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New World Wine Maker Blog - Barrels

Facial for your barrel anyone?

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.

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To oak or not to oak…

Oak: Its contribution to wine aroma and overall quality

Wine odor is one of the key markers of wine quality and, as a part of my series on wine quality, I have set myself the task of identifying and characterizing the sources of wine odor and showing how the interactions of these odor components aid in the perception of wine quality.

Wine is aged in wooden barrels to: (i) enhance its flavor, aroma, and complexity through transfer of substances from the wood to the wine; and (ii) allow gradual oxidation to occur. As a result of its “strength, resilience, workability, and lack of undesirable flavor,” oak is the wood of choice for most wine cooperage applications.

The oak used in the maturation of alcoholic beverages fall into one of three species: Quercus alba, Quercus robur, and Quercus sessilis. Q. robur and Q. sessilis, and their respective subspecies, are European white oaks while Q. alba is the source of 45% of the white oak lumber produced in the US. American oak used in barrel production is sourced from Kentucky, Missouri, Arkansas, and Michigan but there is no apparent regional distinction. European oak, on the other hand, may have designations which reach all the way to the forest from which the oak originated. For example, French oak from the department of Alliers may be sourced from a forest named Tronçais.

For full blog…

http://mowse.blogspot.com/2012/07/oak-its-contribution-to-wine-aromas-and.html

Blog sourced from Wine — Mise en Abyme

 

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On artificial insemination…

Most of us heard about the snappy response of one of South Africa’s greatest winemakers after a lady asked him about the use of oak alternatives…

Lady (living encyclopedia of wine knowledge): “Do you use oak alternatives like chips, dust, staves and balls?

Winemaker (focused and slightly annoyed): “Lady, do you know what artificial insemination is?”

Lady (living encyclopedia of veterinary science): “Why, yes of course!”

Winemaker (with a grin): “Lady, which do you prefer?”

The question remains: Can the use of oak alternatives benefit the wine to such an extent that it can fully replace the use of barrels, i.e. that it induce in wine all the required reactions without jeopardizing the final wine’s quality and/or style?

There certainly are opposing answers to this question!

The “no” school – Investigations into oak derived products and their influence on wine quality yielded certain disadvantages, e.g. no retrieval of complexity compared to oak barrels, occurrence of hydrogen sulfide on wines associated with fermentation on chips and the precipitation of yellow, semi-crystalline substance as a result of wines treated with sawdust or shavings because of extracted ellagic acid. There is also a general lack of information concerning the influence of oxygen provided by oak derived products and its contribution towards wine quality.

The “yes” school – There are, however, important advantages as well.  We all took note of the significant cost reduction in the use of oak derived products opposed to the use of barrels. The addition of oak staves, chips, shavings or powder is a more rapid and economical method of oak treatment. Increased surface area of these oak derived products results in more significant rates of extraction. Some researchers documented the use of 7g/L of oak chips during white wine fermentation to increase the favorable perception of a tasting panel. Ducournau et al. (1999) documented oak chips to be more adapted for consistent toasting, resulting in more homogeneous lots. Zoecklein noted the use of oak derived products in combination with micro-oxygenation to result in wines with increased body, soft tannins, stabile color and enhancement of fruit and oak aroma integration (Zoecklein et al., 2002).

My personal conviction? Staves work as well as barrels. Nevertheless – we are debating the wrong issue here. Perhaps the right question should be: “How does the flavor profile of my wine suit the market where I try to flog it? How can I ensure consistency in my wine in a financially viable way?” Are we afraid of the answers, because we simply do not have them? Or do we acknowledge the fact that we squander money based on our personal opinions of the consumer, what they want, how they want it and where?

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

 

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A glimpse at the complexity of barrel ageing

“I have walked across the surface of the Sun. I have witnessed events so tiny and so fast they can hardly be said to have occurred at all. But you, Adrian, you’re just a man. The world’s smartest man poses no more threat to me than does its smartest termite.” – Doctor Manhattan

The above quote by Doctor Manhattan from the 2009 movie, Watchmen, made a very big impact on me. Not only did Doctor Manhattan have extraordinary physical capabilities, but also boundless intelligence and wit. Most scintillating however, was his ability to observe and control miniscule atomic particles and impossibly fast to imagine metaphysical events. Doctor Manhattan didn’t really strike me as a lush, but I’m sure that he would have been fascinated with the chemically complex and ever changing matrix that is maturing wine.

As a former minor winemaker at quite a few cellars, my favorite place has always been the barrel maturation cellar. Barrel ageing is ostensibly one of a wine’s more important stages of evolution before bottling. But how exactly does wine change during barrel ageing and what effect does it have on the countless chemical reactions taking place in wine every second? The main effect of oak barrel ageing is twofold. Wood character is introduced (the rate and intensity is mostly dependent on fill status of the barrel) and oxygen is very slowly introduced to the wine. Generally speaking, this results in softening of the harsh tannins and flavors present at the end of fermentation. Oak is a fascinating substance, which has a profound and remarkable effect on the flavor chemistry of wine. Key oak derived compounds are tannin, lignin, cellulose and hemicellulose.

Tannin plays a vital role in barrel ageing. Although most tannin in wine comes from the grapes, some of it is also liberated by the barrel during ageing. So what exactly is the deal with tannin? An experienced winemaker will instinctively know how to optimally merge and balance the tannins extracted during the youthful stages (fermentation, skin contact and pressing) and the mature stages (barrel ageing and blending). For instance, more tannic grape varieties such as Tannat, Cabernet Sauvignon, Nebbiolo and Shiraz cannot be approached the same as the less tannic Pinot noir. Once again, winemaker experience is paramount.

OK, now hold on to your chemistry hat, here comes the hard (but interesting) bit! Phenolic compounds (consisting of natural phenols and polyphenols) in wine are largely responsible for imparting taste, colour and mouthfeel to wine. They include phenolic acid, stilbenes, flavonols, dihydroflavonols, anthocyanins, flavanol monomers (catechins) and flavanol polymers (proanthocyanidins). Natural phenols can be separated into flavonoids and non-flavonoids. The latter group includes stilbenoids such as resveratrol and phenolic acids such as benzoiz, caffeic and cinnamic acids. The former group includes anthocyanins and wait for it… tannins!

What would a good red wine be without vanilla flavors, sweet and toasty aromas and notes of tea and tobacco? Specific compounds create these nuances in finished wine, for example: volatile phenols containing vanillin; carbohydrate degradation products containing furfural, a component yielding a sweet and toasty aroma; “oak” lactones imparting a woody aroma; terpenes providing “tea” and “tobacco” notes, and hydrolysable tannins, which are important to the relative astringency of the wine. Take note, every time you’re quaffing a wine (hopefully a worthy vintage), you’re consuming everything you’ve just read above. If this doesn’t sit quite right with you, then I guess nothing much will.

They say you should have respect for your elders. So, tread lightly the next time you pass through a barrel maturation cellar. You might even see Doctor Manhattan skulking around in the dark, silent corners…

Bernard Mocke is a technical consultant for Oenobrands.

 

 

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Snow blower on Enceladus

Have you ever wondered where the circle around Saturn comes from? Interestingly enough it was discovered that one of the moons of Saturn, called Enceladus, is successful in shooting ice grains far enough to form Saturn’s ring…

Just as amazed as I was 12 years ago when I was introduced to Saturn, I was when Ice Jet came to clean some of my barrels. The technology was introduced to me a while ago, and we have decided to put it to the test.

The coopers come to your site with their mobile unit and remove the heads of the barrels to expose the inside of the barrel. And this is where I saw to my total amazement the biggest, deadliest blisters you can imagine! And I was even more appalled when I saw and smelled the puss that drizzled out of these opened wounds…I call on all winemakers to inspect your barrels, please! I have some understanding now of why barrel differences occur, why Brett spoils our wine, why volatile acidity increase sporadically, and, and, and…If only barrel inspection helped…older barrels with these types of blisters induce most of the nightmares in very expensive, barrel maturing wines!

How does this work? The CO2 ice pellets are blasted onto the contaminated barrel surface at -790 C and basically “delaminates” contaminants from the wood. Once the ice makes contact with the wood surface it, returns to its natural gas (CO2) state and expands up to 700 times to create shock waves. This effect drives brittle materials from the surface as tartrate crystals and sediments are frozen, fractured and removed exposing original, unused toasted oak surface.

It removes not only sediment, but also contaminants on up to 99% of the interior surface of the barrel. Most bacteria and mold spores are removed, which leaves the barrel in a cleaner state than any chemical or physical process can.

During the ice blasting process a layer of wood between 0,5 and 1,2 mm is removed, exposing a freshly toasted oak surface to the next cycle of wine. This also restores micro-oxygenation as a result of restored porosity. As toasting during cooperage is typically up to 1 cm deep, there is no need for re-toasting after ice blasting.

In a major project testing this technology in the USA, very promising results were obtained. The tests showed that the treatment allowed the barrels to impart significantly more oak volatiles into the wine. The only volatiles, which showed lower readings, were guaiacol and 4-methylguaiacol, which is responsible for “smoky”, and “chary” flavors. Organoleptic evaluations found the treatment to result in wines with improved fresh oak, vanilla, butterscotch and coconut flavors, decreased smoke/char flavors and fresher, cleaner fruit.

It is not the cheapest way to clean barrels, but as sure as the ice circle around Saturn, the most effective and hygienic way to clean barrels!

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

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