So you want to join our community!

If you already have an account, all you have to do is

Use and continue

New World Wine Maker Blog - Technical Articles

July Pre-Harvest Planning in the Cellar

By: Denise M. Gardner

If you are a wine producer in the northern hemisphere, harvest may feel quite far away.  However, given that it is now the month of July, it will be here before we all know it.

Harvest season is just around the corner! Photo by: Denise M. Gardner

The month of July is a great time to start preparing a few essential pre-harvest tasks including getting a bottling schedule ready, especially if bottling operations have not yet begun, and ordering harvest supplies.   This blog post will focus on these two tasks.

Prepare and Enact a Bottling Schedule

New grapes are about to flood your winery with juice and future wine.  Now is the time to review inventory within the cellar and determine what has to be moved and what has to be bottled before harvest begins.

Freeing up previous years’ inventory by moving it into bottle will free up tank, barrel and storage space for this year’s incoming fruit.  It makes for a much easier transition if all of the wines that need bottling are bottled before harvest season starts.  Bottling during harvest is not only chaotic, but it tires employees, pulls resources from the incoming product, and may lead to harvest decisions that may be regretted later.

Always make sure to get bottled wines properly stored and away from any “wet areas” on the production floor.  If possible, bottled wines should have a separated storage area within an ideal environment that is physically separated from production.  From there, stored wines can be moved into retail space when needed.

For more information on how to get wines prepared for bottling, please visit our previous posts:

Bottling comes with its own set of challenges and risks, but several analytical tests can help put a winemaker’s mind to ease regarding bottle stability. Photo by: Denise M. Gardner

Ordering Fermentation and Lab Supplies

Many suppliers and wine labs offer free shipping in July, which can especially be useful for wineries that are not geographically close to a winery supply store-front.  Planning ahead and determining what fermentation supplies will be needed in August, could save extra money.  Not to mention, having supplies on hand during the busy processing season can be a big stress relief.

Winemakers should also take the time to look at new fermentation products and assess the previous year’s needs in order to adequately supply for the up-and-coming harvest.  Keeping an annual inventory of purchases can be helpful to isolate regular needs.

Things to consider purchasing include:

  • Yeast
  • Fermentation Nutrients
  • Malolactic Bacteria
  • Enzymes
  • Yeast Hulls
  • Salts for Acid Adjustments
  • Tannins
  • Pectic Gums and/or Inactivated Yeast Products
  • Fining Agents
  • Oak Alternatives or Barrels
  • Sanitizing Agents

While new yeasts are released frequently, being constructive about the production’s fermentation needs can help isolate what yeasts are needed for the upcoming harvest.  I typically recommend that all vintners have at least 5 strains on hand for harvest: 2 reliable strains that will get through primary fermentation with little hassle, 1 strain that can be relied upon for sluggish or stuck fermentations, and 2 strains for specialty needs (e.g., sparkling or fruit wine/hard cider production) or experimental use.

Select and purchase your yeast strains in July to take advantage of free-shipping promotions.

Fermentation nutrients should be a must-have for all wineries to help minimize the risk of hydrogen sulfide.  Always double check nutrient requirements for yeast strains purchased.  In general, wineries will need hydration nutrients (e.g., GoFerm), complex nutrients (e.g., Fermaid K), and diammonium phosphate (DAP).

For more information on why YAN is important and how yeasts utilize nitrogen during primary fermentation, please visit the following blog posts:

If you need further step-by-step instructions on how to determine adequate nutrient additions during primary fermentation, please visit our Penn State Extension fact sheet: Wine Made Easy Nutrient Management during Fermentation

Sometimes hydrogen sulfide will arise in a wine by the time primary fermentation ends despite all preventative care.  Making sure there are adequate supplies on hand, such as copper sulfate and PVI/PVP can save time in the future.  Also make plans for ways that the production can reserve fresh lees.  PVI/PVP is a fining agent that can help reduce metals like residual copper, but fresh lees will also help reduce the perception of hydrogen sulfide aroma/flavor and residual copper in the wine.  Having a plan for retaining and storing lees during harvest season can save time during challenging situations that develop through the end of harvest and into the winter’s storage season.  A fact sheet on copper screens and addition trials can be found at the Penn State Extension fact sheet: Wine Made Easy Sulfur-Based Off-Odors in Wine.

I also like to make sure we have supplies on hand in case of heavy disease pressure come harvest.  This includes things like Lysozyme, beta-gluconase, pectinase or other clarification enzymes, and fermentation tannins.  Lysozyme can help reduce lactic acid bacteria levels while beta-gluconase can assist clarification problems associated with Botrysized wines.  For further information on how to manage high-disease pressured fruit, please visit the Penn State Extension website on Fermenting with Botrytis or Managing Sour Rot in the Cellar.

Double check the storage requirements for all materials purchased before and after the product is opened.   It’s important to store all of those supplies in the winery properly as it will ensure their efficacy by the time the product is needed.

Read article

GMO yeast in wine and how to find them

By Erika Szymanski of the Winoscope

The vast majority of wine does not involve genetically modified organisms (GMOs). Let me repeat, the vast majority of wine does not involve GMOs. On to the rest of the story:

Whether wine contains genetically modified organisms (GMOs) is a question I’m asked often. In general, the answer is no. Genetically modified grapevines aren’t being used for commercial winemaking (though not for want of trying). Two genetically modified wine yeasts have crossed the commercial production threshold, but not worldwide. One, the un-charismatically named ECMo01, available only in the United States and Canada, has been engineered to produce an enzyme that degrades urea. That’s a useful property because urea in wine can become ethyl carbamate, which the World Health Organization thinks is probably carcinogenic enough to be worried about it.

The other, ML01 (which rolls off the tongue much more easily), is legal in the US and Canada as well as Moldova, and seems to have won more traction (though not, I dare say, because it’s available in Moldova). ML01 includes genes for two non-Saccharomyces cerevisiae proteins: a malate permease from fellow yeastSchizosaccharomyces pombe, and a malolactic gene from the lactic acid bacteria Oenococcus oeni. Together, those molecules allow ML01 to import malic acid into the cell and convert it into lactic acid, granting ML01 the rather magical ability to perform both alcoholic fermentation and malolactic fermentation simultaneously, all by itself. In addition to speed and convenience, this one-stop fermentation is advertised as a route to fewer wine headaches. Lactic acid bacteria can produce biogenic amines, which can produce headaches and other unpleasantries in sensitive people (I’m one of them); eliminating the need for those bacteria should eliminate the biogenic amines and those symptoms.

For reasons which are probably obvious, North American wineries using these GM yeasts don’t exactly go shouting that news from the rooftops, fewer headaches or not.

>> CLICK HERE TO READ THE FULL ARTICLE

Read article

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.

Read article

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

Read article

An Introduction to Red Wine Blending

By: Denise M. Gardner

Wine blending is often highlighted as the artistic portion of wine production.  However, blending can also be used for practical or economical purposes.  This blog post will explore some of the common introductory reasons for using wine blending to craft red wines.

Why do winemakers blend wines?

Wine blending is a wine production technique that can be used for a multitude of purposes in order to finish a wine.  Some of these reasons include, but are not limited to:

  • Creating a house style
  • Improving vintage consistency
  • Highlighting vineyard terroir
  • Enhancing a wine’s positive sensory characteristics
  • Minimizing a wine’s undesirable sensory components
  • Balancing oak flavors
  • Altering a wine’s chemistry
  • Managing wine inventory
  • Blending out (i.e., getting rid) of problem wines
  • Additional reasons…

House style and vintage consistency can be very important for a brand’s marketability and reliability amongst consumers.

Many Champagne producers rely on blending to create a house style cuvee associated with their sparkling wines.  While these are not red wines, creating a house style is often based on specific sensory or taste characteristics that are desirable by the winemaker and contribute to major blending decisions.  These blending decisions help minimize vintage-to-vintage variation and variation in grower supplies of fruit while enhancing consistency for their brand.

The same concept can be applied to red wines, but with the use of red wine grape varieties.  House blends can be represented with blending names such as “Proprietor’s Red” or “Winery’s Name House Blend.”  Having wines that are labeled as a blend provides flexibility for the winemaker to create a wine that is of a similar style on a year-to-year basis while altering the wine grape varieties that go into the blend every year.

The other advantage of creating house blends is that these wines allow winemakers to work with variations in varietal inventory.  If we take the last example above, Cupcake Vineyard’s Red Velvet wine, while three different varieties make up the blend, the percentages of each variety contributing to the blend can vary from year-to-year.  This may help mediate changes in yield each harvest season.

Improving Annual Wine Consistency or Highlighting Vintage Variation

Blending can a winemaker’s best tool in enhancing vintage consistency, especially in cooler growing regions where vintage-to-vintage variation is prevalent.  There are a couple of ways that winemakers have been able to accomplish this practice.

  1. Reserving previous vintage wines for blending into future vintages.
  2. Purchasing bulk grapes/juice/wine from warmer climatic regions and blending in small amounts to each vintage.

While neither of these practices may be ideal for terroir expression of certain wine blends, these blending practices provide opportunities to expand a winery’s product portfolio and enhance wine style variation associated with the brand.

In contrast, blending can be used as a tool to illustrate and celebrate vintage variation, which is an inherent component of winemaking.  Not only do these wines offer unique educational and marketing opportunities, this is a tactic that can be used to differentiate premium products within a brand and cater to those consumers that are wine enthusiasts or have a greater interest in vintage-to-vintage variations for a particular brand.  This practice can also better capture the brand’s terroir, which can be a key marketing feature for wineries with estate vineyards.  Additionally, these wines offer exceptional tasting experiences for consumers that enjoy vertical tastings of multiple vintage years, and can be used for various sale promotions over several years.

A common example of this practice is demonstrated by Allegro Winery & Vineyards in Brogue, PA.  The Cadenza and Bridge wines are designed as premium brands, vintage dated, and blended to a particular style in those years that produce the best quality red wine blends.

Wine blending to fix problem wines

While less artistic and perhaps a bit less creative, blending can also be used to help minimize the impact of problem wines or wines that have noticeable defects, flaws or quality shortcomings.  Minor problems can often be partially masked by being blended into aromatically rich varieties like Concord, Niagara, or Catawba.   Noiret, a red hybrid variety, also has a relatively rich aroma/flavor of black pepper which may be an alternative aromatically rich blending variety, as well as the utilization of formula wines with strong added flavors.

Wines suffering from minor oxidation problems can often be added to richer, fresher, younger wines at minimal levels without hindering the fresher or younger red wine.  Additionally, wines with a slightly elevated VA (~0.50 – 0.70 g/L acetic acid) can be added to wines with a lower VA (<0.40 g/L) after the high VA wines have been properly treated and stabilized to avoid contaminating a clean wine.

Allegro Winery’s winemaker, Carl Helrich, worked with Penn State Extension Enologist, Denise Gardner, to improve some of the Penn State-produced problem wines with use of wine blending.

Allegro Winery’s winemaker, Carl Helrich, worked with Penn State Extension Enologist, Denise Gardner, to improve some of the Penn State-produced problem wines with use of wine blending.

The key thing to remember when blending clean-wines with problem-wines is that winemakers want to avoid creating a series of lower quality wines in order to get rid of a problem wine.  Keep in mind that it is not likely that one will be able to create a “unique blend” by using problem wines to any degree.  Winemakers are more likely to create a “good enough” or “commercially acceptable” wine when utilizing blending for this purpose.

All wines that have issues should be analytically and sensorially evaluated before and after blending to ensure chemical and microbiological stability.

Read article

When microbiology is a data problem: Putting science together to make better pictures of yeast

By Erika Szymanski of The Winoscope

Short: A Portuguese-based group is suggesting that winemakers could have more useful information about choosing a yeast strain if scientists did a better job of putting together data from different kinds of experiments.

Longer:

Scientific research generates a lot of different shapes and sizes of data. How does anyone make it work together?

Contemporary scientific research has a lot of big challenges, but here are three: funding, replicability, and integration. Funding is a great big gory topic for another day.

Replicability has seen a lot of attention in recent science news: scientists across disciplines have been reporting difficulty duplicating their colleagues’ results when they try to repeat the same experiments. This is worrisome. (Most) science is supposed to be about making observations about the world that remain the same independent of who is making the observations. Two careful people should be able to do the same experiment in two different places and obtain the same results. Well-trained scientists, however, are finding themselves unable to replicate the results described in scientific papers, and the community isn’t sure what to do about it.

Integration – how to fit together large amounts of lots of different kinds of data – looks like a separate kind of problem. Scientists (microbiologists, biochemists, systems biologists, geneticists, physicists…) study a thing – yeast, say – in many, many different ways. They generate data in many different shapes and sizes, using all manner of different kinds of instruments to make numbers that don’t just tidily line up with each other. But, at least in theory, all of those data are about the same thing – the same yeast – and so finding ways to integrate data from different kinds of experiments should massively improve our understanding of how yeast works as a whole.

The problem is a bit like trying to compile lots of different kinds of images of a large building – photos from outside and from inside, satellite images, historic accounts of parties hosted there, watercolors of the grounds, plumber’s bills, paint chips from the last remodel – into a single detailed, coherent model of the structure. You might be happy deciding to rent a house on the basis of a floor plan and a picture of the outside sometimes, but occasionally you’re going to move in and realize that the living room is wallpapered pink or that every room smells like cigar smoke and that you have a disaster on your hands that could have been averted by having more information.

Portuguese-based group of molecular biologists and biotechnologists has suggested that winemakers might have fewer fermentation disasters if scientists did a better job of integrating the different kinds of pictures they take of wine yeast. This, they note, is a “data resource” problem. Solutions lie not necessarily in doing better or different scientific research,* but in using computational or informatic tools to find points of alignment across existing kinds of data. The method they offer is unique because they can find correlations across not just two kinds of data, but three or more, and lots of it. One of the interesting things about their example for demonstrating that method is that it aligns data about yeast behavioral characteristics – qualities like low hydrogen sulfide production** – with data about genetic variability. This kind of information might help wine yeast developers increase genetic variability in yeast strains by making it easier to assess large number of potential yeast strains for the right combination of good winemaking characteristics and genetic diversity. And, consequently, their analyses could help winemakers have more complete ideas about what to expect from the yeast they choose to use.

What’s most interesting about this paper, though, is the way it points out that integration and replicability aren’t entirely separate issues. Yes, scientists doing precisely the same thing should arrive at precisely the same results. But how often do scientists do precisely the same thing? Even in trying to repeat “the same experiment,” unaccounted-for differences might interfere and yield different results. And maybe those kinds of differences are more troublesome when other living things – like yeast cells – are also participating in the experiment, compelled or willing to cooperate with the scientist to some extent but still also doing their own thing. So, a different but related question is: can the results of multiple sets of experiments make sense together? Having better computational methods for lining up different kinds of data makes it easier to find out.

*Though experiments could surely be designed so that results are easier to put together with the results of other experiments, which is very much a scientific problem.

**Important if you want to avoid making wine that smells like rotten eggs.

Read article