Preventing Post-Process Contamination: Don’t Lose Sight of the Basics

With the World Health Organization estimating that one in ten people get sick and more than 400,000 die from foodborne illnesses each year, a public health focus aimed at decreasing this incidence is needed.  The primary goal of the management of risks associated with food is to protect public health by controlling them as effectively as possible through the selection and implementation of appropriate measures. Post-process contamination is one way that foods can become unsafe. There are many ways to prevent post-process contamination and the implementation of effective sanitation practices is one of the most important strategies.

Clean and Sanitary Conditions Are Keys to Preventing Post-Processing Contamination

Recently published violation data from United States Food and Drug Administration (FDA) highlight violations in basic sanitation-related practices that were each recorded about 2% of the time in their inspections during fiscal year (FY) 2022.  These include failure to maintain the plant in a clean and sanitary condition, that equipment and utensils were not designed and constructed to be adequately cleaned or maintained to protect against allergen cross-contact, and microbial cross-contamination. Failures in the key preventive control of sanitation and other aspects of good manufacturing practices have led to many serious food safety incidents with significant public health impacts and barred some exports from crossing borders.  Increasingly, there are much higher regulatory bars being imposed by government agencies.

Preventing post-process contamination from foodborne pathogens like Salmonella, spoilage organisms including spore formers, and cross-contact from food allergens relies on applying various risk management strategies, including effective sanitation. This means that sanitation must be performed flawlessly.  But what are the optimal considerations to ensure that this occurs?

Defining Sanitation Basics

At a minimum, it is crucial that food processing equipment be sanitary prior to producing food. This must start with a definition of ‘clean’.  CODEX Alimentarius, in their General Principles of Food Hygiene, has defined this as “the removal of soil, food residues, dirt, grease or other objectionable matter.”  Beyond just a definition, though, the consistent reality is that proper cleaning relies on effective implementation of a valid process. This includes several steps of sanitation, including both cleaning and sanitizing, that must be done well in a defined order as part of preventing post-process contamination.

Key Steps for Preventing Post-Process Contamination

Experts agree that a pre-rinse is an important first step to remove gross soil, followed by cleaning with a detergent used according to the labeled instructions that will emulsify the soil and allow it to be carried away during intermediate rinsing.  Cleaning is crucial for removing residual food allergens in soil and allowing the sanitizer, which is applied after the intermediate rinse, to sufficiently contact any contaminating microorganisms.  The sanitizer must be applied according to the labeled instructions, used at the proper concentration, and for sufficient dwell time.

As a final step in sanitation to ensure that sanitation is consistently done in a way to control the various hazards, hygiene verification must be done.  This relies on the application of methods, procedures, tests, and other evaluations, in addition to monitoring, to ensure compliance. Verification techniques can include visual inspection, adenosine triphosphate (ATP) swabbing, reviewing records, and checking for proper use of cleaners and sanitizers. An effective method to demonstrate the effectiveness of a sanitation process is inline sampling at relevant points to compare bacterial counts throughout sanitation, such as in a Clean-in-Place (CIP) process.

Basics of Sanitation for Preventing Post-Process Contamination

Thinking Beyond the Basics of Sanitation

There are several other important considerations needed to complement these basic sanitation steps to ensure the process is optimally done.  Among these are sanitary design, choosing the right cleaning and sanitizing products, and following the proper procedures. In addition, the industry needs to be aware of sanitation challenges such as biofilms, which are made of slimy extracellular matrices in which microorganisms are embedded.  The table below highlights biofilm-forming bacteria of relevance to the dairy industry as an example. These contaminants can compromise product safety and quality, including the shelf life of dairy foods and others.

Biofilm Forming Bacteria of Relevance to the Dairy Industry

Knowledge about biofilms and how they can be combatted using sanitation and how certain microorganisms could react against cleaning chemicals, especially with prolonged use, are key.  Sanitation can help to combat biofilms, if the proper steps outlined previously are followed in the right order.  Cleaning is crucially important in biofilm control to remove the soil residues which will then allow the sanitizer to sufficiently contact and eliminate the contaminating microorganisms. For a deeper dive into biofilms, read Biofilms: A Persistent Challenge to the Dairy Industry.

Sanitation Should Be at the Forefront of Every Risk Management Strategy

To overcome the tremendous burden of illness, identifying factors that can cause food safety issues such as post-process contamination, demands the implementation of effective risk management strategies, such as sanitation. This will help ensure that the plant is maintained in a clean and sanitary condition, so public health is assured.

1. Bhosale S, P Brahmane, A Kubade, RJ Desale. Biofilm in the dairy industry: Detection and common process for control biofilms. Pharma Innovation J. 2021; SP-10(8):809-817.  
2. Brown S, JP Santa Maria Jr, S Walker. Wall Teichoic Acids of Gram-Positive Bacteria. Annu Rev Microbiol. 2013; 67: doi:10.1146/annurev-micro-092412-155620. 
3. Cherif-Antar A, B Moussa-Boudjemaa, N Didouh, K Medjahdi, B Mayo, A Belen Florez. Diversity and biofilm-forming capability of bacteria recovered from stainless steel pipes of a milk processing plant. Dairy Sci Technol. 2016; 96:27-38. 
4. de Oliveira MMM, DF Brugnera, E Alves, R Hisldorf Piccoli. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential. Braz J Microbiol. 2010; 41:97-106. 
5. Di Martino P. Extracellular polymeric substances, a key element in understanding biofilm phenotype. AIMS Microbiol. 2018; 4(2):274-288.  
6. Hassan A, J Usman, F Kallem, M Omair, A Khalid, M Iqbal. Evaluation of different detection methods of biofilm formation in clinical isolates. Braz J Infect Dis. 2011; 15(4):305-311.   

Finding solutions for contamination issues can be challenging, frustrating, time-consuming, and sometimes costly! If you have a contamination issue you are having trouble solving or would like to discuss a proactive process monitoring plan, contact us at (651) 501-2337 or complete our convenient “Ask Our Experts” form to have one of our experts contact you.

Additional resources related to dairy micro testing for post-pasteurization contamination:

Sampling: Back to Basics
In-Line Fluid Sampling Without Contamination
Biofilms: A Persistent Challenge to the Dairy Industry

Related Blog Posts:
Hygienic Sampling Practices Are Vital to Protecting Dairy Product Quality and Safety
Clean-in-Place (CIP) Troubleshooting—Following the Water Principle

Why Process Monitoring & Aseptic Sampling Information Sheet
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