The Question of Ageing, and an Unlikely Protagonist

Text and photographs by John Szabo, MS

Consider this more of an around-the-water-cooler type of conversation, neither the first nor certainly the last word on what is a devilishly complex subject: the ageability of wine. At least, this is the sort of thing we chit-chat about around the water cooler at the WineAlign office. I trust your conversations are a tad racier and more interesting.

What prompts these reflections is a recent deep dive into the small sea of Hunter Valley Semillon, arguably the southern hemisphere’s most unique white wine (read about my adventure with WineAlign regular judge Brad Royale here). For every other wine, there is a compass that points north to somewhere in the old world, some original paradigm or model to follow. For Hunter semillon, there is no model; no other region in the world produces semillon in even a remotely similar fashion (or the Hunter has become the magnetic pole). And it’s also one of the world’s most unlikely, most age worthy whites. Just why and how this is so was cause for pause.

A couple of hours north of Sydney by car, the Hunter Valley is an improbable place to make fine wine. It’s blistering hot in the summer. The mercury pushing past 40ºC is a common sight, as are big fluffy white, and frequently dark, clouds. The semi-tropical climate means rot-inducing high humidity and rain, and especially harvest rain, which arrives with Swiss dependability. The most memorable comment from my first visit to the Hunter several years ago came from Scott McWilliams of Mount Pleasant Wines, in answer to my question of how he makes the decision to harvest: “mate, we know it’s time when it’s bucketing rain outside”. (In equally memorable fashion, when I brought up the comment on this visit, Stuart Hordern of Brokenwood didn’t miss a beat with his own quip: “sounds like he was a day late, mate”.)

The point is that the season is compact. Semillon is harvested at a potential alcohol of around 10%-11%, or it rots. The majority is fermented completely dry with little to no skin contact in stainless steel, and bottled young with no exposure to oxygen. The result is a bone dry, low alcohol, high acid (low pH) wine with slim body and slight structure, vaguely fruity (unless some aromatic yeast strain is used to make a sauvignon blanc look-alike, but left to it’s own devices, semillon is a far less aromatic variety). According to the textbooks, this, like most light, dry, reductively-made wines (in the absence of oxygen) should be in the DYA category, a “drink youngest available” sort of proposition. What could such a wine possibly gain over time? The answer, in this case, is everything.

Back to Ageing Basics

The understanding of the mechanisms of wine ageing has progressed considerably in the last couple of decades, though the mystery is far from fully unraveled. Numbers alone do not tell the whole story. There’s the science of wine, and then there’s the reality of wine.

According to conventional wisdom, phenolics, acid/pH, sugar and alcohol are the key components that modulate the ageability of wine. Complex polyphenolic compounds, mostly tannins and colour pigments extracted from grape skins, are what give (mostly red) wines their “structure”. But more importantly, according to researchers, polyphenols are anti-oxidants, which is to say they scavenge and neutralize oxygen molecules that inevitably make their way into wine, preventing them from doing their nefarious work of oxidizing everything else. The more polyphenols, the more soldiers in the war on oxygen. This explains why red wine, which is made by soaking skins in the juice and thus richer in polyphenols, is by and large more ageworthy than white wine made with little or no skin contact.

Acidity, and closely related pH, are also critical for wine’s longevity. Generally the more acid (lower pH), the better for long term cellaring. Like oxygen, acids are responsible for catalyzing a whole series of reactions that create new aromas/flavours from existing “precursors” (stuff already present in grape must/wine). The pH level sets the tempo in which these reactions unfold. Lower pH also makes wine inhospitable to spoilage organisms (yeasts and bacteria) that would otherwise hasten a wine’s demise, or at least send it terribly sideways.

The preservative effects of alcohol are well known. The discovery sometime in the 18th century (or perhaps even earlier) that a generous shot of brandy added to casks of wine would “fortify” (i.e. stabilize and protect) them for long sea journeys under sub-optimal cellaring conditions, to say the least, quite literally changed the world of wine. And sugar, while a great source of nourishment for yeasts and bacteria, also seems to stabilize and slow the ageing process, while contributing a wide range of desirable traits in old sweet wines.

So, wine with all four of these elements in generous measure, like, say, a sweet, fortified wine such as vintage Port or especially Madeira, are certainly good bets for forgetting in the cellar. Conversely, wine with none or just one of these elements usually heads downhill straight after bottling. Hunter Valley semillon, propped by nothing but acidity, should fall apart.

It’s important to note at the same time that all of these elements can be added to any wine. Tannins come in convenient powdered form that can be dosed into wine at will. Acid, too, can (and is regularly) added by the bag-full into vats of wine to raise total acidity and lower pH. Sweetness is an easy fix, usually in the form of concentrated grape must added to adjust a wine’s flavor profile before bottling. And when added in its crystallized form during fermentation, in an old technique called Chaptalization (a bag of standard Redpath will do) you can subsidize nature’s shortfall and boost a wine’s final alcohol level, if dumping brandy into the wine seems too drastic.

Other techniques can improve a wine’s potential for ageing, such as clarifying juice (by settling, centrifuging) before fermentation begins, thereby essentially removing many of the compounds that will otherwise oxidize somewhere down the line. Critical decisions around bottling can also make a big difference, namely dosing out sulphur dioxide, the great wine preserver, or in many cases, particularly with white wine, bottling with some dissolved carbon dioxide, either natural CO2 from fermentation still trapped in the wine, or added on the bottling line, which keeps oxygen at bay. Closure, too makes all the difference, ranging from synthetic cork (the worst, which allows the most oxygen in), to cork (with huge variability in “oxygen transmission rate” – generally the longer the cork the less oxygen gets in), to near oxygen-proof Stelvin screw caps.

So, with all of the possible chemical tinkering and other techniques that can be used to extend shelf life, would it not be possible to tailor-make a wine for long-term cellaring? By this logic, even the most humble wines made by a competent winemaker who knows basic chemistry should be able to survive as long as the grandest of cru classé Bordeaux. But this is patently not the case.

The Anti-democratic Nature of Wine

Here’s where science get’s left behind and the magic comes in. The amazingly complex biochemical stew that is wine is an entirely a dynamic system. Everything affects every other thing. Many, but certainly not all, of the reactions are known. Measuring, and therefore predicting the outcome of ageing is staggeringly complex, and programming it reliably is beyond the grasp of current wine science.

What is clear is that a natural balance and relative abundance of these elements is what makes wine ageworthy. In other words, there’s no substituting what nature provides. Competent farming is thus a sine qua non, but it also follows that only certain regions have the right basic conditions to yield naturally balanced grapes, which stand a chance of being turned into ageworthy wine. As I’ve said before, the wine world is profoundly undemocratic; try as you might, if your region is too hot, cold, wet, dry, cloudy or sunny, you are naturally disadvantaged from the get-go (and you’ll probably have to tinker in the winery). If on the other hand the climate is conducive to yielding fully ripe grapes with a balance of components, naturally, then you have no excuses.

There are also un-measurable elements that work mysteriously to lengthen a wine’s lifespan. One of these is genuine flavor concentration, the kind that comes often, but not exclusively, from low yields and old vines. I call it the “invisible force shield of flavour” that protects wines, ensuring that they don’t just survive, but also improve over time. In other words, a wine needs stuffing. That’s why not all wines from great regions age well – it takes some effort, and expense, to get the stuffing in.

Then there’s the contribution of the soil – structure and chemistry, which is very difficult to quantify (especially chemistry). But yet, it’s as plain as day. Some vineyards naturally produce more ageworthy wines than adjacent ones, with the same macroclimate, and clones/rootstocks/vine age, farmed and vinified in precisely the same fashion. Call it the magic of terroir. Every winemaker with more than one site knows this. Swimming around in the biochemical soup of the greatest, most ageworthy wines is a group of unidentified vigilantes  – the mineral gang – coming to the aid of official forces to protect their turf from time.

All of which brings me back to Hunter Valley semillon. There’s something magic about the combination of grape and place that makes this wine so well suited to ageing, against all odds. The closest paradigm is riesling (there’s good reason why Hunter semillon was called Hunter Riesling for years before the days of official appellations), with the difference that riesling is aromatic and can be enjoyed young. Hunter semillon is neutral and frankly boring before it’s 5th year. Acid is of course a big factor, as is SO2, CO2 and the almost exclusive use of screwcaps. But since none of these things are exclusive to the Hunter Valley, there has to be something more. It’s the ability to reach full ripeness (full flavour potential or phenolic maturity) at high acid/low pH (Champagne, Chablis, Mosel anyone?), thanks to high heat, regular cloud cover, free-draining sandy soils and no doubt a bunch of other unique factors that happen to suit semillon. You can harvest semillon in the Barossa Valley at 11% alcohol to approximate the Hunter style, but the flavours are green and the wines no where near as age ageworthy. As Stuart Hordern, senior winemaker for Brokenwood says quite simply, “you can’t fake it”.

Of course not all Hunter semillon ages gracefully for twenty years (and some wines have acid added to them, I was shocked to learn), but the overall track record of the majority proves the case. Then there are particularly special places, like Mount Pleasant’s extraordinary Lovedale vineyard, which only starts to get moving after a decade. According to winemaker Adrian Sparks, “Lovedale [planted in 1946] has a much lower pH at picking than younger vines, and also retains more of its natural acidity. And the naturally low cropping levels of these wines produce an intensity of fruit [and a large gang of mineral vigilantes] that can age for decades.” He’s not exaggerating. After a decade or so, great Hunter semillon blossoms from relative neutrality into a wildly unique and delicious mix of hot buttered toast slathered in honey, wrapped in a wool blanket and left in a spearmint patch.

So, extrapolating this knowledge to answer the age-old question: “which wines should I age”, my best advice is to check the track record of the region first, and then specific producer. You probably already knew that, but maybe understand now why it’s so important. This may sound unfair to young regions, but frankly without a minimum of 30-40 years history (15-20 for vineyards to mature, plus another 20 to see how wines age afterwards), it’s mostly speculative.

Buyers’ Guide: Hunter Semillon for the Cellar (or mature wines to enjoy now)

Note: availability varies across Canada, but pretty much any semillon from Brokenwood, Tyrrell’s and Mount Pleasant (McWilliams) is worth a look, and time in the cellar.

McWilliam’s 2007 Mount Pleasant Elizabeth Semillon
Mcwilliams 2007 Mount Pleasant Lovedale Semillon
Brokenwood 2014 Hunter Valley Sémillon
Brokenwood 2009 Latara Vineyard Semillon
Tyrrell’s 2010 Vat 1 Hunter Semillon
Tyrrell’s 2013 Brookdale Semillon 2013

Read more on ageing in these great Wines & Vines articles What Really Makes Wine Age Well? and Winemakers’ Views On Why Wines Age by Tim Patterson.

At WineAlign we strive to provide some guidelines on ageing in our reviews – check the drink from/to dates – based on our knowledge of the region and experience with specific producers. But sometimes it’s an educated guess. Have you found any surprisingly ageworthy wines? Let us know in the comments section. (Another of mine is Muscadet.)

Oh, and lastly, once you have one of those ageworthy wines, make sure you store it properly. But that’s a whole other water cooler conversation.

That’s all for this Free Run. See you over the next (old) bottle.

John Szabo, Master Sommelier

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