Five Myths of Winemaking

RE: Five Myths of Winemaking

Fred Swan — Fri, 11 Aug 2017 20:41:19 GMT

Hi Eric, Thank you for the kind words. I'm glad you enjoyed the article.

There are many variables that can effect the amount of diacetyl produced by MLF, even beyond those I mentioned in the article. They include the speed and temperature of MLF, lees stirring during MLF, the amount of bacteria added during inoculation for MLF (more bacteria results in lower diacetyl), the particular strain used, longer lees contact, etc. As far as timing goes, doing MLF more or less at the same time as alcoholic fermentation tends to produce less diacetyl as well. That would be counter to the theory you were given recently.

However, if the fermentations are both non-inoculated, it's possible both are occurring simultaneously and both finish late. That, along with the extended lees/bacteria contact that suggests could result in less diacetyl. The downside is that slow fermentations (and the associated delay in applying SO2) present considerable risk of contamination. And any benefits in lower diacetyl due to simultaneity and extended contact might be be balanced out by higher diacetyl production due to slow, low temperature MLF.

In short, it's an interesting theory but I suspect any correlation between the timing you suggest and the results are most likely coincidental rather than causative.

RE: Five Myths of Winemaking

Eric Entrikin — Fri, 11 Aug 2017 01:35:04 GMT

Hi Fred, late actually getting to read this fantastic article. Hoping to see more. I was recently told that diacetyl production levels were more pronounced if the MLF occurred relatively close to the primary fermentation and this was the reason why you saw more of the character in warmer climate Chardonnay as opposed to Burgundy as the malos there typically occur in spring following harvest. It would seem to follow in with your explanation but does the timing have really anything to do with it? I think sometimes we get a piece of information and if it seems logical it becomes a fact when in truth it is only a piece of the overall picture.

Thanks again for the great article!

RE: Five Myths of Winemaking

Fred Swan — Tue, 11 Jul 2017 15:52:41 GMT

Big "thank you" everyone for the comments and support. Stephen, thank you for discussing your experiences as well. That's great info.

RE: Five Myths of Winemaking

Evan Hufford — Tue, 11 Jul 2017 07:08:08 GMT

Fred this is such a great article, thank you for writing this. Definitely gave me more to think about when asking winemakers about their practices.

RE: Five Myths of Winemaking

Kelli White — Thu, 06 Jul 2017 15:49:16 GMT

A terrific article, Fred! Great information, I learned a lot!

RE: Five Myths of Winemaking

Mark Shipway — Wed, 05 Jul 2017 21:53:28 GMT

This is a great piece for Somms to read as it highlights, amongst other things, that the understanding of and skill in utilising the various techniques in wine production is the ultimate factor in determining wine style and in particular, quality. The human involvement is so often overlooked but the experience of the producer of handling a specific variety or varieties in winery and vineyard as well their knowledge of site is what counts most.

RE: Five Myths of Winemaking

Steven Washuta — Mon, 03 Jul 2017 21:02:08 GMT

It's great to see some more technical stuff here! I really enjoy the discussion on Diacetyl and it's something I think about a lot in wine. Since you mentioned that temperature, pH, and the timing of sulfur additions play a role in the diacetyl level in a finished wine, it makes sense when you put it all together why a stereotypical Cali chard is so different than a Puligny.

From my experience making high quality, small production wines in the USA; most wines, red and white, are pressed into barrel after primary and put into a warmer room where they are inoculated with ML bacteria (oenococcus oeni - my favorite bacteria name). The warmer temp helps MLF proceed quickly and usually finish before the end of the year. Once the test shows no malic the wines are sulfured and then the winemaker can consider the wine "safe" as before that sulfur addition it's more vulnerable to brett or bad bacteria. So the combo of warmer falls and riper grapes coming in at a higher pH, warmer MLF temperatures, and quick sulfur adds leave a wine with diacetyl above threshold. I notice this a ton in highly produced new world wines, red and white, and for me it distracts from the true character of a wine. MLF dynamics are as important in the finished wine as primary fermentation and it's often overlooked as just something that is a necessity to making stable wine and all that matters is that it's done, but how it's done is the key.

RE: Five Myths of Winemaking

Eric Crane — Mon, 03 Jul 2017 15:52:21 GMT

Thank you so much for this.

RE: Five Myths of Winemaking

Ole Thompson — Sat, 01 Jul 2017 01:13:14 GMT

Incredibly informative. Thank you Fred, I'd love to see more articles along these lines.

RE: Five Myths of Winemaking

Dan Pilkey — Fri, 30 Jun 2017 14:33:56 GMT

Fantastic read! Thank you Fred

RE: Five Myths of Winemaking

Christopher Tanghe — Thu, 29 Jun 2017 04:23:30 GMT

Excellent article. I especially appreciated the section on diacetyl and the explanation of pH's effect on diacetyl levels. This clearly defines the variance in Chardonnay from different climates or picked at different dates and ripeness conditions. One note regarding whole cluster is that it can also have an influence on pH and change the texture as well as the perception of other structural elements. Thanks for the awesome info!

RE: Five Myths of Winemaking

Admin — Wed, 28 Jun 2017 20:58:14 GMT

Great stuff. When you are new to wine there is a tendency to equate specific techniques with good or bad or assume a deterministic result just based on one factor. The more I learn about wine, the more I find the answer is "it depends."