Proteomics of wine additives: Mining for the invisible via combinatorial peptide ligand libraries

Combinatorial peptide ligand libraries (CPLLs) have been adopted for harvesting and identifying traces of casein (used as a fining agent) present in white wines. Although minute amounts (200 µL) of CPLL beads are added to the entire content of a wine bottle (750 mL), they are able to sequester with high efficiency (up to 80%) residual traces of casein, permitting a signal “amplification” of at least 5000-fold. It is here demonstrated that as little as 1 µg/L of casein can be efficiently detected in white wines, a major improvement over previous investigations in which the lower detection limit had been estimated at 100 µg/L. The fact that such very low levels of fining agents can still be detected in treated white wines should be taken into consideration by winemakers in labelling their products and by EC rulers in issuing proper regulations.

Graphical abstractAs little as 1 µg/L of casein added as fining agent can be efficiently detected in white wines via capture with combinatorial peptide ligand libraries.Figure optionsDownload full-size imageDownload high-quality image (78 K)Download as PowerPoint slide