Old Mutual Trophy Wine Show 2009: The old question of ageing

Old age is complicated, for wines as for people. Should old wines that have weathered the chemical interactions of their years in bottle automatically be worthy of respect? Is longevity the prerogative of finer wines or is it their hallmark? Most difficult of all, what enables a wine to age well and is 21st-century winemaking - should such a thing exist - conducive to this process?

These are the sorts of questions that have irritated my thoughts, preageing of SA's New World Wines ompted by my first experience of judging in the Old Mutual Trophy Wine Show and by the tasting of older wines that preceded it. My conclusions are experiential or partial - we lack the scientific data to be more certain. And partial also because the classes I judged were limited to Sauvignon Blanc, Viognier, Cabernet Sauvignon and Bordeaux-style red blends. And I am painfully aware that judging wines in the context of a show or tasting is offensively swift compared with the time it takes to nurture vines and turn them into good wine.

During the tasting of older wines - from Uiterwyk Pinotage 1992 back to Lanzerac Cabernet 1957, including wines that might today sell for R200 or more and others that were probably cheaper than R1 in the 1960s - top Australian winemaker and fellow international judge Brian Croser made a fascinating comment about the relationship between tannins and alcohol.

Most of the older wines would have been around 12% alcohol, since grapes rarely got riper than 23 degrees Balling/Brix in the glory days of leafroll virus. Compare this with the 114 wines in the Bordeaux-style Blends class, where the average alcohol was around 14.3% and about 40% of the wines were 14.5% or more. The 16 wines over 15% were mostly a serious challenge to the palate, especially those that also had high levels of residual sugar (only 19 had less than 2 grams/litre). The worst culprit, analytically at least, weighed in at around 15% and 4g per litre, and there was one in the Cabernet class with 8g and 14.9%. Serious headache material. (Wines with higher alcohol levels can be in balance but it's a much harder act to perfect).

Anyway, getting back to Brian and the tannins, he observed that the majority of the older wines had "water-based tannins rather than alcohol-based tannins". Later he elaborated: "I do not have a scientific explanation for my observation but there is a very different mouthfeel and flavour in high-tannin wines at 12 to 13% compared with those at 14 to 15%. The tannins assume more importance at the lower alcohol and their tactile effect is sandier, drier and more evenly mouth-coating. The impression is that they are there for the long haul and will chemically mature over time. In high-alcohol wines the tannins are more slippery and less savoury. The alcohol and sweet fruit dominate the tannins, which seem to have reached a premature richness and don't promise much for the future.

"The reasons for this sensory effect could be numerous," he said, "from a different extraction at lower alcohol than at high alcohol, different maturity of tannins in the grape and just different sensory effects of the same tannins at the different alcohol levels. My instincts tell me that it is more to do with tannin quantities and qualities in the berries at normal maturity as opposed to surmaturité. I don't think it is possible to achieve a true "claret" savoury tannin finish at alcohols above 13.5% (approximate and variable)."

This fits well with my own observations of wines that seem to age well, or those that I am bold enough to predict will age well: wines with a respectable pH and fresh acidity, ideally but not exclusively natural; moderate alcohol; and tannins that may be dense and powerful but yet are tender and finely textured. However, although you can measure the total volume of polyphenols (in 2005 the Bordelais competed for the highest IPT or indice de polyphénols totaux), and their solubility (how easily they can be extracted), you cannot measure tannin quality - except in your mouth and with the passing of time. Crucial to the quality seems to be a respect for the vintage-dependent nature of the fruit and avoiding over-extraction.

To quote the Oxford Companion to Wine's entry on ageing: "In general, the lower a wine's pH, the longer it is capable of evolving. Among reds, generally speaking the higher the level of flavour compounds and phenolics, particularly tannins, the longer it is capable of being aged."

We do not have the pH levels of the wines from the '60s and '70s but it is safe to assume that in general they were lower than the average pH of the reds in the Bordeaux-style class in this year's Show (3.58) and their average titratable acidity (5.84g/litre). Admittedly, the addition of tartaric acid was an automatic reflex in those days but in most of the older wines the acidity did not stick out. In addition, they tasted dry, unlike so many 21st-century reds from warmer climates or designed for Coca-Cola-weaned palates.

To quote the Companion again: "Wines whose pH is between 3.2 and 3.5 not only tend to taste refreshingly rather than piercingly acid, they are also more resistant to harmful bacteria, age better, and have a clearer, brighter colour. Wines with pH values higher than this tend to taste flat, look dull, and are more susceptible to bacterial attack. In the last 20 years, average pH levels have risen considerably as a result of longer hang time and a fashion for riper wines." Any wines in the Show deemed to be affected even mildly by the spoilage yeast Brett (variously smelling of plasters, farmyard, leather) were quickly checked to see if the pH and residual sugar levels were likely to encourage the rapid multiplication of the yeast population to the level of unacceptably flawed. So far I have focused on the anti-ageing aspects of many 21stcentury wines, but it would be a mistake not to applaud and welcome the fact that only a tiny proportion of the wines in the Show exhibited any green, unripe flavours or tannins. I'm sure that a less selective lineup of wines from the 1960s and '70s would have been littered with acidic and attenuated offerings - which makes the wines we did enjoy all the more worthy of respect.

During the judging and in the (sighted) tastings with producers in the two days after the Show, I experienced delicious young wines that had attractively ripe and/or subtle aromatic fresh fruit flavours, a fine texture (whether restrained or bold), and which were not only refreshing and persistent but also expressed their origins. Those wines that came from well-sited and thoughtfully tended healthy vineyards and had been rigorously observed and sensitively managed during winemaking, were proof that the very fine potential of South African vineyards is being realised. Will such wines age? I cannot say for sure but their chances are good and they are surely fine wines.