Mass spectrometry detection of egg proteins in red wines treated with egg white Serena Tolin a, b , Gabriella Pasini a , Andrea Curioni a , Giorgio Arrigoni b, c , Antonio Masi a , Federica Mainente d , Barbara Simonato d, * a Dipartimento di Biotecnologie Agrarie, Università di Padova, Viale dell’Università 16, 35020 Legnaro (PD), Italy b VIMM e Venetian Institute of Molecular Medicine, Via G. Orus 2, 35129 Padova, Italy c Dipartimento di Chimica Biologica, Università di Padova, Viale G. Colombo 3, 35131 Padova, Italy d Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, 37134 Verona, Italy article info Article history: Received 22 March 2011 Received in revised form 10 June 2011 Accepted 16 June 2011 Keywords: Allergy Mass spectrometry Wine Egg Fining abstract The need of label declaration for egg proteins is temporarily suspended when they are used as a pro- cessing aid in winemaking, because of a lack of scientific data concerning their actual permanence as residual proteins in fined wines. The possibility to detect residual egg proteins in red wines treated with a commercial egg white preparation was studied. By using an immunochemical method residual egg proteins were detected in the experimental red wines only for doses of fining agent of 50 g/hL or higher, whereas no residual proteins were detected by this system in a commercial red wine. A simple method based on the recovery and identification of the wine fining proteins by liquid chromatography coupled with tandem MS (LC-MS/MS) in a gel-free approach was developed. This allowed the detection of egg proteins in red wines fined down to 5 g/hL of commercial egg white preparation and also in the commercial red wine. These results indicate that the analytical approach here suggested is superior to the immunochemical methods in detecting egg proteins in wines. Therefore hypersensitivity reactions after consumption of wines treated with egg proteins can be a real risk for egg- allergic people. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Wine fining is the process aimed to remove undesirable substances such as phenolic compounds in order to prevent colloidal precipitation and to reduce bitterness and astringency (Yokosuka & Singleton, 1995). Fining is commonly done by adding proteins to the wine such as gelatine, isinglass, milk casein and albumin from egg white (Boulton, Singleton, Bisson, & Kunkee, 1996). These proteins interact with polyphenols to form complexes which are removed from the wine by decanting, centrifugation or filtration. Neverthe- less, the complete elimination of the fining agents after this process can not be expected for sure and therefore their possible presence in the wine can be seen as a risk for the consumers allergic to the proteins used to treat the wine. For this reason, the European Union adopted the Directive 2003/89/EC, last amended by Directive 2007/ 68/EC which contains a list of allergenic substances, including egg and egg derivatives that, when present in foods, have to be declared on the label. Also in other countries, such as Australia, New Zealand and the United States, a similar regulation has been introduced (Weber, Steinhart, & Paschke, 2007). Nevertheless, the need of label declaration for those allergenic compounds is temporarily sus- pended when they are used as processing aids in winemaking, the reason being a lack of scientific data concerning their real presence or absence as residual proteins in fined wines (Directive 2000/13/EC, Directive 2003/89/EC, Directive 2005/26/EC, Directive 2007/68/EC, Regulation UE 2010/1266). Many red wines rich in tannins are treated with egg white for fining purposes. The doses used to this aim are usually in the range of 5e15 g of fining agent per hL of wine and egg white is used fresh or as a freeze-dried powder. Although the information on the composition and purity of the commercial egg based products is limited, egg allergens are present in those preparations maintain- ing their allergenic potential. As a matter of fact, IgE binding to egg white proteins after technological processes is preserved, indi- cating their stability (Mine & Zhang, 2002). Thus, if some egg proteins remain in the wine they represent a risk for egg-allergic subjects, which are estimated to be around 0.3% of the adult pop- ulation (EFSA, 2007). Although the rules developed for the protection of allergic consumers obviously need the availability of suitable methods for * Corresponding author. Tel.: þ39 (0)45 6835624; fax: þ39 (0)45 6835613. E-mail address: barbara.simonato@univr.it (B. Simonato). Contents lists available at ScienceDirect Food Control journal homepage: www.elsevier.com/locate/foodcont 0956-7135/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodcont.2011.06.016 Food Control 23 (2012) 87e94