Food Processing does not Abolish the Allergenicity of the Carrot Allergen Dau c 1 : Influence of pH, Temperature and the Food Matrix

Scope: The major carrot allergen Dau c 1 belongs to the group of pathogenesis related class 10 (PR‐10) proteins and is homologous to the birch pollen allergen Bet v 1. In contrast to most other PR‐10 allergens, Dau c 1 can elicit Bet v 1 independent sensitisation. Although Dau c 1 is considered heat labile, allergic reactions against cooked carrots are possible. Methods and Results: The pH and temperature stability as well as the allergenic potential before and after treatment of purified natural (n)Dau c 1 and different recombinant (r) isoallergens was investigated: rDau c 1.0104, rDau c 1.0105, rDau c 1.0201, rDau c 1.0301. All proteins except rDau c 1.0201 were able to refold at physiological pH. pH conditions around the pI (4.4 – 5.5) or the presence of the carrot matrix reduced the refolding capacity. Below the pI, most isoallergens were heat resistant and still able to cause mediator release, indicating allergenicity. Moreover, cooked carrot extract was still able to provoke mediator release due to remaining soluble Dau c 1. Conclusions: Patients allergic to carrots should avoid processed carrot containing foodstuff because heating or pH treatment do not completely abolish the allergenicity of Dau c 1.