The Great Riesling Yeast Experiment (Part II)

The Great Riesling Yeast Experiment (Part II)

The saga continues with the racking of my experimental Riesling fermented with two different yeast strains. Read this if you missed part one. Up to this point the two batches of Riesling have been fermenting separately.  One in a primary fermentation bucket and the other in a six gallon carboy. Little could be observed of the two wines save for the airlock activity. However, I recently got a chance to see, smell, and taste the two Rieslings when I racked them into their respective carboys. Here’s what I found. Opening the Primary Fermenters After seven days in their primary fermentation containers it was time to check chemistry and rack off of the lees. I opened up the lid to the plastic fermenter with the R-HST Riesling in it and was greeted by an interesting aroma. Not only was it a different aroma than the W15 Riesling, it smelled odd. I’m not entirely sure what it was but it had a tinge of sulfur to it. My wife really disliked the aromas wafting her way as she helped me prepare to rack. The W15 had been bold and fruity up to this point and didn’t disappoint when I removed the airlock. This wine smelled very fruity. I was expecting the same when I taste tested it. Testing the Wines With the lids removed I drew a sample of each wine to test it’s chemistry. The first thing I checked was the specific gravity. The R-HST weighed in at 1.008. This means there is still a bit more sugar yet to be fermented. The W15 Riesling was at an even 1.000. So in the same period of time the W15 yeast had burned through a bit more sugar than the RHST. This was particularly surprising because both wines came from the same kit and were inoculated at the same time (within about one minute of each other). I expected some differences in behavior between the two but this was a much larger difference then what I was anticipating. The W15 did seem to ferment more vigorously. The airlock looked like it was boiling at its peak. The difference in airlock activity was a solid indication that the W15 yeast was fermenting more quickly. Not only was the specific gravity different, the titratable acidity (TA) different as well. The pH, however, remained the same between the two. Sampling the Wines Any time I take a sample for testing I also taste it. This is why I love making wine. But before I tasted it I took a good look at the two wines. They both had similar yellow colors and were quite cloudy. The W15 Riesling was more cloudy than the RHST Riesling. I tasted the W15 Riesling first and what a surprise! Despite the bold grape smell it had strong grapefruit flavors. My wife picked out lemon and lime. Both of us agreed that it had an intense citrus flavor. Not much grape flavor at all. Then I moved on to the R-HST. This wine was noticeably sweeter, as evidenced by the higher specific gravity. I could taste a faint hint of pear as well as white or unripe...

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The Great Riesling Yeast Experiment (Part I)

The Great Riesling Yeast Experiment (Part I)

Yeast can have a profound affect on the final flavor and aroma profiles of a wine or so we’re told. But how much of a difference is there really from one yeast to another? To answer this question I set up the Great Riesling Yeast Experiment. In this experiment I set out to ferment one Riesling kit in two three gallon batches with two different yeast strains. To find out how I picked out my yeast strains read this. This experiment, I hope, will answer the following more specific question. How much does a yeast affect the final taste and aroma of a wine? Can you make a more complex wine by fermenting the same grapes with two different yeasts and blending them back together? Is it possible to make good wine from a kit while not following the directions? Background Yeast, as you know, is the star of the fermentation show. It is responsible for the creation of alcohol in wine, mead, and many other grown up beverages. For a long time many winemakers did not believe that the yeast used to ferment grapes mattered much when it came to the final character of the wine. They believed that as long as the grape juice was fully fermented it all tasted the same. It wasn’t until fairly recently that wine researchers started to study the effects different yeast strains can have. What they found was that it can make quite a big difference, however, they did say that it takes six months or so for that difference to show up. Today, many winemakers do split fermentations for this reason. They ferment the same grapes with more than one strain of yeast in separate containers. Then they blend these wines back together to create complexities that neither yeast on their own could create. The Yeast Experiment To answer the three questions posed above I set up the following experiment. I purchased a Winexpert World Vineyard Riesling (affiliate link) which makes six gallons of wine. To ferment this kit I selected RHST and W15 yeast strains based on their different aroma and flavor profiles (also affiliate links). These two 3 gallon batches will be fermented and aged separately for a period of a few months. Once they’ve been made into complete and independent wines I will blend them back together in varying proportions. Some bottles will contain 50% of each. Others will be blended at 25% one and 75% of the other. Lastly, I’ll bottle a couple bottles of each independently. Now that we’ve covered the parameters of the experiment let’s talk about how it’s all going down. Currently I’ve got my wines in their secondary fermentation carboys, however, I’m going to cover the first steps in the experiment here. Step 1: Inoculation To get this experiment going I hydrated the grape juice concentrate in a six gallon fermenter per the instructions with the bentonite. Once the wine was properly mixed I started the yeast re-hydration process. The kit instructions clearly state not to do this, however, as I’m not using the yeast that came in the kit I felt I needed to...

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