Validation by a Collaborative Interlaboratory Study of an ELISA Method for the Detection of Caseinate Used as a Fining A
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Validation by a Collaborative Interlaboratory Study of an ELISA Method for the Detection of Caseinate Used as a Fining Agent in Wine Patrizia Restani & Francesca Uberti & Chiara Tarantino & Cinzia Ballabio & Francesca Gombac & Erica Bastiani & Laura Bolognini & Francesco Pavanello & Roberta Danzi
Received: 4 March 2011 / Accepted: 30 June 2011 / Published online: 16 July 2011 # Springer Science+Business Media, LLC 2011
Abstract The clarification or fining of wine removes undesirable substances such as proteins, phenols, and tannin compounds that would cloud the wine and cause bitterness and astringency. Caseinates have useful fining properties, but their residues could present a risk for allergic subjects. A commercial kit that was developed to detect caseinates in food has been examined for its applicability to a wine matrix; it is sensitive to caseinates at concentrations as low as 1 ppm. The general characteristics of the caseinate assay, described below in detail, are as follows. It is a sandwich enzyme-linked immunosorbent assay (ELISA): the microplate is first coated with a specific anti-casein antibody; and after incubation with the wine sample, a secondary anti-casein antibody conjugated with horseradish peroxidase is added to form a sandwich. The antibodies have been tested for their immunoreactivity and the reproducibility of antigen recognition has been measured. An interlaboratory collaborative trial was
P. Restani (*) : F. Uberti : C. Ballabio Department of Pharmacological Sciences, Università degli Studi di Milano, via Balzaretti 9, 20133 Milano, Italy e-mail: [email protected] C. Tarantino : F. Gombac : E. Bastiani Euroclone SpA, via Figino 20/22, 20016 Pero, MI, Italy L. Bolognini : F. Pavanello : R. Danzi Unione Italiana Vini, via San Vittore al Teatro 3, 20123 Milano, Italy
organized to evaluate the performance of this ELISA method and its ease of use by laboratories routinely dealing with wine/food analyses. The results satisfy the criteria established by the International Organisation of Vine and Wine in the Compendium of International Methods of Analysis MA-EAS1-07-ETCOL. Keywords Fining agents . Caseinates . Milk allergens . ELISA
Introduction It is a common practice to add organic or inorganic substances to the must or wine to interact with elements responsible for turbidity and organoleptic imbalances Harbertson 2008; Morris and Main 1995). Unlike filtration, which can only remove particles, the clarification process removes soluble substances such as polymerized tannins, phenols, and undesirable proteins. Protein-clarifying agents have a positive charge at the pH of wine and generally react with polyphenols by forming hydrogen bonds between phenolic radicals and the peptide bonds of proteins. The complexes can then be filtered off. Included among the organic substances used in clarifying are some animal proteins known to have allergenic potential. Milk allergy, though rare in adults, can lead to severe, even dangerous illness (Sackesen et al. 2011). Potassium caseinate is a water
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