1 Scope
This Technical Specification specifies an enzyme linked immunsorbent assay (ELISA)
method for the determination of hazelnut from food samples. In the ELISA the antibodies
bind to hazelnut proteins from the food sample. The result of the ELISA is given in
mg hazelnut/kg (ppm) because the calibrators consist of an extract of whole hazelnut.
Matrices like cereals, ice cream, cookies, chocolate, sausage, cottage cheese, yogurt
and salad dressing were validated by spiking experiments with a carboxymethylcellulose-suspension
containing hazelnut paste [2].
The monoclonal antibodies, raised against the whole aqueous extract of hazelnut, detect
proteins with approximate molecular weights of 14 kDa, 18 kDa, and 42 kDa. The antibodies
detect the major thermostable allergen Cor a9 (11S storage protein). Both antibodies
were evaluated by western blots with partially purified hazelnut extracts and purified
allergenic proteins.
The ELISA test method is commercially available 1 ) . The performance has been validated by an in house validation performed by the manufacturer.
All parameters of interest are indicated.
In addition, the ELISA was successfully validated by a collaborative study in order
to determine the interlaboratory reproducibility. This ring trial was organised by
the working group established by the Federal Office of Consumer Protection and Food
Safety (BVL) for the execution of § 64 of the German Food and Feed Code (LFGB) for
the determination of hazelnut content in dark chocolate. Fourteen German laboratories
participated in this collaborative study.