David Coffaro Vineyard and Winery Winemaker's Diary

Week 50
December 12, 1999 to December 18, 1999 

Monday, December 13, 1999
(By Brendan)

I know that hundreds (and possibly thousands) of our diary readers have been waiting with baited breath for the results of our Brettanomyces (or, in wine lingo Bret) tests from our 1996 Estate Cuvee and Petite Sirah. The samples were submitted on the 29th of November and we got the results back on the 6th of December. Since I'm sure that almost all of our loyal diary reader have degrees in some for of micro-biology I'll give you the straight results. 

For the 1996 Estate Cuvee:

Culture for Brettanomyces: 
0.2 ml spread plate: 40 cfu/ml 
50 ml membrane-filtered: colonies too numerous to count 

Culture for Bacteria: 
0.2 ml spread plate: 320 cfu/ml Pediococcus 
50 ml membrane-filtered: colonies too numerous to count 

For the 1996 Petite Sirah

Culture for Brettanomyces: 
0.2 ml spread plate: 5 cfu/ml 
50 ml membrane-filtered: aprox. 150 colonies 

Culture for Bacteria: 
0.2 ml spread plate: lawn of Pediococcus 
50 ml membrane-filtered: confluent growth 

There are roughly four different levels of  growth (as far as I understand it). The first level is simply counting the number of colonies of bacteria there are on a given perti dish. The second level is "Colonies too numerous to count" which is usually somewhere around 150 or more (there is no absolute cut-off between being able to count and not count colonies). The next level is "Lawn" which is a consistent and solid layer of colonies with no empty space.  Finally, "Confluent Growth" is wall-to-wall growth with no differentiation of colonies. These levels are only as accurate as my understanding of the explanations given to me by people who are FAR more knowledgeable about these things then I am. 

Now you're probably sitting and thinking "Yeah, so what does this mean?  is 40 cfu/ml of Brettanomyces good? Is it bad?  (and, most importantly) How does this affect my wine?" The short answer is that there is no short answer. The longer answer is that the answer depends. Depends on what? Lots of things. For instance, the reading for the Bret on the Estate Cuvee is 40 cfu/ml using the 0.2 ml spread plate. Evidently, 40 cfu/ml is not that bad but not good. The bad part is that Brettanomyces can reproduce in bottled wine so what might be 40 cfu/ml today can end up as much more later. The potentially good part is that since Bret readings can evidently get into the thousands, 40 is pretty small. 

None of this really matters however because of the largest confounding element, multiple species. There are many different strains of Bret (and Pediococcus). Each of these strains has different characteristics. For some strains of Bret 40 cfu/ml is a lot and can effect the flavor of a wine. For other strains readings of 40,000 cfu/ml can leave the wine untainted. Which stains do we have ? We don't know. We have the option of sending the samples to a lab on the east coast who (for $105.00/sample) will separate the strains present. We probably won't do this unless it becomes an actual problem. 

Another simpler answer is to get a 4-Ethyl Phenol test run on the wines. "Of course!" you think, "The 4-Ethyl Phenol test, why didn't we think of it before?"  (or maybe you are thinking, "What in the heck is 4-Ethyl Phenol and why do I want to test for it?"). 4-Ethyl Phenol is a by-product of Bret that is used to impartially quantify the level of actual sensory contamination (i.e. how much can you smell/taste). In general, if you get a 4-Ethyl Phenol number that is less than 500 you are probably fine; From 500-1000 and you have a definite impact and higher, around 3,000, you get Chateau Lynch-Bages (a Bordeaux Grand Cru known for its' pronounced Bret). O.K. now you're thinking "Ah, ha! I understand, this makes sense, I know what the numbers mean!" Unfortunately, my response will have to be a resounding, unequivocal Sort-Of. 

This brings us to the final variable for consideration. Is Bret bad? Lets assume that we get to the point of known that a certain strain of Bret is in our wine and that it has a certain quantifiable effect on the smell/taste of the wine. Should we be unhappy about this? According to some people (and the Vinquiry scientists that run our tests) the answer is a definite yes. To others (myself and Dave included) it really varies from wine to wine and in some cases (i.e. Chateau Lynch-Bages or many Rhone wines) Bret can actually add a very nice level of complexity. So far our opinions of the 1996 Estate Cuvee and Petite Sirah fall into this category. We had the wines tested not because they were bad, but only because they were tasting slightly different that we expected. Whatever the impact of Bret on the wines, they taste wonderful as is.  In summary yes; No; Maybe; Sometimes; Sort-of and "only if you think so". 

Thursday, December 16, 1999

We just finished filtering 16 gals of Late Harvest Sauv Blanc. Hopefully that will stop it from fermenting. We plan on bottling only 150 Half Bottles probably in January. The alcohol is 12.5% and the sugar is 15.1%. 

Pat, Kate, Susie and I leave tomorrow for a vacation to Florida (Disney and a cruise). We will be back Dec 28 in time to cheer in the new year. We hope you all have a great xmas. 

Sincerely,   Dave   ([:-)):: 


Home | Read | Diary | Public Forum | Tell Us What You Think of Our Diary! | Last Week | Next Week