Setup of a procedure for cider proteins recovery and quantification

Development of a sample preparation approach for the analysis of fining agents in wines by liquid chromatography with tandem mass spectrometry

During winemaking a wide variety of processing aids such as albumin, caseinates and lysozyme are often used. These proteins are considered allergenic and could become a human health risk in susceptible individuals. In our knowledge, there are no methods published for the analysis of these three proteins simultaneously by liquid chromatography with tandem mass spectrometry, with electrospray ionization. Therefore, in this work, a sample preparation approach for the analysis of α-casein, β-casein, albumin and lysozyme, in a single run, was performed and compared with published data. Through a pH adjustment, combining the use of cellulose ester membranes, a precipitation with organic solvents and a final concentration/clean-up, we achieved recovery values from 90.7 to 108.6%. The method was validated, showing determination coefficients R² ≥ 0.99. This method was able to quantify proteins even at lower levels (limits of quantification from 0.01 to 0.25 mg/L) than the current legal limits.

Analysis of allergenic residues in wines by triple quadrupole LCMS

During the winemaking are used technology coadjuvants, between them: albumin, caseinates and lysozyme. These compounds have great oenological properties, however, the presence of their residues can represent risks to people who are allergic to them because they are derived from eggs and milk. Mass spectrometry methods enables unambiguous determination of allergenic proteins at low levels in wines. Therefore, the aim of this study was to determine the concentrations of ovalbumin, alpha-casein, beta-casein and lysozyme in experimental wines treated with different concentrations of them by triple quadrupole liquid chromatography mass spectrometry with Jet Stream Electrospray Ionization (ESI). The wines were elaborated and treated with different concentrations of albumin, lysozyme and potassium caseinate. Bentonite and decantation were used for the removal of the fining agents. The quantification limits (LOQ) for ovalbumin, a-casein, b-casein and lysozyme were: 0.002 mg/L, 0.24 mg/L, 0.75 mg/L and 0.04 mg/L, respectively. Non residues of the proteins were identified in the experimental wines treated with the different amounts of potassium caseinate, albumin and lysozyme, analyzed in this study. These results provide an evidence of the absence of residues of caseinate, albumin and lysozyme in the concentrations tested in the wines if good treatment practices are followed.

Hen egg white lysozyme is a hidden allergen in Italian commercial ciders

Hen egg white lysozyme (HEWL) is an enzyme used in alcoholic fermentation for its ability to control the growth of Gram-positive and spoilage bacteria, without inhibiting yeast growth, and it allows a reduction in the use of sulphur dioxide. Nevertheless, considering the potential allergenicity of this protein, the presence of HEWL should be declared on the label of the final product. In this work, we analysed 18 commercial Italian ciders by LC-MS/MS and found traces of HEWL in 12 samples without label declaration. We used Western blot and enzyme-linked immunosorbent assay (ELISA) to verify the immunological activity of HEWL, and to quantify its content in the ciders. Two out of 18 samples were found to be positive both by immunoblot and ELISA. The results indicate the requirement of a more stringent control of commercial ciders and the need of label declaration for ciders treated with such compounds.