Verification of Environmental Control

 4.1 Introduction
The microbiological safety of industrially manufactured foods is based on the effective design and
implementation of Good Hygienic Practices (GHP) and Hazard Analysis and Critical Control Points
(HACCP).
Published case studies demonstrate the impact of postprocess contamination (ICMSF 2002). Even
when strict control at all CCPs ensures destruction or reduction of pathogens to acceptable levels
during processing, foods may become contaminated during subsequent processing and handling. Such

contamination typically results from two general circumstances:
1. Addition of contaminated ingredients after the kill step
2. Contamination from the processing environment
The basic elements of GHP are described in the Codex Alimentarius Commissions document
“General Principles of Food Hygiene” (Codex Alimentarius 1997). These general principles are supported
by numerous product-specific guidelines issued by Codex Alimentarius or organizations.
These elements of GHP are defined to minimize or prevent introduction of a pathogen to a product
during its manufacture. This is achieved through the implementation of combined measures and
multiple protective barriers, which can be described as follows:
1. Prevention of entry of pathogens into areas close to the processing lines.
2. In the event of entry, prevention of establishment in the premises.
3. In the event of establishment, prevention or limitation of microbial multiplication, which would
favor persistence and dissemination throughout the plant.
4. In the event of presence, implementation of corrective actions to ensure control of microbial concerns
at low levels or eradication where feasible.
4.2 Establishing an Environmental Control Program
Elements that contribute to postprocess contamination and measures to control pathogens in food
processing environments are extensively discussed and illustrated in ICMSF (2002) and GMA (2009)
for Salmonella in low moisture food. Testing of in-process and processing environment samples
demonstrates that the GHP measures implemented are effective in achieving the desired prevention
of contamination. The test results can be used to (1) assess the risk of product contamination, (2) establish
Chapter 4
Verification of Environmental Control
42 4 Verification of Environmental Control
a baseline for when the facility is considered under control, (3) assess whether control is maintained
over time and (4) investigate sources of contamination in order to apply appropriate corrective
actions.
While sampling plans applied to verify environmental control are typically not based on statistical
considerations, it is important to consider evaluating results using appropriate statistical tools such as
trend analyses. These elements are discussed in detail in ICMSF (2002) and an approach for establishing
a testing program is illustrated in Fig. 4.1. This approach can be applied for control of pathogens,
hygiene indicators or spoilage organisms.
4.2.1 Step A: Determine the Microorganisms of Concern
Determine the relevant microorganism for the manufacturing process based on a HACCP study, guidance
provided in this book or ICMSF (2005). In many cases, a program is established for a single
A. Determine the organism(s) of
concern
B. Determine the relevant test
organism
C. Review implemented measures to
prevent ingress
J. Establish a plan of action
according to findings
H. Define sampling frequencies
K. Periodic review of sampling
programs
I. Establish a plan for evaluation of
data
D. Review other hygiene control
measures and their impact
F. Perform investigative sampling
G. Develop sampling programs for
(a) in-process
(b) environment
E. Review historical data
Fig. 4.1 Proposed approach for
establishing an environmental
sampling program
4.2 Establishing an Environmental Control Program 43
pathogen; however, it may be done for more than one microorganism if it is deemed necessary for the
product under consideration.
4.2.2 Step B: Determine the Relevant Test Microorganism
Determine if testing should involve an indicator or the organism of concern. Examples of indicators
include Enterobacteriaceae for Salmonella or Cronobacter spp. and Listeria spp. for L. monocytogenes.
In most of the cases to obtain a full picture of the status, testing for the both the indicator and
the pathogen is necessary albeit number of sampling points and frequencies may be different.
4.2.3 Step C: Review Measures to Prevent Ingress
Review the existing preventive measures such as zoning within the premises, the layout of different
processing lines, interfaces between different parts of the factory, elements such as flow of personnel,
equipment and goods (e.g., raw materials, packaging materials, finished products, containers, fork-lift
trucks, pallets, waste, rework etc.), as well as the flow of air and water. This is best done using a
master plan and having detailed discussions on parameters affecting the preventive measures to avoid
the ingress of pathogens in specific areas of the factory, in particular high hygiene areas as described
in ICMSF (2002, Chap. 11).
4.2.4 Step D: Review Other Hygiene Control Measures and Their Impact
Review other factors that may contribute to the establishment or dissemination of the microbiological
concern in the processing areas. This includes reviewing the layout of processing lines, the type of
equipment including hygienic design and interfaces with the environment, cleaning procedures used
for the environment and equipment (e.g., wet versus dry), cleaning schedules etc. Based on the design
of the processing lines, equipment and processing conditions, determine whether the build up of
product residues on food contact surfaces may also lead to microbial growth – e.g., at points where
condensation is more likely to occur or growth temperatures may be experienced for extended periods
of time.
4.2.5 Step E: Review Historical Data
Determine whether historical data on environmental sampling and testing of pathogens or indicator
microorganisms exist and if the data still apply to the current environment. For example, if construction
events occurred after data were collected, investigative sampling may be appropriate.
4.2.6 Step F: Perform Investigative Sampling
If no historical data exist, investigative sampling is recommended to establish a base line that can be
used for the development of the sampling program. It may be useful to initially focus this investigative
sampling on indicator microorganisms (e.g., aerobic colony counts, Enterobacteriaceae) to evaluate
trends that can be used to establish sampling times during production and frequencies for sampling.
44 4 Verification of Environmental Control
4.2.7 Step G: Develop Sampling Programs
With historical or investigative sampling data available and considering critical ingredients that may
impact the quality and safety of the finished product, an environmental sampling and testing program
can be developed. The terminology used to describe in-process and environmental samples may vary
depending on the manufacturer. The following definitions have been used in this book.
• In-process samples: These samples provide a representative sampling for an entire line and sometimes
represent the “worst case.” In-process samples include:
–– Intermediate product collected from different process steps that would end up in a container as
finished product, such as samples of sauces that would top a pizza or grab samples from a
depositor.
–– Samples from equipment or product contact surfaces that could lead to a contamination of
product such as process wash water, sifter tailings, fines, line residues or scrapings.
• Processing environment samples: The most common method of sampling for the processing environment
is with sponges or swabs but it is important to adapt sampling tools to the situation. If air
sampling is performed then air collector devices are preferred. These are used to verify that the
environment is under control, i.e., free of pathogens or the indicator microorganisms of choice do
not exceed target levels. Samples from food contact surfaces taken prior to production and after
wet cleaning as part of the preoperational inspection are included in this category.
The sampling sites for both in-process and environmental testing should be based on a thorough
knowledge of the premises, processing lines and equipment and the outcome of the HACCP study.
Guidance on the relative importance of such sampling programs is provided in individual chapters of
this book. Practical details on sampling tools, sampling techniques, routine and investigative samples
are provided in ICMSF (2002).
4.2.8 Step H: Define Sampling Frequencies
After establishing the sampling plans it is important to determine the sampling frequency. The frequency
may vary depending on the type of product manufactured and the duration of production runs.
For example, daily sampling may be appropriate for sensitive products such as infant formulae, while
weekly or monthly sampling may be appropriate for other product categories. Rotation between different
sampling points in the same area may also be appropriate because conditions in manufacturing
facilities can change.
It is also important to determine whether the sampling frequencies for indicators and pathogens
should differ. Testing for Enterobacteriaceae, for example, provides results within 1–2 days and may
therefore be used as a management tool with a higher frequency than Salmonella in some facilities.
4.2.9 Step I: Establish a Plan for Data Evaluation
To maximize the benefit of an environmental sampling program, it is very important to analyze the
data generated in the most effective and proactive way. Different options such as statistical trend
analyses, mapping or charting of data and findings etc. exist. The most familiar and convenient
method for the establishment should be used. It is important to review the data in a timely manner to
allow for corrective action, if necessary.
References 45
4.2.10 Step J: Establish a Plan of Action to Respond to Findings
When results deviate from standards, guidelines or specifications (e.g., the presence of Salmonella in
a sample or levels of indicators exceed established internal limits), it is important to take appropriate
actions. This is best done according to a preestablished action plan that is “activated” only when a
deviation is detected.
Depending on the findings, the action plan may consider the following options: (1) thorough
investigational sampling to identify root causes of the deviation and source(s) of the pathogen or
indicator, (2) increased sampling frequency over a certain period to demonstrate that control is reestablished,
(3) adjustment of the sampling regime for end products; e.g., change from verification to
acceptance.
4.2.11 Step K: Periodic Review of Sampling Programs
A periodical review (e.g., once per year or when important changes occur) of sampling programs
should be performed. This review should consider changes in premises, layout and type of equipment.
Historical results should also be considered to optimize sampling plan. For example, sampling points
that have not proven to be very useful might be eliminated and new sampling points might be added
in areas where more issues have been detected. Changes in sampling frequencies may also be made
during such reviews.
Such reviews should be combined with a review of the skills and training level of personnel
involved in sampling, as well as a review of the adequacy of sampling tools and techniques.
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