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New World Wine Maker Blog - general

“Late-season fertigation of wine grapes is too late”… “La fertirrigation tardive de la vigne est trop tardive”…

 “Late-season fertigation of wine grapes is too late”… We can demonstrate the opposite!

While fertigation has become an integral part of the cultivation of many crops, it is rarely used by grape growers. Certainly in part due to dogmatic reasons.

On the contrary, vineyard irrigation has experienced a significant development. With the scientific knowledge we have today, we are able to manage irrigation in order to achieve specific quantitative and qualitative production goals. The monitoring methods and available technologies are numerous, each with its own advantages and disadvantages.

From a scientific point of view, very few studies have addressed the subject of vine fertigation directly. From a practical point of view, the experimental data is still scarce.

Fertigation is the best method for efficient vineyard nutrient management,  while being competitive as well as sustainable.

Fertigation has many technical advantages:
-  improved availability and superior nutrient uptake.
- effective nutrient distribution.
- nutrient management based on the vine vegetative cycle and production objectives.
- incorporation of nutrients in dry climates and/or drought periods.

Our topic of interest is late-season fertigation.  What do we mean by “late”? It is fertigation which is administered after veraison, more precisely 15 days after veraison.

These are the four major advantages of late-season fertigation:

Maintaining yield potential and berry shrivel

After fruit set, berry volume is the only factor responsible for a yield increase. The number of clusters and the number of berries per cluster are predetermined and can only be significant  for yield decrease (due to hail, diseases, pests, etc.).

Late-season fertigation allows us to maintain the berry volume and to avoid berry shrivel, which can be detrimental to berry quality (specifically with the development of harsh tannins) and quantity (yield loss). This is especially important for varietals where berry shrivel is more common (Merlot, Tannat, Pinot Noir, Gamay etc.). Cabernet Sauvignon, however, is less sensitive.
We tested the accuracy of the human sensor (the eye) for the detection of loss of berry volume. Our results show that when a decrease in berry volume is established visually, the berry shrivel point is often already reached and the berry volume loss is greater than 20 %, which is considerable. This compares to a yield loss (in susceptible varietals) of up to 30% in less than a week.

Note

For a berry with a volume of 1.5 mL, a decrease in diameter of just 1 mm is equivalent to a yield loss of more than 20 %.

Some experiments in France show that it is not possible to increase yield by more than 30 % with irrigation. This is both true and false.

It is true if one considers only the current year and only after fruit set: the single factor affecting yield is the volume of the berry, which cannot increase indefinitely or otherwise the berries will burst. A threshold of 30-40% yield increase is an acceptable average value (this being dependent on the grape variety).

However, the claim that yield cannot be increased by more than 30% with irrigation is also false, since the yield is already predetermined in the previous year (n-1) during flower initiation and at the beginning of the current year (n) with floral differentiation. If our main objective is yield, we can adapt the vineyard operations after pruning, specifically after the post-harvest fertigation of year n-1 in order to set aside a good reserve.

Note

Vine root activity is dependent on the vegetative cycle and reaches a peak during harvest. Therefore, at this time the vine is able to assimilate any available nutrients, especially if water is available.  There can be no assimilation of nutrients without available water, which is another point in favor of fertigation in dry climates or during dry periods.
This is one of the reasons why a nitrogen addition post-harvest improves the formation of sugar reserves, fundamental for a good bud break (vine growth cycle starts with spending these reserves).

 

 

 

 

 

 

Note that also phosphorus and to a lesser extent potassium enhance the effect of water on berry volume increase, with small added amounts (5-10 kg/ha).

 

 

 

 

 

Late-season deficit, aromatic profile and blocked maturation

As mentioned above, one of the major advantages of fertigation is to provide the plant with nutrients along with water. Therefore, the nutrients become assimilable.

During summer, especially in the Mediterranean climate (but not exclusively), the roots stop assimilating nutrients because of a lack of water in the soil.

In other words, when a nutrient deficiency is  observed (nitrogen or potassium, for example), it is already too late, it is no longer possible to take action. Even foliar spraying is not really effective.

Late-season fertigation resolves nutrient deficiencies which cannot be resolved in any other way. That said, it does not solve all problems because at the time we notice it in the vineyard, it has already been about 3 weeks that the deficiency has been present.

We also found that late-season addition of phosphorus in small amounts (2 x 5 units (kg/h) within 20 days before harvest) increases the intensity of “fresh fruit” aromas in Merlot.

Another important point is that fertigation helps with blocked maturation (due to water stress), specifically with the intake of phosphorus.

Blocked maturation occurs when the transport of sugars to the berry stops before the grapes reach maturity (a plateau in terms of amount of sugar per berry).  In other words, if the concentration of sugars in the berry keeps increasing, we cannot be sure that there is no blockage of maturation. The reason could be berry shrivel, instead.

Finally, with late-season fertigation with phosphorus and potassium, it is possible to manipulate the harvest date (maturation determined by the amount of sugar per berry). Phosphorus delays ripening and potassium accelerates it.

 

 

 

 Acknowledgements
Ms. Biljana Petrova (Laboratory Manager Inozy) is gratefully acknowledged for her English translation.

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“La fertirrigation tardive de la vigne est trop tardive”… Nous allons vous démontrer le contraire!

Tandis que d’autres cultures l’ont déjà bien intégrée, la fertirrigation – ou irrigation fertilisante – est une pratique peu employée sur vigne. Certainement en partie pour des raisons dogmatiques.

Au contraire, l’irrigation seule de la vigne s’est considérablement développée. Nous disposons aujourd’hui des connaissances scientifiques suffisantes pour piloter l’irrigation en fonction d’objectifs-produits quantitatifs et qualitatifs. Les méthodes et capteurs sont d’ailleurs nombreux, avec chacun des avantages et inconvénients.

D’un point de vue scientifique, peu de recherches ont traité directement du sujet de la fertirrigation. Et d’un point de vue pratique, les expériences sont trop peu nombreuses.

Et l’un des meilleurs outils pour fertiliser la vigne, c’est la fertirrigation. Elle permet en effet d’être très performant pour piloter son vignoble de manière compétitive et durable.

La fertirrigation présente également de nombreux avantages techniques :

- meilleure accessibilité et meilleure assimilation des engrais.

- distribution efficace des engrais.

- pilotage possible en fonction du cycle végétatif et des objectifs-produits.

-  incorporation des engrais sous climat sec ou en période sèche.

Nous nous intéressons ici à la fertirrigation tardive. Qu’entend-on par « tardive » ? Nous retenons une fertirrigation qui a lieu après véraison, plus précisement 15 jours après véraison.

Nous présentons ici 4 intérêts majeurs de la fertirrigation.

Maintien du potentiel rendement et flétrissement

Après nouaison, le seul facteur qui peut permettre d’augmenter le rendement est le volume de la baie. Le nombre de grappes et le nombre de baies par grappe sont fixés et ne peuvent que potentiellement diminuer (grêle, maladies, ravageurs etc.).

La fertirrigation tardive permet de maintenir le volume de la baie, et d’éviter un flétrissement préjudiciable à la qualité (notamment un durcissement des tanins) et à la quantité (perte de rendement). Ceci est d’autant plus important pour des cépages qui flétrissent facilement (Merlot, Tannat, Pinot Noir, Gamay etc.). Le Cabernet-Sauvignon quant à lui, est peu sensible au flétrissement.

Nous avons testé la précision du capteur humain (l’œil) pour la détection d’une perte de volume de baie. Nos résultats montrent que lorsqu’on constate une diminution du volume de la baie (visuellement), d’une part le stade flétrissement est très souvent atteint, d’autre part la perte de volume est supérieure à 20%, ce qui est considérable. Ce chiffre est à comparer à des pertes de rendement (sur cépages sensibles) qui peuvent atteindre 30% en moins d’une semaine.

Remarque

Pour une baie d’un volume de 1,5 mL, une diminution de 1mm de diamètre équivaut à une perte de rendement de plus de 20%.

Certaines expérimentations en France montrent qu’il n’est pas possible d’augmenter de plus de 30% le rendement avec l’irrigation. C’est vrai et faux.

Si nous nous plaçons après nouaison l’année de la récolte, c’est vrai. En effet, le seul facteur influençant le rendement est le volume de la baie ; il est impossible de l’augmenter indéfiniment, sinon la baie éclate. Et le seuil de 30-40% est une valeur moyenne (ceci étant dépendant du cépage).

C’est faux, puisque le rendement se fixe en grande partie l’année N-1, lors de l’initiation florale, et au début de l’année N avec la différenciation florale. Si on raisonne objectif-rendement, on adapte l’itinéraire viticole depuis la taille, voire même depuis la fertirrigation post-vendange de l’année N-1 pour une bonne mise en réserve.

Remarque

L’activité racinaire dépend du cycle végétatif et atteint un pic pendant les vendanges. A cette période, la vigne va donc pouvoir assimiler les éléments minéraux à disposition. Et ce, d’autant plus qu’elle a de l’eau disponible. Sans eau, pas d’assimilation d’éléments minéraux. C’est encore un point en faveur de la fertirrigation sous climat sec ou en période sèche.

C’est la raison pour laquelle un apport d’azote post-récolte permet d’améliorer la mise en réserve de la vigne, point fondamental pour un bon débourrement (la vigne démarre son cycle en déstockage).

 

 

 

 

 

Notons également que le phosphore –et dans une moindre mesure le potassium- accentue l’effet de l’eau sur l’augmentation du volume de la baie, avec des quantités faibles (5-10 unités).

 

 

 

 

 

Carences tardives, profil aromatique et blocages de maturation

Comme évoqué plus haut, l’un des intérêts majeurs de la fertirrigation est d’apporter des éléments minéraux avec de l’eau. Par conséquent, ils sont assimilables.

Or, en période estivale, notamment sous climat méditerranéen mais pas exclusivement, les racines n’assimilent plus les éléments minéraux par manque d’eau dans le sol.

Autrement dit, lorsqu’une carence minérale est constatée (azote ou potassium par exemple), c’est trop tard, il n’est plus possible d’agir. Même les pulvérisations foliaires ne sont pas réellement efficaces.

La fertirrigation tardive permet de résoudre les carences impossibles à résoudre autrement. Ceci dit, elle ne résout pas tous les problèmes, puisque lorsqu’on constate une carence au vignoble, cela fait environ 3 semaines qu’elle était présente.

Nous avons également constaté qu’un apport tardif de phosphore à faibles quantités (2 fois 5 unités dans les 20 jours précédents la récolte) augmente sur Merlot l’intensité aromatique Fruits Frais.

Aussi, et c’est un point important, la fertirrigation permet des déblocages de maturation, notamment avec un apport de phosphore.

Nous entendons par blocage de maturation un arrêt du chargement en sucre de la baie avant la maturité (plateau atteint en terme de quantité de sucre par baie). Autrement dit, ce n’est pas parce que le degré augmente qu’il n’y a pas de blocage de maturation. Au contraire, cela peut signifier un flétrissement.

Enfin, avec le phosphore et le potassium en fertirrigation tardive, il est possible de piloter la date de récolte (toujours par rapport à une maturation déterminée par la quantité de sucre par baie). Le phosphore retarde la maturité, et le potassium l’avance.

 

 

Remerciements

Mlle Biljana Petrova (Laboratory Manager, Inozy) est vivement remerciée pour sa traduction anglaise.

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On grape heterogeneity and lack of maturity…

When it comes to red grapes, any winemaker wants to extract grape tannins. Not only do they contribute towards colour and texture, but also aroma. The challenge with heterogeneity is that green tannins will also be extracted during fermentation. Another challenge is that there will be less useful tannins available for extraction. What to do?

 One should avoid cold maceration and rather opt for a hot, short fermentation. For instance, instead of fermenting at 23°C, rather 26°C or even higher. This will give more extraction, but lessen the time that good (and bad) tannins can be extracted. This might sound paradoxical, but we’ll soon get to a possible remedy. The higher temperature should also speed up the ferment. The number of pump-overs should decrease towards the end of the ferment, otherwise too much green tannins will be extracted. In other words, the grapes should be treated quite gently towards the end, because the higher alcohol concentration will increase tannin (good and bad) extraction. For smaller tanks, less punch downs towards the end are recommended. If possible, a closed system will be beneficial (for bigger tanks) and topping with C02 gas at the end of a day and after each maceration event will also prove useful for smaller open top fermenters. Why? Because oxygen needs to be excluded, more about this later. You can also press a bit earlier, possibly at 7°B already and then continue with the ferments sans skins. What about yeast and enzymes? Choice of yeast should be Anchor NT 202®, Anchor NT 50® or Fermicru VR5®. Enzyme choice would be Rapidase Extra Color® (the artist formerly know as Rapidase Ex-Color®). The timing of this enzyme is important, but we’ll get to this later.

 Now for the very interesting part… additions! Grape proteins are indiscriminate and will bind to any tannin (good or bad) and the tannin is thus lost. We don’t want this. In this case there are already insufficient ripe tannins (read good tannins), so the remedy would be to add sacrificial tannins, in order to save good tannins from binding with proteins and forever losing them.

 These added tannins thus “scavenge” grape proteins and saves the good/ripe tannins. Another function of these tannins is that they can contribute towards structure and taste. So yes, the grape might be lacking in ripe tannins and have too much green tannins, but the added tannins contribute towards more “pleasant” tannins again (albeit artificial) and thus the end quality of the wine.

The winemaker probably needs to do some research and trials and make a decision about their possible addition. There are many tannin products (oak and grape derived, for instance) on the market, the best would be to discuss the application of these products with your distributor.

 Rot might be a factor, so the laccase enzyme has to be considered too. The winemaker has to judge the level of rot and make a call on treatment. Laccase is a protein, which will, like grape proteins, also be bounded by tannins. The addition of tannins will bind laccase and thus remove it from the “equation”. And this is where we come to sulphur. Oxygen, in combination with laccase (should it be present) cause enzymatic browning of juice. You definitely don’t want this, so this is why oxygen needs to be excluded (as earlier mentioned), particularly at the beginning of fermentation. Sulphur dioxide will lessen the oxidative effect of oxygen. Total sulphur could probably be increased to 60ppm (if there is indeed rot).

  The timing of enzyme addition for colour extraction is important. Rapidase Extra Color® should not be added at the beginning, but rather towards the middle or end of the ferment. The reason is that the tannins added will bind to it and decrease activity.

 Untoasted oak chips are used for :

Intensification of fruit expression (remove green aroma)

Intensification and stabilization of color

Augmentation of volume and structure (natural polysaccharides lend sweetness to the wine, even as extraction reinforces tannic structure in the mouth)

Increased sweetness (both red & with wines)

 Addition should be done while filling the tank, at the destemmer (preferably a small chip size). La Littorale recommends 50 to 150 g/hL on white must and 100 to 300 g/hL on red must.

For Boisé France, 0,25 g/L to 10g/L. The dose will vary from supplier to supplier.

Good luck!

Bernard Mocke is a Technical Consultant for Oenobrands

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Consumer Perceptions of Sulfites in Wine: How this Perception Influences Purchase Decisions

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For many years Sulfur dioxide has been used as an antioxidant and antimicrobial agent in wine. Interestingly enough there is only about 1% of the population that has a true allergy to sulfites despite the wide-spread perception that sulfites cause negative health effects in a large number of people. Science has yet to prove a connection between sulfites and headaches even though some consumers insist their headaches or migraines are a result of drinking red wine.

 This exaggerated misconception has led some wineries to produce and market “low-sulfite” wines, which are essentially wines with little to no extra sulfites added. Organic winemaking is known for producing these types of wine, as added sulfites is not allowed in the production of organic wine.

Recently published articles argue that if consumers are truly concerned over sulfites in wine, then how much would they value a low-sulfite wine, and how many of them would consider this quality important in their purchasing decision process? The researchers have consequently created surveys as well as performed “best-worst” experiments in order to determine consumer preferences and attitudes toward sulfites in wine; their willingness-to-pay for low or no-sulfite wines; and to identify a particular group of which low-sulfite wines could be successfully marketed.

METHODS

Participants were recruited via an email subscriber list at a wine and spirits retailer in northern Colorado. These surveys were completed over a couple of weeks in March 2012, with a total of 223 participants completing the surveys.

It was noted that the participants in this study do not represent the national average, as they tended to have higher incomes and higher education than the average American.

97% of the participants claimed to have purchased at least one bottle of wine during a typical month, while 32% of the participants claimed to have purchased between 4 and 6 bottles every month.

These surveys asked questions about demographics and alcohol purchasing habits. The participants were also asked if they have ever experienced a headache after drinking moderate amounts of certain types of wine. If participants answered yes to this question, they were then presented with further questions aimed at determining what they thought were the cause their headaches.

The participants were then given information with respect to the role of sulfites in wine, as well as the current state of knowledge on the role of sulfites in human health issues. The information stressed than only 1% of consumers actually have a true sulfite allergy, and that there is no scientific evidence to suggest that sulfites cause headaches in more individuals than that.

For the select experiments, the researchers looked at 4 different quality levels, a “no-sulfites” wine label versus an “organic” wine label, and 4 different price levels. Quality levels were determined by scores from the Wine Spectator. Prices of wine were listed anywhere within $1.50 of three different “base prices”; $10.49, $20.49, or $30.49. Each consumer was randomly assigned to either a Chardonnay or a Cabernet Sauvignon.

Basically each participant experienced different price levels, quality, and no-sulfite/organic labeling, while the price range and the type of wine varied across participants and not within a single participant.

Participants were given 12 choice tests with 3 wines each and were asked to select their “most preferred” and “least preferred” in each set. Participants were allowed to select “would not purchase” if none of the options presented appealed to them.

After the preference selection, participants were then asked if they would actually purchase the wine they chose as “most preferred” …

>> CLICK HERE TO READ THE FULL ARTICLE

This blog was published in The Academic Wino by Becca Yeamans on 9th September 2013

 

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Acid Trip Mea Culpa

Acid_Trip_by_Sergeant_Keroro-copy

The 2013 harvest is coming up in in a few weeks. Every year I start planning the next vintage as soon as the previous one is done, but as the harvest draws near the thought process gets particularly fraught. About now I make a dispassionate, unstinting assessment of what worked and what didn’t, and what I’m going to do differently this year.

Back in April I released out 2010 Estate Pinot Noir. Let me say at the outset — I LOVE this wine. It is complex, fruity, mineral, has great concentration,and is generally representative of our vineyard site and my winemaking goals. I believe that this wine has the potential for at least 20 years of positive development.

And I also believe it could have been better.

I’m absolutely certain that it is my fault that it is not.

This Pinot exhibits two characteristics that are the direct result of things I did or didn’t do in the winery, things that I made a conscious choice about. 1) The wine exhibits ethyl acetate — a very fruity, estery, slightly chemical solvent smell. We used to say “it smells like airplane dope” because model dope is mostly ethyl acetate. But almost nobody builds those kind of planes any more. Anyway, the wine has a pronounced whiff of ethyl acetate. And 2) the wine is VERY acidic.

Both of these things are there because of choices I made in the winery. The ethyl acetate is there because I chose to not inoculate the Pinot Noir with a commercial strain of Saccharomyces yeast. For years I have been allowing the Pinot fermentations to take off on indigenous yeast — the yeast present on the grapes and winery equipment. One of these indigenous yeast is Kloeckera — a fairly robust fermenter that produces ethyl acetate as a by-product of fermentation.

In past vintages, I have allowed the Kloeckera to conduct part of the ferment, and then inoculated with Saccharomyces both to ensure that all the sugar is used up in the ferment (Saccharomyces is more alcohol-tolerant than Kloeckera, and so will complete the fermentation of high-sugar musts that would challenge most Kloeckera strains) but more importantly: for the Saccharomyces to take up and metabolize the ethyl acetate produced by the indigenous Kloeckera.

The 2010 Pinot fruit came in at lower than average sugar — 23.9° Brix. The ferments blasted through, such that Kloeckera pretty much completed the fermentation before the Saccharomyces could take over—much less dominate—the yeast population in the tanks. The ethyl acetate was there, and there it stayed. I actually like it a little, but it doesn’t need to be there. And a part of me still associates ethyl acetate with some nasty-ass “natural” wines I tried back in the 70s and 80s. Lesson for 2013: Don’t allow the strain of Kloeckera I have floating around the winery to dominate the ferments.

But I have a bigger issue with the high acid level in this wine. I have posted before about the 2010 vintage. The vintage presented a number of winemaking challenges arising from the relative coolness of the season. The juices had normal to slightly above normal levels of acidity, more malic relative to tartaric than usual, unusually LOW levels of potassium, and relatively high pH. Trial tartaric adds did not drop the pH significantly, and so I made little or no acid addition to the various lots.

What surprised me with the 2010 Pinot was that very little of the total acidity fell out of solution as tartrates. The resulting wine was tart post-malolactic. And this is where I did something I have sometimes chastised consulting clients for: I let a philosophy trump practicality.

The philosophy was “hey let’s be more natural and true to the site and the vintage, and keep the number of additions to a minimum.” The practicality is that this wine probably would have tasted better if I had added a little carbonate (to precipitate some of the acidity). I never even did the trial. But here’s the reality — with all due respect to Alice Feiring, Raj Parr, Jon Bonné, Dan Berger and all the other writers and sommeliers (and winemakers) touting a lower alcohol, higher acid style of wine:

High acid wines are just not as enjoyable to drink as wines with moderate, balanced acidity.

I’m no fan of what I call “cocktail” wines: the high alcohol, high pH, high extract, high oak, high point score grape-based beverages that have dominated the attention of the wine world for the last decade. I am all for moderate alcohols, by which I mean under 15%—preferably closer to 14%. I have tasted some varieties of North Coast wines that are balanced at even lower alcohol. But I’ve been doing this long enough to remember when this pendulum swung before. I recall that the North Coast produced some really insipid wines in the late 70s and early 80s when last the industry felt it necessary to produce a more “European” style. I don’t want to go back there.

So here’s the lesson learned: Spend some time and money doing acid add forecasting. Don’t hesitate to go to the bag, for tartaric or for carbonate, as needed to get a “balanced” wine — by my definition of balance. Don’t let some dubious “philosophy” dictate what I do in the winery.

 

John Kelly is the owner and winemaker of Westwood Wines, Sonoma California. This blog was originally published on his blog: “notes from the winemaker” on the 19 August 2013

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A List of Details

 

I’ve often said “There are only two processes to winemaking. Flavours are created in the vineyard and extracted in the winery. The rest is only details”.

Every time someone speaks of a great new winemaking process such as cold maceration or délestage, it’s time to ask yourself “Is this consistent with the style of wine I want to make?” Will this improve my process or handicap it? Will this create a greater risk of something going wrong? Break the process down into its individual elements and consider the effect of each element on flavour development. For example, a prefermentation cold soak selectively extracts water soluble compounds whereas extended post fermentation contact selectively extracts alcohol soluble components. The influence of aeration is affected by the stage at which it occurs. An early aeration can oxidize tannins and diminish their solubility whereas later stage aeration will diminish tannin astringency but may contribute to bitterness.

In some ways there is less flexibility during white grape extraction, so winemaking is more affected by grape flavours. If you wish to suppress flavour extraction, for example when working with over ripe grapes whose cellular structure has begun to break down, then you may resort to a whole cluster press. This occurs when making the typical big alcoholic Chardonnays that are left to hang until the berry begins to become flaccid. If the typical destemming were used, then tannin extraction would be a problem. This style of winemaking typically occurs at an elevated pH and runs the risk of developing bitterness in the presence of higher tannin extraction. Whole cluster pressing is also used when making a sparkling cuvée. The first, gentle press will have very little tannin extraction and is considered to be the premium part of the cuvée. Each subsequent pressing will have higher tannin content and should be kept separate, and perhaps treated with isinglass or gelatin to precipitate the tannins.

 When working with aromatic grape varieties the strategy is completely different. In this case the objective is usually to maximize flavour extraction. There is a hierarchy of aggressiveness that can be used. The most common technique is to simply run the berries through a destemmer and then press. The aggressiveness of pressing and the thoroughness of crushed berries affect the level of extraction. Flavour extraction is also affected by berry pH and sulfite. A more aggressive extraction can be carried out by using cold maceration prior to pressing. A convenient timing for cold maceration is to destem and crush in the afternoon and press the next morning. Again, the amount of air contact and presence of sulfite affect flavour. If tannin extraction is expected to be a problem, then a small amount of gelatin or isinglass can be dispensed into the crushed berries after destemming. An even more aggressive extraction of white berries can be made by adding pectinase during maceration. In this case it is highly recommended that gelatine or isinglass be added during the maceration. Tannins will tie up pectinase and inactivate it.

With aromatic varieties much of the aroma is often present as non volatile terpenes. These compounds can only be detected by the nose after they are converted to the volatile form. Many yeast contain a beta glucosidase that can carry out this reaction, but if you’re wanting more aroma, you can buy the pure enzyme preparation from suppliers.

The way in which you extract berries can also affect the stability of the resultant wine and its eventual sulfite requirement. Pre fermentation oxygen contact causes browning, especially noticeable in white wines. This results in wine that has a lower bound sulfite and is more heat stable without treatment. The down side is that you may also diminish varietal character if your oxidation is too aggressive.

I haven’t touched on the ways in which a vineyard can be manipulated to develop flavours nor have I suggested ways of blending different varieties. I’ve heard it said that if an identical batch of grapes were split among a dozen winemakers, they would still produce a dozen different wines. Even winemakers with the same training eventually develop a preferred pattern that results in recognizable differences. The potential process variations are essentially infinite. Every time the winemaker touches the process he leaves his fingerprint.

 Gary Strachan is an expert consultant and planner for the grape and wine industry. He can be reached at gestrachan@alum.mit.edu

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The Trouble with Blind Tasting

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If you’re an American in the wine industry and are within my age range (mid-twenties to early thirties, not to put too fine a point on it), you have, or are somewhere on the path toward, a Master Sommelier diploma. That is barely an exaggeration. (Some folks pursue a Wine & Spirits Education Trust diploma, or go on to a Master of Wine, instead.) For a generation that purports to care little about what the so-called experts have to say about wine, it seems we all want to become one anyway.

“It definitely helps to have it on the résumé when it comes to scoring a great job in the wine world,” said Dustin Wilson, wine director at Wine Spectator Grand Award–winning Eleven Madison Park and MS class of ’11. “It’s a title that earns you some automatic respect.”

The numbers speak for themselves: 63 and 70 people have sat for each Master Sommelier exam this year, compared to 38 and 37 in the two 2009/2010 sessions. (Some people were returning; you can repeat a failed segment of the test twice more, then you have to retake the whole thing.) In 2012, a total of 95 people took the Advanced Sommelier test for the degree a step below, with 39 more this past April. Of the 133 total North American Master Sommeliers, 71 have earned their letters since 2005, and the first test was held stateside in 1987.

By most accounts of people in the program, the series of seminars and degrees leading up to one’s MS is a fantastic immersion in wine knowledge. At $2,870 for the four course levels required to get your MS—and thousands more often spent on tasting practice—it’s also a pricey test to fail, and around 90 percent do in the final stage of each session (this month’s sitting of 70 hopefuls only minted one new MS). There are three segments, two of them perfectly unobjectionable. Deep knowledge of wine and spirits, along with grace under fire on the restaurant floor, should absolutely be required of, well, ideally any sommelier, but certainly one who claims mastery.

But here’s the rub: You also have to blind-taste six wines in 25 minutes and “identify grape varieties, country of origin, district and appellation of origin, and vintages of the wines tasted” at a minimum of 75 percent accuracy. Even if you’re a wine ace, you’ve played this game and lost, perhaps embarrassingly. So as you might expect, the tasting sinks plenty of sad somms. The new film Somm includes scenes when the four documentary subjects/MS candidates (Wilson is one) guess off by a mile, both in their thousands of practice hours and on the big day.

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Mixed case: opinion and advicewith Ben O’Donnell of the Wine Spectator

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