Effect of the Strawberry Genotype, Cultivation and Processing on the Fra a 1 Allergen Content

• Main Authors: Elisabeth Kurze, Vanessa Kock, Roberto Lo Scalzo, Klaus Olbricht, Wilfried Schwab
• Format: Article
• Language: English
• Published: MDPI AG 2018-07-01
• Series: Nutrients
• Subjects: strawberry; food allergy; Fra a 1; pathogenesis-related proteins; indirect competitive ELISA
• Online Access: http://www.mdpi.com/2072-6643/10/7/857

Birch pollen allergic patients show cross-reactivity to vegetables and fruits, including strawberries (Fragaria × ananassa). The objective of this study was to quantify the level of the Fra a 1 protein, a Bet v 1-homologous protein in strawberry fruits by a newly developed ELISA, and determine the effect of genotype, cultivation and food processing on the allergen amount. An indirect competitive ELISA using a specific polyclonal anti-Fra a 1.02 antibody was established and revealed high variability in Fra a 1 levels within 20 different genotypes ranging from 0.67 to 3.97 µg/g fresh weight. Mature fruits of red-, white- and yellow-fruited strawberry cultivars showed similar Fra a 1 concentrations. Compared to fresh strawberries, oven and solar-dried fruits contained slightly lower levels due to thermal treatment during processing. SDS-PAGE and Western blot analysis demonstrated degradation of recombinant Fra a 1.02 after prolonged (>10 min) thermal treatment at 99 °C. In conclusion, the genotype strongly determined the Fra a 1 quantity in strawberries and the color of the mature fruits does not relate to the amount of the PR10-protein. Cultivation conditions (organic and conventional farming) do not affect the Fra a 1 level, and seasonal effects were minor.