Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
Analysis of white and red wine trace proteomes via capture with combinatorial peptide ligand libraries (CPLL) is reported here. Most of the alcoholic beverages tested (all of Italian origin) were found to contain only traces of casein (on average from 20 to 60 µg/L, with a detectability of as low as 1 µg/L) and not any grape protein any longer, as they had been fined with bovine casein (surprisingly also red wines for which the typical fining agent is egg albumin). However, analysis of untreated white wine (Recioto, from Garganega grapes in the Veneto region) via CPLL capture indeed permitted to detect close to 100 unique gene products from the grapes, suggesting the possibility of proteotyping grand crus, i.e. those aged, high quality wines that should not be treated with fining agents. Thus the CPLL technique could become a formidable tool for traceability of beverages in particular and of foodstuff in general. For trace protein analysis, a new, most powerful CPLL methodology emerges: capture at pH=2.2 in 0.1 % trifluoroacetic acid (TFA) under the conditions mimicking reversed-phase mechanisms of adsorption.U radu su prikazani rezultati analize proteina u tragovima u crnim i bijelim vinima i uspoređeni pomoću datoteka rekombiniranih peptidnih liganada (CPLL). Ispitana su vina talijanskog podrijetla. U većini je uzoraka pronađen kazein u tragovima (prosječno od 20 do 60 µg/L, s pragom detekcije već od 1 µg/L), ali ni jedan protein iz grožđa, jer su sva vina bila pročišćena goveđim kazeinom, uključujući i crna vina koja se obično pročišćuju albuminom iz jaja. Međutim, analizom netretiranog bijelog vina (Recioto iz grožđa sorte Garganega, regija Veneto) pomoću datoteka rekombiniranih peptidnih liganada opaženo je gotovo 100 jedinstvenih produkata gena iz grožđa, što omogućava karakterizaciju proteoma vina grand cru, visokokvalitetnih odležanih vina koja inače ne treba pročišćavati. Stoga bi datoteke rekombiniranih peptidnih liganada mogle poslužiti kao odličan alat za otkrivanje proteina u tragovima u hrani i piću. Novom metodom CPLL pri pH=2,2 u prisutnosti 0,1 % trifluorooctene kiseline omogućena je analiza proteina u uvjetima koji oponašaju mehanizme njihove adsorpcije pri kromatografiji obrnutih faza
