Directive EC 2003/89/EC of the European Parliament and of the Council states that certain
ingredients and products derived there of known to cause allergen reactions must always be
declared. Furthermore labelling is mandatory irrespective of the amount included. The National
Food Administration therefore needs methods for monitoring the presence of allergens in food.
Methods already exist for most of the allergens on the EU-list, but an operational method for
celery (Apium graveolens) is missing.
A specific DNA-method was developed, based on TaqMan Real-Time PCR with the celery
mannitol dehydrogenase gene as target sequence. The analysis was started with homogenisation
of the sample followed by extraction of DNA. The Real-Time PCR method was shown to be
specific for celery, producing a 113 bp fragment with two celery varieties and negative results
with other closely selected species commonly present together with celery in food products (12
samples). The detection limit was 2-20 pg DNA, which corresponds to 1-7 haploid genome
copies. When evaluated with model samples of celery in meat, a detection limit of less than
0,01 % was determined. When used to analyse food products from the market, six out of seven
products declared to contain celery were correctly identified as positive.