Archive for May, 2010
May 28, 2010 posted by Louis Nel

There is now a very secret winery in the Winelands that nobody is suppose to know about, where no eye is suppose to roam, and of which no word may be spoken. Could it be that this winery has discovered the hidden secret to winemaking that nobody else have been able to find, and that this group of people have something that can be so powerful, that the effect will be so amazing that their wine quality will far surpass that of icon wines?
Every generation of winemakers think they will discover the secret to winemaking. They think that their understanding and insight far surpass that of every other generation. Every young generation also think that they discover the art of making love for the first time.
Winemakers should get better with years and experience, but sometimes ten years experience of only one situation, is equal to only one year repeated ten times. To grow one has to constantly challenge yourself, otherwise you should just retire.
Every winemaker has a certain pride in what he does, but to me “pride”, is often not remembered as one of the seven deadly sins. This emotion in my book should just not be good practice.
Good stock and commodity traders are always nimble and quick, and have no hesitation about changing their minds about the direction of the market. If they bet on the market going down, and the market goes up, they change the direction they are betting on, without sticking to their original believe or arguing with the market. Pride should always take a backseat to reality, because you cannot argue with reality. People however have a different perception of reality, which makes this argument a bit tough.
Winemakers offended about new ways of thinking, or techniques that challenge their traditional doctrine, should do some soul searching. Are they going to stick to their self imposed religion of winemaking, or are they going to test everything, keep the good and discard the bad?
May 21, 2010 posted by Karien O'Kennedy
From Wikipedia, the free encyclopedia:

Named after the English biochemist Herbert Grace Crabtree, the Crabtree effect describes the phenomenon whereby the yeast, Saccharomyces cerevisiae, produces ethanol (alcohol) aerobically in the presence of high external glucose concentrations rather than producing biomass via the tricarboxylic acid cycle, the usual process occurring anaerobically in most yeasts eg. Kluyveromyces spp. Increasing concentrations of glucose accelerates glycolysis (the breakdown of glucose) which results in the production of appreciable amounts of ATP through substrate-level phosphorylation. This reduces the need of oxidative phosphorylation done by the TCA cycle via the electron transport chain and therefore decreases oxygen consumption. The phenomenon is believed to have evolved as a competition mechanism (due to the antiseptic nature of ethanol) around the time when the first fruits on Earth fell from the trees [1].
Yeah, congratulations to those of you that grasped all of that. Now for the rest of us in plain English the Crabtree effect is that yeast will always ferment and produce alcohol when the sugar concentration of must is higher than 9 g/l, despite the vast amounts of air/oxygen you might introduce into propagation or fermentation. Uh… okay, so how does knowing this improve my life? Well some winemakers believe that by giving the fermentation (or propagation) “lots of air” it will allow the yeast to respire and not form alcohol. Why don’t you want alcohol formation when you try to build biomass? Because, yeasts grown in the presence of alcohol (as with winery propagation and fermentation due to higher than 9 g/l sugar concentrations) have weaker cell membranes than yeasts grown in the absence of alcohol, as is the case of wine yeast production at yeast factories. Weaker cell membranes equal lower alcohol tolerance equal more stuck fermentations. I think you are starting to get my point why knowing what the Crabtree effect is might improve your quality of life by sparing you some stuck fermentations. It could also help you explaining the yeast bill to your boss. And hey, if you are already convinced that inoculating each tank at the recommended yeast dosage of factory grown yeast is better than propagating, then boasting that you know what the Crabtree effect is to your mates is a great conversation starter at cocktail parties – or maybe not…
May 14, 2010 posted by Louis Nel
What makes a winemaker good, and others not? Is it nature or nurture? Many years of winemaking experience have humbled me to the point where I have no illusions regarding the origin of wine quality, and where I have a much better grasp on the influence I have on a wine. My guess would be that if you have stunning grapes, you are 80% there, with the winemaker being able to add another 20% to the total quality that is locked into the grapes.
On the other end of the scale, if you have very mediocre grapes, a winemaker will be able to add, and manipulate the quality of the resulting wine to add maybe 80% to the quality of the final wine. My theory could be illustrated as follows.

As humans our evolutionary process has tried to equip us with survival skills, that amongst others include tools to learn from the environment, but inadvertently, we see patterns and relationships where there are none. This condition known as Apohenia, make us correlate, totally unrelated criteria.
A common bad correlation would be to say that good winemakers inhabit some regions more than others. Good grapes do occur in certain regions more than others, which might be more correct. Some people think that men make better winemakers than woman, but then how many woman winemakers are there, how many chances have they received?
One certain bad correlation often made in interviews is that an extrovert personality correlates with winemaking skills. The personality profile for the ideal technical winemaker, would normally exclude this profile. People would often prefer to vote for somebody in an election because he is a good speaker, or looks the part, rather than on merit. If my theory is correct, and you have stunning grapes, you do not need a very good winemaker, you are 80% there anyway.
Louis Nel is the owner and winemaker of Louis wines in South Africa.
May 7, 2010 posted by Karien O'Kennedy
Now I bet very few of you have given this any thought. After all a rosé and a blanc de noir is a “white wine” made from red grapes. So you use your normal settling enzyme. However, this “white wine” contains a certain amount of anthocyanin, which means this anthocyanin should preferably remain a stable colour to ensure the longevity of the wine. In plain English, the wine should preferably remain pink or onion skin, whatever our style is, for a year or longer. It should not turn slightly brownish. In the absence of tannin from the grapes, or ellagic tannin from wood, or oxygen from micro-oxygenation, how does one stabilise this colour? Well for one; keep stuff that can de-stabilise it in the first place away from it.
Anthocyanin, like I said in a previous blog, is stabilised by sugar molecules. When the sugar molecules are removed the colour becomes unstable and can lose it red tinge and become, well, less red. I am not a specialist on polyphenols and bless the souls of the people who are because I find the topic extremely complicated. I have tried and tried to fully comprehend the colour / tannin chemistry in wine and I am not sure if it is lack of intelligence or sheer boredom with the topic that makes it impossible for me to fully grasp it. Anyway having gotten that of my chest, lets stick to the very simple model of anthocyanin and its sugar molecules.
Settling enzymes (white wine enzymes) can contain a side activity, formed by the fungus during production, called glycosidase. This activity is also known as “anthocyanase.” It removes sugar molecules from more complex structures. Although very positive for white wine aroma, it can also potentially remove the sugar molecules from anthocyanin. Now granted, you need a certain concentration to have an effect and some settling enzymes may not contain high enough amounts to cause any damage to your colour. It is nonetheless a good idea to clear this matter with your enzyme supplier to make sure that there will be no effect on your rosé colour. There are quality and composition differences between suppliers and it is a good idea to be aware of these differences. To make absolutely sure that you don’t have this activity in the enzyme you use for settling, use a red wine skin contact enzyme, where the supplier specifies: anthocyanase free, for settling of your rosé or blanc de noir juice. Skin contact enzymes contain the basic ingredients of settling enzymes as well as added side activities needed for skin pectin breakdown. So, it is a very effective settling enzyme as well, more expensive, due to the added activities, but very effective.