Archive for June, 2005

Enology: wood oxygenation.

Monday, June 27th, 2005

While continuing my investigation into current reports regarding oak and wine I was sidetracked by oxygen diffusion through barrels and microoxygenation. It is difficult to read something about oak in winemaking that does not say that one of principal benefits of oak is slow oxygen diffusion through the staves. I recall some objection to this from Boulton, and vaguely remember reading in the Ven126 reader evidence that suggest diffusion is limited if not nonexistent. If diffusion occurs, why does a vacuum form during expansion and contraction of the wine?

Here is an article from The Australian & New Zealand Grapegrower & Winemaker that is one of the best summaries I have been able to find relating to this issue. Although their citations are limited, they suggest that at most 2.5 ml/litre/month are diffused through the barrel and that this will significantly decline as the barrel becomes ‘winelogged.’ Significant decline? Does that mean after a few months the main oxygen input is from topping? How many times are people racking (I know this depends on the variety)? If diffusion significantly declines, it may become negligible in comparison to the 4ml/litre/racking. Frankly, I don’t really care if oxygen is or is not moving through the staves, as somewhat of a literalist though, I just don’t want to contniue to perpetuate a myth if that’s what it is. I hate saying something because that’s what everybody says, I want to know.

Here is an additional article on micro-oxygenation. Notice the differences (or should I say similarities)between micro-ox and barrel. I don’t have any personal experience with this, does anybody else? If the numbers are true, it is an effective way to improve wine at a lower price point, no? Lastly, the author takes for granted condensation reactions facilitated by acetaldehyde. Did not Boulton’s also reject this hypothesis?


Sunday, June 26th, 2005

Summary: 1)eucalyptus aroma is produced by at least one grape variety.
2) a common monoterpene found in grapes is a precursor to eucalyptol, indicating that this aroma could be an indication of age in certain wines.

What is the liklihood that eucalyptus trees near your vineyard are going to impart eucalyptus aroma to your wine? Certainly it is not difficult to smell eucalyptus when several trees are around and it seems logical that if you can smell it in the air than the volatile compound could potentially settle on grape skins. Fair enough? As far as I can find, no study has been published demonstrating that this occurs at levels which would impact wine aroma, thus bolstering opinions in either camp. But not finding something to be true does not make it false and vice versa. One recent study (published in In Proceedings of the VIIe`me Symposium International d’OEnologie. Actualites OEnologiques 2003. Bordeaux, Francia, 2003; i.e. limited peer review, cited from study below) found Eucalyptol in wines from vineyards surrounded by Eucalyptus sp. trees, though it was not shown that the aroma came directly from the trees.

Before cutting down some of these beautiful giants, look at this recent study that demonstrates the production of eucalyptol (1,8-cineole, threshold of about 2 ppb) in Tannat grapes. Furthermore it was shown that limonene (an apparently common grape monoterpene giving citrus - orange, grapefruit, lemon - aromas and used in bergamont) can undergo reaarangement in acidic media to form eucalytol (slow reaction, white wine pH). Of course this doesn’t mean that the aroma cannot come from trees, but it does mean if your wine smells of eucalytpus, it could have come from the grape itself.

Naturally this begs the questions: how does our viticulture impact the formation of this compound? The aforementioned study shows its concomittant increase with sugar after veraison. Light can increase monoterpenes in general suggesting this may also increase eucalyptol or at least its potential to form after ageing. We’ll just have to wait. Finally, I will note that Tannat wines are purportedly well known for this characteristic and I was unable to find reports on the amount of eucalyptol or limonene in other varieties.

Enology Practice: More methoxy

Friday, June 24th, 2005

Ahhh, that beloved methoxy pyrazine. I have been interested in finding studies that follow its changes and responses to winemaking conditions/practices. Thus far success has eluded me as I have been limited to pdfs downlaodable from the web. This article pertains more to the impact of trellis system and sunlight exposure, but they did make small replicate batches of wine while monitoring 3 different methoxy pyrazines. Besides, the viticulture aspect of this report is suspect and the influence of sun on methoxy levels are well documented. The most interesting observation is that IBMP (isobutyl form) levels increase above that measured in the berry within a day or two of being crushed. I have observed increases in bell pepper aromas with Cab. and Merlot after a day or two in tank as well. Two studies were cited in corrboration that I am trying to obtain. The authors hypothesize that as skins and perhaps stems are crushed, levels will increase. Apparently IBMP from seeds, skins, and stems have been shown to pass into the juice. This is not a new idea but hitherto had only been heresay. Perhaps this is additional rationale for good fruit sorting to remove leaves, stems, and ‘jacks’ from your ferment. Anybody heard any ideas for volatilizing off pyrazines to reduce their level in wines?

Vit Practices: Color and Cab.

Friday, June 24th, 2005

Here is the bottom line on this fairly well done study: Increasing your hang time will impact your color. However, there was no difference between 1 and 2 weeks after ‘normal’ harvest dates. Although the authors try to sell this as a study about ‘wine quality’, no sensory work was performed and they really only looked at color. Nevertheless, slightly riper grapes seemed to have a little better color stability after 18 months. Reading this article after another recent gem on light and color highlights the possiblity that looking at total phenols, or phenols in general is largely deficient in determining quaility (an opinion I am developing). The grapes used here may have had more color later, but what about vegetal, peppery, or fruity flavors? Was there a difference at all in characteristics such as these? It seems to me most of us would take the diminshed color at ripening stage 1 (about 22.5 Brix) and subsequent lower alcohol if we were confident the flavors were delectable and weren’t going to get any better. But do they get better? Or just stylistically differnt? If you want a summary of study details see below.

Perez-Magarino, S et. al: J. Agric. Food Chem. 2004, 52, 1181-1189
Tinto Fino (TF) and Cabernet Sauvignon (CS) were used to assess the effect of the degree of grape ripening primarily on wine color. Color changes durig ageing of each treatment was also examined. The levels of flavanols, anthocyanins, and derivatives of both types of compounds, were assayed immediately after fermentation and at different times during aging in American oak barrels and in the bottle.
The ripening stages were approximately as follows:
1)conventional’ 22.5 Brix, pH 3.36, TA 7.76 (CS) ; 2) 1 week after (23.6 Brix); and 3) 2 weeks after (~24.2).

Fermentation between 25 and 28 °C with 40mg/L SO2. The maceration time was ~ 14 days. Pressed at ~ <3 g/L sugar, transferred into barrels where malolactic fermentation and wood aging were carried out.

The results showed that “maturity date” or “ripening stages” effects were detected, but these are different for each individual component as well as for each of the two grape varieties studied.

In general, the dimer and trimer flavan-3-ol derivatives reached higher levels in the unaged wine made from the grapes collected on the later harvest dates which indicated that the degree of flavanol polymerization increased with the degree of grape ripening. However, this was only true in the CS. The TF had its peak in the middle ripening stage. There seemed to be only small differences between ripening stage 2 and 3, and certain compounds were even statistically higher in stage 2 than in stage 3. No difference in total phenols existed between stages 2) and 3).

WINE AGEING: “No clear trends with grape ripening were observed. In fact, the CS wines with the highest color intensity values were the wines made from the grapes collected on the 2nd harvest date.” The wines made from more mature grapes had higher levels of flavanols and their derivatives. The free anthocyanin content decreased sharply during aging, the greatest losses taking place in the first months of aging. After 18 months of ageing, any initial differences in anthocyanins and its derivatives (termed ‘new pigments’) due to ripening stage were virtually erased. However, color intensity differences were maintained after 18 months and in all cases the percentage of blue increased as ‘new pigments’ increased (i.e. anthocyanin products that are not antho-tannin complexes). Wines made from ripening 2) & 3) showed higher levels in these ‘new pigments’, in both TF and CS wines.

Summarizing: delaying harvest date between 1 and 2 weeks produced grapes with greater color intensity and a higher percentage of blue pigment. This increase in anthocyanin derivative levels contributes to color stability by maintaining color intensity and increasing the blue component.

Additionally, the results showed that the amount of time the grapes are left on the vines may need to be limited, because wines made from the grapes collected on the 3rd harvest date did exhibit better color quality characteristics than the wines made from the grapes collected on the 2nd harvest date.

Tasting: Weingut Assman

Thursday, June 23rd, 2005

Yes, its Assman, except that the double ’s’ is really a charater I don’t have on my keyboard.

2003 Riesling, Spatlese, Geisenheim Klauserweg: Showing a surprising amount of age (petrol, honey) for being so young. Unfortunately the petrol never really blew off and was perceieved by mouth as well. This seemed to depress the freshness of the citrus and floral aromas and flavors by mouth though the honey lemon aroma accompanying the petrol wasn’t entirely unpleasant. The wine was slightly sweet up front but turned a little sour on the finish. If I was tasting with a German, I suspect they would suggest that the sourness (which was biting) at the end means that they probably added tartaric acid, which winemakers could do only in the very warm 2003 vintage. Overall it was simply okay. I have had much better Rieslings thus far.

2003 Saptburgunder (Pinot noir), Rheigau: If you like popcorn butter poured over fried banana chips and strawberries than this is a wine for you! Additionally, a little RS gave a sickly sweet impression and I wasn’t sure if I was drinking children’s cough syrup or some weird movie theatre concoction. On a more positive note, the oak was nicely done.

Tight Grain Oak

Thursday, June 23rd, 2005

I have recenlty been reading current literature on oak in winemaking. From a number of studies, it seems clear to me that there is no correlation between the ‘tightness’ of the grain and any chemicals derived from the oak and imparted to wine. If anything, species seems to be the most imporant factor (if seasoning and toasting is the same). The American Journal of Enology and Viticulture 50(4) 1999 presents several articles from an international symposium on oak in winemaking. Even if there is no correlation between grain and flavor compounds, some may argue that there is a yet uncharacterised benefit to having smaller grain. However a study in this issue of AJEV compared wines aged in oak made from single trees (i.e. different grain size) and found no correlation. Most variation in wine descriptors was attributed to the cis oak lactone. But if we can’t use grain size, how do we know what is the best barrel for our wines. I think more must be done to establish how differences in oak derived compounds impact wine sensoy description, until then I think it must be obtained by trial and error, i.e. experience, no?

Tasting: Ryan’s tasting notes?

Wednesday, June 22nd, 2005

I recently read an excellent review of Lustau ‘Los Arcos’ Armarillo dry Sherry. I am not drawing attention to the wine. This blogger/writer writes a creative review that can be appreciated by those of us (which I think is most of us) who desire not to simply use winespeak devoid of meaning but understand that certain descriptors are somtimes unavoidable. Enjoy!

Vit. Practices: Colorado

Wednesday, June 22nd, 2005

Of course, as soon as I suggest a title format, I find something that is hard to fit under one of our headings. Nevertheless, this pdf is mainly a viticulture survey of Colorado’s plantings and varietal selection. This is a nod to my buddy Rob who makes wine at Two Rivers Winery in Grand Junction and our alma mater conducted the survey. I just thought it may be interesting to see what is going on there. An ‘up and coming’ region (which these days - no offense Rob - seems to be any region that is not CA). Its pretty easy to breeze through the figures and get a general idea of what’s going on, for curiosity’s sake. Here is some other info on CO wine:


Saturday, June 18th, 2005

Uh, I don’t know, I don’t know. Um, it’s a hard grape to grow, as you know. Right? It’s uh, it’s thin-skinned, temperamental, ripens early. It’s, you know, it’s not a survivor like Cabernet, which can just grow anywhere and uh, thrive even when it’s neglected. No, Pinot needs constant care and attention. You know? And in fact it can only grow in these really specific, little, tucked away corners of the world. And, and only the most patient and nurturing of growers can do it, really. Only somebody who really takes the time to understand Pinot’s potential can then coax it into its fullest expression. Then, I mean, oh its flavors, they’re just the most haunting and brilliant and thrilling and subtle and… ancient on the planet.
— Miles Raymond in Sideways


Saturday, June 18th, 2005

We have been here in Germany for several weeks now and have almost exclusively been imbibing on Riesling. This is largely due to the lack of decent reds and the availability (in the Rheingau) of other white varietals. That said, the Riesling has been fantastic, and inexpensive. We recently tasted several wines from Weingut Sohns. The owner/viticulturist/winemaker and his wife took us through several of there Rieslings, and one Pinot noir. Their basic Riesling (which was about 3.50 Euro) was an excellent limey dry quaffer. It was nice to taste this next to the QmP wines: Kabinette and Spatlese. The QmP wines were noticeably more complex and the fruit intensity was higher, particularly in the mid-palate. Tasting the 2004 riesling kabinette after the basic wine I realized how much flavor was missing in the mouth of the basic Riesling, in addition to length on the finish. The QmP wines were like chewing on fresh peaches and grapefruits, whereas the basic wine was like drinking a tart slightly lime flavored drink. This should not steer one away from the basic wine, but it is probably appropirately a warm summer quaffer in late afternoon, with a pretzel or fruit, not a full meal. Incidentally, the Pinot was full of strawberries in the nose, but had an oaky and slightly out of balance mouth.