Celery belongs to the 14 allergens regulated in the EU 1829/2003 and 1830/2003 labeling regulation; therefore it has to be labeled as a food ingredient.
Celery is one of the more rare allergic compounds and might be found as a hidden allergen in various foodstuffs. Usually, it is used as a spice mixture in foods such as meat products, sausages, dressings or instant soups and can be present in processed convenient food in low concentration. All parts of the plant can be used for food preparation – the leaves as well as the stalk and the head. Since celery and parsley plants are very similar, a mismatch in the fields or during harvesting and processing may occur, resulting in cross-contamination. Due to the close botanic taxonomy of celery to other plants, the highly specific real-time PCR is currently the method of choice for detection and quantification of celery traces in food.