Going Nuts for Nuts? The Trace Proteome of a Cola Drink, as Detected via Combinatorial Peptide Ligand Libraries

The "invisible" proteome of a Cola drink, stated to be produced with a kola nut extract, has been investigated via capture with combinatorial peptide ligand libraries (CPLL). Indeed, a few proteins in the M(r) 15-20 kDa range could be identified by treating large beverage volumes (1 L) and performing the capture with CPLLs at very acidic pH values (pH 2.2) under conditions mimicking reverse-phase adsorption. Ascertaining the presence of proteins deriving from plant extracts has confirmed the genuineness of such beverage and suggests the possibility of certifying whether soft drinks present on the market are indeed made with vegetable extracts or only with artificial chemical flavoring.