Crush and Squash

When the grapes are crushed the glycosides will enter the water phase of the must (read wine!), and it is tempting to speculate that some of the aglycons may be less soluble than their glycosylated equivalents. Nevertheless, due to the acid environment of the must and the presence of a rich microbiological fauna (bacteria and yeast) that contain glycoside-hydrolyzing enzymes, some, but not all glycosides will be cleaved and yield flavour-active aglycones. This relase of flavour may very well be responsible for the generation of the flavour that we recognize in wine, since the grape berries and freshly crushed berries seldom taste the same as the resultant wine. Another source for the transformation from a rather boring crushed berry flavour (crushed grapes often have little interesting flavour) to some of the marvellous characters associated with wines of differing origin and cultivars, may be attributed to the chemical and/or microbiologically induced chemical transformation of grape-derived potential flavour compounds. Thirdly, the presence of alcohol may also enhance the volatility of certain compounds.

Reaching Your Nose

Glycosides are small molecular weight compounds that have sugars attached to them. Grape berries, like many, if not all plants contain so-called secondary plant metabolites that often, but not always, accumulate as glycosides in the vacuoles of plant cells. Many famous flavour compounds, such as the monoterpenoids geraniol and linalool (muscat flavour of muscat grapes), certain ketones of raspberry (raspberry flavour) and benzaldehyde of almonds (nutty flavour), accumulate both as aglycones (ie. without sugars) and as glycosides. In many cases, but most likely not always, the glycosides have reduced volatility, due to the higher water solubility imparted by the sugar component, than the corresponding aglycones. With a lowered volatility, the chances that the glycosides will reach your olfactory system in your nose, either through your mouth or through smelling, are less than for the corresponding aglycones. Therefore, most often, the glycosides are regarded as “flavourless”, whilst the aglycones, if they indeed are capable of provoking a stimluation of your olfactory system, have a much better chance of inducing flavour perception.

Grapes contain hundreds of potential flavour-active compounds.

In grapes, several hundred different potential flavour compounds (ie. secondary metabolites) accumulate as both glycosides and aglycones. It is also possible (although I don’t know of any study clarifying this) that some major flavour active compounds present in grape berries are present as aglycones only.

Glycosides & Wine

The flavour of wine is a major part of what makes wine interesting. Now, what are glycosides and what do they have to do with wine flavour? This short story is an attempt to give curious followers of arakoon wines an insight into some of the biochemical aspects relating to the flavour of wine made from Vitis vinifera (The grape species used to produce wine grapes).

Our Philosophy and Reality in the Vale

So what then is our philosophy? More than often, practical reality takes over. However, as our experience increases, we simply try to choose growers that give us a variation of wines with as high quality as possible, or at least as high a quality as we perceive it to be. Interacting with growers is another topic on it’s own. There are limits to what we can do, offering advice to some and hoping that they will follow it or do something better. Grape growing is a risky business and one that is very exposed to seasonal, financial and wine-buying trends. It’s particularly expensive to establish vineyards and requires good decision-making over continuous periods of time. Choosing wise growers with well managed and well situated vineyards is one of our most important decisions in the wine making process! However, there is great competition between wineries to contract the best growers, so choosing between different dry-land grown 100-year old Shiraz vineyards from nice Sites is not realistic, unfortunately! Nevertheless, we try our best!

Unripe, Ripe and Over-ripe

Anyone who has set their teeth into an unripe or overripe banana or mangoe, or even a winegrape, will agree that ripeness is an important concept and that the flavour of fruit, together with many other components important for winemaking, changes drastically as ripening progresses. Unfortunately all the components, ie. acid, sugar, phenolics and flavour, do not always reach optimal levels in synchrony, a synchrony where the timing of individual elements may vary with each unique batch! Furthermore, as explained in the glycoside section, it is difficult, if not impossible to evaluate what the flavour quality of the resultant wine will be like until your sample has been transformed into wine. Other aspects which influence our ability to judge the “best” picking date include weather conditions and the need for grapegrowers to go on holiday as planned!

What is “optimum” ripeness? Is riper better? Most winemakers must agree that somewhere in the middle is best. Since the beginning of the 1990’s alcohol levels in general have been on the rise. Look at the alchol levels of Penfold’s Grange or Henschke’s Mt. Edelstone over time, I’m sure you will notice a general increase. Alcohol levels are a good indicator of ripeness as the sugar level (ethanol precursor) usually increases as ripeness progresses. Riper grapes means bigger and softer wines, a trait that Australian wines are increasingly becoming famous for. However, with increasing ripeness there may be a loss of varietal characteristics and more importantly, big, fat and alcoholic wines don’t always match food as well as wine made with more moderately ripened grapes. That is part of the reason why we at arakoon like to prepare blends of different wine styles. While offering big, fat & gutsy wines such as 2000 Sellicks Beach and doyen, we also want to offer more food-friendly wines such as the Lighthouse, and Clarendon Shiraz. Of course, I’m sure one can find dishes that will be well complemented by big wines too! Sometimes it’s nice to have a selection of wine styles to choose between if one doesn’t want the wine to dictate what food to make, rather than the opposite.

Graceful Age Part II

Hill of Grace is a famous vineyard located somewhere between the Barossa and the Adelaide Hills. The vines are old, small and cannot possibly yield a lot of fruit per vine. Meanwhile, back in McLaren Vale, an explosion of new vineyards have made young vines a near ubiquitous sight. As we have come late onto the scene we have sourced many of our grapes from new vineyards. Surprisingly, some of the youngest vines have given us amazing wines.

Older vines are thicker and contain more carbohydrate “reserves”, which is one main component of older vines producing “better” wines. Older vines also have reduced vigour/capacity and produce less shoot and leaf material as well as less fruit. That is another factor to consider. Are older vines “struggling”? Certainly, reduced vigour is a good sign of “struggle”. Is it possible to compare animals with plants with respect to ageing and its inevitable toll? Nevertheless, I’m pretty sure that it is possible to produce fruit worthy of all superlatives even with young vines, as long as they are managed well. Certainly, E. Guigal is doing just that with his La Turque. Maybe older vines simply make managing for quality easier?

The Vineyard Manager

The vineyard manager can influence the way his vines are growing, and every vineyard and variety needs its own unique consideration. Two basic principles include capacity or vigour of plants and canopy management. Pruning and watering are important ways to influence these principles once a vineyard has been established. In such a dry country as Australia, irrigation is important to achieve economic return in many, if not most, but not all locations. Irrigation strategies not only influence the capacity of vines but may also be used to directly influence the quality of grapes. Here is where the struggling vine concept comes in. It is believed that “struggling vines”, ie. short of perfect growth conditions – for example, due to reduced water or nutrient uptake – may produce higher quality wine. Is it possible to separate crop load in relation to energy input and struggle? I think so, although the two are somewhat interconnected. One question to answer then is whether a struggling vine produces fruit with more flavour than a medium-sized or big vine? Could it be that a “struggling” vine spends more of his energy on his offspring than a happier vine?

Crop Load, Yield and Energy

The influence of yield, or crop load, on wine quality is one topic that a lecturer at the Waite institute – Peter Dry – strongly argued against. Although, if I recall correctly, his colleague – Patrick Illand – leant a bit the other way judging by some of his papers at least… Anyway, I feel that this old myth has some degree of truth even here in the Australian environment, although a different angle in our approach may be required!

Many factors influence the crop load of grapevines, and one of these is fruit size. Next time you get a chance, compare fruit or berries of different size, but equal ripeness. If you have a basket of strawberries, there is usually a good chance that there are at least some giant berries and some tiny ones. Which one has the most aroma and flavour? Most often, but not always of course, the smaller fruit has the greatest intensity of aroma, that at least is my personal experience. Although the total yield relates to the number and size of crop units per plant, this example still bears merit. On the number front, one basic principle in nature is that of the number of offspring (which fruit is!) and the amount of energy that the parents spend on each offspring. Just consider rabbits and humans, or mangoes vs. grass. The more offspring one has, the less energy there is to spend on each one. Thus, even a big berry, if all alone on a single vine, should be absolutely loaded with flavour..? If we then regard two vines with an equal number of berries of equal size, but with differing amounts of energy (read sugar), which one is more likely to be “nurtured” more?

The latest basic principle drawn up by Dr. Illand and Dr. Dry and co-workers, surrounds this latter idea, that the more energy a vine has to offer per crop load, the better the grape, and therefore wine, quality will be, within certain limits. This rhymes in with Richard Smart and his idea of “sunlight into wine”, although he focused very much on the sunlight actually reaching the berries, and not the leaves, where the majority of sugar (energy) synthesis (conversion rather) takes place. So, is this the final answer? Now we know what to do, so let’s go out there and bless the world with some more La Landonne and Grange Hermitage clones… Unfortunately, this isn’t the final answer. A practice whereby a grower produces little crop is not economically advantageous. A vine with little crop will divert “excess” energy into the growth of foliage (shoots and leaves), which results in shading of both berries and other leaves. Shading is a big no-no with regards to wine quality, and Dr. Smart has written a whole book on that topic. Vines in famous vineyards are often small to medium-sized and produce little crop per vine and little energy per vine. I know of no examples of great wines with fruit grown on large vines, although I’d love to see one. Thus, I don’t think we know the full answer just yet, although some strong cues are available.

Old Myths

There are many “myths” surrounding the optimal growth of grapevines for wine. Older vines make better wine than young vines. A lower yielding vine will produce a more intense wine. The longer and slower the ripening of the berries, the better. The riper, the greater. Etc.. Some of these thoughts originate in Europe and there they have alot of experience, historically, they even allowed some of these ideas to influence rules governing the growth of grapevines for winemaking in France with regards to labelling! Since the inception of arakoon wines we have brought in grapes from vines that have yielded miserably and from vines that have had reasonably large crops, from vines that were two years young up to close to one hundred years old, from vines that have ripened their fruit early and late, and with varying degrees of ripeness (10.5 to over 16% potential alcohol!). In Summary, the best wine so far (doyen) have come from two year old vines that ripened early. We have seen examples where low yielding vines produce wine that is not too special, whilst reasonably high yielding vines have given us very nice fruit (and therefore wine).

Not only is there a substantial difference between the environment in Europe and that of Australia, which results in great differences between our wines, but it is always possible to find examples to contradict (or “disprove”) these “rules”. Albeit, we nevertheless believe that there are good reasons to keep some of these “myths” in our minds, whilst remembering the most important principle of all; every vineyard, every year and every grape variety is unique and will very likely differ from what we think we can predict!

Viticulture

Although we don’t own, nor manage any vineyards we still have a philosophy on viticulture!? Yes, as explained in the winemaking section, “the wine is made in the vineyard”, and therefore we need to consider what happens in the vineyards of our growers.