New World Winemaker Blog

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.