Fall in Our Vineyard

It seems that all is calm and quiet in the vineyard but, our hunter friend recently sent us some photos that he took when he saw a bobcat in the vineyard.

Racking Off the Gross Lees

At the end of our fermentation we consolidated our newly made wine from the two kegs that we had it in during fermentation into one keg. My husband purchased all of the equipment, nitrogen gas, regulator, racking wand, etc.
Since the pH, titratable acidity and sulfur dioxide values were very similar in the two kegs, we felt that we could combine it without unduly affecting any of the parameters. We let the wine settle in the one keg. What we hoped to accomplish with this step was to settle out the yeast that were floating around in the fermentation.
We left the tank in the refrigerator from Friday, October 23 until Tuesday, October 27 to allow the yeast and other large particles of fermentation to settle out of solution. We used the same setup with nitrogen gas to rack over just the clarified wine. It was a tricky little maneuver because we only had visual cues to guide us in determining when to stop racking. We think we did a pretty good job. When we went to empty what remained in the bottom of the fermentation tank, we decanted over some pretty gross lees, shown at the left in the photo and we took out about 10 mL of wine in order to do more tests, including a sensory (i.e. tasting) test.

Unfortunately, I messed up the titratable acidity test, but our sensory exam leads us to believe that our wine is still searingly acidic.

Our Fermentation is Over

On Friday, October 23, we checked our fermentation by running a few tests using our Vinmetrica SC-300 Pro. We tested the Vinmetrica system using a wine we had on hand so we were reasonably confident that our technique could be used to test our wine. There are online videos provided by Vinmetrica that give step-by-step instructions on the following:

• How to Calibrate the Vinmetrica SC-300 Prior to Making pH and Titratable Acidity (TA) Measurements
• How to Measure the pH
• How to Take a Titratable Acidity Measurement
• How to Take an SO₂ Measurement

On this fateful day, we conducted our tests on the juice in the two kegs that had been fermenting since September 30th. Our last reading that we took on October 13th gave us a Brix reading of 9. We ran the tests on our fermentation including the Accuvin Residual Sugar Test and we found that we had the following values:

• pH = 3.15
• TA = 12.25 g/L
• SO₂ = negligible
• Residual Sugar = ~500 mg/L

We stopped the fermentation by adding potassium metabisulfite into our two kegs. I used the: Sulfite Calculator
to determine that we needed to add 1 gram of potassium metabisulfite to achieve the required 0.825 mg/L molecular sulfite level.
We had hoped to leave a little residual sugar in our wine, but the values indicated that we had far over shot our mark. We also have a lot of acidity, some might call it searingly acidic. We are hoping that our tartrate stabilization might take out some of the titratable acidity and lower the TA a little.
We are consoling ourselves with the good news.

• First, our fermentation was long and slow and we didn't run into any problems with a stuck fermentation, indicating that our fruit came in with enough food for the yeast.
• Second, we didn't have any volatile acidity (acetic acid) issues, or fingernail polish (ethyl acetate) issues, or rotten egg (hydrogen sulfide) issues.
• Third, we have approximately 5 gallons of wine from the 65 pounds of fruit that we harvested.
• And last by not least, we learned a lot and hope to apply this knowledge into configuring a working lab and getting the appropriate equipment for scaling up to a full harvest, hopefully in the near future.

Steps to Consider After Fermentation is Over

Measuring Residual Sugar
So far, we have managed to conduct a constant temperature (60^o Fahrenheit), slow fermentation, resulting in a decrease of 1 ^oBrix a day. We are approaching the end of the fermentation and we are giving careful consideration on how to proceed. When the fermentation was evolving a lot of carbon dioxide, we felt comfortable in opening the fermentation lock to check on the Brix, but now, with most of the sugars converted to alcohol and the carbon dioxide evolution is on the decline, what do we do?
We want to make wine in the style of Domaine Huet and we found a Domaine Huet Fact Sheet published by Europvin. In that fact sheet is the following information:

• Sec: 11.5 - 12% alcohol; 3 - 5 g/L residual sugar
• Demi-Sec: 12 -13% alcohol; 10 - 20 g/L residual sugar
• Moelleux: 13 - 14 % alcohol; at least 30 g/L, but can be anything up to 200 g/L residual sugar

Vinification of the Chenin Blanc grape is about the proper balance of alcohol, acid and residual sugar. Without some residual sugar, the acids take over, so we do want to have a bit of residual sugar in our wine.
To measure the sugar left in our fermentation, we purchased the Accuvin Residual Sugar Test to get an approximate idea of how much residual sugar we have that is below the level of 1 ^oBrix since:
1 ^oBrix = 1% sugar (wt/vol) = 1 gram sugar/100 mL = 10g sugar/1L
The range of the test goes from a low of 100 mg/L to 2000 mg/L and if we want to test for 5-8g/L (5000-8000mg/L), we would have to do some dilutions:

Stay tuned!
References:
1. UC Davis Online Course: Wine Production, VID252, Lesson 3, page 6.
2. Daniel Pambiachi, Measuring Residual Sugar: Techniques, WineMaker, April/May 2002.

Vintage 2015: First Freeze Event

Our first freeze event happened this past weekend. We were warned about it so we knew it was coming, we just didn't expect to see dead leaves.

We came prepared to download our HOBO temperature data, so we learned that the temperatures dipped below freezing on Sunday, October 18 from 2:30 a.m. to 8:30 a.m. and then again from 7:45 p.m. until 9 a.m. on Monday morning, October 19.

Vinmetrica SC-300 Pro

We recently received a long awaited for shipment. Actually, we ordered this Vinmetrica SC-300 Pro before our harvest on September 26, 2015 intending to use it when harvest time came. Unbeknownst to us, the company was moving their operation and somehow, our order got lost in cyberspace.
The nice thing about this kit is that it will do pH, titratable acidity, as well as free and total SO₂ measurements. All of the reagents are included. The kit also comes with a stand, stir bar and a mini-stir plate as shown in this picture on the left.
Our fermentation has been going now since September 29th and we have taken 3 Brix readings. Our latest reading was taken on October 13th and we had a Brix reading of 9! Since we have to open the keg to take the reading, and since we know that the rate is about 1 ^oBrix a day, we have decided not to open the keg until our nitrogen gas arrives, crossing fingers, on Monday, October 19th.

Fall Wine Lineup

Our friends are leaving soon for an extended vacation in the southern hemisphere. While we will be hibernating in the coming winter, they will be playing outdoors in summer! We got together with them and polished off 5 bottles of wine while gnoshing on fried harico verts and smoked steak. Our friends brought the Pahlmeyer and LeFlaive Puligny-Montrachet---so generous. We will miss them.

One Autumn Grape

Our Chenin Blanc fermentation is bubbling happily and fall has descended on our part of the world. Here is one grape that grew on a tendril. The periderm of the Chenin is developing, getting ready for the winter that is to come. Our thoughts are turning to the irrigation we need to put into the vineyard before winter drives us indoors.

Fermentation Progress

Our fermentation has been bubbling away. We inoculated the must on September 29 around 11 a.m., saw the first signs of very slow evoluation of bubbles in the fermentation lock on the following day, September 30th around 5 p.m. Our initial Brix reading was 22 degrees. We don't have all of the measuring tools that we need to record pH, TA, SO₂ values, but we can take Brix readings with our refractometer. I found a very nice Brix to SG Conversion Utilizing Refractometer chart as well as a management chart on line that we have been filling out to record the progress of our fermentation. Our temperature in our temperature controlled refrigerator is a constant 62 ^oFahrenheit.
In order to take the Brix reading, we have to open the fermentation lock, so we have only taken 2 readings so far. Once on October 3rd, and both of the kegs were at 17 ^oBrix and the next time on October 6th, when the reading was at 15 ^oBrix. The other things that we can do is to smell the fermentation and give it a little taste. So far, we can smell yeast and now, a little bit of alcohol. We have not smelt hydrogen sulfide (rotten eggs) or ethyl acetate (nail polish) and the taste so far is pretty good, but of course I am so biased!

How to Dedicate Your Refrigerator to do Low Temperature Fermentations

The title of this blog is "How to Dedicate Your Refrigerator to do Low Temperature Fermentations". We definitely wanted to keep our must temperature at a constant temperature during fermentation to ensure that the volatile esters and yumminess that we tasted in our Chenin Blanc juice was retained throughout the fermentation. First, you need to have some good friends that have a spare freezer so that you can dump all your frozen goods in their freezer. My husband (ace online researcher) found that people converted their refrigerators into a temperature controlled fermentation space by procuring something like this Johnsons Temperature Controller A19AAT-2C.

The copper wire that you see to the right of the controller is the sensing element. My husband threaded the sensing element through the door of the refrigerator and placed it on the top rack of the frig. The sensing element can be set to a temperature any where within the specified range of 20-80 degrees Fahrenheit. The plug from your refrigerator is plugged into the plug for the Johnson Control and the sensing element will keep the refrigerator at the temperature that you specified on the controller. We have set our temperature for 60 ^oF.
Why is this important you might ask? Well, it is common knowledge that the conversion of sugar to alcohol gives off carbon dioxide, but may be not so known is that the conversion also gives off heat:

Once the fermentation is in the stationary phase and the yeast are rapidly converting sugars into alcohol, the heat generated needs to be controlled. We hope that the favorable surface to volume ratio of our kegs as well as the constant temperature that we are achieving in the refrigerator will help to keep our fermentation cool.

Rehydrating and Tempering Yeast

On Tuesday, a full 3 days after putting our juice in the refrigerator to cold settle, we started to rehydrate our QA 23 yeast. I looked at various sources to figure out how much yeast I needed to add to the juice. I went back to my notes from the U.C. Davis Online course that I took and I also found an excellent online article from MoreWine! Inc called Guide to White Wine Making.
Rehydrating Yeast

• Rehydration procedures are important to yeast viability.
• This procedure took approximately 45 minutes.
• I used Poland Spring water that was warmed to 100 degrees Fahrenheit, as recommended.
  It is recommended not to use tap water or juice that may contain fungicides or preservatives which will significantly decrease yeast viability, for this first step of yeast rehydration.
• The recommended reconstitution and inoculation procedure calls for 25 grams of dried yeast per 100 liters (0.25g/L) of must or juice to achieve approximately 5 x 10⁶ viable yeast cells per milliliter of solution and a peak cell density of 1.2 to 1.5 x 10⁸ cells/mL. This inoculation density helps ensure a rapid onset of fermentation and dominance over indigenous yeast.
  For our purposes, I scaled this to our volume of 5 gallons or 18.9L and calculated the addition to be 4.725 grams of yeast. Our yeast, QA 23 comes in 5 g packets so I used one packet.
• We rehydrated the dried yeast by slowly sprinkling into 10 to 20 times its own weight (100 – 200g yeast/L), in our case, 50 mL of clean Poland Spring water pre-heated to between 38(100°F) to 42°C (108°F). The recommended procedure is that gentle stirring may be used to improve yeast wetting and dispersal to avoid clumping. Vigorous stirring or mixing should be avoided as it may damage or lyse rehydrating yeast cell walls. We gently swirled the Pyrex 2 cup measuring cup that we used to rehydrate our yeast.
  

Tempering Yeast

• We let the yeast bloom for approximately 15 minutes while we waited for our juice to warm up to 60 degrees.
• Our next step was to lower the temperature of our rehydrating yeast from 100 ^oF in incremental steps by adding in our juice. We took 25 mL of juice and added it in 5 mL aliquots every minute and then let the mixture acclimate for 15 minutes. This brought the temperature down from 100 ^oF to approximately 85 ^oF. We waited 15 minutes.
• We repeated the above step, taking another 25 mL of juice and added it in 5 mL aliquots every minute and then let the mixture acclimate for 15 minutes. We were able to bring the yeast mixture down to 70 ^oF.

At the end of the rehydration, our yeast mixture looked like this:

We were ready to pitch the yeast into our cleaned fermentation vessels, which are stainless steel beer kegs that my husband procured for the fermentation. After moving the juice from the Poland Spring jug into the kegs, we moved the kegs into our refrigerator which my husband converted into a temperature controlled (at 62 ^oF) environment, to ensure a slow and long fermentation.

1. VID253, The Regents of the University of California 2007, Lesson 6 – Page 8 of 25.
2. Scott Labs Yeast Rehydration Protocol
3. MoreWine! Inc, Guide to White Wine Making