*2.6. Evaluation of the Presence of Milk/Egg Traces in Biscuits Labelled without Milk and Egg*

Biscuits samples used in OFC and SPT were stored at −80 ◦C in powder form and analyzed by immunoblot and Liquid Chromatography–ElectroSpray–tandem Mass Spectrometry (LC-ESI-MS/MS) for the detection of very small amounts of milk and egg allergens. The samples underwent the proteomic workflow for allergen detection and quantification as depicted in Figure 1. We adopted two different strategies in order to assess the contamination by egg and milk allergens:

