PCR methods, which are more sensitive and detect the DNA molecules of these
allergens, can be used in raw and cooked products and are not affected by the heating
process because DNA typically remains intact after being exposed to the cooking
temperatures of most foods. PCR methods are also not subject to the typical
interferences that inhibit ELISA-based methods because the DNA is purified away from
these inhibitors before analysis begins. PCR, however, cannot be used on all products.
Oils and other products, such as milk or egg whites, cannot be tested by PCR because
they do not contain DNA. These products must instead be tested using ELISA-based
methods for detection.