Toward Hypoallergenic Therapeutic Foods: Preliminary Proteomic Characterization of Treated Hazelnut Samples

Hazelnut (HZ) allergy is very common, representing a significant public health issue in developed countries due to the severe immune reactions that might induce in sensitive individuals, including anaphylaxis, along with skin, respiratory, and gastrointestinal symptoms [1]. Based on the use of cutting‐edge methodologies like proteomics and genomics, researchers have identified several hazelnut proteins causing allergic reactions in sensitive individuals [2]. These proteins are often stable and difficult to digest, therefore increasing the likelihood of causing an allergic reaction. Allergenicity of HZ proteins might also be affected by methods used for food preparation and some treatments have been optimized in order to modulate hazelnut allergenicity such as hydrolysis, fermentation or heating treatments [3, 4]. The development of innovative strategies based on physical treatments for HZ allergenicity reduction could pave the way for the production of hypoallergenic hazelnut-based therapeutic foods. Aiming at HZ allergenicity reduction, we optimized a protocol based on an autoclaving treatment of roasted hazelnut flours (HZFs). In particular, HZF samples as such or previously hydratated in water were autoclaved at 134 °C for 10 min. Untreated roasted HZF were also included as controls. After protein extraction in denaturing buffer, treated and un-treated samples were quantified by using Bradford assay and final extracts were characterized for their protein profile by SDS-PAGE. In parallel, HZF extracts underwent in-solution tryptic digestion and partial purification before proteomic analysis by UHPLC-HRMS using a Quadrupole-Orbitrap high-resolution hybrid platform. Mass spectrometry analyses, were acquired in positive mode using a Full-MS/dd-MS² acquisition mode, which alternates between full-scan MS spectra and data-dependent MS/MS spectra. The raw data generated from HR MS/MS analyses of the protein digests were further processed by Proteome Discoverer™ 3.3 software (Thermo Fisher Scientific, Waltham, MA, USA) to assess the impact of the applied treatments on the identified peptides and to evaluate chemical modifications induced by the processing. Finally, the residual allergenic potential of HZF samples was investigated by in-silico analysis of allergenic epitopes using the Immune Epitope Database (IEDB), in order to provide insights into potential changes in HZ allergenicity upon the processing applied. . Preliminary results revealed noticeable differences between untreated and treated hazelnut samples, mostly in terms of residual protein amount and peptide profiles. Notably, a total of 261 peptides were identified with only 4 allergenic epitopes retained belonging to Cor 8 and Cor 9 found in hydratated and autoclaved HZFs. These findings highlight the potential of the applied treatments to modulate HZ protein composition and the likelihood to cause a reduction of HZ reactivity, also underscoring the promise of this approach for the development of hypoallergenic or therapeutic hazelnut-based products.