Winemaking Category

A Year In The Life: Part 2

February 11th, 2010 by Marc in In the Vineyards, Winemaking

“Wine gives a man nothing…it only puts in motion what
had been locked up in frost.”  - 
Samuel Johnson

 Happy New Year, everyone. I hope the coming year brings you joy and peace.  This is a good time to reflect upon the last year for VS14, our Chardonnay that we are following.  In reflection, we shall discuss the vineyard block where the grapes came from.

In 2007, Hess Collections’ viticulturist Sander Scheer, had a soil map of our Veeder Summit vineyards performed.  They used soil resistivity results and GPS coordinates overlaid on a map of the site.  The company, Coastal Viticultural Consultants, has a device that they drag along the surface of the soil which measures the electrical resistance of the soil which can determine what kind of soil is present at the site.  Additionally, they dig a test pit to look at the soil strata which allows us to look at the underlying soil conditions of a vineyard block.  We then compare that to the condition of the grapes that are grown there.  The long term goal is to match the root stock planted to match the sites soil conditions.  Not only in a vineyard block but possibly vine to vine.  This way the larger portions of a block will ripen uniformly.

VS14 Soil Map

Soil Resistivey Map

The interesting result from this survey for block VS14 is that there are two different soil-type bands that run through it.  The northern band is clay while the southern band, is common gravel.  These bands divide the block, almost exactly, between the long rows and the short rows of planted vines.  What we have noticed that within this acre of vineyard block the south corner of the long rows there are some vines that ripen later than the rest of the long row which can be a problem at harvest time.  However, now that we have had the soil tested we can now determine what rootstock would match the soil which would help the grapes mature at the same time.

Almost all modern vineyards are planted with vines as a graft.  This graft is made between the rootstock and the fruiting portion of the vine, usually French varietals.  The rootstock is grown from seed, pollinated from a grapevine with a specific characteristic that you would like in the final plant.  For instance: disease resistance, draught tolerance, ease of grafting and nutritional requirements.  3309, is a cross between V. riparia and V. rupestris.  V. riparia is a grape vine that grows along the banks of rivers, while V. rupestris grows in sandy soil.  There is a good likelihood, that the difference between the short and long rows of VS14 can be attributed to the rootstock.  V. riparia which grows along riverbanks would grow better under soil conditions of the long rows.  The clay soil structure would cause water to remain near the surface, while V. riparia has a shallower root system.  This would be a good match; as opposed to common gravel soil, where the water and nutrient availability would be deeper.  3309 would be less of a match for this soil type.

 


A Year In The Life of Mount Veeder Chardonnay

December 21st, 2009 by Marc in Winemaking

A Year In The Life: Mt. Veeder Chardonnay
Part 1

“It is not a wine that commands your attention, but rather, rewards it.” 
- author unknown

Today I am starting a project following the life of one lot of wine from the reception of the grapes to bottling of the finished wine.  Christian Brothers Blessing Hess Grapes-Harvest 2009This is a chance for me to bring to you one of the things that brings me joy in wine production; being part of an entire process. The wine in question is one of our estate wines Veeder Summit block 14 or as we call it VS14. This also happens to be the lot we used for the blessing of our harvest, vintage 2009 by our neighbors The Christian Brothers.

 So how did we choose the moment to pick these grapes?  VS14 is an 809 musqué clone.  Brix, which is a measure of sugar levels, and pH doesn’t tell the entire story.  These are good landmarks for when the grapes are nearing maturity, but the final decision is based on taste.  When not a matter of necessity, such as the grapes are dehydrating or the rainy season is imminent, then this is our guiding factor.        

The grape samples taste good and the call goes out to Sergio, our vineyard crew manager, that we are ready to pick. Sergio organizes the picking of the grapes and we prepare to process what arrives. 

 In the blog posts to follow I will talk more about how we process the grapes and update the status of our new friend VS14.


Yeast Nutrition

October 9th, 2009 by Marc in Winemaking
“Behold the rain which descends from heaven upon our vineyards, and which incorporates itself with the grapes, to be changed into wine” 
- Benjamin Franklin

Harvest has arrived in Napa. Right now, all up and down the valley grapes are being received and processed. We crush the grapes and ferment the juice. The fermentation process is performed by our friends the yeast organisms. Like us, yeast cells like to be warm and well fed. When yeast cells are not well fed they can get stressed and produce off-odors or lack the energy to finish fermentation. Yeast requires these nitrogen components to grow and if it is not readily available then they break down amino acids to get it. Some of these amino acids contain sulfur groups that are released when the amino acids are broken down, which is why low nitrogen containing juice can give off sulfur smells. To ensure that that the yeast has enough nutrient supply to complete fermentation and not be stressed we test for YAN or yeast assimilable nitrogen.

The YAN has two components. The first component is the ammonium level and the second component is the NOPA, which measures the assimilable amino acids in the grape juice. What this all means is that, these two components make-up the available building blocks of the yeast. These building blocks go together to form proteins which further go together to produce cell walls, enzymes, etcetera.

We test the YAN by using an enzymatic test that uses ultra-violet light to determine a change in the reaction chamber. Enzymes are organic catalysts that speed up chemical reactions. These reactions cause a color change that is measured by our ultra violet- visible light meter which is called a spectrophotometer.

After we get our results we then add the optimal amount of yeast nutrients at various intervals of the yeasts’ life cycle, to maximize their healthy growth and fermentation of juice. This is the beginning in our facility of what can be a multi-year process; from fermentation to full maturation of the wine.


White Wine Protein Stabilization

August 25th, 2009 by Marc in Winemaking

“The Spirit of Wine Sang in my glass, and I listened
with love to his odorous music, his flushed and
magnificent song.”  – William Ernest Henly           

After wines are sold and leave the ideal, temperature controlled conditions of our winery, they are moved around and can be subjected to many elements – like heat—that are out of our control. And one of the biggest threats to wine quality is exposure to heat. As winemakers, we must take steps to ensure sure that the wine you purchase is in the same condition as it was when it left our warehouse, even if it is exposed to heat and other elements.

Wine is made up of many components, one of the most important being proteins, which are responsible for many of the aroma, flavor and visual characteristics of a wine. Proteins bend, taking specific shapes according to electrical charges on the wine’s surface. When proteins are subjected to heat—such as when wine is left in the car during the middle of the day—it cases the proteins to shake. If they shake hard enough they become unraveled and fall out of solution—this is called a “protein haze.” We love the brilliant clarity of our white wines and want them to remain so. To ensure this, we fine our white wines with bentonite, which is volcanic clay of aluminum silicate anions. Anions have a negative electrical charge and bind to the positively charged proteins. To provide the greatest clarity at the lowest addition to minimize any loss of flavor or aroma, we perform a fining trial.

To perform a bentonite fining trial we experiment with adding different levels of bentonite (at one pound intervals). We add between one to five pounds of bentonite per thousand gallons of wine, and then let it settle. We then filter the wines and bake them in the oven to simulate the extreme temperatures that a wine might experience in its travels.  At the conclusion, we examine how clear each bottle is, and when there is no difference in clarity between the bottles we know have found the right amount of added bentonite needed to achieve heat stability in the wine.


The Importance of Topping Barrels

July 28th, 2009 by Marc in Winemaking

Like human beings, a wine’s taste is going to depend
a great deal on its origins and its upbringing.
- Linda Johnson-Bell, Pairing Wine & Food 

 

Here in wine production we have one chance, during harvest, to make great wine. We have many chances after that, to take great wine and mess it up.  One of the easiest ways to do that is through neglect. This week we are topping up our wine barrels and I thought I would talk about the importance of this process.

 

During the course of aging in barrels, wine evaporates through the barrel staves. The evaporated wine we affectionately name the “angels share”. This evaporation leaves a space in the barrel called head space which increases the wines contact with oxygen.

 

Oxygen in wine is a fickle friend; it makes our wines more supple and less astringent. It also makes the color in the wine more stable and of a richer hue. However, it oxygen invites wild yeasts, molds and bacteria to multiply and be merry which can lead to some organic chemistry interactions that produce acetaldehyde and other reactions that can turn the rich hue of wine from ruby or garnet to tawny or the extreme of brown.

 

Some of the usual suspects of yeast and bacteria growing in wines are; Acetobacter, Film Yeasts, and Lactic Acid Bacteria.  Acetobacter is an Obligate Aerobe.  This means that it requires oxygen to grow.  Its growth leads to an increase of acetic acid and other volatile acids as it converts ethyl alcohol to acetic acid.

 

Film yeasts are another group of micro-organisms that require oxygen to thrive in wine. There are a number of yeasts that make up this group and there is a characteristic white film that forms on top of the wine.  These yeasts also produced acetaldehyde as part of their growth process. Acetaldehyde is responsible for the nutty sherry aroma in Sherries and gives the same smell to oxidized wines.

 

One of the most effective ways, besides topping the barrels, to control both oxidation and spoilage organism is to add sulfur dioxide to the wines.  It is added to the wine during topping when it is needed.  Sulfur dioxide is produced naturally by yeasts via amino acid metabolism; however, not in enough volumes to protect the wines.  So we bolster this protection with more sulfur dioxide in accordance to its pH.  The amount of sulfur that is free to bind oxygen and inhibit spoilage organisms is dependent on the acidity of the wine.  The higher the acidity the less sulfur dioxide is needed to actively protect.

 

We protect these wines from the time we get the grapes in the door, until we put the finished wine in a bottle.  From our cellar to your table, please enjoy.

 topping-barrels-12topping-barrels-22topping-barrels-32


Smoke Taint

May 29th, 2009 by Marc in Winemaking

The Flavor of wine is like delicate poetry
-Louis Pasteur

Two thousand eight was a challenging year for vintners in the Napa Valley. The late frost decreased the yield of many vineyards in the valley, followed by wild-fires-a-plenty throughout Northern California.  Here at Hess Collection Winery (USA) grapes are purchased from a number of grape producers located in a number of areas which were the hardest hit by the smoke from the wild fires.

The smoke from these fires is composed of many volatile aromas that can be integrated into the grapes.  The grapes are most adversely affected just after veraison; therefore, when anthocyanins are being produced in the grape skins the vines integrate these volatile chemicals into them.  The largest constituents of the smoke are two related molecules, Guaiacol and 4-methylguaiacol.  These two molecules are less soluble in water than in alcohol so the grapes and juice generally smell smokier than wine. They are easier to smell in juice than finished wine.

When wines are affected by smoke, we can use a process called reverse osmosis to remove the smell.  Reverse osmosis works as a three part process.  First, the wine passes through a reverse osmosis machine.  This is essentially a wine pump with a selective membrane attached to it.  The membrane is semi-permeable, only allowing molecules of a certain size to pass through.  Water, alcohol, the smoke taint molecules and a number of other small compounds may pass through the membrane.  This fraction of the wine is called the permeate.  Anthocyanins, tannins, large aroma compounds and other large molecules do not pass through the membrane.  This fraction of the wine is called the retentate. 

 The permeate, in the second phase of this process, passes through a series of activated charcoal filters.  This is not a very selective procedure. The activated charcoal binds many of the smoke taint compounds, but, it also binds other flavor profile compounds. This procedure would not be used injudiciously.  We would only use this procedure if the process will improve the resulting wine.

The final phase of the process, is the return of the permeate and retentate to the tank it came from.  This process occurs in a continuous loop.  The Guaiacol, 4-methyguaiacol and the myriad of other smoke taint compounds are removed until the impact on the palate is minimized.  When the final treated wine is put into the master blend, with other wine that has not been smoke tainted, the smoke is difficult to notice at all.  It becomes an interesting flavor component as opposed to overwhelming the palate. 

filtersTesting for Smoke Taint osmosis filter control panel


Egg White Fining

May 8th, 2009 by Marc in Winemaking

It is well to remember that there are five reasons for drinking:
the arrival of a friend; one’s present or future thirst; the excellence
of the wine; or any other reason.  – Latin Saying

Today I wanted to talk a little about fining wines.  Last time I wrote about blending and the use of barrels.  Wine is aged in barrel for approximately eighteen months.  This softens the tannins, among other things.  However, it often occurs that the tannins are still not where we want them to be when we are ready to bottle

 wine-lab-trials2

In wine production trials are very important.  Before we do anything on a large scale, we test the process on each lot of wine on a small scale in the laboratory.  We also try to make the trial as similar to the process used in the cellar as possible. 

In red wines we sometimes find a wine component that has a bit too much astringency. Therefore we use fresh egg whites from locally grown organic farms, to fine or polish the wine.  The egg whites contain albumin and globular proteins, which form hydrogen bonds with astringent tannins in the wine.  Hydrogen bonding is a weak chemical interaction, which is why this is a gentle process.  Most proteins in the wine do not interact with the egg whites.  The egg white/tannin composite, fall out of solution to the bottom of the tank.  After the wine has had time to settle, we rack the wine and the resulting wine is just as aromatic and complex as before the fining with less astringent tannins.


Blending Wines: Part Two, Barrels

April 13th, 2009 by Marc in Winemaking

Barrels are an important factor when it comes to blending. Specifically, barrels made from French oak  vs. old / neutral French oak. 

 

Neutral barrels allow the wine to display more of the varietal characteristics, while new French oak barrels add vanilla, smoky, chocolate, espresso and oak flavors to the wine.  New barrels also add weight to the palate, sometimes giving the wine an almost chewy aspect.

 

Using oak barrels is a way of adding complexity to the wine, through added oak components.  However, these components are not the only thing we are after in using the barrels. The barrels also allow very small amounts air to pass through the air-stave interface.  This oxygen is very important for the wine aging process.  The oxygen allows for softening of the tannins by complexing or binding of tannins with other tannins to make large protein compounds. This makes the tannins softer and more stable in the wine.

 

 As the blender for your own wines, your audience is going to be different then ours. When we make our blends we are looking to maintain a consistent style, which our customers enjoy. Our decisions attempt to produce the most constituent and highest quality example of the particular wine in question. 


Blending Wines: Part One, Wine Components

April 3rd, 2009 by Marc in Winemaking

“When there is plenty of wine, sorrow and worry take wing.”  The Art of Love by Ovid

 

Welcome to my inaugural entry for my blog.  I will be talking about winemaking techniques used at The Hess Collection and fielding questions posed to me and our winemaking team.  

 

This weekend, at The Hess Collection, we hosted our annual wine club blending party.  At the party participants were given samples of Mount Veeder wines, first to taste and then to make their own blend.  So I thought, this would be a good opportunity to talk a little about blending; how to decide on blending components, goals for blending and the audience for whom you are blending.

 

Our first step, with blending, is to evaluate each wine component. Our winemaking team looks at the balance of the wine, structure, concentration of flavors and complexity.  We also look for flavor and aroma defects.  This information is used to determine what we blend into our wine.

 

If a wine is overly astringent, meaning that it has a chalky mouth texture, we will look to soften the tannins with another wine, for example, Malbec.  Or, if the wine lacks tannic structure, we will add a wine with good structure to enhance the blend. Mount Veeder wines generally do not have this problem, so we usually look for wines to showcase more of the fruit that grows here. For example, Mount Veeder Cabernet Sauvignon showcases flavors of cassis, anise, plum and black cherry.  In Syrah, you will get pepper, black cherry and sometimes a smoky tar flavor. With Malbec, you may perceive plum, blackberry and cherry.  These wines are frequently used as blending components and were used in last week’s blending party.

 

 Check out photos from the event: http://www.flickr.com/photos/22768914@N08/sets/72157616223242695/detail/


Is That a Tree in My Bottle?

May 2nd, 2008 by admin in Winemaking

Well, it could be. I think most of you know that cork comes from trees. They are the bark of cork oak trees, which means that this closure is a renewable resource. Fortunately you do not have to cut down the tree to collect the cork; however they can only harvest each tree 1 out of every 10 years. In fact it takes 50 years before the cork company can harvest the tree for wine cork!

At any rate, it is part of my job to look at and smell the cork we buy. For some of our programs I actually smell every cork that goes into the bottle! I am still a little shocked by this. We soak the cork in diluted alcohol (13%) for 24 hours then we smell them for off odors. The clean ones go in the bottle; the bad are destined for the trash. Off odors you may find in corks are the following: the compound that provides the “corked” aroma in your bottle is known as TCA, 2,4,6-trichloroanisole, and it smells of various things, but is mostly described as wet newspaper. Other compounds that may be found in cork are 2-methylisoborneol (think dirt) and geosmin (described as earthy).

Before you get to the point of smelling the cork there is a visual inspection. Who knew there was such attention to the look of cork, right? So, first you send your cork to “school”, yes you give it an A – D letter grade. This is done by looking at a representative sample of cork for your bottling. My grading scale goes a little something like this:

A – No lenticels on the ends of the cork (lenticels are the lines or channels running through the cork) and an almost perfect body, meaning very small channels, if any.

B – One end of the cork with lenticels, the other clean. The body has channels, but fairly small. No cracks, or bark grain.

C – Both ends of the cork have lenticels. The body has bigger channels, it may have bark grain, cracks or small holes as long as they do not traverse more than ¾ of the cork length.

D – These are “defective” corks. They do have bark grain, cracks or small holes that traverse more than ¾ of the cork length.

After you sort your sample you can make a designation of quality of the cork lot. If the grading suits your standards then you can weed out off odors by soaking that sample of representative cork. After all that work you’ve got your cork lot you can use for that bottling.

Julie Murrell
Assistant Winemaker