Rapid Shotgun Proteomic Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry-Based Method for the Lupin (Lupinus albus L.) Multi-allergen Determination in Foods

Allergy to lupin is a growing food safety problem because this legume, increasingly exploited in the food industry, is one of the allergens that, according to law, must be declared on the labels of food products in the European Union. In this context, a rapid targeted proteomic approach based on liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis was proposed and aimed to unequivocal confirmation and reliable determination of the major lupin allergens, i.e., conglutins, in pasta and biscuits. Detected concentrations were around 1 mg of lupin/kg of pasta and biscuits, proving the capabilities of the MS-based method in terms of the sensitive allergen screening method. Good precision was observed in terms of both intra-and interday repeatability, with relative standard deviation (RSD) lower than 23%. Recoveries from 95 +/- 10 to 118 +/- 12% and from 103 +/- 1 to 110 +/- 12% ranges were calculated for biscuits and pasta, respectively. Finally, the applicability of the devised method was investigated by analyzing market samples containing lupin and samples that may possibly contain traces of lupin deriving from cross-contamination between products and production lines.