Impact of Cultivation and Storage Conditions on Total Mal d 1 Content and Isoallergen Profile in Apples

The allergen Mal d 1 is often responsible for adverse allergic reactions to fresh apples in northern and central Europe. The Mal d 1 content and isoallergen profile are proposed to have an impact on the allergenic potential of the fruit. Therefore, we investigated the impact of the cropping system on the Mal d 1 content and the isoallergen profile of apples by mass spectrometry for the varieties 'Jonagored' and 'Topaz'. To monitor the impact of storage time and conditions, apples of the varieties 'Santana' and 'Jonagold' were stored for up to 12 weeks under regular air (RA), under RA in combination with 1-methylcyclopropene (1-MCP) treatment, and under a controlled atmosphere (CA). The impact of the cropping system (integrated production vs organic production) was negligible. However, a significant increase in the Mal d 1 content during storage was observed, being higher when stored under CA conditions than under RA conditions. An additional treatment with 1-MCP prior to RA storage drastically reduced the level of Mal d 1 expression in the flesh of the apples by ∼50%. Furthermore, the content of isoallergens 1.03 and 1.06 increased disproportionately under CA conditions, while under RA conditions, only isoallergen 1.06 was affected. With the 1-MCP treatment, no changes in the isoallergen profile were obvious.