Further Commentary on High Alcohol Levels in Pinot Noir (Devil’s Spit)

High alcohol levels in Pinot Noir is clearly a contentious and polarizing topic. More readers of the PinotFile responded to my recent feature, “Tiptoeing Around the Perception of Alcoholic Warmth in Domestic Pinot Noir,” than any other article I have written in recent memory. Here are some of their comments summarized.

Scott Flora (proprietor and winemaker for Native Flora wines) wrote, “I liked your note on wine alcohols, as I hate to get above 14% ever. One point you touched on (Aussie strain), but didn’t really explore is the conversion factor for different yeast strains within the Saccharomyces family. Anecdotally, I’ve seen 24+º Brix ferments only reach 13.5% ABV, and still be dry. Sugars are being converted, but not to alcohol. I have also noted that the wild yeasts that we nearly always let run seem to produce a lower ABV than packaged strains and this is one of the reasons I like wild yeasts.”

Chris Clark writes, “Thanks for the article on alcohol. I’m not a supertaster either, but have observed the increase of alcohol over the years. I read the labels and it is difficult to find wines of modest alcohol. This was a worthy issue to put on the table.”

William Jones told me, “I greatly enjoyed your article about ‘hot’ Pinot Noir. As usual, you brought a reasoned tone to what is often a heated discussion (pun intended). What caught my attention was your connection between ripe to overripe grapes and Brettanomyces. Can you point me to some articles about that please?” I gave him two references: www.wineanorak.com/brettanomyces.html, and www.aromadictionary.com/articles/ brettanomyces_article.html. Jamie Goode (The Science of Wine) remarks, “A vital risk factor for Brettanomyces is the presence of residual sugars and nitrogen sources left over at the end of fermentation. With the gradual rise in alcohol levels over the last 20 years, the yeast commonly isn’t metabolizing the last bit of sugar....A winemaker who is serious about managing Brettanomyces should work their vineyards to get fruit maturity at lower levels of alcohol.”

Thomas Hughes said, “Your story about alcoholic warmth in Pinot was quite timely for me. I recently tasted two Pinot Noirs with some friends. The 2011 Kutch Savoy Vineyard Pinot Noir was very good, but I could taste a little heat on the after finish. I noticed I wasn’t the only one. The 2011 Littorai Savoy Vineyard Pinot Noir was tasted side-by-side and it was very similar, but finished without the heat. Our group of tasters liked it better. That caused us to check alcohol levels: the Kutch wine was 12.9% and the Littorai wine was 13.0%.”

Adam Lee, the winemaker at Siduri Wines, who appreciated the opportunity to respond to my article, had a number of issues with my article so I chose to publish his extensive comments and my responses.

1. “I did fully agree with what I believe to be is the basic takeaway from the article, namely, your comment, ‘....the absolute ABV is not as important to the taster as the sensory experience. It matters little that a wine is 13.0% ABV or 14.9% ABV if the wine is perceived as hot.’ Certainly, as a wine reviewer, communicating that sensory experience to the reader is incredibly important. What does confuse me a bit, is how you go forward from that point to address almost exclusively the ABV of the wines you have reviewed over the years. Rather than share with us the actual ABV of the wines that you have reviewed, why not share the number of wines that you have downgraded due to perceived heat? Perhaps even correlate that to the reported alcohol levels and/or classify them by regions. Given your statement that it matters little what the ABV is, this information would seem far more useful to the reader.”

Answer: Your request for more information is understandable but unreasonable. I would have to go back through thousands of tasting notes to find ones that contained a comment about alcoholic warmth or heat to determine which wines were downgraded as a result and then correlate with the reported ABV. I can tell you with great assurance that the vast majority of wines I have downgraded because of perceived alcoholic heat have had a labelled ABV above 14.5%. I should have included this statement in the article. That is not to say a wine with higher alcohol cannot be balanced. I had a 2013 Aubert Ritchie Chardonnay this week that was 15.1% ABV on label and was impeccably balanced with absolutely no sense of alcoholic warmth.

2. “You mention, ‘riper grapes have lower acidity and higher pH levels.’ While that is almost always true within the same section of the same vineyard, it is not true from vineyard to vineyard, or region to region. Within the same vineyard, one clone or one section may have higher acidity and lower pH levels at higher Brix than another clone. This happens all the time.”

Answer: Your point is well taken. It is obviously a generalization but one that often holds true, especially with high ºBrix levels.

3. “The study that you cite, ‘What Can the Brain Teach Us About Winemaking? An fMRI Study of Alcohol Level Preferences’ is fascinating but particularly limited. The subjects of the study were Spanish citizens and the wines used for the study were not Pinot Noir. Citing it ignores significant differences in national and cultural reaction to alcohol levels as well as the differing interplay between alcohol and grape type.”

Answer: This is a well-cited article in a respected peer reviewed journal. Although the wines were not Pinot Noir, they were red and were closely matched for all physical attributes except for alcohol content. This study only begins to explore the complex relationship between a wine’s characteristics and the consumers’ gustatory and neural responses, and obviously more study needs to be undertaken. I am simply trying to make the reader aware of this study that had intriguing results.

Ethanol makes aroma compounds more reticent to leave solution. A 2000 analytic chemistry study by Whiton and Zoecklein showed that as alcohol rose from 11% to 14%, there was a reduced recovery of the typical wine volatile compounds.

4. “You write, ‘The higher the alcohol, the less chance the wine will be balanced.’ Not only does that statement seem to somewhat contradict your earlier statement that it matters little what the ABV is, but it seems unduly broad. Do you really believe that a 13% alcohol Pinot Noir is less likely to be balanced than a 12.5% alcohol Pinot Noir. Is there no such thing as an unbalanced Pinot Noir because of too little alcohol?”

Answer: I still stand by my statement that the higher the alcohol, the less chance the wine will be balanced and does not contradict my statement that lower alcohol wines can also be unbalanced. However, that former statement may be a bit broad as you point out. Perhaps, I should have stated, “Once the alcohol reaches a significantly high level, say 14.5% and above, there is less chance the wine will be judged as balanced because of alcohol perception.” And yes, a Pinot Noir with too little alcohol can be unbalanced, but not usually because of alcohol perception.

5. “You write, ‘Higher alcohol wines imply advanced ripeness of grapes at harvest, and this increases the risk of Brettanomyces and bacterial-induced volatile acidity (VA) during vinification.’ A fascinating comment but not one that I have seen much correlating proof for. The range of alcohol levels you cite from your tastings is from 14.7% down to 13.4%. If you have it, I’d love to see a study that shows an increase in Brettanomyces or VA as that range increases. The sources of Brettanomyces in a winery and consequently in a wine are numerous but I don’t believe I would point towards alcohol as the leading cause, but rather winery cleanliness. I might also look towards fruit condition and winemaking decisions as sources of VA levels.”

Answer: Refer to the references on Brettanomyces above as justification for my statement. Low grape acidity and higher sugars create a milieu that can predispose to microbial contamination, but are not the major causes of Brettanomyces and VA as you point out.

6. “You cite some unusual conversion ratios of sugar into alcohol in your article. Can you tell us where you got these numbers? Doing the quick math those conversion ratios range from .563 to .585. You later go onto to write, ‘Since sugar converts directly to alcohol, this (an increase in Brix levels) indicates a corresponding 9 percent increase in the average alcohol content of wine occurred.’ And yet, from your numbers earlier, the changes in conversion ratios indicate that sugars don’t convert directly into alcohol. What gives?”

Answer: The sugar to alcohol potential strength was obtained from the following chart. The chart relates the three principal systems for measuring the sugar content of grapes (German, French and American) to each other, to specific gravity, and the potential alcohol of the wine if all the sugar is fermented. The chart was in my files and taken from a reference book, but I have misplaced the exact source.

ºBrix to alcohol conversion is as follows as you know: for every gram of sugar that is converted during fermentation, about half a gram of alcohol is produced. The alcohol conversion factor can be between 0.55 to 0.64, so the conversion factors in this chart are reasonable.

I was simply trying to give the reader some idea of how ºBrix relates to potential alcohol and not meant to imply these conversions are absolute. Perhaps I should have given estimated conversion ranges rather than exact predictions. Actual conversion ratios are subject to variability depending on yeast properties and fermentation conditions, so the final alcohol may be higher or lower than the estimate. In addition, more accurate conversion ranges can be determined using glucose plus fructose (potential alcohol = glucose + fructose g/L / 16.83) rather than ºBrix, but this leads to a rather technical discussion unsuitable for much of my readership that is simply trying to relate ºBrix, a term they are familiar with as an indicator for maturity of the grape, to final alcohol (ethanol) percentage.

Referencing the cited article in the Journal of Wine Economics, I was quoting the authors who stated, “Since sugar converts essentially directly to alcohol, a 9 percent increase in the average sugar content of wine grapes implies a corresponding 9 percent increase in the average alcohol content of wine (over 28 years).” The authors are making a general assumption which is fair enough in the context of their discussion, although strictly speaking, as you point out, conversion ratios vary with different levels of ºBrix. There have been a number of reputable reports showing a parallel escalation of alcohol content of wine and increase in average sugar content of wine grapes. One of these studies in California showed that the average alcohol levels in wine rose from 12.7% in 1971 to 14.8% in 2001 (an increase of 16.5%), as the average level of ºBrix at harvest rose from 20.5 in 1971 to 24.2 in 2001 (an increase of 18%).

7. “You mention the Australian Wine Research Institute study showing that some yeast strains are capable of preserving flavor of fine wine at lower alcohol levels. While that research is fascinating, it has thus far only been successful in the laboratory and only after the juice has been treated to remove all microbes. In other words, it is incredibly preliminary and thus far not practical in the real world.”

Answer: I agree with your comments. However, it is well known that different strains of currently used yeast have different levels of attenuation, so they will all convert different percentages of sugar to alcohol. No reason to think that at some point yeasts will potentially be isolated and commercially used that preserve flavor at lower alcohol levels (see also Scott Flora’s comment above).

8. "You write, When data from the Liquor Control Board of Ontario was examined, it was found that label claims systematically understated the alcohol content of California wine and this was thought to result from a perception that higher alcohol content diminishes the consumer value of certain wines. That’s a pretty biased report of this study.”

Answer: The authors of the article in the Journal of Wine Economics were only expressing an opinion, “was thought to result from,” although it could be interpreted as bias. That said, can you give my a better reason why label claims systematically understated the alcohol content of California wine? Why do a number of Pinot Noir producers put 14.1% ABV on the labels of practically every one of their wines when it is highly unlikely every wine was bottled at 14.1% ABV? Is it simply they just don’t want to be bothered getting it right?

9. “Lastly, you mention that the Santa Lucia Highlands is a ‘warmer Pinot Noir growing region.” I’d encourage your readers to look at the following study on the region, which shows fewer Heat Summation Degree days in the Santa Lucia Highlands than in the Russian River Valley or the Sta. Rita Hills and roughly in line with the Santa Maria Valley: www.santaluciahighlands.com/wp-content/uploads/pdf/SLH%20Climate.pdf.”

Answer: I said, “The Russian River Valley and Santa Lucia Highlands, both warmer Pinot Noir growing regions......” That should have been qualified by noting “in comparison to some of the other regions I studied such as Santa Cruz Mountains and Marin County.”

In the report by viticulturist Mark Greenspan that you (Adam) encourage readers to look at, I would point out that Heat Summation Degree Days is not the only relevant climate temperature data influencing ripeness at harvest. Greenspan points out the importance of maxima/minima, extremes and diurnal temperatures as well. If you look at high/low temperatures during ripening, Santa Lucia Highlands has the highest average minimum temperature of every region studied and is second only to the Russian River Valley in average daily temperature maximum during September. This is important since the last month is most critical for ripening. On the other hand, the Santa Lucia Highlands shows the lowest average diurnal temperature curve during ripening (18ºF) compared to Russian River Valley (33ºF), Sta. Rita Hills (26ºF) and Santa Maria Valley (25ºF), which means cool, not cold night temperatures. Jeff Pisoni of Pisoni Vineyards in the Santa Lucia Highlands chimed in with some relevant comments on the Santa Lucia Highlands climate. He also was alerted by my mention that Santa Lucia Highlands is one of the warmer growing climates in my alcohol study. He believes, “The higher average alcohol level in the Santa Lucia Highlands is due to the growing season being longer (starts early). This puts harvest decisions in the hands of the winemaker, who can choose to pick later. For example, we are normally the very first winery to harvest from our Pisoni Vineyard, with others waiting another couple of weeks after us.”

I admit that climate is only one factor in interpreting my data, and broad statements like “Santa Lucia Highlands is one of the warmer growing climates” serves no verifiable purpose.

As John Haeger points out in his reference book, North American Pinot Noir, “It is surprisingly difficult to collect genuinely comparable data about the main regions in which North America’s Pinot Noir is grown.” In his excellent discussion of climate data of Pinot Noir growing regions, he fails to mention the Santa Lucia Highlands specifically. A comprehensive and comparable climate study on the various domestic Pinot Noir growing regions would be valuable, but would be a monumental and complex undertaking.

It could be argued ad nauseam which Pinot Noir growing regions are the “coolest.” What I was attempting to reveal in my study was the average ABV by vintage of 9 California major Pinot Noir growing regions for the wines I tasted. For whatever reason, be it climate, length of growing season, timing of harvest, soils, vine age, predominant clones, or undoubtedly a myriad of other factors, the data still indicates that in every vintage studied, the average ABV was highest in Pinot Noir from the Santa Lucia Highlands.