Effect of tomato variety, cultivation, climate and processing on Sola l 4, an allergen from Solanum lycopersicum

Summary

Tomatoes (Solanum lycopersicum) are one of the most consumed vegetables worldwide.
However, tomato allergies in patients suffering from birch pollen allergy occur frequently.
Due to highly similar protein structures of the tomato allergen Sola l 4 and the major birch
pollen allergen Bet v 1, patients cross-react with allergenic proteins from tomato as well as
other fruits or vegetables. The aim of this study was to quantify Sola l 4 in various tomatoes
differing in color, size and shape for identification of varieties with a reduced allergen level.
Therefore, an indirect competitive ELISA using a specific polyclonal Sola l 4 antibody was
developed. In addition, two varieties, both cultivated either conventionally or organically and
furthermore dried with different methods, were analyzed to investigate the influence of the
cultivation method and processing techniques on Sola l 4 level. Within 23 varieties, Sola l 4
content varied significantly between 0.24 and 1.71 μg Sola l 4/g FW. The tomato cultivars
Rugantino and Rhianna showed the significantly lowest level, whereas in cultivars Farbini
and Bambello the significantly highest concentration was determined. Drying of tomatoes in
the oven and by sun resulted in a significant decrease. The thermal instability was verified
for the recombinant Sola l 4 emphasizing the results for the native protein in dried tomato
samples. Overall, the Sola l 4 content is cultivar-dependent and no correlation between
color and Sola l 4 amount was found. During the drying process of tomatoes Sola l 4 level
was significantly reduced due to thermal instability. Growing conditions have a minor effect
whereas seasonal effects show a more pronounced impact. These findings could extend
the knowledge about the allergen level of different tomato varieties and may help to improve
food safety to potentially increase the life quality of patients suffering from birch pollen
allergy.