalized or “one size fits all” approach is simply not appropriate or effective.

    From a buyer perspective, the key issue is not so much which program is being used, but rather if the system used by the suppler is validated. Can a supplier show the data that validates its treatments are working? And, can the supplier provide verification data demonstrating adherence to its wash water sanitation program?

    Before employing or requiring any wash water sanitizer, it is important to fully understand how or if its use will improve product safety and wash water quality, change the microbial ecology of the finished product, impact the operational aspects of the process and affect quality of the finished product. 

    Thus, in evaluating the efficacy of a new wash water sanitizer from a scientific perspective, several questions should be addressed. First, consider how effective the product is in controlling or killing suspended microorganisms (primarily bacteria and viruses) in the wash water and how its effectiveness could be impacted by organic load, material surface, pH, dwell time, or temperature. Then look at how the new sanitizer compares to other established wash water sanitizers and how the effective level can be monitored. Consider what the mode of action for the sanitizer is. What are the chemical, physical and biological interactions? Can they be reversed? What are the consequences of concentration?  Under what conditions is equilibrium achieved or lost? Lastly, is the product labeled as a processing aid or a disinfectant, sanitizer, pesticide, etc?  Has the product been approved by FDA and/or EPA?  Are the ingredients GRAS?

    As far as microbial ecology goes, consider that all microorganisms might not be equally susceptible to the sanitizer. Look at how continued use of the sanitizer could result in the evolution of resistant microorganisms. In looking at operational impact, see if the sanitizer is effective under normal processing conditions.  Take into consideration the practical logistical aspects as well. For example, how is the sanitizer mixed and delivered to the wash system?  What are the training requirements? How versatile is the new sanitizer? What is the environmental impact of sanitizer use?  Will the sanitizer impact waste water removal?  Is the sanitizer compatible with the construction of your equipment?

    Lastly, consider the finished product quality taking into account the impact on shelf life and if the postharvest physiology of the finished product changed. These are just a few of the many questions involved in truly analyzing a wash water system. For more details and a comprehensive list of the questions to consider, stay tuned for my Wash Water Paper being produced in 2012.

    Remember, food safety is not passive, food safety is personal.  Each company must accept the responsibility to experiment and validate different technologies with its specific system. This is an area of developing technology and I look forward to sharing new development and information with you in future posts. Please contact me at AskDrBob@pma.com with any comments or questions. Your feedback is always valuable.

    Subject Matter Expert Q&A: Epidemiology with Dr. Michele Jay-Russell

    Tuesday, December 13th, 2011

    PMA’s Chief Science & Technology Officer, Dr. Bob Whitaker interviewed epidemiology expert, Dr. Michele Jay-Russell to introduce her to PMA members and provide a snapshot of her background and her passion for epidemiology.

    BW: What drew you into epidemiology?

    MJR: My interest in epidemiology probably started as a kid. I was always curious about animals and nature. I did my own little epi-investigation as a kid into die off of tadpoles in our neighborhood pond. After doing interviews, I discovered it was because a neighbor was putting gasoline and doing some dumping in the pond. So that was stopped. I always had a curiosity, and going into my education I was very interested in applying to veterinary school, but I didn’t take the traditional route as an undergrad. I went through medical entomology and theater as well as focusing on writing. Eventually I went into vet school and at UC Davis they have a combined program in preventive medicine and epidemiology, so I signed up for the duel degree program and knew that I would ultimately end up having a role in public health and doing epidemiologic investigation.

    BW: What do you think is most misunderstood about the role of epidemiology in public health and the combination of art and science that makes up its practice? You did a great job writing these two companion papers, but what do you see most often as industry misperception of what epidemiology does?

    MJR: I think the misperception relates to the strength of the association and the understanding of how statistics can be used. Having the science of epidemiology isn’t as straight forward as having for example a laboratory test. Not that all microbiology test are unambiguous but it is a lot easier to understand that you cultured E. coli O157:H7 out of a food or you didn’t versus discussing the nuances of an epidemiology investigation where you have outliers and statistical criteria. You have people that ate the contaminated food and didn’t become ill, and people who appeared not to have eaten the food and are part of the community and had an exposure. So the level of uncertainty in epidemiology is much greater than what you typically find in a standard microbiological test. Also, along that line, there is an expectation by some in the industry that you are always going to truly prove the cause of a foodborne outbreak. Sometimes that is just not possible because of the perishability of our products and the sampling limitations for testing for pathogen presence.  You have to rely on epidemiology and not having that laboratory result should not ever be an excuse not to protect public health if your epidemiology is strong. Where things get difficult is that not all epidemiology investigations are the same.  Some are stronger than others, some have weakness and uncertainty.

    BW: Is there anything that makes fruits and vegetables more difficult when doing epidemiological studies versus another food group? I know that you have been involved across the board in different food groups. Is there anything about produce that is particularly different or any key learnings that you have gained over the years in cases where fruits and vegetables have been involved? 

    MJR: The difficulty can be when you have an emerging vehicle or any food product that has not been seen before with a certain bacterial pathogen. For example, when strawberries were implicated with E coli. O157 earlier this year, that was not an expected vehicle. Also early on with sprouts, it took a number of repeated epidemiological studies before sprouts were actually linked to outbreaks. Some of that work was done in California by some of my colleagues, and one of their major clues was having a disproportionate number of women that were eating that produce item. The other part relates to what I was saying about having laboratory evidence. With milk, dairy, produce, and those items by time you identify the outbreak and start interviewing people that product can be long gone. And because contamination can be intermittent or in a short period of time, not ongoing, you may never isolate the implicated strain out of the food product.

    BW: Ok switching gears, you just recently completed a PhD at UC Davis correct?

    MJR: Yes, I did.

    BW: Can you describe to PMA members what your current research interests are and how does that relate to some of the work you have done recently in the epidemiological field?

    MJR: Well currently I am working as the project director in the Western Center for Food Safety at UC-Davis. I have been in this position for a little over 3 years now. The center was created with FDA to be what they call a “center for excellence” and is funded by CFSAN. Our center focuses on the interface with animal and plant agriculture as well as the environment. We in particular focus on pre-harvest food safety with an emphasis on produce. There is some dairy but the dairy component relates more towards manure management. So we do have strong produce research effort right now. Because I am a veterinarian, with a background in epidemiology, I am doing studies that primarily look at domestic and wild animals, and whether or not they are carries of foodborne pathogens, and what potential risks and mitigation strategies are available to prevent direct transmission of pathogens onto produce plants out in the field or to protect watershed from contamination by animals.

    BW:  Thanks Michelle.  Also, thank you for preparing two excellent papers on epidemiology.  These papers can be found on pma.com in the “Information” section of the Food Safety Resource Center.

    Preventive Control Approaches for Small Growers

    Tuesday, October 25th, 2011

    PMA repeatedly emphasizes its commitment to bringing real-world solutions to our industry’s food safety needs. This applies to all industry members, large and small. We know local, smaller growers in particular can find it challenging to access the information and resources they need. But despite the challenges, it is important for operations of all sizes to have risk- and science-based food safety programs and preventive controls in place.

    From a food safety perspective, it doesn’t matter where the produce comes from; consumers do not expect to be injured in the consumption of a food product. In the eyes of the marketplace, small and local growers are expected to have effective and verifiable food safety programs. Retail and foodservice buyers are looking to support suppliers in their neighborhoods, yet these very same suppliers could find themselves at a market disadvantage if they do not have adequate risk and science based food safety programs.

    The good news is that food safety can be completely scalable to any size operation, large or small. It makes sense that a larger processor might have to expend proportionally more resources to manage a large, multi-production line processing plant with hundreds of employees manufacturing a half million pounds of product a day. Of course these expenses can be offset by proportionally larger pack-out volumes.  By way of contrast, a small processor with a handful of employees and who processes washes and packs a thousand pounds of cut fruit or vegetables in small operation could expect to spend considerably less than the large operation. However, the degree of sophistication employed may be much less which helps offset the costs.  Risk management practices and preventive controls can be designed to match the risk and the scale of the operation.
    Preventive control programs can seem overwhelming to someone who has not previously considered food safety as central part of their operations. Yet many preventive control approaches and practices, like wash water verification or supplier qualification controls, are practical for small and very small businesses to implement. My experience with smaller companies has been that once processors understand the concepts of hazard analysis and management, they come to see how simple practices that are not expensive to implement can be effective preventive controls.

    Often these controls are simply good operational or business practices. For example, a preventive control on wash water quality for a small processor’s wash system that uses single pass batch equipment might be as simple as a visual inspection of organic load through a portal in a flume tank, sanitizer and pH test strips, a tested water source and a verified sanitation program. These scale-appropriate preventive controls can be just as effective as more sophisticated continuous flow spectrophotometric methods for monitoring organic loads and state of the art electronic sanitizer probes that might be employed by a large processor to monitor multiple production lines in an automated system. The key factor is identifying the need for monitoring wash water quality and the importance of organic load as a risk factor, taking the responsibility to do so and having the freedom to develop preventive controls appropriate for the size of the operation to manage the risk.

    At the next level of preventive control, a microbial test to verify sanitation efficacy or a food safety audit to verify adherence to a food safety program is routine for many processors, yet many smaller processors not accustomed to applying these controls might fear the costs of these services. Again, to those not using these types of preventive controls, they can appear daunting, but they are rapidly becoming part of doing business. We have seen far too many instances where failures to provide adequate sanitation or adhere to a rigorous inspection program can lead to breakdowns in the safety of foods and cause illnesses among consumers.

    A company’s specific risk assessment/hazard analysis plan should serve as a guide as to which preventive controls should be employed to manage identified potential risks. No matter the size, basic measures such as providing training for worker hygiene, wash water sanitation, facility and equipment sanitation and supplier qualification apply to all operations and can help assure food safety. The liabilities associated with foodborne illnesses increasingly are requiring buyers to use only producers with risk-based food safety programs and verifiable preventive controls. Many buyers have worked with their smaller, local suppliers to explain their requirements, and several buyers offer specialized training and workshops in this area.

    PMA also offers training to help small growers understand how food safety programs can be incorporated into their operations, can be cost-effective, and can open or maintain market channels where buyers require effective food safety programs. PMA has conducted six local grower food safety worshops in 2011 to reach out to small growers and we already have several workshops planned for 2012. This local grower outreach is part of PMA’s overall food safety program, which also includes industry education, advocacy, knowledge generation and outreach.  

    For all of us in the industry it comes down to offering the consumer a healthy, safe product. Consumers want local food and our responsibility is to work together to ensure our entire supply chain can verifiably present effective food safety programs. If you would like to access any of PMA’s local grower food safety resources, please contact PMA’s Solution Center staff by telephone at (302) 738-7100, or by email at solutionctr@pma.com. As always, you can contact me via email at askdrbob@pma.com.