By: Denise M. Gardner
The eastern U.S. growing seasons can be somewhat unpredictable. Late season rains or untimely hurricane events can be a recipe for disaster for local grape growers, and a few have been unprepared for such events in the past. These weather events can lead to higher incidences of the grey-rot form of Botrytis in addition to other rots, which may also be related to pest damage. Furthermore, these weather incidences and pest damage can ultimately impact picking decisions for growers and wineries (Osborne, 2017).
It is almost inevitable that wineries need to be prepared for end-of-season weather flops, and plan for the best possible ways to manage or maintain wine quality in light of above-average disease pressure.
One disease that winemakers can prepare for prior to harvest is Botrytis. For the purpose of this article, we’ll be using the term Botrytis to indicate the grey-mold or grey-rot form of the disease. Grey-mold, the form of Botrytismore commonly noticed in humid regions or during heavy-precipitation seasons, can ultimately affect wine quality. Peynaud (1984) has defined 4 ways in which the grey-mold can negatively affect wine quality:
- Deplete wine color (especially important in red varieties),
- Increase the risk of premature browning (through oxidative enzymes),
- Deplete varietal character (through degradation of grape skins), and
- Contribution to off-flavors developed by the mold’s presence on the fruit.
Botrytis, grey-mold, infection can force winemakers into alternative winemaking techniques in order to retain wine quality. Photo by: Denise M. Gardner
Based on a 1977 study by Loinger et al., guidelines pertaining to wine quality were developed with regards to a visual assessment of Botrytis incidence on incoming fruit:
- 5-10% Botrytis rot on clusters: noticeable reduction in wine quality; wine quality is still “good” (as opposed to very good with 0% rot on clusters)
- 20-40% Botrytis rot on clusters: marked reduction in wine quality; wine quality is “low”
- >80% Botrytis rot on clusters: wine is commercially unacceptable
With a noticeable sensory and chemical difference in Botrytis-infected clusters, it is best for wineries to develop a standard operating procedure (SOP) for assessing rot-infected fruit, as well as how the grapes should be handled and processed during production. While there is no one correct way to work with the wine, below are some suggestions or options that wineries can integrate when dealing with Botrytis-infected grapes. For a full list of possibilities, please visit: http://extension.psu.edu/food/enology/wine-production/producing-wine-with-sub-optimal-fruit/fermenting-with-botrytis-101
Some wineries will sort through all incoming grape clusters prior to the crushing/destemming process to assess for any cluster damage or presence of unwanted material. If your operation is not set up with this equipment, sorting can also take place in the vineyard. Depending on the concentration of disease and on the projected wine style or quality parameter the fruit will go towards, disease portions of clusters can be cut out in the vineyard. Or diseased fruit can be left in the vineyard to deal with after the harvest is complete. Sorting out diseased fruit from that of decent quality will reduce the impact of the mold on the wine’s aroma, flavor, and quality.
Limit Contact Time with Skins
Depending on the resource, there are various recommendations for how to handle diseased fruit. In whites, some recommend whole cluster pressing and tossing the first 10+ gallons, which are rich in Botrytis metabolites (Fugelsang and Edwards, 2007). Many recommend separating juice press fractions for white and rosé wines, as this will give the vintner more control over the chemical constituents (e.g., phenolics, enzymes, and disease-related off-flavors) in the final wine.
Depending on the desired outcome for a red wine, treating or limiting skin contact with diseased fruit may be ideal post -primary fermentation. This would include avoiding extended maceration processes. Due to the fact that the presence of Botrytis on red varieties reduces anthocyanin and phenolic extraction (Razungles, 2010) in addition to the varietal aromatics, excessive skin contact may not be ideal during primary fermentation. Whole berry fermentations, as opposed to a more aggressive crush and destem process, may help minimize extraction of Botrytis metabolites, which can also contribute to mouthfeel variations or off-flavors.
Tannin additions pre-fermentation may also be good considerations to compensate for phenolic losses associated with Botrytis infection. Pre-fermentation and post-fermentation additions may help rebuild the wine’s structure or provide constituents for color stabilization.
Flash pasteurization (i.e., flash détente) has been previously recommended for Botrysized fruit to inactive the laccase enzyme associated with Botrytis, enhance color stability in reds, as well as improve the aromatics and flavors associated with the final wine. Wines that undergo a thermovinification step tend to extract more anthocyanins and phenolics compared to traditionally fermented wines (Razungles, 2010). Additionally, this heat step helps to inactivate laccase, which can contribute to early browning or oxidation of young wines. However, commercial producers may not find this technological application easily accessible.
Therefore, in addition to minimizing skin contact time, winemakers will want to reduce contact time with the gross lees, and may also remove the wine from fine lees associated with the mold-infected fruit quickly. The integration and use of clean, fresh lees, however, is still encouraged. Removing the lees associated with mold-infected fruit can help reduce additional contact time with rot metabolites that have settled out with the lees. This inhibits further integration of those metabolites into the wine.
Inoculate with a Commercial Yeast Strain
The presence of rot is one incidence in which processing techniques (e.g., cold soak) that encourage native microflora to dominate the fermentation are probably not desired. Things like cold soak and native ferments allow ample opportunity for the mold to progress and contribute to the wine’s flavor.
Fruit that has rot or microflora issues is best inoculated with commercial yeast and malolactic bacteria strains to outcompete the native microflora (including those microorganisms that contribute to the rot), and to give the fermentation its best chance at completing the fermentation cleanly. Remember that proper yeast nutrition is important to support the yeasts’ growth and to reduce the risk of hydrogen sulfide development. For more information on determining the starting nitrogen concentrations (YAN) and how to properly treat your fermentation with added nutrients, please refer to:
Penn State Extension’s Wine Made Easy Fact Sheet: Nutrient Management During Fermentation
With high Botrytis concentrations, a more robust yeast strain may be preferred in order to quickly get through primary fermentation. A quicker fermentation may simplify the aromatics associated with the wine, but it will also ensure little opportunity for additional spoilage. Saccharomyces bayanus strains are often selected as more robust yeast strains.
Use of commercial yeast strains can be a valuable tool when dealing with disease-infected fruit. Photo by: Denise M. Gardner
Use of Sulfur Dioxide
Sulfur dioxide additions at crush will be determined based on the style of wine in which you are producing (e.g., white, rosé, red, etc.), but in general, the use of sulfur dioxide can help inhibit further spoilage of your product and retain antioxidant capacity. Sulfur dioxide additions in the juice stage will help minimize early browning, but primarily inactivate PPO.
In general, botrysized wines tend to require more sulfur dioxide as Botrytismetabolites bind with free sulfur dioxide (Goode, 2014). This is true even when processing wines with the noble rot version of Botrytis.
When primary fermentation, and malolactic fermentation (dependent on style), is complete it is a good idea to ensure that the wine has an adequate free sulfur dioxide content in order to retain its antimicrobial protection.
Some fining agents may also be applicable in the juice stage. For example, some producers find it helpful to fine juice with bentonite in order to reduce protein content, as well as help minimize rot-associated off-flavors or partially reduce laccase concentrations.
PVPP can be added to the juice to reduce potential browning pigments or their precursor forms (Van de Water, 1985).
In both of these scenarios, neither bentonite or PVPP is specific for rot-related constituents, but each could be helpful to avoid potential challenges later on in the production process.
The presence of Botrytis can also contribute glucans to the must/wine, which can cause filterability problems for heavily-infected wines. In this situation, many suppliers have beta-glucanase enzymes that can be applied either to the juice, wine, or both, to help breakdown the glucans and enhance ease of filterability.
A Word about Laccase
Both polyphenol oxidase (PPO) and laccase can cause early browning in grapes and wine. However, PPO is inhibited by the alcohol content that is developed during primary fermentation. Laccase, however, is not inhibited by the presence of alcohol, and can only be inactivated by a pasteurization step, heated to at least 60°C (140°F) (Wilker, 2010).
Grapes tend to be higher in laccase concentration when infected with Botrytis, and, thus, wines produced from grapes that had a high incidence rate of Botrytis can develop a brown hue post-primary fermentation. This oxidative activity can occur even in young wines.
If you are concerned about the prevalence of laccase in diseased-fruit, wineries can submit wine samples to a wine lab for a laccase test. Or, if you own a copy of “Monitoring the Winemaking Process from Grapes to Wine: Techniques and Concepts” by Patrick Iland et al., pg. 90 and 94 have 2 laccase test protocols that outline how wineries can assess oxidation by laccase. The results of these test will indicate if extreme treatments are required during production to avoid the rapid and early oxidation caused by laccase.
Goode, J. 2014. The Science of Wine: From Vine to Glass. (2nd Ed.) University of California Press: Berkley, California. 216 pg.
Fugelsang, K.C. and C.G. Edwards. 2007. Wine Microbiology: Practical Applications and Proceedings. (2nd Ed.) Springer: New York, NY. 393 pg.
Loinger, C., S. Cohen, N. Dror, and M.J. Berlinger. 1977. Effect of grape cluster rot on wine quality. AJEV. 28(4): 196-199.
Peynaud, E. 1984. Knowing and Making Wine. Wiley-Interscience: New York, NY. 391 pg.
Razungles, A. 2010. Extraction technologies and wine quality. In Managing Wine Quality, Vol. 2 Oenology and Wine Quality. Andrew G. Reynolds, Ed. Woodhead Publishing: Philadelphia, PA. 651 pg.
Van de Water, L. 1985. Fining Agents for Use in Wine. The Wine Lab.
Wilker, K.L. 2010. How should I treat a must from white grapes containing laccase? In Winemaking Problems Solved. CRC Press: Boca Raton, Florida. 398 pg.
With the heart of winter looming heavily over the wine producing regions of South Africa and the coldest part of the year slowly creeping in, red wine shows a higher preference amongst its consumers. South Africans are already well-acquainted with our beautifully crafted, full bodied and spicy red noble cultivars, but few are aware of their lesser known tantalizing relatives.
The chill of winter can often be fought off with a tot (or two) of port, now known as Cape Vintage, especially if said winter-delicacy is accompanied by a roaring, wood-crackling fire. Few consumers know that one of the major Cape Vintage producing cultivars, Touriga-Naςional, also produces a full-bodied varietal wine, driven by dark fruit and a smooth mouth feel, that is just as welcoming on a chilly winter’s eve.
So, instead of grabbing the well-known bottle of Pinotage, leaning into the comfort of a hearty glass of Cabernet Sauvignon or welcoming the familiar pizazz of a Shiraz, I want to encourage and challenge you to try something new and different. As you reach for that less familiar bottle of Touriga-Naςional, Malbec or Mourvèdre, think, “Wine not!”.
The next time you venture out to one of our many well-known wine retail stores, take a closer look at the order in which wine is shelved. You’ll be pleasantly surprised to note that even South African retailers have recently taken to the increase in non-noble varietal wines and no longer shelve these wines together. Each cultivar now has its own section! I love being able to approach a section in a shop and know exactly where to find the Touriga-Naςional, Malbec or Mourvèdre. This leaves us, avid wine consumers, with an increased awareness of these wines. This also boosts their popularity and familiarity in the market because they are more visible in stores.
Our winemakers are now beginning to challenge larger wine producing countries like Argentina and Chile, by producing outstanding varietal wines from cultivars, that were previously better known for their excellent blending capabilities. You may have heard of some of these cultivars before, Barbera and Malbec for example, were previously used in blends mainly for their beautiful and deep colouration, which often added extra colour to lighter cultivar wines. Malbec, a familiar Bordeaux style cultivar, is fast proving that it can in fact find its legs, without the help of its four well known blending counterparts (Petit Verdot, Cabernet Sauvignon, Cabernet Franc and Merlot).
Elegant and full bodied SMV and SMG Rhône style blends have also shown face in the South African wine industry, both blends sharing a mutual cultivar of Spanish origin, Mourvèdre. This cultivar is certainly capable of creating beautiful varietal wines and is no longer considered for the sole purpose of blending. The typical wine characteristics of Mourvèdre include aromas of liquorice, violets, dark fruits and a long, lingering finish on the palate. If you ever get stuck while trying to identify a glass of red wine, Mourvèdre is most recognisable by its predominant ‘anys’ or liquorice aromas.
Familiarising yourself with these cultivars can be quite entertaining too! I often catch myself and other inquisitive wine-lovers pronouncing these unfamiliar cultivar names with a dash of Italian, Spanish and French flair on the tongue. This becomes increasingly fun after a glass or two of wine, after which creative pronunciations and various accents begin to surface. Malbec, for example, is an easy wine to integrate into our South African ways, simply by remembering that the wine is indeed, “Mal-in-my-bek”. A wine like Barbera rolls off one’s tongue, Barrr-Ber-rah, much like the wine rolls over one’s taste buds with fruity and spicy notes. Mourvèdre, also a bold wine, offers an almost tantalizing tango of flavours that dance on the palate much like the sound of the word itself.
If the winter chill does not deter you from drinking white wine, fear not! Cultivars such as Roussanne, Riesling, Viognier and Gewürztraminer are also on the rise. Many of these white wine producing cultivars are packed with fruity, floral and Muscat-like aromas that have proven to be particularly refreshing on a warm summer’s day. If the good and trusted Chardonnay and Chenin blanc no longer excite you, try something new and different. New cultivars are constantly introduced into the South African market, one of the most recent and lesser known cultivars being of Austrian origin, Grüner Veltliner. This cultivar produces softer wines, displaying an almost hybrid flavour profile combination between Sauvignon blanc and Chardonnay. In America, this cultivar is more well-known as Gru-v, a rather fitting name for a very groovy wine!
One of the rarest white wine cultivars in the world, produced by less than five South African wineries, is Bukettraube. With only seventy odd hectares of Bukettraube left in the world, approximately sixty-eight of which are planted in South Africa, it is a wine not to miss out on. This unique wine is not only a blast to attempt pronouncing, it is also equally packed with a blast of crisp stone fruit flavours and a refreshing acidity on the palate.
Popping the cork on a bottle of one of these ‘bad-boys’ can add something unique to any experience. Whether its experimenting with friends and family at a braai or impressing a first-date at dinner with your wine knowledge, bringing something different to the table can be a fun and memorable experience for both you and those close to you.
First impression is that here is someone who is very different and an individualist. Well groomed albeit dark stubble on chin and cheeks topped by a dark engineers cap confirm the impression as does the difficult to determine accent which turns out to be Belgium. English is spoken with an engaging turn of phrase.
Q. What made you come to South Africa ?
“On a visit to the Cape my wife and I fell in love with the beautiful Elgin Valley and knew that this was where we could produce elegant wines that would be sexy and pure but at the same time unique and, maybe, even a little wild. “
Q. Where were you born ?
“In Belgium in July 1974.”
Q. Where did you study ?
“I studied Engineering at Kortjk in Belgium.” “I also became a Sommelier because of my love for wine.”
Q. Do you consider your approach to winemaking to be different to others ?
With great enthusiasm and emphasis “Oh, most certainly yes !! I’m an alchemist and have an unbelievable feeling with my vineyards , I love vineyard architecture and don’t believe in irrigation. We must listen to the vine and do what the vine asks us. That means don’t trellis a vine like we want but how she wants like lyre and gyot and so on.”
Q. How involved do you get in the vineyard ?
“I probably spend 70% of my time with my vines.”
Q. Do you have any varieties you prefer to work with ?
“Pinotage and pinot noir.”
Q. Have you been influenced by any particular winemaker or by a wine region ?
“Francois Naude was my teacher and my mentor. He showed me to understand pinotage and that winemaking is a gift and not something you learn at school.”
Q. What would you consider your greatest achievement as a winemaker ?
“ I am still waiting for it but it comes ! But on the way, maybe my first one was to reinvent pinotage. Pinotage in Elgin. Elegant in style and walking away from the jammy, alcoholic, over extracted style like we all know. I had my Five stars in 2012 for it. The next one was to show the world that Riesling can be made in South Africa and that it can reflect it’s terroir if you understand the vine. Teaching South African people that she is the Queen of grapes so handle her like a queen. Minerality, expensive and give her a beautiful bottle and don’t make her a sweet thing of here, we are not in Germany ! “I did not mention Chenin Blanc. Planting Chenin in Elgin was a dream that came true because if your figures work well, poor soil, high density, great drainage, wind, aspect, you can make something great that is so pure, clean, shinning that it brings you to fine dining of the world of top chefs.” After some thought he adds “The Elgin area is the future gold of the Western Cape.”
Q. What “secrets” have you “developed” that make your wines different to others ?
His answer is direct “Secrets ? Understanding your vineyard and working with nature. Nature provides it all. No need to add anything ! Nature is on the inside and not how pretty the bunch looks on the outside!”
Q. How important is modern winemaking equipment in your winemaking ?
“Not at all. Give me small stainless steel tanks, a basket press and a cooling system. Also a cool store and I am happy. Of course, also, a brush to clean.”
Q. And the future ?
“ Very easy, winemaking is just part of my vision as it is to educate people showing them what passion can do in winemaking which is the key to success. Do the things that you are good at and work with the grapes that are made for you and your region. If not take them out but do not try and make something average.”
Dearest balling meter,
Our relationship has always been a delicate one. You have been there when I needed you and have offered me insight and support when everything around me was in pandemonium.
But it has also been a hazardous relationship.
You have always been around. Gathering dust in a draw for 9 months of the year only to be yanked out and used by a novice but you see past my fumbling moments when I have been dense. Because that’s what you do. You take density and calibrate the sweetness.
We saw each other every day. Twice a day. For three months. Every morning I would walk into the cool cellar still sleepy and tired from the labour of harvest the day before and there you would be – waiting for me in the lab, ready to be plunged into 30 samples of cold white fermenting must. Then again at the end of day – covered in a mess of sugar and yeast I would return to you and we would complete our bi-daily ritual.
It’s not you – it’s me. I was too young. I didn’t have years of experience. Our interaction was still one of bustling activity and commotion. Everything was going at full speed. I did not give you the gentle nurturing care of an experienced winemaker living their glory years in the cellar.
And that is how I broke you.
The first time it happened I was so scared. I did not mean to break you so brutally. I was worried. What would people say? How would we survive without your utility and convenience? I did not realise the fragile state in which you existed. I promptly promised never again to break you and I intended to fulfil that promise.
But then it happened again. This time it happened by dropping you from the stainless steel stairs.
It was so quick. We seemed fine but then I turned my back and you rolled away from me. I only heard the soft tinkle as you shattered on the dark orange tiles near the robust red wine tanks.
The third, fourth and fifth time became a blur. I could not say how or when it happened. Only that it did. Each time the clean-up became swifter; gathering glass in tissue paper; rinsing the floor or any discarded shards apparent of your destroyed state… and finally the hasty disposal of any evidence which could be incriminating.
You are a luxury I cannot afford. I am a student living off a measly intern salary. My idea of a luxurious date night involves going to Spur on a day when the two for one special isn’t on. So, I can’t afford your R500 aesthetic upkeep. No matter how pretty you come in your new packaging and the beautiful slip of calibration paper that accompanies you.
The cellar has always been the hub of chaos and dishevelment. To be honest I don’t know how managed to survive through the mayhem of previous harvests. You are far too delicate to survive in this robust environment. It’s a tough world and your lack of tough exterior is the fatal flaw in your design.
But I know why we keep you around. You offer a valuable service by tracking the rate of our tricky friend, fermentation. There is no better tool to measure density and we would be lost without your guidance. Without you we have no way of knowing when to add our nutrients. When to adjust temperatures. When to rack. You are the decision-maker and because of that you are irreplaceable.
So I ask you. Why are you designed this way? Why are you made of flimsy glass and filled with mercury? I have heard it is the only way you work. Archimedes first uncovered the secret to your success when he stated his buoyancy principle. Thomas Thomson knew what he was doing when he designed the shape and material of your frame. Winemakers celebrated when they realised the impact of your function. Your way of determining specific gravity is nothing short of remarkable.
You have been there for tiring times and I am indebted to you – as is every other cellar worker, intern, winemaker and cellar master. But our relationship cannot survive. You deserve someone who will treat you better and I need someone who will not break so easily.
I have been told that I am the weak link in our partnership; my mentor has only broken you once in 17 years. Maybe one day I will be able to treat you with the respect you deserve – fulfilling your purpose in life. And I will be happy knowing you have done your job so that I may do mine.
The intern who broke you