Why add Sulphur Dioxide (SO2) to Wine?
SO2 is added to wine for two main (and very important) reasons. SO2 has an anti-microbial and anti-bacterial effect when added to wine. Unwanted yeast and bacteria can cause unpleasant and offensive odours and taste in wine. The other important role it plays is as an anti-oxidant, helping prevent browning and odours similar to old sherry or browning apples. In short, it is very difficult to make good wine that will last more than a few months without the addition of SO2. So why do lower quality or cheaper wines seem to create more of an irritating effect and side effects such as headaches. For the most part it is because much more SO2 is added. Generally lower quality grapes are used, such as those that have undergone premature oxidation or have bacterial problems. Consequently, more SO2 is added. A typical example of this is bag in box or “cask” wine. Many of these wines are expected to be opened, and then drunk over a period of time. Bag in box wines generally will be opened and
