Proteomic Investigation of Hazelnut Allergen Profile upon Thermal and Mechanical Processing

Hazelnuts are recognized as one of the most frequent cause of food-induced allergic reactions [1,2], and their allergenic potential can be influenced by processing methods such as roasting and creaming [3]. This study investigated the effects of thermal (roasting) and mechanical (creaming) processing on the hazelnut protein profile and allergenic potential, using an integrated approach combining SDS-PAGE and high-resolution mass spectrometry-based proteomics. Protein extracts were obtained from raw and roasted hazelnuts, as well as from hazelnut pastes derived from both raw and roasted nuts, following a defatting step. SDS-PAGE analysis revealed noticeable differences in the protein profiles between raw and processed samples, particularly within the 40–65 kDa range, where specific bands showed changes in intensity and integrity after roasting. Immunoblotting with sera from hazelnut-allergic individuals identified several IgE-binding bands around 60, 45, 30, and 23 kDa. These reactive bands were excised, digested with trypsin, and analyzed by LC-HRMS/MS. Major hazelnut allergens—Cor a 9, Cor a 11, and Cor a 14—were identified in all sample types. Notably, Cor a 9 and Cor a 11 remained detectable in roasted and creamed samples, suggesting these allergens maintain structural stability despite processing. Bottom-up proteomics confirmed the presence of allergens and revealed processing-related peptide modifications. Immunoblotting showed that IgE-binding activity persisted after processing. While roasted hazelnuts and both types of paste shared similar IgE-reactive profiles, raw hazelnuts displayed unique bands, suggesting that processing alters protein conformation but does not eliminate allergenicity. In conclusion, the data demonstrate that neither roasting nor creaming significantly reduces hazelnut allergenicity. The persistence of major allergens post-processing highlights the importance of advanced analytical strategies for allergen detection and the need for accurate food labeling and risk assessment to ensure consumer safety [1–3]. References List reference quoted sequentially in the text and marked as [1]. Reference text 10 pts. Journal title in italics. Paper title is not requested. 1. G. C. Spolidoro et al., (2024) Allergy, 79(2), pp 302-323. 2. A. Luparelli et al., (2022) Foods, 11(5), 728. 3. E. De Angelis et al., (2022) Nutrients, 14(4), 874.