Towards quantification of residual milk allergens in caseinate-fined white wines using HPLC coupled with single-stage Orbitrap Mass Spectrometry

Linda Monaci (1) , Ilario Losito (2) , Francesco Palmisano (2) , Michal Godula (3) , Angelo Visconti (1)

1 ISPA - Istituto Scienze delle Produzioni Alimentari
2 Chemistry
3 ThermoFisher

A method based on LC-ESI-High Resolution (HR)-MS analysis, using a single stage Orbitrap mass spectrometer, was developed for the quantification of casein allergens potentially present in white wines as a result of fining by caseinate. The method consists of i) extraction from the matrix by ultrafiltration, ii) digestion with trypsin and iii) detection/quantification of residual caseins, obtained by monitoring the LC-MS response of representative tryptic peptides (peak areas in extracted ion chromatograms). Method linearity was assessed first on caseinate solutions prepared either in water or in wine matrix (the ultrafiltration retentate of a protein-free white wine). Limits of detection (LOD) ranged from 0.1 to 0.3 µg/mL (S/N = 3) in water, and between 0.15 and 0.7 µg/mL in wine matrix, depending on the selected peptide. Method repeatability and reproducibility, meant as response variability (standard deviation) due to LC-MS analysis alone and to both enzymatic digestion and LC-MS analysis, were assessed on caseinate standard solutions in water and ranged from 5 to 12% and from 8 to 20%, respectively. A higher variability was usually observed for the peptide marker response in the case of matrix-matched samples, the only exception being peptide GPFPIIV from α-casein, the marker providing also the highest sensitivity. The method was finally applied to a casein-free white wine ("Greco di Tufo") fined with caseinate at different concentrations, after discarding the precipitate due to casein-wine components aggregation. Minimum detectable added caseinate concentrations (i.e. those corresponding to responses with S/N = 3) were estimated between 39 and 51 μg/mL, according to the peptide marker chosen. These limits are compatible with caseinate concentrations typically adopted for wine fining purposes. Moreover, a cross-check with the calibration performed in wine matrix led to estimate the concentration of dissolved caseinate to be in the low ng/mL range.

Mots clés: Life Sciences

Linda Monaci, Ilario Losito, Francesco Palmisano, Michal Godula, Angelo Visconti. Towards quantification of residual milk allergens in caseinate-fined white wines using HPLC coupled with single-stage Orbitrap Mass Spectrometry. Food Additives and Contaminants, 2011, pp.1. ⟨10.1080/19440049.2011.593191⟩. ⟨hal-00719820⟩