The apple allergy in Northern Europe is a cross-reaction to the birch pollen allergy. No correlation between the allergenicity of an apple variety and the content of the major apple allergen Mal d 1, a homologue to the Bet v 1 allergen in birch, could be found using ELISA, so far. Therefore, an impact of polyphenols and/or differences in the isoallergen profile are discussed. To allow a more detailed analysis of the Mal d 1 content and the isoallergen profile, a mass spectrometric method was applied to investigate differences in the flesh and peel of 10 traditional varieties and 10 commercial breeds. The data revealed often, but not always, lower Mal d 1 contents in traditional varieties grown in orchard meadows, which was more obvious in the flesh. Differences among the peels were less pronounced. A closer look at the individual isoallergens 1.01, 1.02, 1.03, and 1.06 reveals an increased impact of the minor isoallergens 1.03 and 1.06 on the allergenic potential, since commercial breeds like Braeburn, Santana, and Holstein Cox, which are considered to have reduced allergenic potentials, were characterized by low levels of these isoallergens.
Keywords: Malus domestica L. Borkh; apple allergy; bottom-up proteomics; isotope dilution analyses; marker peptides.