Decoloration of wine and subsequent enzymatic quantification of histamine

We would like to present a simple decoloration procedure for (red) wine and the subsequent enzymatic method for the specific quantification of histamine. The test kit for sample preparation contains three solutions that are used to decolorate wine by two simple precipitation steps within 15 min. The enzymatic test kit consists of a microtiter plate coated with two substrates and ready to use reagents (buffer, calibrators and enzyme histamine dehydrogenase). The determination is performed within 15 min and the measurement wavelength is 450 nm which is the common wavelength for ELISA procedures. The linear range is from 1 to 20 mg/L in the extracted sample (corresponding to 2.4–48 mg/L in wine) and the recovery is >85% in red wines and more than 90% in white and rose wines. The limit of quantification is calculated to 1 mg/L. Wines at this low histamine levels showed CVs of less than 7%. The assay shows a high precision with a relative within-lab reproducibility standard deviation of less than 7%. A method comparison between HPLC and the new enzymatic system revealed a very high degree of agreement. The enzymatic procedure contains no dilution steps, no washing steps like for an ELISA, and a clear defined end-point of the enzymatic reaction.