Archive for April, 2010


You want me to put it where?

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April 30, 2010  posted by Louis Nel

I am not a non-interventionist winemaker, simply because I do not trust fate at the wheel of my winemaking career.

We are often warned of the danger of processed food to our health, but what constitutes processed food? The common definition of processed food is any food that is handled through a process. Basically slaughtering and animal to get meat, or picking or handling food constitutes a process that leads to processed food. William S. Burrough’s name of his novel “Naked Lunch” refers to the fact that food is never as naked, as it is at the end of a fork. But the purest would argue that often food is not “raw” anymore, but “dead” by the time it is naked at the end of your fork. Is wine natural by the time it is in your glass? My current winemaking philosophy is that I do not want add anything to wine that will take anything away from it.

Basically I do not want to add fining agents, as far as possible, while at the same time I would consider tannin additions, acid and similar additions that will add something to the wine and make it better, more favourably. Dominique Delteil always warned of the effect yeast has on a wine’s colour, because the proteins in the cell wall would bind tannins that are bound to colour, and thereby reduce he colour of the wine. The real world effect of yeast reducing colour is difficult to fathom, but the possibility and effect exists.

One should therefore in theory either use wild yeasts (very small amount of yeast) or yeast that you know will do the job of fermentation well, so you would not need to re-inoculate and thereby fine some colour out with the new yeast cells. One of my pet peeves is the economical use of the truth by chemical and additive suppliers. Their graphs show the speed and efficiency clearly visible on their graph at presentations. They never ever show the correlation of their product with quality.

Does speed of malolactic fermentation correlate with quality? Was their microbial experiment that they used to get the data from, representative of the whole industry? When I buy malolactic bacteria, imagine my reaction, when together with my expensive packet of bugs, I am given a bag of yeast hulls, to help along the kinetics of the malolactic bacteria, and to help fine the colour out of my wine.

What??

Wine is a complex soup of chemicals, with interactions and kinetics quite impossible for any human brain to fathom exactly. Just because there is potassium in potassium metabisulphate, will it affect the pH of my wine significantly? Will my wine treatment improve the quality of the wine, or will throwing salt over my right shoulder have the same effect? I have said it many times, may we never stop learning, and wondering what is around the next corner.

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


Where did this term come from? I’m not the first person to ask these questions. Check out Eric Asimov’s piece in the NY times from October 2006. I think it may be that the term was first used in the film “Mondovino” which, for dramatic effect, built its narrative around facile differences between the “…old world and new, simple peasants and billionaires, and between the local and artisanal styles of wine production and the multinational and mass-produced ones.” Award-winning New Zealand winemaker and writer Drew Tuckwell put it as succinctly as such a vague concept might be clarified: “Non interventionist winemaking is not easy to explain. There are no defined or common rules. It is essentially a very natural form of winemaking… where, in general terms, winemakers resist the use of modern technology and simply allow the wines to express the terroir of the vineyard.” (1) My sainted Dallas-bred grandmother had a term for this kind of marketing-speak: “horse-puckey”. The craft of winemaking is the transformation of grapes with alchemist skill. For centuries the French have applied the terms “elevage” and “affinage” to the winemaking process. The winemaker facilitates the birth of the wine, and then raises it and refines it into something which, if not always transcendent and sublime, is at least palatable. I believe the most apt analogy for winemaking is child-rearing. I for one don’t believe that child rearing can be at all non-interventionist. And neither can winemaking be. I shall step on a slightly taller soapbox to proclaim: I believe that ALL wines – artisanal and mass-produced alike – are valid expressions of the grape, and of the winemaker’s craft. There is no way to define a cutoff between these arbitrary classifications; wines are produced along a technological continuum. On the other hand, all wines are not created equal. There are distinctions between the aromas and tastes of wines made by hand and those produced by machine that are no more arbitrary or subtle than the differences between, say, Redwood Hill Farm crottin and processed American cheese spread, or Boont Amber Ale and Bud. But there is no doubt that the makers of the crottin and the ale are interventionist to a fault in crafting their products. I believe that there is not a capital-poor winemaker worth the title that has not wished for a centrifuge (for clarification), a spinning cone (for alcohol reduction), or for ion-exchange (to remove volatile acidity) at some point in their career – I know I have. In my opinion, any winemaker that will claim in print or in person that they are truly and completely “non-interventionist” with a straight face, or at least without a little lurch (perhaps of self-loathing?) in the pit of the stomach, is a charlatan or worse – delusional. I don’t believe I’m a charlatan, or delusional. My wines are hand-made, with all the attention and care I can lavish on them. Many may disagree with my position and tone here, and call me a bombast. Fine with me. Just don’t call me “non-interventionist”.

John Kelly is the winemaker of Westwood Winery in Sonoma, California. This blog was originally posted 14 June 2008.


A new record for wine yeasts!

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April 16, 2010  posted by Karien O'Kennedy
I have been involved in “the world of wine yeast” since 1991 and the highest alcohol produced by a yeast during fermentation that I have ever encountered during all these years is 18.2%. I have however read that 18.6% has been observed in Japanese saké wine. During the past southern hemisphere harvest in the South African wine industry we experienced a massive heat wave in the first half of March which lasted a week and was disastrous for wine production. Cellars could not pick the grapes fast enough, and dehydration caused sugars to skyrocket. One poor chap phoned me requesting advice on how to ferment his 32 °Brix Cabernet Sauvignon. Since water addition is illegal in South Africa I suggested Anchor VIN 13 at 40 g/hl, Lallemand Go-Ferm Protect at the recommended dosage, a fermentation temperature of 23°C, the judicious use of complex yeast nutrients and prayer. The winemaker phoned me yesterday to report that the wine’s residual sugar is now indeed at 17 g/l and the alcohol at a staggering 19%! And the sugar is still dropping! This is the highest alcohol produced by wine yeast during fermentation of grape juice that I have personally ever encountered. I would be very curious to know if anyone out there has encountered something similar or even higher?
 
So, it seems the recipe for ludicrous sugars in the absence of the black snake (yellow snake…depending on the colour of the resident cellar hose) is VIN 13 wine yeast at 40 g/hl or more, Go-Ferm Protect, a low fermentation temperature to minimise alcohol toxicity, everything short of gold and diamonds in terms of yeast nutrition and faith in abundance. 
 
VIN 13 – the first hybrid wine yeast patented and commercialised by Anchor Wine Yeast in 1993. It is a hybrid between S. cerevisiae subspecie cerevisiae and S. cerevisiae subspecie bayanus. It has the fermentation capability (and more it seems) of “bayanus” yeasts and the aromatic capability of “cerevisiae” yeasts.
 
Go-ferm Protect – a yeast rehydration protectant patented and commercialised by Lallemand. It is an inactivated yeast based product very high in sterols and long chain fatty acids for the purpose of enhancing alcohol tolerance in live yeast cells.

Yeast cell walls versus inactivated yeasts…

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April 9, 2010  posted by Karien O'Kennedy
Yeast cell walls are also known as yeast hulls or yeast ghosts. Many sales reps sell yeast nutrients that they claim contain yeast cell walls when in fact they contain the whole yeast that has been inactivated. So what is the difference in application between cell walls and the whole inactivated yeast?
 
First a basic lesson in yeast cell morphology: yeast consists of a cell wall, on the inside of that you get the cell membrane and on the inside of that, well… the rest of the yeast. The cell wall consists mainly of glucans and mannoproteins (so-called polysaccharides) and the cell membrane consists of lipids (the fancy scientific name for fat). The lipids are made up of sterols and long chain fatty acids.
 
Both cell walls used on their own, and inactivated yeast containing the cell wall, membrane and yeast insides, stimulate fermentation. They do this in different ways though. Inactivated yeasts serve as a yeast nutrient in that they can be a source of vitamins and minerals. They can also be a source of sterols and long chain fatty acids. Live yeasts are little cannibals feasting on their dead counterparts when the going gets tough, i.e. the alcohol gets higher. To survive they need to strengthen their cell membranes and to do this they need more sterols and long chain fatty acids. They produce the latter in the presence of oxygen only. During fermentation oxygen is limited so they go for option B and that is to obtain these components from their dead mates. Reminds me of the movie Alive about the soccer team whose plane crash landed in the Andes Mountains. Yummy… Inactivated yeast insides also contain compounds such as amino acids and nucleotides that can “leak” out into the must and serve as a nutritious bite to the live cells.
 
Yeast cell walls are not a source of nutrients. They detoxify the must by removing medium chain fatty acids from the must, making the environment nicer and easier to ferment in for the live cells. Okay…long chain, medium chain, what’s the story? Live cells need to have an intact cell membrane containing long chain fatty acids to survive increasing alcohol toxicity. As alcohol levels become higher during fermentation, the live yeast starts to produce more fatty acids; however this process requires oxygen, which is limited or completely absent. The manufacturing of the fatty acid gets interrupted and the result is a much shorter chain that cannot be used in the cell membrane. These chains either stay associated with the yeast cell or get secreted into the medium. They physically block sugar uptake. For some reason they bind to yeast cell walls added to the must and the inhibition gets lifted.  
 
The commercial production of yeast cell walls is a much more complicated and expensive process than that of producing inactivated yeast. It is therefore usually a more expensive product. Depending on your specific fermentation conditions, you will use one or the other.
 
For a more comprehensive and slightly more serious explanation of the different types of yeast nutrients read the article, Wine yeast nutrients 101.