Determination of the bovine food allergen casein in white wines by quantitative indirect ELISA, SDS-PAGE, Western blot and immunostaining.

This study describes the characterization of allergic bovine casein and caseinate fining agents by SDS-PAGE analysis and the development of a quantitative indirect ELISA for the detection of these substances in wines. The ELISA was applied to various experimental wines that were treated with different caseinate dosages and went through different processing steps and to a panel of commercial wines. Positive results were assured by SDS-PAGE, Western blot, and immunostaining. Comprehensive literature research was done to evaluate the demanded sensitivity of the ELISA. The results showed that alpha- and beta-caseins remain in some wines and are detectable. Estimated amounts were in the range or below an estimated no-observed adverse effect level (NOAEL) of 0.9 mg/L, but it was concluded that there is still an uncertainty about this NOAEL. Additional applied processing, referring to bentonite treatment and successive filtration, was determined to contribute to a significant decrease of casein residues in wines.