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be validated again for any different formulation even if run on the same equipment. By employing several procedures
simultaneously, companies may be able
to validate that visually clean (or ATP
or general protein testing) is a suitable
alternative procedure. In the case of particulates, visually clean should always be
used as an additional approach, because
the allergen swabs will test positive only
if the swabbed area happens to contain
a particle. Validation test results must be
saved as documentation for auditors.
Once the SSOP for a particular formulation on a specific line is validated,
further allergen testing is not needed on
each subsequent occasion. However,
approaches must be developed to verify
that the SSOP was applied each and every time. Visual inspections, ATP testing
or general protein testing can be used
for verification purposes.
The SSOP should periodically be
revalidated. Certainly the SSOP should
be validated again when anything
changes—ingredients, ingredient supplier, formulation, equipment matrix,
processing conditions, SSOP parameters, even changes to the allergen test
kit. Under stable manufacturing conditions, the SSOP should still be revalidated periodically, but the periodicity
is not specified. Revalidation should be
done more frequently (perhaps every 6
months) if the formulation is manufactured regularly. More frequent revalidation may be desirable as experience is
gained with this SSOP and its use on a
particular line for a particular formulation. As time goes by, the degree of confidence in the suitability of the SSOP
for allergen control will increase and
you can revalidate less frequently.
The ultimate test of the adequacy
of the allergen control program would
be a test for residues in the finished
product using quantitative ELISA.
Of course, testing of finished product
should be done only after a validated
SSOP has been developed when you
are reasonably confident that no undeclared allergen will be detected in the
finished product. Finished product test-
occasion when the SSOP is revalidated
using the swab testing approaches.
Qualitative ELISAs can also be used
to test the final rinse water from clean-in-place systems. The final rinse water
will likely be quite dilute. Particularly in
this case, finished product testing is recommended to ensure that no detectable
residues are present.
Qualitative ELISA can be extremely
sensitive in some situations. Small areas
are often swabbed. Any protein/allergen
residue on the swab is then released into
a small volume of extraction solution
before testing with lateral flow strips.
While positive test results may be found
on equipment areas that are difficult
to clean, detectable residues may not
always be found in finished product.
The volumes of product flowing down a
manufacturing line in many processing
facilities are quite large. The residues
remaining on the equipment would be
considerably diluted by the subsequent
product. Thus, finished product testing
can sometimes reveal that occasional
positive swab test results on equipment
surfaces are still tolerable. Of course,
great caution should be exercised in interpreting such results and the possible
presence of particulates could be especially worrisome.
Recommendations for Testing
FARRP advocates the use of qualitative ELISAs often in combination with
quantitative ELISA testing of finished
product to validate allergen control approaches. Additionally, several cautions
should be emphasized as this approach
and ensure that the qualitative ELISA is suitable for your needs.
companies. Not all swabs are cre-
ated equal. Cheaper swabs may not
remove protein/allergen as readily
from equipment surfaces. Cheaper
swabs may not release that protein/
allergen into the extraction solution
for the ELISA test. Q-tips® do not
work well in our experience. The
plastic rods of the inexpensive swabs
are sometimes manufactured from
recycled milk cartons, which can
cause false positives for milk.
Joseph L. Baumert, Ph.D., is assistant professor in
the department of food science & technology and
codirector of the Food Allergy Research and Resource
Program at the University of Nebraska, Lincoln.
Steve L. Taylor, Ph.D., is professor in the department of food science & technology and codirector of
the Food Allergy Research and Resource Program at
the University of Nebraska, Lincoln.