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

Abstract

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 trisÁ glycine buffer at 458C 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 SDSÁPAGE. Fresh and roasted (10 min at 1708C) 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.

A systematic review of the effect of thermal processing on the allergenicity of tree nuts

“…A similar phenomenon was reported for almond Pru du 1 . In contrast, nsLTPs and seed storage proteins in hazelnut and almond appeared very stable . Studies examining the effect of thermal processing on the allergenicity of cashew nut, Brazil nut, pecan nut, walnut and pistachio were scarce and limited in their scope.…”

“…IgE binding to roasted and unroasted hazelnut was comparable in two different studies: two patients with severe hazelnut allergy [180°C, 15 min, by ELISA (enzyme‐linked immunosorbent assay)] and five patients sensitized to Cor a 9 (±170°C, 10 min, using ELISA and immunoblot). Intact Cor a 9 was detected in roasted hazelnut paste . Another study showed that Cor a 9 and Cor a 11 and an allergen <14 kD (Cor a 14) were stable after roasting at 185°C for 15 min .…”

“…Dooper et al. found a decrease in detection of a Cor a 9 using ELISA and immunoblot after storage of more than 6 months, likely due to loss of solubility of the protein than a true decrease in allergenicity.…”

Hazelnut Allergens: Molecular Characterization, Detection, and Clinical Relevance

“…However, even after being submitted to high temperatures, the secondary structures of these proteins remain unchanged or with minor modifications, suggesting that the characteristic beta-barrel motif is highly stable. Preliminary studies on raw hazelnuts submitted to dry heat treatment at 170ºC, indicated that the protein profile and the amount of Cor a 9 was not affected until after 20 min of roasting (Dooper et al, 2008). More recently, López et al (2012) verified that Cor a 9 is a highly well-structured protein, enriched by a beta-sheet core and with long unstructured loops.…”

Effects of the Varietal Diversity and the Thermal Treatment on the Protein Profile of Peanuts and Hazelnuts

“…So far, only a few papers were reported on the evaluation of food processing effects on hazelnut proteins, and most of them focused on the fate of allergenic proteins upon thermal treatment. In particular, Cor a 1, Cor a 2, and Cor a 8 were proved to be thermolabile proteins [40][41][42], whereas Cor a 9 and Cor a 11 allergens were considered more thermostable [43][44][45]. In addition, Cor a 9 and Cor a 11, under particular processing condition, could generate Maillard reactions and advanced glycation end products [44,45].…”