Winemaking Spooky Moments

Pumpkins and corn, grapes and vines. The final days of harvest are upon us!

Is it any surprise that Halloween and winemaking happen around the same time of the year? This Halloween, it seems apt that I should share three spooky moments of winemaking and the tricks to get out of them.

Halloween and winemaking

Spooky Moment #1: Starving Yeast

Two years ago, I was working on my second vintage. While my first vintage was part of a class, this was the first time I made wine with the training wheels off. I was in charge of the yeast, nutrients, and chemicals to ensure good sanitation and health for the fermentation process.

Healthy starter

It had been a year since I had prepared a yeast starter. (The downside of a once-a-year hobby.) I activated the yeast with warm water and nutrients, paying close attention to temperature control. To the hydrated yeast, I then added crushed grapes (known as the "must" in winemaker speak) diluted with an equal amount of water. The idea was to whet the appetite of the activated yeast several hours before introducing it to the eventual feast of grape-y sugary goodness.

While I thought I had kept good notes from my first vintage, it became clear that I missed some details. Important details. Like how how much must mixture I should add to the starter.

Starving yeast

I returned home from my day job to find the sad state that was my yeast starter. Instead of being round and full with tiny air bubbles, the starter was straggly and almost lifeless. Clearly I did not add enough must mixture. The yeast did not get enough sugar and was starving.

The Trick: Thankfully, it was early in the fermentation process, literally two days after harvest and crush, and this was highly recoverable. As long as there were some bubbles going on in the starter, adding more must mixture should revive the yeast in less than an hour. That was what I did and it worked. Failing which, I would have to get a new yeast starter. I added to my notes: 1 cup of must and 1 cup of water per 5 grams of yeast.

Spooky Moment #2: Rotten Eggs

Why does my must smell like rotten eggs?

H2S compound

You learn about this in class, and you are told not to panic. Still you pray it doesn't happen to you. But if you have been making wine for a while, it is inevitable.

What contributes to the rotten eggs smell is the compound hydrogen sulfide (H2S). By the time you can smell it, it typically means the yeast is stressed. The cause could be inadequate nitrogen, excessive sulfur, and/or lack of oxygen. And I believe we might have hit the jackpot on the trifecta.

• Nitrogen - Washington grapes are infamous for having a low nitrogen level. This year's particular crop had less than a third of the healthy amount of Yeast Assimilable Nitrogen (150 mg/L) for fermentation.

• Sulfur - While I had treated the must with the same amount of sulfur every year to inoculate the grapes from wild yeasts. It is possible that the vineyard had also added sulfur to preserve the fruit for the four-hour ride back to Seattle, resulting in a double dose.

• Oxygen - With the two factors above, weak air circulation and low oxygen contact with the yeast could just seal the deal for H2S production.

The Trick: First, we increased aeration with more rigorous and frequent punchdowns. We even removed the lid on the primary fermenter for several hours to improve circulation and let excess sulfur dissipate. Finally, we moved up the nutrients schedule by a day and beefed up the yeast with diammonium phosphate (DAP) to compensate for the low nitrogen level. That seemed to get the yeast going. By the next day, the rotten eggs smell was gone. Phew!

Spooky Moment #3: Sluggish Fermentation

While we fixed the H2S problem and kept fermentation going for the next few days, the drop in Brix started to slow down again at 11 degrees. (Our goal is to get to -1 or -2, which indicates that fermentation has completed.) Brix measures the sugar content in the must. Yeast coverts sugar into alcohol during fermentation. The slowdown indicates that the yeast might be experiencing stress again and might not be able to complete fermentation.

Hyrdometer to measure Brix

Sluggish or stuck fermentation is problematic. The unfermented sugar could attract bacteria. Additionally, there would not be enough carbon dioxide, a byproduct of fermentation, to provide a protective layer against oxidation. In both cases, the wine would be prone to spoilage.

The Trick: Depending on where you are in your fermentation process (high Brix or low Brix) and your winemaking skills, there are different ways to fix a sluggish or stuck fermentation. Given that we were nine days into primary fermentation and had only reached midpoint in the Brix, our best bet was to re-pitch with another yeast strain, Premier Cuvee, that is known for a fast and clean fermentation. (We normally use Premier Rouge for primary fermentation of red wine.) That was what we did, and we did manage to get the fermentation going through dryness in the next four days.

An added bonus of this second pitch of yeast is that we happened to catch the yeast starter on video, which was pretty neat!

 

My Verdict: While this is my fourth vintage, I find that I am constantly facing new challenges in winemaking and learning new things. Sure, these are spooky moments. But once you learn the tricks to overcome each challenge, you get a deeper appreciation of the process and you are rewarded with the ultimate treat! So move aside, Halloween, with your trick or treat. This is Hallowine time!

Feeding the Beast

I am fascinated by yeast, especially the species known as Saccharomyces cerevisiae. S. cerevisiae is responsible for alcoholic fermentation and baking. These single-celled microorganisms convert carbohydrates into alcohol and carbon dioxide. The happy outcome of the process is wine or beer or a delicious slice of sourdough.

Wine yeast

Experienced and skilled winemakers in established wine countries often use native yeasts for alcoholic fermentation because the right type of yeasts have been cultivated over centuries and thrive in the environment. Hobby winemakers, like myself, who purchase grapes from fairly young vineyards, are better off using commercially produced wine yeast. This is sold dry in packets the same way you get bread yeast or in bricks for larger quantities.

But before we add wine yeast to crushed grapes (also known as the must), we have to first kill off any existing wild yeasts and microorganisms by adding sulfite. If not, these can contribute to off flavors and spoilage during the fermentation process. Two days after adding sulfite, wine yeast is then introduced to the must.

A key job of the winemaker then is to nourish the yeast so that it can complete alcoholic fermentation. Here are two things I've learned in making the 2017 vintage.

Yeast Gets Hungry  

Very much like baking sourdough, you first make a starter by activating the dry yeast in warm water that is supplemented with some nutrients. (I used Go-Ferm.) Then you feed it with sugar; in this case, a 1:1 ratio of must and water. Temperature control is important as the yeast is quite thermosensitive.

Activating yeast

Several hours later, the yeast would feast on the sugar and start to multiply. A healthy starter expands in size and bubbles happily. However, if the yeast is starving, it tells you in the most dramatic pitiful way, which was what happened to me.

Healthy starter

Starving yeast

Thankfully the fix was simple enough. I just had to add more juice to the starter, and within a half-hour, the starter came back to life. But just in case, it is good to have spare yeast and nutrients around.  

Slowly acclimatize the starter by putting the bowl on the must in the primary fermentor for a few hours before pouring it in. Soon, the primary fermentor should feel really warm, and the must should be bubbling away. If you are really quiet, you could almost hear your yeast having a blast with all the sugars in the juice. 

Sugar Alone Ain't Enough

While sugar may be delicious, it alone can't keep the yeast healthy. Other nutrients are also needed, and an important one is nitrogen. Unfortunately, Washington grapes are notorious for having a very low nitrogen level, which could inhibit yeast activity and cause a stuck fermentation. 

We did an additional measurement on the must this year, known as the Yeast Assimilable Nitrogen (YAN). True enough, our YAN reading was at 33.7 mg N/l, a far cry from the targeted 250 mg N/l. Under the guidance of more experienced winemakers, I measured the amount of nutrients that I needed to add to the must. 

Hydrometer records 0 Brix

I went with Fermaid K, which consists of a complex formulation of nitrogen, vitamins, and minerals. In addition, I threw in a small dose of diammonium phosphate (DAP) for extra nitrogen. The nutrients and supplements gave the yeast such a nice boost in the fermentation process that I reduced the second dose and didn't even bother with a third dose.

By the tenth day after harvest, the juice was fermented to dryness. Alcoholic fermentation was completed. The must was no more, and I officially had wine. 

The next step was to start malolactic fermentation on the wine, and then it was time to press. More to come on that!

First Vintage

Last October I posted about my first winemaking experience; well at least from crush through the primary fermentation and press. That was probably the most involved part of winemaking, when twice to thrice-daily punchdowns took place with constant measuring of temperature and Brix. That was when the juice was transformed from 'must' to wine as sugar got fermented into alcohol and carbon dioxide.

Secondary Fermentation

After the press, we moved into secondary fermentation of the wine in air-locked vessels. We used a 5-gallon glass carboy and three gallon jugs to use for top-up (I'll get into that later). This period was generally uneventful and less involved, but there were a few things that required attention.

Controlling the temperature. Malolactic (ML) bacteria, which was added to the juice the day before press, were quietly converting tart-tasting malic acids into fuller-bodied lactic acids. ML bacteria are sensitive to numerous factors (e.g. pH, SO2, and alcohol levels), but the one thing that worried me was my ability to keep the wine within the optimal temperature range (>70 degrees). The carboy and gallon jugs were wrapped in blankets, snugged in cardboard boxes, and gently warmed by a heating pad. My biggest fear was stuck fermentation since there were no easy tests to perform at home or measurements to track progress. I resorted mostly to prayers.

Lees left behind from racking

Racking, racking, racking. Even though most of the solid remains of the grapes and yeast (also known as pomace or marc) were removed during the press, there were still some remaining in the wine as it went through secondary fermentation. These are called the lees. Decomposing yeast in wine could cause off flavors. In order to remove the lees, we did multiple racking of the wine during secondary fermentation. Racking is the process of siphoning wine off of dead yeast into new containers.

We siphoned a total of four times; the first time was 24 hours after press, the next two were a week apart, and the final one was a month out.

Racking also has two other advantages:

• It clarifies the wine. You could literally see that the juice got clearer after each racking. In many cases, clear wine is just a matter of aesthetic. If the wine tastes good, cloudiness may not indicate flaws.
• When done correctly, racking can introduce controlled amount of oxygen into the wine. During the early part of secondary fermentation, oxygen has positive effects on unfinished wine by stabilizing the color and tannins. It allows the wine to mature gracefully and become more complex. In the later part of the secondary fermentation, caution is needed to minimize oxygen contact. If acetic bacteria is exposed to wine and oxygen, it will turn the juice into vinegar (acetic acid). 

It is important to note that you will lose wine during racking due to spills and as you avoid siphoning lees. The loss of wine during racking may increase the air space between your wine and the airlocks. You can top up the carboy with wine from the jugs or similar store-bought wine (preferably same varietal and AVA). Alternatively, you can add sterilized marbles into your containers to raise the wine level. I personally put some of my top-up wine into a sanitized plastic container, squeezed out as much air as possible, and capped it. It worked!

Final Testing

After more than three months of secondary fermentation, we performed the final testing of our wine to check on sugar, acidity, and ML fermentation. During the primary fermentation, which lasted less than two weeks, I was constantly monitoring and measuring progress. For the much longer secondary fermentation, I really had no idea what to expect. But I was pleasantly surprised by the outcome.

• Residual sugar was at 0.3%. This was probably the least of my concern since we pressed the wine at a really low Brix. Residual sugar over 0.6% is a concern for still red wine as it may cause re-fermentation in the bottle.

Measuring residual sugar in the wine

• pH was 3.78. This was slightly higher (or less acidic) since harvest, which was at 3.53. But it was still within the normal range.
• Titratable acidity (TA) was 7.3125. TA measures the amount of total acids and was higher than our reading during harvest, which was 7.125. It was a bit higher than I like, but not bad.
• ML fermentation appeared to have completed. While not the most accurate way to test the concentration of malic acid, the chromatography test is cost-effective. The solvent used for the chromatography is extremely toxic, and the test takes several hours. After putting dots of wine sample onto a piece of chromatography paper, it was left in a big glass jar with the solvent and the lid closed tight. 

With one exception, most of the wines appeared to have completed ML fermentation. Yellow patches indicated presence of acids. The top row of yellow revealed the presence of lactic acid, which is the goal of the ML fermentation. The bottom row of yellow revealed the presence of tartaric acid, which is also what we expected. Any yellow in the middle role revealed the presence of malic acid, which would indicate that ML fermentation has not completed. This would show that the wine has not stabilized and will need more time for ML fermentation to complete.

Chromatography test revealed that one of the wines still had malic acid

Bottling

Once the wines had passed all the tests, they were ready to be bottled. We got the bottles that we have saved up, cleaned, and sanitized. (We recycled bottles. If you buy new bottles, you can skip the above steps.) Sulfites were added to the wine just before bottling. Sulfites are a preservative and will keep the wine fresh. They are also anti-oxidants and will protect the wine from oxidation.

Adding sulfites to wine

Siphoning wine into bottles

Corking wine bottles

Finally, five months after harvest and crush, our first vintage was bottled and proudly named Abscession - a joke, as my husband was recovering from an abscess the day of the harvest. Special kudos go to my partner-in-wine, Alisa. That's her work on the label, making an access look classy. The wine will officially be released in the summer, so check back later.

Abscession 2016 Syrah

My Verdict: I am having so much fun learning about winemaking. It gave me a greater appreciation for wine. I don't think going commercial is my calling, but I'm planning for my next vintage already! 

First Crush

It was a breathtaking drive from Seattle to Snoqualmie that sun-soaked September afternoon. I was exhausted and a bit cranky, having to juggle work and taking care of a sick husband and an injured dog.

However, mother nature had chosen the harvest date, and then we were given but a few days notice to get ready for the crush. I left my invalid family members in the good hands of our house guest, packed the primary fermenter, towels, and rubber boots into the Forester, and headed out to the crush facility. My excitement grew as I approached the facility - my first crush!

Crush Day

Our Syrah grapes were picked earlier that day from Chandler Reach Vineyards, technically considered to be in the Yakima Valley, but within close proximity of the Red Mountain AVA. My partner-in-wine, Alisa, and I decided to share 100 lbs of grapes between us, which would make us about two cases of wine.

At the crush facility, the winemaking class instructor, Steve, showed us how to set up the crusher and de-stemmer. All equipment were rinsed appropriately before we proceeded. Working in a group, we gently dropped bunches of grapes into the machine, which quite efficiently removed the stems and lightly crushed the grapes into the primary fermenter. But just in case, there were two of us who manually picked out stems that were missed by the machine.

There was a certain rhythm to crushing grapes that relaxed me. It was almost therapeutic! This was the first crush for most of us, and we were eager to learn and to help. As we got the hang of it, we moved faster through the bins of grapes. Our sticky grape stains were evidence of our achievement that day.

Gently dropping grapes in

Crushed and de-stemmed

More stems manually removed

Must in primary fermenter

The freshly crushed grapes, also known as must, smelled terrific. Sulfite was added to remove any wild yeast and bacteria from the must. After crushing nearly a ton of grapes (literally) and cleaning up all the equipment, it was time to take some measurements before we took the must home.

• Brix, which measures the sugar content of the must, was at 26 degrees. It was higher than the desired range of 22-25. A higher than desired Brix might lead to high alcohol content before fermentation could complete. This could result in a stuck fermentation.
• pH, which measures acidity, was at 3.53 and was within the desired range of 3.5 and 3.8.
• Titratable acidity (TA), which measures the amount of all the combined acids in the must, was at 7.125g/L and was slightly higher than the desired 4-6g/L.

The adjustment to the must needed was thankfully simple enough. To correct the Brix without adversely impacting the pH and TA, we diluted the must with water with precise measurements that Steve provided.

Alisa, my partner-in-wine, and I with our must

Primary Fermentation

A full day after the crush, we introduced re-hydrated yeast into the must and proceeded with the twice to thrice-daily punch downs. Punching down is a process to keep the juice and the crushed grapes, particularly the skins, in contact during primary fermentation. As must ferments, the crushed grapes tend to rise to the top forming what is known as the cap. Pushing the cap down into the juice allows for flavor extraction and also prevents unwanted bacterial activities.

A pack of nutrients were added to the must two days later to feed the yeast, and a second pack was added after another two days. The must was bubbling happily and got hot (around 75 to 80 deg F) with yeast activities. Unfortunately, I never got to the desired temperature range of 80 to 90 deg F. But the house smelled like a winery during primary fermentation so I took that as a good sign!

Yeast hydrated in must and warm water

Must bubbling during fermentation

In less than a week after the crush, the Brix had dropped to 6 degrees. Twice-daily punch downs continued, and four days later, the Brix measured at -1 degree. The must was then inoculated with malolactic (ML) bacteria as we prepared for the press the next day. The ML fermentation process allowed for a controlled conversion of the tart-tasting malic acids to softer lactic acids, which would hopefully enhance the body and flavor of the wine.

Press Day

To prepare for the press, all equipment needed to be sanitized. It was not the most interesting part of winemaking but very necessary to ensure that no wild strains of yeast or bacteria would enter the juice. ML bacteria was added a day before the press so that it could benefit from being evenly distributed in the juice during the pressing process.

Sanitizing 

There were three batches of must at Steve's house that day, ready to be pressed. Steve pulled out his beautiful press from the turn of the 20th century. It belonged to his grandfather and was quite the treat!

Our must had been in primary fermentation for about ten days at that time. We poured the must into the wine press and let the juice flow into a container at the bottom of the press. This is what is known as the free run. Following that, we placed heavy blocks of wood onto the crushed grapes and exerted pressure to press the remaining juice out. The unfinished wine went into the sanitized carboys and gallon jugs, that were then air-locked.

Beautiful wine press and free run

Pouring pressed wine into carboy

The day ended with a quick sampling of the three different juices. Within only ten days, you could already taste the difference among them. Some of us (not me) had clearly done a better job with punch downs and keeping the temperature at the higher and more desired range. Those juices showed a bit more tannins and structure. My juice, which was fermented cooler and with less intervention, was more fruit-forward. I can't wait to see how our wines will continue to evolve.

My Verdict: I was a skeptic when it came to winemaking. Given the abundance of great wines available, there is hardly any need to make my own wine. However, I've been having great fun so far. I've also learned a lot about what goes on in a wine. Stay tuned for my post on secondary fermentation and bulk aging.