New World Winemaker Blog

This blog can be regarded as the sequel for “Snow blower on Enceladus”, which I have posted in November last year. The blog was all about technology that uses CO₂ ice pellets to clean and rejuvenate the inside of barrels by “blowing” these ice pellets under immense pressure against the inside staves of barrels, leaving them clean and “disinfected”. Another advantage of course remains the fact that the condition of a used barrel can be inspected. Many winemakers was struck with complete and utter dismay at the sight of many a blister in the inside of these very pricy barrels…and most probably found the puss that “oozed” from these blisters a terrible reality.

Yet the challenge remains to manage barrels in such a way that you get what you want from them: Extraction of flavor, and introduction of oxygen. Yet both decrease as a result of extraction and blocked pores, as the barrels grow older. The other challenge is of course to maintain a good sanitary status after these barrels are emptied and filled with new wines, as spoilage organisms such as Brett and acetic acid bacteria literally get a “breather” in between emptying and filling…

Several techniques are at the disposal of winemakers to clean barrels. Many high tech barrel cleaning systems are currently on the market, from “ordinary” pressure cleaners, to units that can empty the barrel and clean it afterwards without having to move the barrels from the stack. It is possible to use dry steam or wet steam. You may even use chemicals such as SO₂ treatments or the patented “Thales cleaning” method. Yet again – different strokes for different blokes.

The purpose of this blog however, is to take a view on the “Barena” method. One of the differences to the Ice Jet System is that they do not physically dismantle the barrel. A rod is simply placed through the barrel’s bung hole, and quartz crystals are sprayed under pressure against the inside of the barrel. These crystals were sterilized by heating it up to 300 degrees Celsius several times. Approximately 30 kilograms of these crystals are used per barrel. The quartz removes less than a millimeter of the surface of the staves, almost like peeling off a skin from a litchi. The barrel is then rinsed with de-chlorinated cold water. Step 3 in the process is the “disinfection stage” where the barrel is steamed for 12 minutes.

The barrel is now ready to dry naturally. A disinfected silicone bung is put into the bunghole, and a needle through which SO₂ gas is injected, penetrated through the bung. This leaves the barrels treated and ready to be filled yet again.

Unfortunately the downside remains the transport of the barrels to the depot where they are treated and back to the cellars. I also like the fact that I can physically inspect the inside of the used barrels when I used the Ice blast technology, although you may argue that it is possible to look into a barrel with optical fibers…honestly, how many of us actually use these gadgets on barrel inspection day?

Nevertheless, I also like the idea of “blasting” (and opening blisters I suppose) away deposit and residue by force, “steaming” the pores open and bugs away, and finally treat it with sulphur. It all makes sense…almost like giving your barrel a facial.

The technology will soon be available in South Africa, and I really think it’s time to look at some hardcore evidence – which method will ultimately prevail? Let the wine decide…(or the bottom line?)…

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

During my recent harvest stint in Germany, my host, Christoph Hammel uttered many memorable (and some that I am not allowed to mention here) pearls of wisdom. He told me about a meeting where some of the biggest names in German winemaking and professors associated with the wine industry were present. A very well know professor publically stated that his belief system does not have any room for the theory that yeasts impart any aroma to a wine fermentation. At this, Christoph got up and glibly replied: “My dear sir, it is not a question of belief. It is a question of knowledge.” The subsequent pandemonium that ensued was apparently quite noteworthy (hence the photo above).

Christoph is a big believer in using technology, specifically technology that can be used to make wine, and wine processing, better. Even more specifically, he is a big believer in additions.  He always said to me that he makes wine that people want to drink and if this can be achieved with the addition of enzymes and other winemaking tools, so be it. Every addition that he does is done for a reason. One thing can be said with certainty and that is that Christoph believes in the “interventionist” approach to winemaking. A lot of winemakers like to claim that their wine is made “naturally” and with the least possible human intervention, but Christoph is at the complete opposite of the spectrum. He has some pretty far out and amazing ideas and some might even call him a renegade or a cowboy after hearing about his yeast mixing and addition regimes!

As far as the additions are concerned, Optiwhite (Lallemand) is one of his stalwarts. This is usually added at the beginning of fermentation. β-glucanase and β-glycosidase enzymes  are added at the end of fermentation (at about 0°Brix). Depending on the structure and quality of a specific wine, ascorbic acid is also added right at the end of fermentation. DAP is added at three stages and is sometimes even added in divided dosages during the day, depending on the fermentation bouquet. In addition to DAP addition, thiamine is added to all musts. This is done simultaneously with sugar addition. It is well known that fungal infection on grapes depletes thiamine and it is therefore an excellent prophylactic measurement against stuck, sluggish or smelly ferments. For each addition, a cost to benefit decision is made. For instance, light and easy drinking wines will not get all the bells and whistles. The more expensive wines will get a full range of stuff added.

If Christoph was not such an excellent winemaker, I would have said that he missed his true calling in life: A chef! A chef who is forever mixing, adding and tasting, mixing, adding and tasting…

I remember reading and hearing about the next big thing, ascorbic acid when I was just starting out winemaking. It was going to revolutionize white winemaking and everybody who did not know about it was simply out of the loop. Since then, very little has happened, and the practice is not widely employed. I wonder about things that people propagate as fact, simply why it is not used by everyone, it just seems to be so obvious, you would think. Now the next big thing might be gluthathione (GSH). Yes, did I pronounce that correctly?

When you look at all the chemicals in wine that can act as anti-oxidants, SO₂ is not very high up in the chain, and is much less effective relative to other compounds. The series from “worst” to best would be something like, SO₂, ascorbic acid (Vit C), vitamin E, gluthathione (GSH) and then tannin. In white wine there is not a lot of tannin, so the next best thing would be GSH. Many of the flavourful compounds in wines have thiol groups, and when they oxidise, they lose their flavour. This is where GSH can save some flavour, because the source of its power is its thiol groups, which will take a bullet for the flavour compounds.

GSH gets used by yeast during fermentation, so if you want to add this lovely compound you have to add it after two thirds of the fermentation has been completed, because then the yeast will not assimilate it. GSH can be added in the form of yeast derived products.

Recently someone suggested that the use of ascorbic acid can lower the amount of SO₂ needed, but what would be much truer, is that low oxygen pickup can lower the SO₂ needed, since this is actually what is combated by SO₂. When you are evaluating practices and trying to compare two different wineries, you are dealing with different grapes, lots of different micro components, different bottling practices, never mind different ascorbic acid regimes.

Ascorbic acid started as the thing to do, but practical experiments and lots of anecdotal evidence suggest that it is not as powerful as first suggested. The grapes seem to have a much bigger influence than anything else, and ascorbic is not the silver bullet that it was first touted to be. In a few more years we must look back and see what GSH accomplished.

For  technical article on glutathione click here.

Louis Nel is the owner and winemaker of Louis wines in South Africa.