The Great Riesling Yeast Experiment Part III

The Great Riesling Yeast Experiment has drawn to a close. The two different Rieslings produced during the experiment have now been finished, blended, and bottled. If you missed the first two parts here is Part I and Part II. Otherwise here’s a brief summary of the experiment.

Starting with a single six gallon World Vineyard Riesling Kit from Winexpert I split it into two, three gallon batches. Each batch was then fermented with a different strain of yeast.

The purpose of the experiment was two-fold:

1. determine if different yeast strains could produce different flavor and aroma profiles.

2. see if I could create a more complex wine by blending wines made from the same grapes that had been fermented with different yeast strains.

Parts I and II cover making the wine. In this part I’ll share how the wine was finished, blended, and bottled.

Degassing

Degassing turned into quite a project. I ended up degassing on two separate occasions because of how long it was taking.

Up until the first degassing the wine had been stored at around 66 degrees (F). When wine is stored below 72-75 degrees (F) the degassing process can take much longer because the cooler temperatures help carbon dioxide stay suspended in the liquid. This was evidenced by the 20+ minutes of degassing during this first round that didn’t get all of the carbon dioxide out.

After my first attempt I moved both wines where I could store them in the low 70’s. They sat for one week before I started round two of the degassing process.

The increased storage temperature made all the difference in the world! I was able to fully degas both wines in about 30 minutes.

Clarifying The Wines

The problem with degassing in two stages was that the second degassing stirred up everything that had cleared up to that point. I added the isinglass fining agent at the time of the first degassing per the kit instructions. However, when I degassed the second time the wines were just as cloudy as they were prior to the first degassing.

The RHST Riesling cleared completely within a week of the second degassing without any additional fining agent. This wine was never really that cloudy to begin with.

The W15 Riesling was another story. This wine had always been really cloudy. The isinglass didn’t do much to begin with but the second degassing undid any progress it had made to date.

To clear the W15 I had to add a bentonite slurry. It took two more weeks but it did finally clear. Just in time for my parents to give me a hand  blending and bottling.

All in all both Rieslings sat for four weeks during degassing and clearing. This was much longer than I would have liked, however, it was necessary to keep from bottling sediment and floating isinglass. No off flavors were picked up from sitting on the lees though. That was a relief.

Blending and Bottling

The last step was to get these two wines blended together and into the bottles. Keeping in mind the purpose of the experiment I decided on the following blending scheme:

• 100% W15 Riesling
• 75% W15 / 25% RHST
• 50% W15 / 50% RHST
• 25% W15 / 75% RHST
• 100% RHST Riesling

Not all of the wine could be blended or bottled this way due to complications that arose during the bottling process. Namely the autosiphon stirred up the lees and the last gallon or so got cloudy all over again. However, most of the wine produced was blended and bottled according to this scheme.

To blend these different percentages accurately I used two one gallon glass jugs in which the two wines were blended four bottles at a time.

I filled the jug pictured here with two wine bottles worth of water (1500 ml) and marked a line on the glass with a permanent marker. I then added another two bottles of water and marked that line. This is where I blended the 50/50 Riesling. (The jug currently is housing some additional W15 left over after blending)

For the other blends I filled the second jug with three wine bottles worth of water (2250 ml) and marked a line. Then I added a fourth bottle of water and marked that.

All the water was poured out and all the jugs, bottles, and equipment were meticulously sanitized.

The first four bottles my parents and I blended were the 50/50 blend. We racked one wine to the 50% line and then the other wine up to the 100% line. After a good stir we filled the first four bottles.

Then we moved on to the 75% W15 / 25% RHST. We siphoned W15 up to the 75% line in the second jug and filled the remaining 25% with RSHT. Again, we gave it a good stir and bottled that blend.

We continued through all three blends and bottled some of each wine by themselves.

As I mentioned before the lees did get stirred up in the W15 so I wound up with more unblended wine than I would have like. The cloudy W15 was siphoned into a sanitized one gallon jug and left to clear…yet again.

Conclusion

I did find that the two yeast strains produced not only different flavor and aroma profiles, but they also behaved quite differently with the same clearing agent.

I was really surprised to see just how different these two wines really were. My expectation was that only a trained and discerning palate would have been able to tell the difference. However, the samples I tasted all along the way proved that the yeast accounts for vast differences in flavor, aroma, color, and clarity.

Even the chemistry between the two differed. However, the pH and TA did come back into alignment as the wines reached their fully fermented state.

There is one last thing to do with the five Rieslings I’ve created. Host a blind tasting!

That’s right, I will be hosting the first ever Winemaker’s Academy Wine Tasting. With the help of a few friends we’ll taste all five wines next to each other to see which one the group likes best but also whether or not they too can pick up on the differences in flavor and aroma.