Antibody binding to hazelnut (Corylus avellana) proteins: the effects of extraction procedure and hazelnut source

The quality of an applied protein extract is important in both serological and in vivo diagnosis of allergy, and for allergen detection methods. In the present study the effects of the extraction procedure and hazelnut source on antibody binding to hazelnut (Corylus avellana) proteins were investigated. An overnight extraction procedure in tris-glycine buffer at 45°C was compared to a quick, vigorous extraction in a tris buffer at room temperature (RT). Antibody binding was studied by the use of polyclonal antiserum, a monoclonal antibody against the pollen-unrelated allergen Cor a 9, and human IgE from hazelnut allergic individuals. The extraction procedure, as well as the storage time and degree of processing of hazelnuts affected the protein constitution of the extract, as visualised by SDS-PAGE. Fresh and roasted (10 min at 170°C) hazelnuts generally contained a higher amount of intact hazelnut proteins than elder (>6 months) raw hazelnuts stored at RT. The time of storage of raw hazelnuts was inversely related to the amounts of Cor a 9 and IgE-binding proteins. In general, a rapid extraction procedure increased the efficacy of protein extraction and antibody-binding capacity to the proteins compared to an overnight extraction protocol. The present study indicates that for the production of hazelnut protein extracts, the use of fresh hazelnuts is important. A quick, vigorous extraction in a tris buffer might contribute positively, at least for extraction of Cor a 9.