Effects of autoclaving and high pressure on allergenicity of hazelnut proteins

Abstract

BackgroundHazelnut is reported as a causative agent of allergic reactions. However it is also an edible nut with health benefits. The allergenic characteristics of hazelnut-samples after autoclaving (AC) and high-pressure (HHP) processing have been studied and are also presented here. Previous studies demonstrated that AC treatments were responsible for structural transformation of protein structure motifs. Thus, structural analyses of allergen proteins from hazelnut were carried out to observe what is occurring in relation to the specific-IgE recognition of the related allergenic proteins. The aims of this work are to evaluate the effect of AC and HHP processing on hazelnut in vitro allergenicity using human-sera and to analyse the complexity of hazelnut allergen-protein structures.MethodsHazelnut-samples were subjected to AC and HHP processing. The specific IgE- reactivity was studied in 15 allergic clinic-patients via western blotting analyses. A series of homology-based-bioinformatics 3D-models (Cora 1, Cora 8, Cora 9 and Cora 11) were generated for the antigens included in the study to analyse the co mplexity of their protein structure. This study is supported by the Declaration of Helsinki and subsequent ethical guidelines.ResultsA severe reduction in vitro in allergenicity to hazelnut after AC processing was observed in the allergic clinic-patients studied. The specific-IgE binding of some of the described immunoreactive hazelnut protein-bands: Cora 1 ~18KDa, Cora 8 ~9KDa, Cora 9 ~35-40KDa and Cora 11 ~47-48 KDa decreases. Furthermore a relevant glycosylation was assigned and visualized via structural analysis of proteins (3D-modelling) for the first time in the protein-allergen Cora 11 showing a new role which could open a new door for allergenicity-unravellings.ConclusionHazelnut allergenicity-studies in vivo via Prick-Prick and other means using AC processing are crucial to verify the data we observed via in vitro analyses. Glycosylation studies provided us with clues to elucidate, in the near future, mechanisms of the structures that contribute to hazelnut allergenicity, which thus, in turn, help alleviate food allergens.

Hazelnut Allergens: Molecular Characterization, Detection, and Clinical Relevance

“…As for Cor a 1, the allergenicity of Cor a 8 was significantly affected when submitting hazelnuts to high temperatures and wet processing, such as autoclave (121ºC and 138ºC, for 15 and 30 min), since autoclaving induces the disorganisation of almost all possible epitopes in this protein. The application of high pressure processing (300 to 600 Mba) to hazelnut samples did not affect the IgE-binding capacity of Cor a 8 in the test population (López et al, 2012). Like the profilins, the nsLTP are also considered pan-allergens, suggesting that these proteins are well spread throughout the nature.…”

“…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. Those loop regions are estimated not to be modelled due to their lack of stable structure, but they are predicted to exhibit linear epitopes located at the external faces of the protein and thereby being exposed to solvent.…”

“…Structure models for Cor a 1 proteins revealed that most part of the amino acid sequence is well organised, with loops located almost exclusively at the apical structures of beta-turns and thus being very influenced by the beta arrangement itself. López et al (2012) reported that the application of autoclave processing (121ºC or 138ºC, 15 or 30 min) to hazelnut samples allowed decreasing the allergenicity of Cor a 1, since the location of the epitopes is mainly dependent on the conformational structure of the protein, which is affected by heat treatment. This finding is in good agreement with data reported by Hansen et al (2003), stating that Cor a 1 allergenicity is highly influenced by the tri-dimensional conformation of the proteins.…”

“…As an alternative to thermal processing, new technologies such as high pressure processing have been exploited to evaluate their effect on the structural conformation of allergens and hence to decrease their allergenic activity (Mills et al, 2003). The application of high pressure processing with increasing pressures, ranging from 300 to 600 Mba, was performed aiming at testing its effect on the allergenicity of Cor a 1 proteins, though resultant allergenic profile remained the same as from raw hazelnuts (López et al, 2012).…”

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].…”