Practical investigations
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I have been following the wine analysis tutorial on your website. However when I tried to decolourize the red wine with activated charcoal it did not work. I put some charcoal in a filter funnel (using a suction pump), but the colour remained. I also tried adding a sample of charcoal and the wine in a beaker and stirring it, however this did not work either. I have now tried using a large filter funnel with cotton wool, plugging the funnel and with lots and lots of charcoal on top of that. Hopefully this will work but I thought I should email you just incase it doesn't - as I then will have no idea how to use the charcoal to decolourize the wine.
Igloo writes ...
You do seem to have had some problems, and, from what you say, it is obvious that you have persevered with several different techniques too.
I have found that the best method is to add a spatula of activated charcoal to the wine contained in a beaker, stir the mixture and then filter using ordinary filtration (i.e. no need for suction filtration).
There are two reasons why you might be having difficulties. First you may be dealing with a particularly “difficult” wine which doesn’t easily lose its colour. Secondly, you might be using the wrong sort of charcoal. It must be designated as being “activated charcoal”. Any old charcoal simply won’t do. Perhaps your sample of charcoal has in some way lost its activity, so you might try using a fresher sample.
I have carried out this process several times on many types of red wine, so I suspect that it’s your charcoal which is responsible.
This technique does work, I can assure you, so please keep trying. Good luck!
Student replies ...
Thanks. I eventually managed to decolourize the wine, but it took a very long time and I used a large amount of activated charcoal in the process.
I also want to measure the alcohol content in the wine. In the tutorial on Re:act it advises that you use a density bottle. My school does not have a density bottle and I was told that a hydrometer should work just as well. Would a hydrometer work, and would I use the hydrometer with a sample of volatile acids from the distillation process?
Igloo says ...
I am glad that your perseverance with the charcoal paid off!
I should think that the use of a hydrometer would be an acceptable alternative. However, using a density bottle is undoubtedly a more accurate way of proceeding, provided that you are also using it in conjunction with a “good” balance. In this case, one reading to 0.001 g would be ideal.
I am sure that you will be able to achieve results almost as good with an accurate hydrometer, assuming that you have enough distillate to take the hydrometer!
As to your final question: yes, you would use the distilled liquids, i.e. those which contain all the volatile components of the original wine.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 03 March 2006
