Organic molecules

Paul Boulden (chief winemaker at the Sandalford winery)

When I went through secondary school, a number of years ago now, I did my matriculation (or TEE, as it's now known) and I majored in physics, chemistry, biology, maths and English and because of that I was accepted into the University of Adelaide, into their Bachelor of Applied Science course, which specialised in enology which is wine science and viticulture which is the growing and cultivation of grape vines. So I spent three years at university doing the Bachelor of Applied Science at the University of Adelaide and graduated some 20 years ago now, after I completed my degree.

There are two streams to wine-making in Australia now, one of which is the pure enology, or the wine science side. The other side is viticulture. Viticulture is primarily concerned with the primary resource of grapes and vine health and vine growing and cultivation and management of the grape vines, whereas wine science or enology is purely concerned with the applied science side of actually making the wine. There has to be an understanding of viticulture, obviously, but the wine science students tend to specialise more in what happens with the production of the wine in the winery itself.

So, in terms of that, we cross over into biochemistry, microbiology, organic chemistry, inorganic chemistry. There's a lot of engineering components because you're using equipment like crushers, presses, pumps. There's a lot of sensory stuff, especially in terms of using oak in winemaking and various other methods that we use; stabilisation of wine using bentonite clays (and that's a chemical reaction in itself), cold stability in wines to stop the wine diamonds from forming when you chill them down (that's a potassium bi-tartrate type equation). So there's a lot of chemistry used within the purely wine science side of it, which the people doing viticulture wouldn't have to worry about at all.

New technologies have become very important to both the analysis side of wine making, and in terms of winemaking itself. One of the major new technologies that we now use in winemaking is reverse osmosis and the principal reason that we use reverse osmosis is for lowering alcohol in wines. That's the main reason that we use it here, but there's other ways we can use it now. For instance it can remove chemical compounds such as 4-ethyl phenol, which is produced with a Brettanomyces yeast, a spoilage yeast in the fermentation. It gives an unpleasant sort of 'band-aid' character to the wine, so we can use reverse osmosis to remove that from the wine. It can also be used for things like smoke taint, which is quite common across Australian vineyards. You can use reverse osmosis for that as well.

Some of the other technologies we use now are things like crossflow microfiltration. In the old days of winemaking, or not so much the old days (some people still do it) is that wines are filtered through diatomaceous earth, cellulose fibres, membranes, all these sorts of various methods, but now with crossflow microfiltration we basically just run the wine past some hollow fibres and the wines are filtered sterile in one pass, without having to use all these sort of extraneous agents which can in fact be quite dangerous to people using them, so there is a lot of new technology being used in the winery these days.