Detection of Cashew Allergens in Foods by Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry

A quantitative method for the detection of cashew allergens in foods was established based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Cashew samples were extracted, trypsinized, purified, and separated using an Easy nLC 1000 nano-liquid chromatograph, and then data were collected in the full-scan acquisition mode by quadrupole/orbitrap high-resolution mass spectrometry. The scanning results were analyzed by ProteinPilot software search against the UniProt protein database, and the peptide specificity was verified using the basic local alignment search tool (BLAST). Finally, six cashew specific peptides were selected, and actual samples were detected by UPLC-quadrupole/orbitrap MS in the multi-reaction monitoring (MRM) mode. The results showed that the proposed method had good linearity in the range of 0.005‒10 mg/mL with correlation coefficients (R²) greater than 0.99. The quantitation limit was 2.5‒5 mg/kg and 0.005‒0.01 mg/mL for solid-state and beverage matrices, respectively. The average recoveries were 82.5%‒109.9%, and the relative standard deviation (RSD) was not more than 8.9%. This method has high sensitivity and specificity, and it can be used for the detection of cashew allergens in six food substrates including biscuit, bread, cake, walnut cookie, chocolate and beverage.