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New World Wine Maker Blog

Syrah and Soirees

The art of being a winemaker requires us to be versatile enough to get down and dirty in the cellar, and then completely transform into suave socialites flaunting ourselves at the Veritas awards. Many spectators only know the sleek, well groomed winemakers, wearing bow ties, as opposed to the hidden cellar ninjas that we prove to be.

My first encounter of this phenomenon, where I was truly exposed to the industry as a ‘professional’, was at Elsenburg’s annual wine launch, where our 2015 wines were showcased. We, as students, were expected to introduce our wines, with some vinification specifications, to a mighty audience. This audience consisted of various well established winemakers from the industry, including Minister Alan Winde. A vast group of members from the audience listened to us cautiously explaining our wines, while the respective food pairings where underway. An interactive and very successful event had come and passed, and left us with great exposure to the industry as future contributing role players.

As ‘winemakers’ we are exposed to a vast assortment of people at winemaking events like the Young Wine Show, and Caroline’s Red Wine Review, to name a few. We get to taste the most prestigious wines our country has to offer, leaving us with an endless desire to reach new heights of our own – both nationally and internationally. However, one does notice certain people at these events, both overdressed and underdressed, who consider these events to be ‘selfie-filled’ wine festivals - a warm-up to the after party. Interestingly, I once had an experience where it was the latter that yielded the most “fruitful” conversation concerning the tannin structure of the Sauvignon Blanc we were sipping on. Yes, this actually happened. You seem to develop an ability to network and socialize relatively quickly the more you frequent these gatherings.

My personal highlight attending these events is to see the very unique and interactive relationships that winemakers have with each other, and the level of mutual respect they have amongst themselves. It reminds me more of a group of friends coming together for a ‘braai’, than a competitive, business orientated gathering.  As you walk through the crowds you are guaranteed to walk into a familiar face, whether it is a fellow wine student from a different university, or a winemaker you met prior to this occasion. Having a ten minute conversation with a winemaker you had only just met leads to him/her knowing your name, your history, your number and, more often than not, a killer contact to use in your future ventures.

To me, these are the environments that stimulate the need for one’s own identity and creativity. The choice of area of specialisation, the style of philosophy you will follow, and what you would do to be refreshing and unique in order to stand out in the sea of competition are essential. Tasting through the same cultivars produced in different regions, made by different artist with their own signature, opens your mind up to the endless possibilities of what you could become and what your own creation would look like one day, as well as how you would get there.  These big decisions all fall under “adulting” which is a colloquial term used for the passage of time that takes place between the transition from student to young professional, a dreaded period of the unknown. We, as students, all know it’s coming, but we continue to deny it ‘til the last minute. Nevertheless, your final year is inevitable – ask me, I know. Finding harvest work for the next year is the first part of the quest, followed by having to manage ones own finances and plagued by lingering thoughts of not being under the blanket of your parents’ care for much longer. The struggle is real.

I cannot wait to be at the receiving end of the Veritas Awards as a winemaker, and looking back at these memories building up to it and saying, “Damn, what an unforgettable adventure”. This is only the beginning…

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Introducing Carl Van Der Merwe – Winemaker at De Morgenzon

Q. Where do you originate from ?

“Born and bred in Cape Town.” With a bit of after thought “I have stayed near the sea and mountains ever since. I live in the greatest wine producing area in Africa, namely Stellenbosch.”

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

“Before deciding on a career, I did an in-depth analysis of what I wanted and needed in a job to best express my values and interests. I narrowed it down to natural sciences in an agricultural field and being a lover of outdoors, figured that working in the winelands, which tend to occupy some of the most beautiful spots on earth, was the best option.  I studied a BSc majoring in Business management and Oenology at the University of Stellenbosch.”  “ I planned my course of study and have spent a lot of time travelling around the world to various wine regions in search of inspiration and perspective.”

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

“Yes, very definitely, I am not mainstream !”

Q. How involved to you get in the vineyard ?

“Very. I am involved in all practices that have a qualitative impact. We try to match vineyard to wine style and thereafter the production team works very closely together.”

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

“Chenin Blanc and Chardonnay really sow the hand  of the winemaker , and therefore  pose a great challenge in the winery in order to let that vineyard shine.”

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

With sincerity “I try to learn from all people and have made it my mission to meet and taste wines made by people who are driven by passion and conviction. They may not always be right, but I find that I learn much more from these types of winemakers than winemakers who make wine according to a recipe.”

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

“Winning Platters “white Wine of the Year” two years in a row.”

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

Very serious “I don’t have any secrets …..I only try to understand the vineyard site I am working with, and in doing so create a style for a particular wine that is great quality and consistent from year to year. I guess what makes my wines different is that I use a minimum intervention approach and use a little additive as possible. Natural yeast, natural settling, minimal to no use of tartaric acid, minimal to no filtration, minimal use of SO2 etc.”

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

Sort of matter of fact “Not very important. We could probably be seen as “old fashioned”   in that we don’t use modern sorting machines, centrifuges, cross flows, etc. Having said that, technology is all a part of human advancement, and there is a place for it, however it’s not a turnkey solution to great wine.”

Q. How do you see the future ? 

“As you know I studied at Stellenbosch and chose to blend a mix of business subjects. This has proven invaluable in running a successful wine business. I am married to the woman of my dreams and am gifted with three wonderful children. I have been working at De Morgenzon with the Appelbaum’s for six years and I am enjoying the challenge of building an iconic South African estate.” After some deep thought he continues “I am motivated by success stories, and the more time I spend at De Morgenzon the more driven I am to continue the success.”

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Summer in the Cellar

By: Denise M. Gardner

As the growing season turns into full swing, now is the time to get things tidied up in the winery and prepare for this vintage’s harvest season.  The cellar offers the advantage of being relatively cool in the summer months, so it offers an oasis away from the beating sun or those rainy, humid days.  Managing some time for the up-and-coming harvest is a good way to keep cellar work current.  Otherwise, the summer months can appear rather dull in the cellar.  Here’s a list of considerations for the cellar crew:

Give your wines a regular analytical check

For anything that is sitting or aging in the cellar, now is a good time to schedule quality control monitoring.  Wines in barrel need regularly topped off (every other month or every other 2 months) and checked for free sulfur dioxide concentrations if they have completed malolactic fermentation (MLF).

There’s a lot of good information out there on sulfur dioxide.  If you feel slightly uncomfortable with sulfur dioxide additions or analysis, please refer to these current informational pieces that can be a valuable resource to any winemaker:

Wines that are getting ready to be bottled should go through a full analytical screen and recorded into the lab record books.  This will provide insight for the winemaker in terms of how the wine should progress or need altered prior to bottling:

  • pH
  • titratrable acidity (TA)
  • residual sugar
  • residual malic acid concentration and malolactic fermentation completion
  • free and total sulfur dioxide
  • cold stability
  • protein (heat) stability
  • volatile acidity (VA)

AO apparatus set up to measure free sulfur dioxide. Photo by: Denise M. Gardner, Penn State Extension Enologist

AO apparatus set up to measure free sulfur dioxide. Photo by: Denise M. Gardner, Penn State Extension Enologist

For more information pertaining to how to set up wine analysis in your winery, please refer to Penn State Extension’s website on “Starting a Lab in a Small Commercial Winery.”  Information on how to utilize analytical testing labs to the advantage of the winery can be found on the Penn State Extension website, “Wine Analytical Labs.”

For those wineries that have not previously measured cold stability, read Virginia Mitchell’s report on “Cold Stability Options for Wineries,” which explains the importance of testing and how to best treat your wines.

For more information on wine stabilization (sulfur dioxide additions, cold and heat stabilization), please refer to our previous blog post on “Stabilizing Wines in the Cellar.”

Get wines ready for blending or finishing

Now is a good time to pull samples of those wines that you are planning on bottling prior to harvest.  After getting a good analytical evaluation, make sure you check the wines for their sensory perception.  Is the wine at the caliber of quality that you were expecting?  If no, what can you do to fix the wine and get it ready for bottling?  Utilize fining agents or product additions to tweak the wines and enhance the quality.

Also consider blending.  Blending can be a tool to help mitigate problem wines.  But blending can also help you create a spectacular wine out of several great varietals.

Always remember to prepare bench trials before making changes to the entire tank or barrel of wine.  Make sure that several people evaluate the wine and give you their individual evaluation.  Have people write down their perceptions, as opposed to talking in a group, to avoid the power of persuasion and to minimize tasting insecurities.  This practice will give you a more honest, objective evaluation of the wine.

Prepare for Bottling

The summer months are the ideal time to get your wines bottled and ready for release.  Most wines need at least 2 to 6 months of bottle conditioning (i.e., time in the bottle before sale) to stabilize and minimize the effects of bottle shock.

Bottling is a time intensive process and requires a bit of planning by the cellar crew.  Prepare a calendar for bottling days to ensure that all supplies are received for bottling, that wines are fully ready to be bottled, and that there is adequate time to get everything bottled prior to the estimated start date of harvest.  For information pertaining to bottling considerations – how best to sanitize and monitor sterile filtration integrity – please refer to our previous blog post titled, “Bottling Tips and Considerations.”

Take Inventory

Now is a good time to go through all of the supplies that are currently available in the winery and record how much you have of each.  Recording inventory each year is a good way to evaluate what supplies are being purchased, what is being used, and what supplies are typically left over.  It is possible for wineries to find some redundancies through this exercise and identify places to save money.

Suppliers’ “Free Shipping in July” promotions are just a month away!  So being prepared with an accurate inventory can release some stress from the winemaker when it comes to ordering this season’s harvest supplies.  Things to consider include:

  • Yeast and Malolactic Bacteria
  • Yeast Nutrients
  • Any Enological Agents (e.g., Enzymes, Tannins, Polysaccharides/Inactivated Yeasts)
  • Fining Agents
  • Sugar and Acid
  • Potassium Metabisulfite
  • Cleaning and Sanitizing Agents

Make sure that all of the materials currently stored in the winery are being stored properly (i.e., dry chemicals away from wet chemical storage, food grade away from non-food grade, and the requirement that some may need stored frozen), according to the supplier’s recommendations, and that their expiration date has not expired.  For some expired products, some suppliers may be evaluating their efficacy of the product past the expiration date.  If you contact the supplier, you may be able to find an extended expiration date so that the product can be retained.  Otherwise, expired products should be thrown out and re-ordered.

Additionally, going through an equipment inventory can be advantageous.  Make sure all processing equipment is getting prepared to get a good cleaning and sanitizing regimen prior to the start of harvest.  Unused equipment should not be a storage vessel for left-over, dirty rice hulls or mouse droppings.  Use the summer months to check all of the equipment and make sure it is functioning properly.  If there are problems with equipment, it is best to identify it over the summer and, hopefully, get serviced before the start of harvest.  Don’t forget to check tank valves, pumps, inspect hoses for cleanliness, and all of the processing equipment.  Using an inventory, or check sheet, is a good way to ensure equipment is up to par is a good way to keep track of everything’s condition.  Also, evaluating barrel needs and tank space available for harvest can be added to the inventory sheet.

If you have a wine lab, now is also a good time to check the chemical and supply inventory in the lab.  Remember – free shipping in July is just around the corner!  Document expiration dates of chemicals and make a list of new chemicals, analytical standards, or equipment (e.g., hydrometers, pipettes, pipette bulbs, sampling bottles, etc.) that should be purchased prior to harvest.

Inventory all of your supplies to get prepared and organized for the upcoming harvest. Photo by: Denise M. Gardner, PSU Extension Enologist

Inventory all of your supplies to get prepared and organized for the upcoming harvest. Photo by: Denise M. Gardner, PSU Extension Enologist

Take time to evaluate and write SOP’s

Standard Operating Procedures, SOP’s, can help minimize the chaos during harvest.  Having up-to-date SOP’s in the cellar and lab will help minimize the number of times people will always have to ask “the boss” for help.

If you don’t have SOP’s, consider starting small and documenting protocols for things like lab analysis.  Plenty of resources (e.g., websites, text books) are available and can be used to create a standard protocol that works for your winery.

After tackling lab analysis, consider writing an SOP for harvest operations.  Think about writing an SOP for each piece of equipment that your harvest team will need trained on.  Take the crusher/destemmer for example:

  • How is the crusher/destemmer hooked up?
  • How to prepare the crusher/destemmer for fruit arrival (include cleaning and sanitizing procedures).
  • Do you have validation measures to ensure that the equipment is properly cleaned (a visual evaluation? Some sort of analytical testing?)?
  • Do you have a record system that documents the equipment has been properly prepared, cleaned, and sanitized?  If so, where is that documentation and how does your staff document this step?
  • What is the protocol for running the crusher/destemmer?  What safety features should all employees be trained on?  Document all safety procedures.
  • How is the crusher/destemmer cleaned and sanitized after each lot (varietal) of fruit that is run through the equipment?
  • How is the crusher/destemmer cleaned and sanitized after each processing day?  Where is the equipment stored and how is stored?

Winemakers can also document processing decisions.  For example, if you know that you are going to process Vidal Blanc every year, consider writing an SOP specific for how the Vidal Blanc is processed.  Write out each step, the quality control checks (i.e., checking fruit chemistry or monitoring fermentation) and what processing aids are typically added to the Vidal (e.g., yeast, enzymes, etc.).

Winemakers should also have an SOP ready for when fruit arrives to the winery in less than ideal conditions.  For information on what winemakers should consider, please read the two articles on Penn State Extension’s website titled “Producing Wine with Suboptimal Fruit.”

Botrytis disease pressure on Pinot Grigio grapes. Photo by: Denise M. Gardner

Botrytis disease pressure on Pinot Grigio grapes. Photo by: Denise M. Gardner

Having a fully functional and trained cellar crew is a good foot forward as the harvest months approach.  While preparation is tedious, it can save some time and resources during the busy harvest season… and hopefully, minimize the chaos!

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Jumping on the food & wine (band-) wagon

We are all well aware of the recent worldwide culinary explosion and the resulting snowball effect it has had on food and wine pairings. In our little Stellenbosch district alone you can now not only attend wine pairings with the usual suspects like cheese, chocolate, olives or biltong, but with new – and sometimes slightly strange – pairings with meringues, pizza, cupcakes and ice cream (?!) So I sat down for a while to try and understand what the hype is all about.

Before beginning, I should probably mention that I consider myself to be quite the foodie. And as I find myself working in the wine industry, I couldn’t help but marry these two great passions of mine. It all started the first time I used wine in my food while preparing some spaghetti bolognaise. That is when I realized that wine is not always just for drinking on its own or pairing with an array of food items, but it can be used to literally fuse the two into something spectacular. The addition of wine to a dish just brings flavours together in a way that not many other ingredients can.

The fusion of food and wine can of course also be observed from a scientific point of view. The internet and countless books are overloaded with charts and diagrams explaining what to pair with what and why exactly Riesling pairs well with rosemary etc. Some say it all comes down to the molecules and the pairing of similar flavour compounds, others believe it is about mouth feel or the balancing of astringency with fattiness. For the home cook and casual wine drinker all these terms and concepts might seem a bit daunting or even far-fetched, but there are some interesting and easy to apply flavour combinations out there. Just remember that pairing your favourite wine with offal is not going to help you to suddenly like it more, no matter what the science says about the similar aromatic compounds.

Personally, I think food and wine go together so well, because they both have an unique way of bringing people together. The incredible success of food & wine festivals are surely a testament to that. There is something nostalgic about sitting down with family and friends around a great big table filled with all the gloriously glazed food you can think of, and uncorking a bottle of your favourite vino, filling everyone’s glasses and being merry. And it’s no surprise as this is certainly not a new concept- the accompaniment of wine with food has come along since, possibly, the dawn of time and there is absolutely no sign that the tradition will fade away any time soon. We drink red wine and eat chocolates or ice cream out of the tub in front of the TV when we’re sad; we drink wine (or MCC) and eat canapés when we are celebrating a special event- and we hardly ever do these things on our own. There is always that best friend that will cry (and drink) with you, and be it your colleagues or closest friends, they will share in your joy and raise a toast to your accomplishments.

People of all shapes and sizes and different cultural backgrounds are excited by food and a good bottle of wine and enjoying it with great company makes the experience just that much more memorable. And as I always say, having wine with your food makes it a meal.

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Natalie Kuhne – Assistant Winemaker Perdeberg

Q. Where do you originate ?

“I am another non-Kaapenaar. I was born in Kempton Park, Gauteng.”

Q. Where did you study ? 

“I am a product of the University of Stellenbosch where I did a BSc. Agric Oenology and graduated in 2007.”

Q. What made you interested in wine ? 

“I came to Stellenbosch to study Bio-organic chemistry to get into Forensics but then made a friend who was doing viticulture. One day I went to a practical with her  and fell in love with the vineyards. That made me change my degree.”

Q. How did you come to be at Perdeberg ?

“Perdeberg has experienced considerable growth  and have a new barrel cellar and needed someone to assist cellar Master Albertus Louw. I was lucky to be appointed to that new post in 2015.”

Q. What did you do before Perdeberg ?

“ While still at University I worked in the experimental cellar then I worked at Avontuur Estate near Stellenbosh for a few years then moved to Allee Bleue Wines at entrance to Franschhoek .”

Q. Do you consider your winemaking to differ to others ? 

“I think winemaking is a bit like cooking, while it is good to follow  recipe, sometimes you must be guided by your taste buds and your mood. I try not to overthink the wine….I try and let the wine speak to me and from there I will fine tune things.”

Q. How involved do you get in the vineyard ? 

“At the moment, at Perdeberg, not much.  Our viticulturist , Heinie Nel and Production manager, Albertus Louw look after the vineyards.”

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

“I have an affair with Pinot noir and Cabernet franc ! I love the finesse you can get in Pinot noir and I think you either get it right or not ! It can be diverse, depending on the area it is planted in. I prefer the more fruity style, but have had some lovely earthy styles. Cabernet franc is such an interesting variety and prefer the Helderberg area., mainly because you get that greater greener style.  I had success with these varieties at Avontuur in 2008 and 2009.”

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

“As yet I have not travelled  overseas but each area I have worked in the Cape has taught me just how important origin is.”

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

“It is early days yet but my first four star wine was a great moment.  It was a Shiraz I made at Avontuur. This wine was to become part of their premier range, named after their first stallion, Dominion Royale.  It took a lot of tasting and selection with many potential blends. After some five months I was pretty sure of two combinations and a good idea which would be best.  It was confirmed by the GM and bottled as the 2008 which was a very hot year  with high alcohols. It is a big robust wine with a mixture of white pepper, and black fruits with 15 % alcohol. It is developing beautifully.”

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

“I don’t have any secrets but as mentioned I treat each wine on it’s own and listen to the wine.”

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

“It makes life a lot easier especially when working in big volumes.” Then adds, after a bit of thought “As long as things are working properly !”

Q. What do you think the heat of 2016 will “do” to the vintage ?

“It will keep me on my toes, for sure. It will be another interesting year for reds. Very concentrated flavours.”

Q. What do you prefer to drink when relaxing ?

“In summer I love dry rose. Some would say I am in my “Rose phase” ! I enjoy  fresh Sauvignon Blanc or a slightly chilled Pinot Noir. In winter our Cape red blends or Shiraz. I n very good company I will take out my special Cabernet Franc.”

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Stabilizing Wines in the Cellar

The long months post-harvest require regular attention by cellar staff and winemakers to ensure that wine quality is upheld through storage conditions. Wine stability, while somewhat nebulous, is essential to obtain in order to ensure the wine’s quality will be upheld post-sale.  Below is a list of cellar maintenance practices that are recommended in preparation before the growing (and bottling) season.

Monitor Sulfur Dioxide Concentrations

Now (i.e., the winter and spring months) is a good time to regularly check sulfur dioxide concentrations of wines sitting in tanks and barrels waiting to get bottled.  At minimum, wines should be checked once a month for free sulfur dioxide concentrations.  Some winemakers opt to check barreled wines every other month in order to minimize frequently opening the barrel.

Proper sanitation and sampling is required for best analytical results:

  • Use clean sampling bottles when taking wine samples
  • Make sure that you sanitize any valves or sampling ports before and after releasing a sample from a tank.  At the very least, you can use a food-grade alcohol solution spray or a citric acid-sulfur dioxide mix as a sanitizing agent.
  • Properly clean and sanitize wine thieves or other sampling devices each time you use it to take a sample from a barrel or the top of tank. Warm water is not enough to sanitize a wine thief.  We recommend using a citric acid-sulfur dioxide mix for quick dipping in between barrel sampling.

For wines that have completed primary fermentation and/or malolactic fermentation, maintaining a molecular free sulfur dioxide concentration is helpful to reduce the risk of yeast and bacterial spoilage.  For a review on sulfur dioxide and making sulfur dioxide additions, please refer to this Penn State Wine Made Easy fact sheet.

It is essential to clean and sanitize your wine thief in between sampling from barrels. Photo from: Denise M. Gardner

It is essential to clean and sanitize your wine thief in between sampling from barrels. Photo from: Denise M. Gardner

Cold (Tartrate) Stabilization

Cold stabilization is often utilized to avoid the precipitation of tartrate crystals, which is common in instable wines at cooler temperatures.

In 2012, Virginia (Smith) Mitchell, now head winemaker at Galer Estate Winery, wrote a primer on cold stabilization techniques available for wine producers: http://extension.psu.edu/food/enology/analytical-services/assessment-of-cold-stabilization  This primer covered everything from how to analyze for cold stability to the use of carboxymethylcellulose (CMC) to avoid tartaric acid crystallization in wine.

Prior to putting a wine through cold stabilization, it is worth the time and effort to analyze the wine for cold stability.  Not all wines end up having cold stabilization problems.  For those wines that do not, going through the cold stabilization process can actually minimize wine quality by stripping out delicate aromas and flavors, or altering taste or mouthfeel attributes of the wine.  This doesn’t touch upon the amount of wasted time and effort to cold stabilize wines that are otherwise cold stable.

The above report recommends several testing procedures to ensure tartrate stability of a wine.

With the relatively warmer 2015-2016 winter, many winemakers may need to turn to artificial chilling in order to cold stabilize their wines properly.  Again, this could be used as an argument to test wines prior to cold stabilization to minimize the use of electricity and to better manage the flow of wines in and out of the cold stabilization tank.

Wines that do undergo cold stabilization will likely have changes in pH and titratable acidity (TA) that can ultimately affect other parameters of the wine: protein (heat) stability, color, sulfur dioxide concentrations, and volatile acidity.  It is prudent to check these components analytically following the cold stabilization process.

Protein (Heat) Stabilization

Proteins in wine can elicit hazes in wines post-bottling that may be off-putting to some consumers.  While the proteins cause no effect on wine quality, they do cause an alteration in the appearance of the wine.  Some varieties, like Gruner Veltliner, have naturally high concentrations of proteins, and, therefore, require a more aggressive approach to protein fining.  Other varietals, however, may not require protein fining with bentonite at all.

Wines should undergo protein (heat) stability after they are cold stabilized due to the fact that cold stabilization will affect the acidity (pH and TA) of the wine, and therefore, alter protein stability properties of the wine.  Again, winemakers are encouraged to check the wine for protein stability prior to treating a wine with bentonite.

Bentonite is a fining agent used to bind any proteins in a wine that would otherwise be considered unstable.  However, if the addition of bentonite is unnecessary (i.e., the wine is protein stable and does not provide a component for bentonite to bind to, bentonite can bind to other components in the wine, most specifically: aroma and flavor active compounds.  While this has been shown in the research literature, it is unclear how detrimental the loss of aromatic compounds is to the wine (Marchal and Waters 2010). Additionally, bentonite additions have been noted to strip color out of rosé and red wines (Butzke 2010).

A summary from UC Davis on heat stability testing can useful to understand the positive points and limitations of protein stability testing.  Protocols for heat stability tests can be found here from Dr. Bruce Zoecklein.  Additionally,ETS Labs has provided a small summary of how to interpret heat stability results, which can be helpful for wineries that are not used to reading analytical results on this test.

Additionally, wineries can submit wines to ISO-accredited labs for a bentonite trial in which the lab pinpoints the exact concentration of bentonite needed to heat stabilize the wine.  This may be helpful to avoid making too little or too much bentonite additions, which costs time and labor in the winery.

Bench Trials

Bench trials may be needed to determine how much bentonite is needed to obtain protein stability of your wine. Remember to use the same source and lot of bentonite in both your bench trials and commercial application. Photo from: Denise M. Gardner

Finally, if wineries are conducting their own bench trials, they are encouraged to use the same lot of bentonite in both the trials and the commercial application (Marchal and Waters 2010).  This is due to the natural variability associated with most bentonite products.  Finally, unless otherwise stated by the supplier, bentonite should always be blended in chlorine-free, hot (60°C, 140°F) water (Butzke 2010), and allowed to cool to room temperature so that the bentonite can swell.  Allowing the slurry to cool will ensure that the wine is not exposed to a hot slurry.

References Cited

Butzke, C. 2010. “What Should I use: sodium or calcium bentonite?” In: Winemaking Problems Solved. Christian E. Butzke, Ed. Woodhead Publishing Limited and CRC Press, Boca Raton, FL. ISBN: 978-1-4398-3416-9

Marchal, R. and Waters, E.J. 2010. “New directions in stabilization, clarification and fining of white wines.” In: Managing wine quality, volume 2. Andrew G. Reynolds, Ed. Woodhead Publishing Limited, Great Abington, UK. ISBN: 978-1-84569-798-3

Additional Resources

Iland, P., N. Bruer, A. Ewart, A. Markids, and J. Sitters. 2012. Monitoring the winemaking process from grapes to wine: techniques and concepts, 2ndedition. Patrick Iland Wine Promotions Pty. Ltd., Adelaide, Australia. ISBN: 978-0-9581605-6-8.

Penn State Extension Wine Made Easy: Sulfur Dioxide Management:http://extension.psu.edu/publications/ee0093

Penn State Extension: Assessment on Cold Stabilization:http://extension.psu.edu/food/enology/analytical-services/assessment-of-cold-stabilization

UC Davis: Heat Stability Testing:http://wineserver.ucdavis.edu/pdf/attachment/88%20stability%20tests%20and%20haze%20formation%20.pdf

Virginia Tech: Protein Stability Determination in Juice and Wine (1991):http://www.apps.fst.vt.edu/extension/enology/downloads/ProteinS.pdf

ETS Labs: Interpreting Heat Stability Tests:https://www.etslabs.com/assets/PTB011-Interpretation%20of%20Heat%20Stability%20Results%20and%20Turbidity%20Readings.pdf

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