New World Winemaker Blog

Have you ever wondered why two bottles of wine, supposed to be identical in almost every way, sometimes differ in taste and aroma? In other words: Why would two bottles stored under identical conditions taste different?

A few years ago, I was privileged to select and receive a couple of cases of wine that were stored for more than three decades in a decrepit garage. Storage conditions were, to say the least, not ideal. Nevertheless, I’ve found a few gems within this evolutionary challenged lot of wine. Like the 1980 Vergenoegd Cabernet Sauvignon that I opened last night. It was obviously far past its prime, but still shouted Cabernet Sauvignon with a creaky voice. This made me ponder upon the question right at the beginning of this blog.

Bottle variation becomes much more accentuated with time, which is why modern wineries crave uniformity when it comes to bottling of their future old-timers. Gone are the days of barrel by barrel bottling (an exception is Domaine de la Romanee Conti), uneven fill levels and bottling at different temperatures, times and venues. Before the wine trade exploded in Hermitage, wine was sold and bottled barrel by barrel as orders came in. The impact of bottling date barrel variation in this case was huge.

The type of closure (cork or screw cap) plays a critical role in bottle variation. It is even suggested that the cork is the most important factor in bottle variation and I am inclined to agree. A high quality cork will ensure a more uniform wine and will reduce the incidence of embarrassment following the opening of an expensive wine and having someone declare with a snooty voice: “I believe this wine is corked.” No two corks are similar and there can be a remarkable difference between two seemingly similar corks in terms of oxygen transfer into wine. If you want to know more about the effect of oxygen on wine, feel free to read my previous blog about the effect of ageing and micro-oxygenation on wine. By the way, you can treat a wine affected with cork taint at home. Simply line a bowl with polyethylene plastic food wrapping and pour the affected wine into the bowl. The taint will disappear or be much reduced after only a few minutes.  TCA (the molecule usually responsible for cork taint) has a very high affinity for the polyethylene molecule and will adhere to the plastic sheet. If you were wondering, I did not see this trick on MacGyver.

If you still do not believe that evaporating wine (from a bottle) is replaced by air, consider that you’ll very seldom see a cork that is sucked into a bottle. This is because the wine that escapes the bottle is replaced by air. Now that we’ve established that air does indeed find its way into a bottle of wine and that this is very dependent on cork variation, I will conclude this blog. You can read more about the other factors critical to bottle variation in Part 2 of this blog.

Until then, why not open a golden oldie and reminisce about the good old days. A good bottle of old wine might be hard to find, but the reward is totally worth the anguish as you pull, inspect and smell the ancient cork…

Bernard Mocke is a technical consultant for Oenobrands.

Trinity: Dodge this…

Unfortunately, like most things in life I suppose, too much of a good thing can be bad…and sometimes even dangerous. Although there is a significant upside to the use of healthy, “light” lees, there can be a very destructive downside! And this of course, is what every winemaker wants to dodge…

Some of the solid particles and flakes which form part of lees may be the origin of vegetal aromas and flavors, sometimes up to a point where it almost smells a bit reduced. I have heard the term “sauerkrauty” which is actually a very good descriptor for this phenomena, as it refers to both the elements of vegetal and reductiveness. Another potential risk is the fact that our “friend” the bisulfite ion, which, to a certain degree has an anti-microbial function (although not as significant as molecular SO₂), as well as some free SO_2, are also bound by these solid particles. Of course in the bound form, SO₂ lose most of its antimicrobial function and probably all of its anti-oxidative properties.

This of course is a time bomb, simply because we are now managing all the good microbes in parallel with the high risk ones from which we are normally “protected” as a result of the effects of SO₂: Brettanomyces, Pediococcus, Lactobacillus. And – the higher the pH, the higher the risks.

Another risk related to lees contact is the development of reductive odors and metallic tastes. The release of these sulfur compounds may be the result of light lees that is very tightly compacted during wine maturation. This phenomenon is potentially even more hazardous in situations where reductive odors appeared during primary fermentation.

The release of “bitter” substances in wines, combined with reductive and “Brett like odors” is another risk associated with lees contact and is related to contamination by living yeasts such as Brettanomyces and Pichia, as well as lactic acid bacteria like Pediococcus. We are well aware of exactly where they come from: insufficiently disinfected cellar equipment, lack of optimal SO₂ management, high pH’s and the release of nutrients into the wine as a result of autolysis.

And speaking of release of nutrients…living lactic acid bacteria may have the ability to metabolize different amino acids with the production of biogenic amines. Hence the importance of hygiene and optimal SO₂ management!

What do I propose?

To keep it simple. Manage hygiene. Manage SO₂ and pH optimally. Taste frequently. And great will be your reward.

Bertus Fourie is a winemaker, turned Enology lecturer and creator of the Barista coffee Pinotage.