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New World Wine Maker Blog

Minimizing Spoilage of Wines in Barrel

By: Denise M. Gardner

The use of oak in the winery offers many options from winemakers.  With today’s availability of various oak products (i.e., chips, staves, powders), winemakers have more choices than ever before to integrate a wood component into their product.  However, the use of oak barrels remains an intrinsic part of most winery operations.  During the aging process, oak barrels have the potential to:

  • integrate new aromas and flavors into the wine.
  • add mouthfeel and/or aromatic complexity to the wine.
  • change the wine’s style.
  • add options and variation for future wine blends.

Additionally, the barrel room is often romantically viewed upon by consumers, and it is not uncommon for visitors to find barrel show cases in many tasting rooms, private tasting rooms, or while on a guided winery tour.

The barrel room at Barboursville Vineyards (VA) gorgeously catches the eyes of their visitors. Photo by: Denise M. Gardner

 

Oak fermenters at Robert Mondavi Winery (CA) that guests can see on their famous guided tour. Photo by: Denise M. Gardner

Nonetheless, barrels also offer challenges to wineries.  One of the most inherent challenges associated with a barrel program is maintaining a sanitation program.

The growth of spoilage yeast, Brettanomyces, is often discussed amongst wineries that utilize barrel aging programs.  However, additional spoilage yeast species such as Candida and Pichia have also been associated as potential contaminants in the interior of wine barrels (Guzzon et al. 2011).  Brettanomyces, commonly abbreviated as Brett, was first isolated from the vineyard in 2006 (Renouf and Lonvaud-Funel 2007) and until that point had most commonly been associated with the use of oak in the winery.  The growth of Brett in wine has the potential to impart several aromas as a result of volatile phenol [especially 4-ethylphenol (4-EP) and 4-ethylguaiacol (4EG)] formation in the wine.  Descriptors used to describe a Bretty wine include: barnyard, horse, leather, tobacco, tar, medicinal, Band-Aid, wet dog, and smoky, amongst others.  It should be noted that the presence of these aromas does not necessarily confirm that Brett is in the wine; there are other microflora, situations (e.g., smoke taint) or oak chars that can impart some of these aromas, as well.

Brettanomyces aroma descriptors. Image by: Denise M. Gardner

When barrels are filled with wine, it’s important to monitor the wine regularly for off-flavors while it is aging.  Wines should be regularly topped up with fresh wine to avoid surface yeast or acetic acid bacteria growth that can contribute to the volatile acidity (VA).  We usually recommend topping barrels up every-other-month.  Keep in mind that free sulfur dioxide concentrations can drop quicker in a barrel compared to a tank or wine bottle (MoreFlavor 2012) and free sulfur dioxide contractions should be checked (in conjunction with the wine’s pH) and altered as necessary to avoid spoilage.  Finally, when using a wine thief, both the internal and external part of the thief need cleaned and sanitized in between its use for each and every barrel to avoid cross contamination.  Dunking and filling the thief in a small bucket filled with cold acidulated water and potassium metabisulfite (acidulated sulfur dioxide solution) is a helpful quick-rinse sanitizer.

Barrels offer a perfect environment for microflora to flourish.  Wine barrels are produced from a natural substance (wood), which has its own inherent microflora from the point of production; obviously, barrels are not a sterile environment when purchased.  However, the structure of wood is rigid and porous, which provides nooks and crevices for yeast and bacteria to harbor within.  The porosity of the wood also makes it difficult to clean and sanitize, especially when compared to cleaning and sanitation recommendations associated with other equipment like stainless steel tanks.  Guzzon et al. (2011) found that barrels used over 3 years in production had a 1-log higher yeast concentration rate retained in the barrel compared to new and unused oak barrels.  This demonstrates the ideal environment within the barrel for retaining microflora over time, even when adequate cleaning and sanitation procedures are utilized in the cellar.

Common barrel sanitizers include ozone (both gas and aqueous), steam, hot water, acidulated sulfur dioxide, and peroxyacetic acid (PAA).  A study conducted by Cornell University on wine barrels used in California wineries found the use of sulfur discs, PAA at a 200 mg/L concentration, steam (5 and 10 minute treatments) to be effective sanitation treatments for wine barrels (Lourdes Alejandra Aguilar Solis et al. 2013).  In this same study (Lourdes Alejandra Aguilar Solis et al. 2013) ozone (1 mg/L at a 5 and 10 minute treatment) was also evaluated and found effective in most barrels tested, but a few barrels that did not show adequate reduction with the ozone treatment.  While the research conducted by Cornell indicated the potential lack of cleaning the barrel thoroughly before the ozone sanitation treatment, Guzzon et al. (2011) cited ozone’s efficacy is most likely caused by its concentration.  Both are important considerations for wineries.

Barrels should always be effectively cleaned of any debris and or tartrate build up before applying a sanitation agent.  This is essential to allow for maximum efficacy during the sanitation step.  High pressure washers, a barrel cleaning nozzle, and the use of steam are some options available to wineries in terms of physically cleaning the interior of barrel.  Additionally, some wineries use sodium carbonate (soda ash) to clean some of the debris (Knox Barrels 2016, MoreFlavor 2012) in addition to the use of a high pressure wash.  Always remember to neutralize the sodium carbonate with an acidulate sulfur dioxide rinse prior to filling with wine.

Dr. Molly Kelly from Virginia Tech University has previously recommended a 3-cycle repeat of a high-pressure cold water rinse, followed by high pressure steam before re-filling a used barrel and assuming the wine that came out of that barrel was not contaminated with spoilage off-flavors (Kelly 2013).  If the barrel is hot by the end of this cycle, it may be advantageous to rinse with a cold, acidulated sulfur dioxide solution before filling the barrel with new wine.  If there isn’t wine available to refill the barrel, it can be stored wet with an acidulated sulfur dioxide solution or using sulfur discs (Kelly 2013).

It is not usually recommended to store used barrels dry for long periods of time, and wineries can use an acidulated sulfur dioxide solution (top off as if it had wine in it) for long-term storage.  However, wineries that store their barrels dry need to rehydrate the barrels prior to filling with wine.  Check the cooperage for leaks, air bubbles, and a good vacuum seal on the bung.  Steam or clean water (hot or cold, overnight) are adequate rehydrating agents (Pambianchi 2002).  Barrels that leak wine offer harboring sites for potential yeast, bacteria, and mold growth, which can all act as contaminants to the wine itself.

It should be noted that contaminated barrels (barrels that produce a wine with off-flavors) may need extra cleaning and sanitation steps to avoid future contamination when the barrel is refilled.  It is typically recommended to discard barrels that have a recorded Brett contamination.  If the barrel has picked up any other off-flavors, especially during storage, it should probably be discarded from future wine fillings.

Barrels undoubtedly offer several challenges for wineries, including proper maintenance, cleaning and sanitation.  Nonetheless, engaging in good standard operating procedures for maintaining the barrel’s cleanliness can help enhance the longevity of the barrel and minimize risk of spoilage for several wine vintages.

 

References

Guzzon, R., G. Widmann, M. Malacarne, T. Nardin, G. Nicolini, and R. Larcher. 2011. Survey of the yeast population inside wine barrels and the effects of certain techniques in preventing microbiological spoilage. Eur. Food Res. Technol. 233:285-291.

Kelly, M. 2013. Winery Sanitation. Presentation at Craft Beverages Unlimited, 2013.

Knox Barrels. 2016. Barrel Maintenance.

de Lourdes Alejandra Aguilar Solis, M., C. Gerling, and R. Worobo. 2013. Sanitation of Wine Cooperage using Five Different Treatment Methods: an In Vivo Study. Appellation Cornell. Vol. 3.

MoreFlavor. 2012. Oak Barrel Care Guide.

Pambianchi, D. 2002. Barrel Care: Techniques. WineMaker Magazine. Feb/Mar 2002 edition.

Renouf, V. and A. Lonvaud-Funnel. 2007. Development of an enrichment medium to detect Dekkera/Brettanomyces bruxellensis, a spoilage wine yeast, on the surface of grape berries. Microbiol. Res. 162(2): 154-167.

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Meet Annamarie Fourie – Winemaker at Holden Manz

Q. Where and when were you born ?

“Born in in Vredendal in May 1981, My folks were living in Saldanha at the time.”

Q. Where did you study ? 

“I obtained a B-Agri at Elsenberg  in 2009.”

Q. Do you  consider your approach to winemaking to be different to others ?

“No, not really.  Those of us who were lucky enough to go to Elsenburg were very thoroughly trained and if you did the basics correctly and paid attention to detail you should produce decent wine.”

Q. How involved to you get in the vineyard ?

“I am very much involved with the day to day decisions in the vineyard. Where I have previously worked there were very good viticultural people from whom I learned a lot and here at Holden Manz we have Tertius Oosthuizen who is very good at what he does. However , I still like to know exactly what is going on in the vineyard throughout the season.”

Q. Do you have any varieties you prefer to work with ?

“Syrah and Chenin Blanc.”

Q. Have you been influenced by any particular winemaker or region ?

“Working with a man like Thierry Haberer you can’t not be influenced and I am sure what he does has rubbed off on me. Then my visit to the Rhone had  a great impact and there Edward La Beye certainly was influential.”

Q. What would you consider your greatest achievement as a winemaker ?

“Finding my feet and my voice in the wine industry and to be treated as a winemaker and not a woman ! I think this is the best achievement I could have asked for.”

Q. What “secrets” have you “developed”  that make your wines different to others ? 

“No secrets. Just pick when the grapes are ready to be picked and taste, taste, and taste !”

Q. How important is modern winemaking equipment in your winemaking ?

“Here at Holden Manz we have some lovely modern equipment to work with but  I guess there will always be something that would work better. Although, having said that, modern equipment  is not as important as functional equipment . I would rather have the latter.”

Q. What made you go into winemaking ?

“I grew up in a small town in the Swartland, Moorreesburg, and in my heart, I always wanted to be a farmer. I knew I would not do well with livestock. So I chose something that I love to drink, wine ! I still love to get my hands dirty and you can do that with wine ! Also, I love the intimacy of a small winery and the total involvement. So this will be my focus for years to come, to perfect my craft/art and find my place !”

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Dry eyes, full hearts

Drought has been the talk of the town for some time now. Unsurprising that when one of the most vital resources of all biological and mechanical activity goes missing, so too does any state of calm. It’s a true natural disaster, one that manifests itself as directly as a hurricane or as indirectly as an economic recession. This has impacted us all in the Southern tip of Africa and has been felt from the veld of the Karoo right to the gardens of Constantia.

As we all know, the grapevine is a well rooted plant. And it’s not one of those pseudo plants that can just up and move (like tumbleweed), nor is it a crop that can simply be replanted elsewhere. It’s a commitment plant. Trade in your wedding ring, the vine is your new life partner. It’s there to stay, and it’s going to need just the right amount of care (and neglect) to make the journey.

This journey largely takes place below ground, in the subterranean; the biological dungeon; the organic labyrinth; erebus … (soil often needs hyperbole to keep people interested). This underworld supports everything that sits on top of it – and is actually quite fascinating – but it can’t do that without water. Water feeds not only the vine, but the millions and billions of fauna and flora that inhabit the soil and are quintessential for the operation of the vine. They provide food and protection from other harmful parasites. Without these the vine now has to do it all by itself.

Take away water and take away the soil life and strain sets into the vine, often a beneficial state that helps concentrate the flavours in the grapes, like a light sweat on the brow of an athlete.

Around the start of summer, the vine is growing in all directions – literally and figuratively. It’s trying to grow physically larger and ripen its fruit, like a pregnant lady in third trimester training for Ms Olympia. You can imagine what that must be like if, on top of all of that, you have no water and it’s hot: the pregnant lady’s gym is now in the Sahara desert. In the vine, stress would set in at this point. This is when things cross into danger the zone: acids in the berries degrade, leaves wilt, growth stops, the vine’s ability to fend off pathogens diminishes. It burns out all of its supplies to keep going and produce fruit, and by winter time the reserves it needs to make it to next spring have taken a heavy hit. The poor vine may lapse into a state of weakness for some years to come.

This stage was set in the summer of 2016 in South Africa. We are now well into 2017 and the biblical rainfall the vine needs is still yet to come. It’s going go deeper and deeper into the red zone. We must simply pray this dry period comes to end. South Africa – its dry(er) regions in particular – sit on the boundary of viticultural possibility. I’ve heard it said, in Burgundy the vine goes through a summer about as difficult as a Sunday morning fun-run; in South Africa, it’s the Comrades Marathon and more. And it’s only getting more and more difficult. The world is getting warmer, if you live in Iceland or own a Sunscreen brand, you’re one of the very few who is benefitting.

In the meantime we watch and wait with baited breaths for relief this coming winter.

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Carbonation and the pain of Champagne

By Erika Szymanski of The Winoscope

Sparkling wine – or beer, or soda, or seltzer* – triggers an unmistakable set of sensations, addictive or repellent depending on your predilection. But is that sensation a taste? A physical sensation? Something else? Probably some combination of the above, though figuring all of that out is trickier than you might imagine.

First, the bubbles in sparkling wine are carbon dioxide, either the product of yeast fermenting a last little bit of sugar in the bottle or mechanical carbonation with a tank of pressurized gas. Carbon dioxide plus water makes carbonic acid: CO2 + H2O ⇌ H2CO3 . Acids, by definition, are molecules with hydrogens which can and do pop on and off when dissolved in water. If the hydrogens tend to disassociate themselves easily, you’re dealing with a strong acid (e.g. hydrochloric or sulfuric) best used for cleaning glassware or dissolving an inconvenient corpse. If only a small number of hydrogens hop off at any one time, you’re dealing with a weak acid. Carbonic acid, needless to say, is a weak acid, or else seltzer water would be an industrial solvent rather than a cocktail mixer. Chemists were associating the perception of sourness with those free hydrogen ions back at the turn of the twentieth century, but they’re not sufficient to explain sourness alone, and twenty-first century chemists are still trying to work out the remainder. The ongoing search for a complete explanation of sourness is one of those excellent examples of how very simple daily phenomena can end up being unexpectedly complicated when scientists try to explain them in terms of chemistry and biology.

Second, the bubbles in sparkling wine are mechanical stimulation. If you stick your hand into a glass of sparkling water, you’ll feel the “prickle” of bubbles bursting along your skin, and your tongue and the interior of your mouth receives the same sensation. That’s not surprising.

A third component of how we sense carbonation is surprising, or at least it’s surprising to me as a carbonated beverage-lover. Carbonation appears to trigger nociceptors, the specialized receptors we have for sensing pain. Carbonation is, physiologically speaking, irritating.

>> CLICK HERE TO READ THE FULL ARTICLE

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Irene Waller General Manager and Winemaker at La Bri

Q When and where were you born ?

“I was born in Cape Town at the Kingsbury Maternity hospital in Claremont in June 1968.”

Q Where did you study and what qualifications do you have ?

“I first trained as an accountant so have a Bcom (Accountant) from UCT. I then went on to be a maths and accounting teacher. I did my HDE part time through UNISA during my first two years of teaching. I quit teaching officially in 1996 as I had made up my mind to become a wine maker. I then spent  the next five years travelling between Australia, South Africa and Europe to gain wine experience. To pay my way I taught maths in the UK.  In 2001 I returned to Maties (University of Stellenbosch) to study BSC Agric which I achieved  Cum Laude  and was awarded  the Professor Perold trophy  as the top student. “

Q. Do you consider your approach to winemaking to be different to others ?

“I like to think I combine both the science and the art of winemaking in one. The chemistry is there to guide  but ultimately it is the gut  feel and experience that allows for the creativity of expression.”

Q. How involved do you get in the vineyard ?

“I believe you cannot make wine in the cellar if you have not been involved in the vineyard”.   She continues “We are fortunate to have Gerard Olivier managing the estate and vineyards, but we work closely together when it comes to decisions of new plantings, canopy management and ultimately harvesting.”

Q. Do you have any varieties you prefer to work with ?

Without hesitation she replies “Chardonnay for our MCC, Syrah and the difficult child, Viognier.”

Q. Have you been influenced by any particular winemaker or by a wine region?

“I was extremely fortunate to be appointed  as a winemaker at Graham Beck Wines in Robertson being straight out of varsity. It was here that I developed my passion for MCC under the expert guidance and mentorship of Pieter “Bubbles” Ferreira. I take from him the adage ‘there is no recipe – we don’t make coca cola !’ “

Q. What would you consider your greatest achievement as a winemaker ?

“The release of our first MCC under the La Bri Label, our Sauvage La Bri. A work of patience and passion with over five years on the lees before degorgement. A wine I am extremely proud of.”

Q. What “secrets”  have you “developed”  that make your wines different to others .

“I don’t really think it is a secret as I hope you can taste it in the wine . The passion with which the wine is made  and our attention detail at every stage of it’s journey.”

Q. How important is modern winemaking  equipment  in your winemaking ? 

“We like to think we make old world wines with the benefit  of new world technology. At La Bri we have a state-of-the art 120 ton boutique cellar built in 2008 which allows the benefit of making wines with all the ‘bells and    whistles’ “

Q. How important are the cellar dogs in your wine quality ?

With a gorgeous smile “Oh, couldn’t do anything without those old two. Jake the Jack Russell and Peggy-Sue the aging Staffie.”

Q. Whatever made you change direction from accounting to winemaking ?

“I did a Cape Wine Academy  prelim course in  1996 and Louise-Ann Grinstead was my lecturer. She ignited in me a desire to know more about  wine and after much travelling and studying I finally became a winemaker at the ripe old age of 36 ! You are never too old to find your true calling and passion in life. “

Q. Now the future ?

“ I am very fortunate to work  for an owner, Robin Hamilton, who allows me the freedom to experiment. We have released  the first MCC at La Bri and have reintroduced Semillon to the range. Semillon which is a variety synonymous with Franschhoek.”  Then ends with enthusiasm “The future is exciting with the challenges it holds.”

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Wine of Origin: Mars

With tickets on the shuttle almost being sold already, the world is making quite a fuss about colonising the red planet next door. The major motion picture, The Martian, has left us to believe that is plausible to survive on Mars and even grow some very “organic” potatoes, but would you really want to live there? Without wine? Certainly not. And seeing as it costs about $10 000 a pound to send something to space, “exporting” a bottle of wine to Mars isn’t exactly in my budget- especially after I have to pay $10 billion just to get there myself. After I’ve spent that amount of money, I am definitely going to need a glass of wine and if I’m on Mars, it seems I am going to have to make it myself.

Turns out, I’m not that far off thinking that it is possible to grow grapes and make wine on Mars. There has already been successful studies that indicate crops like tomatoes, radishes and peas can not only be grown in simulated Martian soil, but are also safe to eat. Martian “soil” or regolith contains all the macro- and micronutrients that are required to grow grapes. The amounts that are found in the substrate vary on different parts of the planet (as it does here on earth too), so general fertilisation will almost certainly be required. The substrate is unfortunately also very fine and of a dust like nature. This means that it probably has an inadequate water-holding capacity. Previous studies have added grass cuttings as an organic compound to help with the retention of water. Another possibility, of course, is the use of hydroponic systems where nutrients are fed to the roots of the plant through a soilless substrate, usually in the form of liquid fertilizer. As our neighbouring planet is further away from the sun than earth, it experiences much colder temperatures. Winter temperatures near the poles can drop as low as -125 ºC and a summer day near the equator won’t get much warmer than 20 ºC. So it’s a bit too cold for growing crops on the exposed exterior of the planet, but a simple greenhouse with a controlled atmosphere can easily regulate the temperatures and carbon dioxide levels that the plants are exposed to. Then there is the issue of water, that doesn’t really seem to be an issue anymore. In September of 2015 already NASA had announced that I had found evidence of flowing, liquid water on Mars. Although this water is believed to be salty, it may potentially be used for irrigating vines.

Now, at the moment it seems that all “growing operations” on Mars will have to take place in a controlled environment like a greenhouse. We can only hope that one day, future generations will have found ways to plant vineyards on the surface of the red planet and that they will be able to utilise the terroir of the Patera Mountains and other unique terrains found on the surface. Of course the soil will also contribute to the extra-terrestrial terroir and it is important to note that the current surface substrate contains a lot of heavy metals. These will be less desirable characteristics to pick up in your Martian blanc. Again, by the time we get there I’m sure we would have figured out a way to remove all the harmful metals from the soil or the filtered wine.

The production of wine on Mars will not only make the people living there a lot happier (seeing as there is wine to drink), but the social repercussions of such an activity can have an immense impact on a developing community or colony. By involving the community in every step of the process, from the soil preparation to the upkeep of vines to harvesting and ultimately the wine making, a sense of camaraderie is established among them. And at the end of the season they all get to sit down and enjoy the fruits (wines) of their labour together.

The likelihood of all of this happening in our lifetime, is rather slim. It probably won’t be another 100 years before we get to taste the first Martian vino. But I am excited for the generations to come and I hope that I can be a part of making this dream become a reality.

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