What the taste of a wine should be is not so easy to explain. The taste of wine has been evolving for hundreds of years and as science turns up its light on the topic we can expect more shifts. These can come from new ideas like altering the bottle closure from cork to another method like stelvin caps which has resulted in fresher more vibrant wines. Tastes may change from improving the quality of grapes in the vineyard or by concentrating the flavours in grapes by reducing the yields. Understanding a lot more about the chemistry of wines we like and discovering which of the thousands of chemicals compounds are responsible for the most agreeable tastes offers another way to shift the taste profile and one that suggests intriguing consequences.

Enologix, a Californian wine firm, owned by Leo McCloskey, has featured in several recent books and articles, most recently in the New York Times, August 7th, 2005. This company specialises in grape and wine chemistry. By measuring selected compounds in the grapes before harvest they advise clients when to pick. Now that is not remarkable as most wineries will get a measure of the balance of sugar and acidity and all wine makers worth their salt will wander the vineyards tasting grapes and looking for small signs that tell them the grapes are ready.

Enologix takes this chemical evaluation several steps further. They measure chemical compounds that they believe affect the colour, aroma, texture and taste of the final wine. What are these chemicals is not revealed although it is hinted that they are compounds like terpenes (floral aromas and flavour compounds), phenols (these are also know as phenolics or polyphenols) and anthocyanins (which is part of the phenolic family). McCloskey is reported as saying that he has identified about 100 compounds (another report records these as 52 for whites and 32 for reds) that can affect a taster’s response and from this works out a potential quality index of the likely wine that will result from the grapes. Each sample is compared against his large data base of wines and a score out of 100 is assigned to the potential wine. The profile for the likely wine can be matched for example against Chateau Latour or Penfolds Grange.

Then advice is given as to how the wine should be fermented to reach this score. Thus he might advise that full colour extraction is needed by pumping over but pressing should be light because the tannin count is high. It is apparent, as you would expect that McCloskey has data that can compare wines before and after fermentation on his data base. The example used in the New York Times article is ‘draining down sweet’ which is separating the fermenting red juice from the grape skins and pips before fermentation has finished, followed by pressing of the skins and pips, in order to lessen the harsh tannins in the final wine. In this instance waiting for the final conversion of sugar to alcohol which is a solvent, can leach too much tannin from the grape pulp which will lower the score of the final wine.

The most interesting feature of McCloskey’s methods is that he can show that high scoring wines, as determined by experts in magazines and newsletters, can be measured by chemical analysis. In other words of the chemical compounds he measures, the correct ratios of the ‘good’ ones will lead to wines of which experts approve. Further he believes that wines made by following his methods score on average 5/100 extra points. This of course is gold dust as lifting a wine score in America from 88/100 to 93/100 can mean firstly selling out quickly and in later vintages getting tens of dollars more per bottle. Now that is a consultant worth employing.

It can be seen that this approach, based upon making wines that the leading American critics like may lead to more and more wineries making a style that scores these high points. There is nothing wrong with this but it is a wonderful illustration of how tastes are changing. The international taste change to what McCloskey calls his Style 4, the highest rated style, which shows; ‘rich, concentrated flavour and a soft, velvety sensation in the mouth’, is generally ascribed to the American wine critic Robert M. Parker. He was very enthusiastic about the 1982 reds from Bordeaux, a year that made rich, velvety wines when many other critics were not keen. It is said that this was a turning point and as his stature grew consumers turned from the old Bordeaux Style 3 of McCloskey; ‘dark and tannic’, to Style 4.

The Australian Wine Research Institute is investigating just the same idea, and in its annual report for 2004 a brief review is provided of a whole series of topics to do with identifying wine flavours and the precursors to these flavours in the grapes and most importantly the sensory properties of these compounds. Looking back through the papers the Institute has published shows that they have been preoccupied with a vast number of other topics requiring more immediate attention than sensory research. Thus odd as it may seem the Enologix team seem to be well in front in this area of identifying which compounds we enjoy in our wine drinking.

A recent an article in Winestate, July-August, 2005, by Richard Gawel gives us an insight into the current thinking at the AWRI. Two polysaccharides from grapes were isolated (part of a much larger family) as was a mannoprotein, produced by yeast cells during fermentation. These were added to a model wine to see how they changed the taste. Of the three discussed, one of the polysaccharides decreased roughness and dryness and if it had been naturally concentrated in a wine it would have made the wine soft and supple on the palate; while the other two made the palate fuller with a lighter, powdery, fineness. This led Gawel to add, they "...may be the gatekeepers of flavours in wine". The tasters also looked at the role of anthocyanin (a polyphenol), which is the red pigment colour of wine, when added to a model wine. Gawel found, "a clearly fuller, ‘bouncier’ thicker glycerol-like texture. Hard to describe but decidedly pleasant".

Now we are getting closer to the Style 4 of McCloskey and how it is produced.

There are other examples of the taste of wines shifting and we only have to think of the influence of Australia on the world markets over the last 15 years to realise that the wines sell because of the taste they deliver. Australia introduced a juicier, riper, richer and softer style of wine than had previously been seen on the world market. Partly it was the product of a warm climate that naturally led to riper, less acidic styles but it had already been shown in Australia that this was the style wine buyers wanted. Why wouldn’t it also appeal overseas?

It was no accident that when the American wine critics, in the mid 1990’s, discovered the very best of this Australian taste they pointed the wines highly. In turn it is not far fetched to say that as this style became the norm and other countries altered how they made wine the growth of wine as a beverage of choice in Britain and America accelerated. The popularity of Jacobs Creek in the U.K. and of Yellow Tail in the U.S.A. confirms the shift in taste and has if anything forced all countries to ponder how they should make wine and at the very least capture as much of this forward, delicious fruit style as they can or their climate will allow.

Other new approaches to alter the ‘old wine profile’ are also being tested or are accepted. Micro-oxygenation is now in common practise and is a method of slowly streaming micro bubbles of oxygen into a tank of wine to alter the flavour profile. As wines age oxygen is a provider that softens the wine by bringing together short strands of often bitter tannins into longer, smoother, rounder, tannins. It also stabilises the colour and may give richer flavours. The normal way of introducing oxygen is by racking the barrels and storing wine in oak which is porous to a tiny amount of oxygen. The uptake of oxygen by wine continues after the wine is bottled. By using micro-oxygenation in large tanks, wines that are to sell cheaply can be given some of the roundness and texture of wines that have been given these far more expensive treatments.

Other methods that alter the flavour are to extract some water from wine to concentrate the flavours. This can be done in the traditional manner by running off weakly coloured juice after crushing or by using a reverse osmosis method or by using vacuum evaporation. This concentrates the must before fermentation. Other methods are those of the ‘garagistes’ who crop at very low levels, as low as 1.2 to 2.4 tonnes per hectare to make hat fulls of super concentrated wines.

Many of these methods are quite recent and seem to be a desire to get closer to McCloskey’s Style 4 and to the American critics preference for rich, deeply coloured, fleshy wines. It also looks as if it is the style preferred by most drinkers.

Which begs the question of the concept of terroir, the flavour that many believe comes from the ‘sense of place’ of the vine, and whether it can possibly shine through this new way of making wine. The flavour that is produced by the special site of the vineyard is an article of faith in France and in many parts of Europe and is now being embraced in California.

While terroir makes sense and would seem to be undeniable you have to wonder if the flavours the location imparts can be isolated from or are strong enough to emerge through the depth of flavours that are imparted by these new wine making methods. Perhaps these methods will be refined and that part of flavour attributable to terroir will be enhanced. Although looking at the new way of making wine today, and this is just the start of the coming chemical changes that will be used to enhance desirable flavours in grapes, you could not be optimistic.