food hygiEnE & safEty 27
Immunoanalysis tool monitors
unwanted substances in food
Yuri Lebedin and Alexandr Grachev report on
and lateral flow rapid test can form immunoassay pairs
the development of an immunoanalysis tool
capable of detecting minor quantities of pork specific
antigens (down to 1ng/ml) in food extracts by means of
for monitoring foods from fields and farms to
routine laboratory immunoassays. The great advantage
the kitchen table.
of these assays is an extreme thermal resistance of target
epitope (up to 30 minutes at 300˚C).
oods, from raw materials to supermarket
Prolamins
F
shelves and kitchen tables, can be tested for Prolamins are the group of closely related storage
qualitative and quantitative determination proteins from the grains of cereals (wheat, rye, barley,
of normal or unwanted components – toxic oat and others) enriched by proline acid residues.
substances of different origin, hormones, vitamins and Prolamins are the major components of human
the components affecting product quality. nutrition; their processing is the pivotal part of bakery
Some population groups are also concerned about and beer production; many other food technologies use
specific properties of foods – the presence of allergens gluten for stabilisation, stiffening and forming.
– the components causing intolerances or which are To study the immunochemistry of prolamins, we have
prohibited by dietary or religious restrictions. developed a set of monoclonal antibodies for wheat
gliadin.
Methods of detection
The resulting antibodies, however, show broad
Methods of immunoanalysis mostly detect proteins, and variable reaction with other cereal species and
proteoglycans, polysaccharides, or low molecular weight electrophoretic groups of prolamins.
antigens (haptenes). Based on our anti-gliadin mAbs, we have constructed
Immunoassays, due to their comparative simplicity, a group of the assays for determination of different
can be used for broad screening of foods, leaving the prolamin varieties:
final decision for more accurate and sophisticated
methods. p Total gliadin kit based on two-site binding method
Moreover, some of immunoassay modifications and LMW Total gliadin kit based on single antibody
(for example, immunochromatographic rapid tests) competition principle – to be used for quantitative
are simple enough to be used outside laboratories, in determination of gliadin in ethanol extracts of foods and
kitchens. control of gluten-free foods, which is important for celiac
patients.
Fish
Fish is the only of the ‘big eight’ of most important food p Antibody XGY20 specifically binds gliadin of Triticum
allergens which is still not detected by commercial assays. aestivum but not Triticum durum species. The properties
Recently we have obtained a single monoclonal of this antibody enabled us to construct ELISA kit for
antibody X21 recognising heat-resistant muscle derived pasta quality evaluation, showing the consistent results
antigen for all species of finfish tested up to date. independently of pasta drying temperature.
The immunoassay, consisting of this monoclonal
capture and affinity purified rabbit polyclonal, reaches p Antibody XGY7 shows differential binding activity
subnanogram sensitivity from which it is essential to with barley sorts; it distinguishes between the sorts in
protect the allergics. individual grains and control barley for sort purity.
Other anti-prolamin mAbs of XGY family can be used
Pork
for more advanced applications, for example monitoring
Meat detection and meat speciation testing is especially of beer production, beer brand adulteration control,
important for some social and religious groups. For determination of wheat in rye bakery products, etc. p
example, the immunoassay for presence of pork may be
used for continuous control of foods. We have developed Enter 27 or ✔ at www.scientistlive.com/efood
the set of monoclonal antibodies which are able to
distinguish heat-resistant pork-specific epitopes on Yuri Lebedin is R&D Manager, Xema Co.Ltd., Moscow,
tropomyosin complex. Russia, and Alexandr Grachev is Senior Researcher, Xema Co
These antibodies being used in microplate ELISA Ltd, St Petersburg, Russia. www.xema-medica.com
www.scientistlive.com
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