CCO 410 Wine Finishing

Copper Trials

Today was our first lab session and we began with a diagnostic test for reductive wine characters also known as a cu/cd test. This test can be used to deduce the type of reductive compounds that are causing the wine to have a reductive wine fault/character. The main sources of reductive wine characteristics are Hydrogen sulphide, Mercaptans, Disulphides and Dimethylsulphides. Each of these have a distinctive aroma and the cu/cd test is used to determine which on is present.

The reason this test works is because the compounds react with the different fining agents e.g. copper and cadmium salts. This test is useful as it can be used to determine the best course of action to remove the fault.

For this test we needed 250ml of 3 different wine samples that each had a different sulphide fault, 12 wine glasses and pipettes. The reagents we used were a copper sulphate solution and Cadmium Sulphates solution and ascorbic acid. The wine was filled into each glass (50ml), the glasses were labelled control, copper, cadmium and ascorbic acid. The fore mentioned agents were then added to the glasses. Then each glass was sniffed but not tasted and any difference was observed. A interpretation table was provided and from the we were able to infer what type of reductive compound was present in the wine.

The trial was tough as we had to use our noses to uncover what compound was present and my nose is not the best. I proceeded to find Dimethylsulphide in the first wine, however got a bit lost with the other two wines where I thought there was Disulphides and Mercaptans and it turned out to be Mercaptans and H2S.

Overall I found this trial quite interesting but you would definitely need to train your nose to detect the slightest hint of a reductive compound in the wine as some of the thresholds are very subtle and can be missed by an inexperienced nose.               

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