How to test foreign material detection systems: validation, verification & monitoring
In this article about testing contaminant detection and production inspection devices, Sesotec food safety experts explain the importance of validation, verification and monitoring and their role in ensuring the effectiveness of a foreign material control programme.
For food manufactures and processors, product
inspection and contaminant detection devices are an important part of an
effective foreign material control programme. In order to ensure the safety of
their products, food industry businesses rely upon detection technology – often
metal detectors and x-ray inspection systems – to
identify physical contaminants and remove defective products from the
production flow.
But just as production processes vary tremendously
according to a plant’s products and scale, contaminant detection devices also
differ. In order to safeguard consumer health, international food safety
standards require that companies validate, verify and monitor their contaminant
detection technology on an ongoing basis.
Validation, verification, monitoring: what they
mean and how they differ
Validation, verification and monitoring are three
distinct phases of testing product inspection devices. Each phase relates to a
different period in a device’s lifecycle and uses different criteria to
evaluate the effectiveness of the device within a given process.
Depending
on the global food safety and quality standards applied, specific requirements
for each phase of testing inspection devices may vary slightly. In this piece,
we refer to the requirements laid out in IFS Food Version 7.
1. Validation: can my device achieve the intended outcomes?
In testing contaminant detection technology, validation
refers to the initial processes of qualifying whether a device can adequately fulfil
the specific, documented requirements of its intended use.
Validation
takes place before a food company purchases and/or implements a contaminant
detection system. According to IFS Food V7, validation requires “the provision
of objective evidence.” This evidence takes the form of specific criteria, such
as the probability of detection (POD) and the false rejection rate (FRR), which
are determined and documented before testing begins.
For instance, after assessing the foreign body
risks present in their process, a company may determine they require a metal
detector that can detect metallic particles of a certain size with a POD no
lower than 99.998% and a FRR no higher than 0.001%. Factors such as packaging,
product effect and production line speed should also be taken into account. These
metal detector sensitivity criteria are then documented and different metal
detection devices are tested accordingly. Only the devices that perform
according to these standards will pass the validation phase.
2.
Verification: is my device performing as expected?
After a contaminant detection device has been
implemented, verification refers to scheduled, periodic testing
procedures designed to ensure the device continues to function as expected.
To be compliant with IFS Food V7, verification
should take place annually and include a series of thorough control tests,
training sessions for personnel and the complete documentation thereof. Beyond
detection sensitivity, the verification process should also include controls to
ensure the device is reliably separating defective and/or contaminated products
from the production flow.
As it only happens once annually, IFS Food V7
stipulates that the verification process should involve tests and documentation
that are more exhaustive than the regular monitoring protocols detailed in the
next section.
3. Monitoring:
is my process under control?
In regard to foreign material controls, monitoring
refers to frequent, ongoing performance tests designed to assess whether any
changes have taken place since the last test that could impact the performance
of an inspection device.
Monitoring
is a routine protocol carried out multiple times per shift, usually at the
beginning and end of a shift and whenever a product or batch is changed over. According
to IFS Food V7, monitoring consists of “a planned sequence of observations or measurements
of control parameters.” Such observations and measurements include, amongst
others:
ensuring the device is operating according to the
correct settings
running a series of test pieces thru the device to
ensure they are rejected
ensuring
the catch basin for rejected products has been emptied and nothing is
obstructing the ejection chute
Monitoring processes must also be documented,
though not with the same exhaustiveness required in the verification process.
The importance of testing product inspection systems
While validation, verification and monitoring are distinct
testing phases, all three phases are interconnected and serve broader food
safety goals. These include, amongst others:
Ensuring
food industry businesses implement contaminant detection technology that is
appropriate and effective for their products and processes
Ensuring
contaminant detection technology is consistently calibrated to perform with the
necessary sensitivity
Promptly
identifying variables that may impact the performance of a detection device, enabling
businesses to make adjustments accordingly
Enabling
thorough, ongoing documentation of food safety protocols
Reducing
the number of false rejects and thus the volume of wasted food
Reducing
the risk of undetected contaminants which could lead to costly product recalls
How to test your metal detectors and x-ray
inspection systems
Monitoring the performance of your product
inspection device is not only necessary in compliance with food safety
standards, it is also essential for protecting your customers and your brand.
The performance and sensitivity of your device can change over time and so
thorough controls can help you identify and correct minor issues before they
escalate.
Here is an overview of the steps involved in
regular performance monitoring for metal detectors and x-ray systems:
1.
Select a representative range of test pieces
Control procedures for x-ray inspection and metal
detection devices should use a range of test pieces that are representative of
the risks inherent in your process. Amongst these test pieces should be a few
that represent the worst-case scenario: the smallest, most difficult to
identify particles that could be present in your products.
X-ray and metal detector test pieces come in a
variety of formats (cards, sticks, cubes, balls, etc.), materials (FE, NFE,
V2A, etc.) and sizes, each of which are suitable for different processes and
applications.
2.
Use the correct test packaging & positioning
In the case of packing and filling lines, test
pieces should be placed inside the same type of packaging as your products, be
they glass jars, plastic trays or tin cans. Additionally, some test pieces
should be placed inside the packaging in positions where the device sensitivity
is at its lowest, such as the very centre of the detector.
3.
Select the appropriate control procedures
When it comes to control procedures, the number of
tests you run, the frequency with which you run them and types of contaminants
you test for are ultimately dependant on the requirements with which you must
comply and the level of risk your company is willing to tolerate.
One of the quickest and most basic control
procedures involves placing a series of test pieces (FE, NE, V2A) at different
positions (front, middle, back) in three packages one after the other. These packages
should be spaced at normal distances and flow thru the metal detector at normal
operating speeds to test whether the device can reliably eject all three
packages in succession.
This procedure may be combined with other, more
extensive procedures performed at different intervals.
4.
Establish intervals for testing
As part of routine monitoring, controls should be
carried out at the following times:
At
the beginning and end of a shift or production cycle
At
regular intervals during a product cycle, such as once every hour
Immediately
following a batch or product changeover
After
the settings on the device have been changed
After
locating and correcting errors on the device
After
maintenance or servicing on the device
5.
Document your tests results in compliance with
requirements
Different distribution networks, food safety
standards and legal authorities have different standards for the documentation
of ongoing performance controls. Sophisticated product inspection technology is
equipped with software that can be programmed to automatically log and send
test results to the responsible parties.
Every food product and processing line is unique
and brings its own particular set of challenges for foreign material controls. Extensive
validation testing is necessary to choose a contaminant detection device that will
reliably protect your products and ongoing verification and monitoring are
necessary to ensuring the device continues to perform as expected. Because the
ongoing testing of equipment performance requires a significant amount of time
and resources, contaminant detection technology should be designed to simplify
control procedures for companies.
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