Investigation of allergen peptides and their heat stability using proteomics in almond and hazelnut

Food allergy is a hypersensitive reaction of the human immune system to consumed food. Although tree nuts such as hazelnuts and almonds have an important place in nutrition due to their positive effects on health, they can cause food allergy reactions. Today, the only way to prevent food allergy is to avoid consuming foods containing allergens. Despite all precautionary and legal regulations, misleading recall and detection of alerts in cross-contaminated products pose significant risks in food security. For this reason, investigation of allergens in food products is important in terms of ensuring food safety and protecting consumer health. In this study, it is aimed to determine the peptide sequences of allergenic proteins in hazelnut and almond using proteomics technique. After protein extraction and enzymatic digestion, unroasted hazelnut and almond samples were analyzed by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q/TOF/MS). Mass spectrum data were searched in the databases and allergen peptide sequences were determined for almond and hazelnut. To investigate the thermal stability of allergen peptides, almond and hazelnut samples were roasted at 130℃, 150℃, 170℃ for 15 and 30 minutes and two heat resistant peptides were selected to detect hazelnut and almond allergen in food samples. The analysis of spiked cake and ice cream samples gave limit of detection of 10 ppm for almond and hazelnut. Additionally variations of allergen peptides were investigated in various hazelnut and almond varieties growing in Turkey. Although no difference found in allergen composition of different varieties, concentration of marker peptides in hazelnut and almond varieties were found statistically different (p<0.01).