June 25, 2019

In my April 29, 2019 blog about My Quest for Top-Quality Fruit for Making Superlative Wines I talked about my challenges in sourcing good fruit (or must) in my area, i.e. Montreal (Quebec, Canada). So I decided to try three pails of frozen must of WineGrapesDirect’s best of the best for evaluation purposes. I chose the following varieties, one white and two reds, from the 2018 harvest (prices are in US$ for 5-gal pails unless stated otherwise):

• Sonoma Chardonnay, Russian River Valley AVA, Olivet Lane Vineyard ($250 – 5.25-gallon pail)
• Napa Valley Cabernet Sauvignon, Calistoga AVA ($230)
• Oregon Pinot Noir, Willamette Valley, Chehalem Mountains AVA ($175)

In that blog I presented a set of measurements from my analysis of each must, i.e. pre-fermentation, and described some general and specific winemaking procedures I intended to use to craft these musts into the best wines possible.

All three wines have completed alcoholic fermentation (AF) and malolactic fermentation (MLF), and are now aging in my cellar at a cool 13°C (55°F). Following is an update of what has transpired since and a set of measurements from my analysis of each wine immediately post AF and MLF. The volumes indicated post AF/MLF are from the first racking. Final Brix measurements were taken using a high-accuracy (±0.1B) hydrometer. MLF completion was ascertained through both paper chromatography and enzymatic/UV-VIS analysis of malic acid; all wines measured less than 5 mg/L of residual malic acid. Measurements highlighted in yellow or red are potential points of concern and which need close attention.

2018 Russian River Chardonnay, Olivet Lane Vineyard

My desired style of Chardonnay here is for a softer but full-bodied wine with oak aromas and flavors with sur-lie aging to give it some extra mouthfeel and greater aging potential. So I fermented with a Lalvin Bourgoblanc CY3079 yeast followed by MLF with Lactoenos B7 (LF16) Direct bacteria. I had initially wanted concurrent AF and MLF but the AF had problems starting, therefore, I fermented slightly cooler and then re-inoculated at warmer temperature for MLF at the end of the AF. Yeast assimilable nitrogen (YAN) was 271 mg N/L, so no adjustment was necessary given the 22.2 Brix. Total days in AF and MLF were 15 and 43, respectively.

The AF completed perfectly to –2.1 B leaving less than 0.7 g/L (0.07%) of reducing sugars (RS). ABV as measured by ebulliometry is 12.5%, which is 0.7% lower than the expected ABV using my theoretical yield outlined previously. The lower ABV suggests that the yeast possibly metabolized sugars to a lesser extent into ethanol. 12.5% ABV is however ideal for this style of wine and for my palate.

I originally stated that some attention would be required with regards to total acidity (TA) as I had measured a low tartaric acid (H₂T) concentration, meaning that MLF could potentially bring TA to a very low level assuming that there was a considerably higher proportion of malic acid (I was not able to measure malic acid in the must). But everything worked out well with the final TA coming in at 5.84 g/L. What is interesting here is that both tartaric acid concentration and pH increased. That would seem odd until we look at potassium (K⁺) ion concentration, which also augmented, explaining the increase in pH. The most plausible explanation here is that potassium bitartrate (KHT) formed during the must freezing process ionized, which increased tartaric acid (as bitartrate) and K⁺. We can expect a small drop in TA following tartrate stabilization when the wine is ready for cold-crashing.

The data on tartaric acid, K⁺, ABV, and pH can also be used to calculate what is known as the Concentration Product (CP) and predict tartarte (cold) stability ahead of future tests (Zoecklein et al. 1999); here, the CP calculation predicts that tartrate stability fails.

Measurement of volatile acidity (VA) was well within the detection threshold of 600 mg/L; CY3079 is a low-VA producing yeast.

Dissolved oxygen (DO) was at a very low 43 μg/L with now just about 6 mg/L of free SO2. The drop in A₄₂₀ absorbance measurement indicates that any browning previously measured in the must is effectively gone. This means that the SO₂ (from KMS addition to the must) and GSH-containing OptiMUM White have done their job. GSH, or glutathione, is a strong antioxidant naturally occurring in grapes. I added potassium metabisulfite (KMS) to obtain 66 mg/L free SO₂; this is based on 0.8 mg/L molecular SO₂, pH, ethanol content and cellar temperature.

I added one carboy-sized WineStix oak stick to give the wine an oak profile. Given the small test volume, barrel aging was not an option. During aging, I will be stirring the lees occasionally to release more mannoproteins from the dead yeast cells to increase mouthfeel and aging potential.

All in all this is shaping up to be a great wine. The aromas and flavors are already quite attractive making it a game of patience now to let the wine age gracefully into something even bigger.

2018 Napa Valley Cabernet Sauvignon, Calistoga AVA

Here too I’m going for a full-bodied wine with oak aromas and flavors but without sur-lie aging choosing to experiment with exogenous tannins and mannoproteins to give it some extra mouthfeel and greater aging potential. I went with a sequential inoculation of Uvaferm BDX yeast and Lactoenos B7 (LF16) Direct bacteria after a drop of about 10 Brix. YAN was 155 mg N/L, so I bumped that up with a Thiazote pH addition to 250 mg N/L given the 23.0 Brix. I performed 3-4 punchdowns per day to extract maximum color and tannins. Total days in AF and MLF were 9 and 21, respectively.

The AF stopped at –0.6 Brix, which initially concerned me as the wine might not be completely dry and opening the possibility of microbial instability due to residual sugar; however, RS measured 2.86 g/L, which is below the industry-accepted threshold of 4 g/L for microbial stability but above my own threshold of 2 g/L. There is a risk given the high pH, but proper SO₂ management should keep things in check. I will re-evaluate this before bottling and decide whether “sterile” filtering is needed.

ABV measured 12.4%, only 0.4% lower than the expected ABV using my theoretical yield outlined previously. I had not adjusted the initial Brix thinking I would get close to my desired 13–13.5% ABV.

There was an increase in TA to just under 8 g/L; this is a little high for this style of wine but there is sufficient tartaric acid and K⁺ ions to get a drop in TA to under 7 g/L, maybe more. The expected drop in pH is due to the production of fermentation succinic acid and the drop in tartaric acid and K⁺ ions forming KHT. But the still-high K⁺ and pH will be an ongoing concern. The CP analysis predicts that the wine is tartrate unstable here too.

VA was measured to be well below the detection threshold, and so, there are no concerns here.

DO was at a very low 13 μg/L with little free SO₂ left. I added KMS to get approximately 120 mg/L of free SO₂ and 0.5 mg/L of molecular SO₂. This was the first KMS addition and, to account for quick binding, I doubled the amount needed (from 60 mg/L) at this high pH. For those who have attended my seminars will know that the idea here is to sulfite less frequently but with larger doses that will result in lower total SO₂ at bottling. It’s counterintuitive but that’s SO₂ chemistry for you.

Let’s look at color and tannin (phenol) numbers and interpret their meaning.

You’ll recall that absorbance (A) measured at 450, 520, and 620 nm are indicators of yellow/brown, red, and blue color, respectively, in red wines. A₅₂₀, i.e. the red component, should be as high as possible for deeply rich, dark reds, and this being a young wine, there will be some blue tones in the color as evidenced by the A₆₂₀ measurement; this will decrease over time as the wine ages. I had pointed out in my earlier blog that the must had a not-insignificant yellow component, which was due to polyphenol oxidation in the absence of SO₂, but that this should disappear with a small KMS addition. In fact, as expected, A₄₂₀ dropped substantially, causing a drop in color intensity (IC) as well as hue. What is interesting here is that there was essentially no change in A₅₂₀, meaning there was no further extraction of red color during maceration and fermentation. I was hoping to get the IC in the 8–12 range. The net result is that this Cab will have a lighter color than I would have liked though this was to be expected given the very high pH and K⁺, most likely due to a rainy season. On the upside, because of the drop in A₄₂₀ and A₆₂₀, brilliance of red jumped to over 50%, so that’s good.

TPI, or total phenol index, is an indicator of total phenol content. Post AF/MLF, TPI is just about 37, which means that, in the range 30–50, the wine is relatively full-bodied with a good structure. So we did well here extracting and adding tannins, which helps add body to the wine given the relatively lower ABV, although this will not be a turbo-charged Cab.

The A₂₈₀ measurement is an indicator of the wine’s astringency although more recent research demonstrated that A₂₃₀ measurement is a better indicator. I am monitoring these measurements over the life of the wine to see how bitterness and astringency evolve, and to associate tasting notes to the measurements. Right now, they are in the expected range for this wine.

At this stage the wine is (as expected) very closed in and characteristically young. Here too I added one carboy-sized WineStix oak stick to give wine an oak profile and increase complexity. Given the small test volume, barrel aging was not an option.

2018 Willamette Valley Pinot Noir, Chehalem Mountains AVA

My expectations for this Oregon Pinot Noir have been and remain very high as I am on a mission to make the best Pinot possible. It has been a challenge sourcing good Pinot fruit (or must) here. My initial analysis of must parameters indicated that this might just be that elusive Pinot I have been longing to make. The numbers looked just about perfect in every respect.

As with the Cab, my desired style here too is for an oak-influenced, full-bodied wine. I went with a sequential inoculation of Lalvin RC-212 yeast and Lactoenos B7 (LF16) Direct bacteria. YAN was at a low 99 mg N/L, so I bumped that up with a Thiazote pH addition to 250 mg N/L. I performed 3-4 punchdowns per day to extract maximum color and tannins. Total days in AF and MLF were 9 and 17, respectively.

ABV measured 13.3%, only 0.3% lower than the expected ABV using my theoretical yield outlined previously, but just perfect – for me – for this style of wine. RS is at 3.26 g/L, which, as with the Cab, I will need to evaluate how to manage at bottling, i.e. if sterile filtration will be required.

There was a fairly big jump in TA to about 7 g/L; again, a little high for this style of wine but a cold stabilization treatment should bring this back down just a tad and in perfect balance with tannins and sugars. VA came in at 658 mg/L, which is just over the detection threshold although I am not detecting any smell or taste of VA. I don’t know the cause of this at this point, but it’s definitely something I’ll need to watch closely.

Interestingly pH increased from 3.39 to 3.55 in spite of the relatively large jump in TA and tiny drop in K⁺, and so I need to investigate this to understand why this happened.

Here too the CP analysis predicts that the wine is tartrate unstable.

DO was at a very low 17 μg/L with little free SO₂ left. I added KMS to get approximately 60 mg/L of free SO₂ and 0.5 mg/L of molecular SO₂. This was the first KMS addition and, to account for quick binding, I doubled the amount needed (from 30 mg/L) at this high pH.

Looking at color and tannin (phenol) numbers, we see very comparable results to the Cab, which is excellent given that we are dealing with Pinot Noir here. As with the Cab, we see a drop in yellow- and blue-color components but with a small increase in IC due to the higher red component. Hue also dropped below the 0.8 threshold. So I was successful with this Pinot in extracting more color during maceration and fermentation. TPI and astringency numbers are exactly where I want them to be, so this is all good news. I’m definitely excited about this Pinot.

Although characteristically young, the wine is already evolving nicely exhibiting pleasant fruity aromas. I added one carboy-sized WineStix oak stick that should provide added complexity to what I believe will be an outstanding Pinot, the likes of commercial Oregon Pinot Noirs I have been enjoying.

Could this be that best Pinot I have been longing to make? Time will tell.

Stay tuned for further updates on how these wines are evolving during their graceful, slow aging.

Cheers,

Daniel

References

Ough, C.S. and M.A. Amerine. 1988. Methods for Analysis of Musts and Wines. 2nd. John Wiley & Sons, New York (NY).

Ribéreau-Gayon, P., Y. Glories, A. Maujean and D. Dubourdieu. 2012. Traité d’œnologie, Tome 2 – Chimie du vin. Stabilisation et traitements. 6e édition. Dunod, Paris.

Zoecklein, B.W., K.C. Fugelsang, B.H. Gump and F.S. Nury. 1999. Wine Analysis and Production. Aspen Publishers, Gaithersburg (MD).