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As I started to think about how I would organize this blog I came to the realization that there really should be a fourth category – the “maybe good, maybe bad, maybe innocuous”, with a large aside on the pros and cons of inoculating with pure yeast strains. 

The list of species that can grow in grape juice is quite small, and even fewer can grow in wine.  The low pH and high sugar and/or alcohol levels make for a very hostile environment.  No pathogenic or toxin producing microbes can grow or even survive in wine, which led Louis Pasteur to declare wine the most hygienic of all beverages.  Only two species, Saccharomyces cerevisiae (wine yeast) and Oenococcus oeni (malolactic bacteria), are widely accepted as “good” wine microbes.  Even malolactic bacteria are considered spoilage organisms if malolactic fermentation (MLF) isn't desired...

Saccharomyces cerevisiae is widely distributed in nature, and thousands of different strains have been identified.  It is responsible for most leavened bread and virtually all beer, wine and other alcoholic beverage fermentations.  Whether you add one of scores of available pure yeast strains or just let nature take its course, it is wine yeast that are responsible for alcoholic fermentation.  Commercially available wine yeast strains are not bioengineered “Frankenyeasts”, they are merely yeasts that have been isolated from successful fermentations.  Often they are named for their origin (e.g. Bordeaux Red, Montrachet).

Quite a few artisanal wineries and even some large producers do not use commercial yeast strains (or at least not intentionally).  Some confusion has been created by the terminology used to describe this practice.  We read or hear terms like wild yeast, native yeast, vineyard yeast, indigenous yeast, etc., with pure yeast strains referred to as commercial or industrial yeast.  “Wild yeast” refers to non-Saccharomyces genera, and really shouldn't be used to describe wine yeast of unknown origin.  Although wine yeasts have been found on grapes in vineyards, they don't seem to be abundant enough to be consistently responsible for wine fermentations; apparently the main source of incidental wine yeast inoculation is the winery itself.  Brand new facilities have experienced difficulty getting uninoculated grapes to ferment.  A few years ago, someone (Clark Smith, perhaps) published a brief discussion of how best to describe “natural” fermentations, and came to the conclusion that “not intentionally inoculated” was most accurate.

Oenococcus oeni (the bacterium formerly known as Leuconostoc oenos) is the preferred species for performing malolactic fermentation, a process that converts malic acid to lactic acid.  This reduces acidity (lactic acid is a weaker acid than malic), and, more importantly, stabilizes the wine against unwanted ml fermentation in bottle.  ML fermentation in bottle is undesirable because it also produces  CO2 and aromas reminiscent of cheese or sauerkraut. 

Wild yeasts such as Hansenula, Kloeckera, and non-cerevisiae species of Saccharomyces fall into the maybe good, maybe bad category.  In grape must that is not inoculated with a wine yeast culture (and particularly in unsulfited must), wild yeasts often initiate fermentation.  Almost all these species have low alcohol tolerance and are soon overwhelmed by wine yeast, which finish the fermentation.  All yeasts produce “secondary” metabolites other than alcohol and CO2.  Proponents of “natural” fermentation contend that the secondary metabolites produced by wild yeasts are important aspects of wine quality and regional character.  Others believe that the potential benefits of natural fermentation are minor, disappear during aging, and are outweighed by the risks.  The biggest risks of encouraging wild yeast are increased volatile acidity (VA – vinegar), stuck fermentations and unpredictability.  A supporter of the use of pure yeast strains once asked, “You wouldn't make wine from randomly harvested grape varieties, so why would you use randomly selected yeast?” A few years ago one of the yeast companies introduced a couple of mixed wild yeast / wine yeast cultures for wine; they didn't catch on.  There is debate as to how much of the observed differences in natural fermentations are attributable to wild yeast versus different population dynamics of the wine yeast.  Some winemakers try to replicate natural fermentations by “micro-inoculating” with pure strain wine yeast.

In addition to wild yeast, a number of mold species can grow on unfermented grapes.  These are  generally only a problem if the incoming grapes have rot and are not treated with sulfites. 

Most of the bad guys in winemaking are bacteria.  Lactic acid bacteria other than Oenococcus are the most frequent cause of problems during fermentation.  They can multiply faster than wine yeast, gobbling up nutrients the yeast need and releasing acetic acid, which is toxic to yeast.  This can result in a stuck fermentation and elevated VA.  One particularly virulent species that emerged in the 1990's was named Lactobacillus kunkei in “honor” of the esteemed UC Davis wine microbiologist, Ralph Kunkee.  Sulfite addition at crush is usually sufficient to suppress lactic acid bacteria, but some wineries use lysozyme, a natural antibiotic found in tears and saliva and isolated commercially from egg whites.

Acetobacter sp. (vinegar bacteria) can also produce large amounts of VA quickly.  They need oxygen, so they can be controlled by protecting wine from air.  During active fermentation CO2 displaces air from fermenters; after fermentation, tanks and barrels must be kept “topped up” or blanketed with an inert gas such as CO2 or argon.

There are some incidental microbes that don't grow in wine but have caused severe headaches for wineries.  Foremost amongst these are the molds that produce trichloroanisoles and tribromoanisoles.  These are the compounds responsible for cork taint and, even worse, “cellar taint”.  They can grow in wooden tanks and barrels, wine hoses, drains, and even posts and beams.  Use of chlorine bleach sanitizers, once common in the wine industry, has become a big no-no, as these can provide substrate for the formation of TCAs. 

Finally, the truly ugly, many winemakers' greatest fear: Brettanomyces (“Brett”).  My comments here will be limited; if you want more in depth information, a Google search will yield thousands of references.  Brett is hard to detect, can produce compounds that smell and taste awful, and can grow even in bottled dry wine.  Historically, the aromas imparted by Brett were accepted as part of the regional character of Bordeaux and other areas.  The spoilage occurred slowly, without signs of microbial activity such as cloudiness and effervescence and was assumed to be an aspect of age related bouquet.

Brett has been isolated from the skins of grapes and other fruits, but used barrels are generally implicated as the presumed major source of introduction to wineries.  It is difficult to track Brett because it grows slowly, is inhibited by SO2 and is not easy to culture.  Wines that test negative for Brett right before bottling can go through full blown Brett spoilage in bottle.  While Brett can use alcohol as a carbon source and can grow anaerobically (without oxygen), it grows more rapidly with some oxygen and/or reducing sugars.  Residual sugar in wine increases the risk of Brett growth, as does the use of new oak with its contribution of sugars that are not fermentable by Saccharomyces.  New oak may be a major factor in the high historic incidence of Brett in Bordeaux.

Common descriptors of Brett spoilage in red wine include “horsey”,  “mousy”, “wet dog” and “bandaid” for aromas and “metallic” for taste.  The main compounds responsible are 4-ethylphenol (4EP), 4-ethylguaiacol (4EG) and isovaleric acid (IVA).  There is a school of thought that small amounts of these compounds can make a wine more complex and interesting, but virtually nobody cares for wines dominated by these aromas.  White wines don't have the substrate for 4EP and 4EG production, but can develop high IVA levels and smell like vomit or worse.

Brett is sensitive to SO2, which inhibits its growth but does not kill it.  It can usually be controlled in wineries through stringent sanitation and maintenance of sufficient SO2 levels in aging wine.  SO2 levels decline after bottling, eventually to the point where any dormant Brett cells can begin to grow.  Many wines are sterile filtered as insurance against Brett.  Otherwise, dry wines (less than 0.3% RS) that have completed MLF (less than 0.01% malic acid) could be bottled unfiltered with little fear of anything ever growing.  An alternative to sterile filtration is pre-bottling treatment with Velcorin™ (dimethyl dicarbonate), which will kill Brett and any other living thing in wine and breaks down very quickly.  Velcorin loses effectiveness if the wine is anything less than brilliantly clear prior to treatment,.  You need a permit, training, and special equipment to use it, and many of us are philosophically opposed to the concept as well.  One other factor can be a very effective inhibitor of Brett: alcohol.  As far as I know, Brett has not been found in wines of 15% alcohol or more.  In our case, if we have a wine above 15%, we feel comfortable bottling unfiltered, but we don't aim for 15% in most of our wines.

Lighter


quality posts: 10 Private Messages Lighter

Good writing! I was scared to click on this because this sort of biology causes my eyes to cross and my teeth to molt. No problems and now I know something new!

gcdyersb


quality posts: 141 Private Messages gcdyersb

Re-post from Epiphant thread:

"So the follow up, kind of tangential. If there's no ML, then you sterile filter prior to bottling to prevent secondary fermentation in bottle.

Is this one reason white wines rarely show Brett, because many are sterile filtered? Or is high acidity coupled with less extraction of yeast fuel from skins a bigger reason why there's no Brett?"

OK, this is partially answered by the explanation of 4EP and 4EG lacking the substrate to form. But what exactly is lacking, and what else factors into the Brett chemistry?

Cabernet Franc: it's not just for blending! It's also for blogging.

gcdyersb


quality posts: 141 Private Messages gcdyersb

And another question. Are there any understood methods to influence 4EP vs. 4EG vs. IVA production by Brett, like changing the balance of nutrients in the must? Or perhaps strains isolated with different byproducts?

I'm curious because I tend to find "French" Brett more Barnyardy, while "American" Brett makes me think more of rancid puke. Obviously not a large sample size. But maybe there's a reason why vomitous IVA character is more pronounced in some Bretty wines, and less pronounced in others.

Cabernet Franc: it's not just for blending! It's also for blogging.

kylemittskus


quality posts: 234 Private Messages kylemittskus

No questions yet; just a big thanks for the time spent in writing this.

"If drinking is bitter, change yourself to wine." -Rainer Maria Rilke

"Champagne is a very kind and friendly thing on a rainy night." -Isak Dinesen

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
gcdyersb wrote:Re-post from Epiphant thread:

"So the follow up, kind of tangential. If there's no ML, then you sterile filter prior to bottling to prevent secondary fermentation in bottle.

Is this one reason white wines rarely show Brett, because many are sterile filtered? Or is high acidity coupled with less extraction of yeast fuel from skins a bigger reason why there's no Brett?"

OK, this is partially answered by the explanation of 4EP and 4EG lacking the substrate to form. But what exactly is lacking, and what else factors into the Brett chemistry?



You did already give some of the answers to your own question. White winemaking is generally less conducive to microbial growth. Lower temperatures, lower pHs, more protection from oxygen, higher molecular SO2 levels, lower amounts of solids and shorter time in barrel all work in concert to inhibit growth of Brett and spoilage bacteria (and also Saccharomyces and Oenococcus - the good guys). Sterile filtration does prevent Brett spoilage from getting worse in bottle, but white wines have pre-bottling Brett infections much less frequently.

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
gcdyersb wrote:And another question. Are there any understood methods to influence 4EP vs. 4EG vs. IVA production by Brett, like changing the balance of nutrients in the must? Or perhaps strains isolated with different byproducts?

I'm curious because I tend to find "French" Brett more Barnyardy, while "American" Brett makes me think more of rancid puke. Obviously not a large sample size. But maybe there's a reason why vomitous IVA character is more pronounced in some Bretty wines, and less pronounced in others.



I don't know of any methods to influence 4EP / 4EG ratios. My guess is it's most likely the amounts of the various precursors in the wine. Nutrients such as sugars and vitamins can be growth stimulants, but I don't know if they affect the balance of aromatic byproducts.

One California winery did a lot of work with different Brett strains in the 1980's. They had observed significantly different amounts of "spoilage" with different strains. I think they even had a working hypothesis along the following lines: Brett is hard to control or stop, so if a benign strain of Brett can be grown in a wine it will render the wine stable against nasty strains of Brett. I don't think they ever found a strain of Brett that was benign enough.

Aromas and flavors in wine are complex and react with each other, so Brett does express itself differently in various wines. Are we talking Bordeaux Brett? Chateauneuf du Pape Brett? Napa Cab Brett? Chilean Merlot Brett? SA Pinotage Brett? They all seem different, but I'd guess it's more the substrate (wine) than the strain.

otolith


quality posts: 24 Private Messages otolith

So you're saying my big dream of "Lake Home '09" is going to be a little more difficult than harvesting the grapes, pressing them, letting them ferment, then age with some oak chips and bottle?

Here's a pic of the wild '08 vintage

"When we try to pick out anything by itself, we find it hitched to everything else in the universe."
--John Muir

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
otolith wrote:So you're saying my big dream of "Lake Home '09" is going to be a little more difficult than harvesting the grapes, pressing them, letting them ferment, then age with some oak chips and bottle?

Here's a pic of the wild '08 vintage



At the end of the day it's all about the grapes. Everything else is just the details. Looking at your grapes I'd say you have an uphill battle ahead;-)

PS: If you're going to use oak chips, put some in the fermenter - better integration and color stabilization.

woopdedoo


quality posts: 36 Private Messages woopdedoo

"Brand new facilities have experienced difficulty getting uninoculated grapes to ferment."

I seem to remember you saying that grapes WANT to ferment - mentioning that it was quite the revelation that Welch was able to keep them from doing so. Perhaps he began his grape juice dynasty as an unsuccessful winemaker.

Also, your mention of the antibiotics in tears makes me think of the Phoenix tears in Harry Potter.

As always, thanks for the most informative post!

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
woopdedoo wrote:"Brand new facilities have experienced difficulty getting uninoculated grapes to ferment."

I seem to remember you saying that grapes WANT to ferment - mentioning that it was quite the revelation that Welch was able to keep them from doing so. Perhaps he began his grape juice dynasty as an unsuccessful winemaker.

Also, your mention of the antibiotics in tears makes me think of the Phoenix tears in Harry Potter.

As always, thanks for the most informative post!



Well, there's ferment and there's ferment successfully to dryness. In absence of sufficient wine yeast populations, wild yeast will start the fermentation, but will be inhibited by alcohol before the fermentation is complete (a "stuck" fermentation), leaving the wine susceptible to Lactobacillus and other spoilage organisms. The cure for stuck fermentations is inoculation or re-inoculation with large quantities of very aggresive wine yeast. This strain then become dominant in the winery and will likely be the dominant strain in future "uninoculated" fermentations.

otolith


quality posts: 24 Private Messages otolith
SonomaBouliste wrote:At the end of the day it's all about the grapes. Everything else is just the details. Looking at your grapes I'd say you have an uphill battle ahead;-)

PS: If you're going to use oak chips, put some in the fermenter - better integration and color stabilization.


Ouch. I'm assuming because the grapes are too small? lol

I may still have to try this. There's a pretty good home brew store in town. If I get a bottle or two out of it, great! It'll be fun to try anyway.

"When we try to pick out anything by itself, we find it hitched to everything else in the universe."
--John Muir

Lighter


quality posts: 10 Private Messages Lighter

How much yeast? I'm kinda wine vat size challenged. Is there a weight per gallon for yeast when you are tossing in a block of ready made?

How much natural float-in-the-air-yeast to get things going? I'd always figured a pin head so long as a winemaker was patient. More?

Does quantity of yeast make much difference in time fermenting?

What daily tests do you do during fermenting?

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
otolith wrote:Ouch. I'm assuming because the grapes are too small? lol

I may still have to try this. There's a pretty good home brew store in town. If I get a bottle or two out of it, great! It'll be fun to try anyway.



It's the variety, not the size. Small berries means higher skin/juice ratio - all else equal, more color and flavor. Sugar and acid levels may both need adjusting, but it's hard to adjust flavor.

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
Lighter wrote:How much yeast? I'm kinda wine vat size challenged. Is there a weight per gallon for yeast when you are tossing in a block of ready made?

How much natural float-in-the-air-yeast to get things going? I'd always figured a pin head so long as a winemaker was patient. More?

Does quantity of yeast make much difference in time fermenting?

What daily tests do you do during fermenting?



1) The yeast manufacturers recommend 1 gram per gallon. This will give a huge initial cell count and initiate fermentation rapidly. You should rehydrate the yeast first; 10 parts very warm water (100-105F) to one part yeast for about 15 minutes (until the mixture starts to foam a lot). If you're adding it to cold must or juice, you need to mix your starter one to one with juice so as not to cold shock it.

2) There isn't much "float-in-the-air yeast" around, unless you're in a winery or bakery or similar setting.

3) Quantity and yeast strain are two things that I didn't address in detail in the blog. Wineries that need to utilize their tanks to maximum efficiency will use large inocula of vigorous, rapid yeast strains. The biggest difference with smaller inocula is a longer lag phase - more time before the fermentation really gets cooking. Many of us believe that the biggest effect of "natural" fermentation is the different fermentation curve. Both "natural" fermentations and "micro-inoculations" have a much longer lag phase, but then proceed faster and hotter at the peak of fermentation.
Although some of the commercial strains are touted as having enzyme activity that enhances fruitiness or color extraction or some other character, most of the differences appear to be due to fermentation dynamics - rate and temperature. Some strains are more tolerant of low or high temperatures, low nutrient availability, and/or high alcohol levels. Yeast strain choice comes down to cost, convenience, reliability and wine style goals.

4) We check brix (density) and temperature twice daily during the rapid phase of fermentation (about 20 brix to 7 brix), once daily before and after that phase. We want to make sure we're building up enough heat but not too much. We also want the earliest possible warning of potential problems; it's a lot easier to re-invigorate a sluggish fermentation than restart one that's dead in the water. We also smell for problems and taste reds for extraction.

Lighter


quality posts: 10 Private Messages Lighter
SonomaBouliste wrote: You should rehydrate the yeast first; 10 parts very warm water (100-105F) to one part yeast for about 15 minutes (until the mixture starts to foam a lot). If you're adding it to cold must or juice, you need to mix your starter one to one with juice so as not to cold shock it.


Just like baking bread. Inc temperatures.

SonomaBouliste wrote:
2) There isn't much "float-in-the-air yeast" around, unless you're in a winery or bakery or similar setting.


Then my question was inartfull. When you are not adding yeast and relying on what is floating around in the air for natural fermentation, what are the time and quantity differences. Or am I not understanding "natural" fermentation?

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
Lighter wrote:Then my question was inartfull. When you are not adding yeast and relying on what is floating around in the air for natural fermentation, what are the time and quantity differences. Or am I not understanding "natural" fermentation?



I'm not sure what you mean by "time and quantity differences". Typically there is enough residual yeast in winery equipment and tanks to get a strong fermentation going within three to five days.

ScottHarveyWines


quality posts: 157 Private Messages ScottHarveyWines

Peter,
Wonderfully written blog. I need to print this one out and hand it out. Your blog does such a good job answering the questions we are always being asked as winemakers.
Scott

paryb


quality posts: 17 Private Messages paryb

One of the issues that I've always understood about Brett happens to small wineries...the guys who can't afford new barrels or even 2nd or 3rd year barrels every year...or ever for that matter. Any ideas on how to control things, other than cleaning as best they can?

189 Bottles of wine from Woot so far!
$3319.36or a mere $17.56 per bottle.

wine.woot Keeping Paryb in the red(and sometimes white) since 5/9/2007

SonomaBouliste


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paryb wrote:One of the issues that I've always understood about Brett happens to small wineries...the guys who can't afford new barrels or even 2nd or 3rd year barrels every year...or ever for that matter. Any ideas on how to control things, other than cleaning as best they can?



Risk shouldn't necessarily increase as barrels get older; new barrels have more Brett food. Large wineries tend to have the resources (full-time lab staff) to do more monitoring, and may do a better job of limiting Brett spoilage to reasonable levels. Even so, I do know of some larger, deep pocketed wineries that are somewhat notorious for Brett. Quite a few small wineries may not even test free SO2 frequently, much less have samples analysed for 4EP/4EG or plated for Brett growth.

Brett is managed / controlled by a combination of sanitation, maintaining adequate SO2 levels, getting wines dry and stable, and monitoring.

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
ScottHarveyWines wrote:Peter,
Wonderfully written blog. I need to print this one out and hand it out. Your blog does such a good job answering the questions we are always being asked as winemakers.
Scott



Scott,
Thanks for the kind words. Feel free to use as you please.

Peter

wombativ


quality posts: 1 Private Messages wombativ

Whoops! Sorry I've been slacking on the forums lately. Its been a busy last week or two of combining thesis work, moving stuff to my St Helena apartment for harvest, and mourning my impending old age (turned 29 on Sunday).

So many topics to discuss . . . Brett, acetic acid bacteria, lactic acid bacteria, indigenous yeasts, inoculated yeasts . . . I'll come back and expand when I find more time. Hopefully tonight.

In the mean time, just a couple thoughts:
1.) I thought it was the ratio of 4-vinylphenol to 4-ethylphenol that had more effect on the aromas produced by Brett (ie whether its more manure/barnyard/leather or more medicinal/bandaid). I could be wrong though. I'll have to check my wine micro notes when I get home.

2. Does anyone ever check to see if their fermentations actually finish with the strains they inoculated with? I wouldn't really be surprised if a lot of inoculated fermentations were overrun by whatever flora is on winery equipment without winemakers ever realizing it. Not so much if they've been using the same inoculum for a long time, but more in experiments when they are trying new yeasts.

3. Do you think Lactobacillus kunkei is more of an issue now than Pediococcus (damnosus or otherwise) for MLF? I definitely encounted Pedio in a few spoiled wines I was looking at under the scope this year. Of course, its also a lot easier to recognize than a number of other ML bugs (Gram positive cocci in tetrads are fairly distinctive). And on the Pedio note, have you ever encountered a wine that was so populated with Pediococcus that it went "ropy" from exo-polysaccharides?

kylemittskus


quality posts: 234 Private Messages kylemittskus
wombativ wrote: 3. Do you think Lactobacillus kunkei is more of an issue now than Pediococcus (damnosus or otherwise) for MLF? I definitely encounted Pedio in a few spoiled wines I was looking at under the scope this year. Of course, its also a lot easier to recognize than a number of other ML bugs (Gram positive cocci in tetrads are fairly distinctive). And on the Pedio note, have you ever encountered a wine that was so populated with Pediococcus that it went "ropy" from exo-polysaccharides?



Hey there Wombat,

Mind speaking English for these boards?

"If drinking is bitter, change yourself to wine." -Rainer Maria Rilke

"Champagne is a very kind and friendly thing on a rainy night." -Isak Dinesen

wombativ


quality posts: 1 Private Messages wombativ
kylemittskus wrote:Hey there Wombat,

Mind speaking English for these boards?



sorry . . . where did I go bad in there? Not much I can do with the genus/species names (I tried shortening Pediococcus damnosus to Pedio . . .).

Bacteria are generally divided into two categories based on their cell wall composition: Gram + and Gram -. That term is used because one type of cell wall (+) absorbs Gram stain (named after its creator). Gram - cells have the purple stain rinsed off and are thus easy to visually differentiate under a microscope. In wines terms, pretty much all lactic acid bacteria (those responsible for malolactic fermentation) are going to be Gram +. For the most part, the only Gram - bacteria are acetic acid bacteria that thrive at the wine surface due to their oxygen requirement.

The ropy thing is something I've seen written about wines but never experienced. There are a few strains of Pediococcus damnosus that have an extra couple hundred base sequence (probably from a horizontal gene transfer from another bacteria) that produces a thick, viscous substance in excessive amounts. Supposedly when you try to pour a wine this has been growing in, it kind of looks like long, stringy mucous in your wine (wine that drinks like a meal as it were).

PS - I know you were being facetious, but I never pass up an opportunity for a dorky conversation, as some of the Joseph Phelps tasting room staff found out last weekend while another future winemaker and I debated 20th century interpretations of Beowulf for ten minutes . . .

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
wombativ wrote:Whoops! Sorry I've been slacking on the forums lately. Its been a busy last week or two of combining thesis work, moving stuff to my St Helena apartment for harvest, and mourning my impending old age (turned 29 on Sunday).

So many topics to discuss . . . Brett, acetic acid bacteria, lactic acid bacteria, indigenous yeasts, inoculated yeasts . . . I'll come back and expand when I find more time. Hopefully tonight.

In the mean time, just a couple thoughts:
1.) I thought it was the ratio of 4-vinylphenol to 4-ethylphenol that had more effect on the aromas produced by Brett (ie whether its more manure/barnyard/leather or more medicinal/bandaid). I could be wrong though. I'll have to check my wine micro notes when I get home.

2. Does anyone ever check to see if their fermentations actually finish with the strains they inoculated with? I wouldn't really be surprised if a lot of inoculated fermentations were overrun by whatever flora is on winery equipment without winemakers ever realizing it. Not so much if they've been using the same inoculum for a long time, but more in experiments when they are trying new yeasts.

3. Do you think Lactobacillus kunkei is more of an issue now than Pediococcus (damnosus or otherwise) for MLF? I definitely encounted Pedio in a few spoiled wines I was looking at under the scope this year. Of course, its also a lot easier to recognize than a number of other ML bugs (Gram positive cocci in tetrads are fairly distinctive). And on the Pedio note, have you ever encountered a wine that was so populated with Pediococcus that it went "ropy" from exo-polysaccharides?



1) You've had this stuff in class a few decades more recently than I have, so if you don't know then I sure as hell don't.

2) Very few people check, but if you use the recommended amount of yeast and prep it properly the numbers are so overwhelming that it will almost always dominate start to finish. If your yeast poops out for one reason or another, then that's another story.

3) In my experience and from talking to other winemakers, the big concern with Lactobacillus kunkei is stuck fermentations due to toxic effects on yeast, followed by further acetification. There was a trend in the late 80's - early 90's toward not adding SO2 to reds at crush. That's when people noticed / discovered L. kunkei. One L. kunkei stuck fermentation in 1992 cured me of that practice.
Pediococcus is a huge worry in the brewing industry; I've heard of, but never encountered it in winemaking. I've never seen a ropy wine other than demonstration bottles.

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
wombativ wrote: There are a few strains of Pediococcus damnosus that have an extra couple hundred base sequence (probably from a horizontal gene transfer from another bacteria) . . .



Way to dumb things down!

wombativ


quality posts: 1 Private Messages wombativ
SonomaBouliste wrote:Way to dumb things down!



Touche! Epic Bobo-style on my part. What can I say, when I decided to bail on the biopharma industry, my two dream careers were 1) winemaker or 2) get a PhD in Microbiology or Virology and become a CDC Virus Hunter.

In real life I usually know when to stop talking by all the blank stares. Its a little harder on here . . .

bhodilee


quality posts: 32 Private Messages bhodilee
wombativ wrote:Whoops! Sorry I've been slacking on the forums lately. Its been a busy last week or two of combining thesis work, moving stuff to my St Helena apartment for harvest, and mourning my impending old age (turned 29 on Sunday).

So many topics to discuss . . . Brett, acetic acid bacteria, lactic acid bacteria, indigenous yeasts, inoculated yeasts . . . I'll come back and expand when I find more time. Hopefully tonight.

In the mean time, just a couple thoughts:
1.) I thought it was the ratio of 4-vinylphenol to 4-ethylphenol that had more effect on the aromas produced by Brett (ie whether its more manure/barnyard/leather or more medicinal/bandaid). I could be wrong though. I'll have to check my wine micro notes when I get home.

2. Does anyone ever check to see if their fermentations actually finish with the strains they inoculated with? I wouldn't really be surprised if a lot of inoculated fermentations were overrun by whatever flora is on winery equipment without winemakers ever realizing it. Not so much if they've been using the same inoculum for a long time, but more in experiments when they are trying new yeasts.

3. Do you think Lactobacillus kunkei is more of an issue now than Pediococcus (damnosus or otherwise) for MLF? I definitely encounted Pedio in a few spoiled wines I was looking at under the scope this year. Of course, its also a lot easier to recognize than a number of other ML bugs (Gram positive cocci in tetrads are fairly distinctive). And on the Pedio note, have you ever encountered a wine that was so populated with Pediococcus that it went "ropy" from exo-polysaccharides?



I think you get 10 years if you're caught with that much Cocci

"The power of accurate observation is commonly called cynicism by those who have not got it."

– George Bernard Shaw, author (1856-1950)

ScottHarveyWines


quality posts: 157 Private Messages ScottHarveyWines

3. Do you think Lactobacillus kunkei is more of an issue now than Pediococcus (damnosus or otherwise) for MLF? And on the Pedio note, have you ever encountered a wine that was so populated with Pediococcus that it went "ropy" from exo-polysaccharides?[/quote]

I've done a little consulting on the side and have run accross some wines where they were attempted to produce the wine in the 4.2 pH range. A perfect environment for the growth of pediococcus. This particular wine had counts as high as 7,600,000 cells/ml. and a very nervous owner. The wine did have a ropy septic character, but I did not see ropy strings. By dropping the pH below 3.65 an environment was created where the pediococcus could not live. It died and fell out. A clean racking with a little aeration and free SO2 adjustment brought the wine back around. It took about a month to six weeks, all the time the wines owner needed a little baby sitting.

wombativ


quality posts: 1 Private Messages wombativ
ScottHarveyWines wrote:3. Do you think Lactobacillus kunkei is more of an issue now than Pediococcus (damnosus or otherwise) for MLF? And on the Pedio note, have you ever encountered a wine that was so populated with Pediococcus that it went "ropy" from exo-polysaccharides?



I've done a little consulting on the side and have run accross some wines where they were attempted to produce the wine in the 4.2 pH range. A perfect environment for the growth of pediococcus. This particular wine had counts as high as 7,600,000 cells/ml. and a very nervous owner. The wine did have a ropy septic character, but I did not see ropy strings. By dropping the pH below 3.65 an environment was created where the pediococcus could not live. It died and fell out. A clean racking with a little aeration and free SO2 adjustment brought the wine back around. It took about a month to six weeks, all the time the wines owner needed a little baby sitting.[/quote]

Hmmm . . . reminds me of my old vaccine job . . . lots of process owners who got too emotional and couldn't make decisions when things went wrong.

1. Did you need to do an filtration (depth, crossflow, or ultra) to remove the accumulated polysaccharide?

2. Do you happen to recall what the final TA on the wine was after that significant of an addition?

3. Did that large of a tartaric addition affect the downstream stability of the wine (ie throwing out lots of tartrates/proteins/colloids) later on? Or was the cleaned up wine just blended into other lots so it didn't have much effect?

-j

ScottHarveyWines


quality posts: 157 Private Messages ScottHarveyWines
wombativ wrote:Hmmm . . . reminds me of my old vaccine job . . . lots of process owners who got too emotional and couldn't make decisions when things went wrong.

1. Did you need to do an filtration (depth, crossflow, or ultra) to remove the accumulated polysaccharide?

2. Do you happen to recall what the final TA on the wine was after that significant of an addition?

3. Did that large of a tartaric addition affect the downstream stability of the wine (ie throwing out lots of tartrates/proteins/colloids) later on? Or was the cleaned up wine just blended into other lots so it didn't have much effect?

-j


Peter, hope it is okay to answer questions on your blog.
No filtration, the wine will be sterile filtered when bottled.
Final pH is 3.64. After the tartaric addition, the initial acidity goes up as the pH goes down. After the tartrats drop out the acidity comes back down, but the free hydrogen ions are left behind and the pH stays low enough.
Other wines will be blended into this wine.

SonomaBouliste


quality posts: 240 Private Messages SonomaBouliste
ScottHarveyWines wrote:Peter, hope it is okay to answer questions on your blog.
No filtration, the wine will be sterile filtered when bottled.
Final pH is 3.64. After the tartaric addition, the initial acidity goes up as the pH goes down. After the tartrats drop out the acidity comes back down, but the free hydrogen ions are left behind and the pH stays low enough.
Other wines will be blended into this wine.



No problem. I certainly can't answer those questions

gcdyersb


quality posts: 141 Private Messages gcdyersb
ScottHarveyWines wrote:I've done a little consulting on the side and have run accross some wines where they were attempted to produce the wine in the 4.2 pH range. A perfect environment for the growth of pediococcus. This particular wine had counts as high as 7,600,000 cells/ml. and a very nervous owner. The wine did have a ropy septic character, but I did not see ropy strings.



Is there a danger of high pH wine "going ropy" or otherwise spoiling in bottle from Pediococcus, assuming it wasn't sterile filtered? Or is this only an issue before malolactic fermentation is complete?

Cabernet Franc: it's not just for blending! It's also for blogging.

gcdyersb


quality posts: 141 Private Messages gcdyersb
wombativ wrote:
3. Did that large of a tartaric addition affect the downstream stability of the wine (ie throwing out lots of tartrates/proteins/colloids) later on?



Is precipitate actually considered a result of poor stability? Or only in specific cases? I always get excited when I find a wine with lots of tartrates and other gunk because it seems "natural" for it to evolve in this way. As in there was minimal handling, and as TA and tannins subside to drinkable levels, the precipitate is expected. You wouldn't want that in a grocery store wine, but I'd be disappointed if a wine meant for aging had no gunk after several years.

Cabernet Franc: it's not just for blending! It's also for blogging.

ScottHarveyWines


quality posts: 157 Private Messages ScottHarveyWines
SonomaBouliste wrote:No problem. I certainly can't answer those questions



That's because you make wine correctly from the start. Good winemaking sure shows in the this wonderful glass of 2007 Wellington Marsanne I'm enjoying right now. Was enjoying, the bottle is empty.

bhodilee


quality posts: 32 Private Messages bhodilee
ScottHarveyWines wrote:That's because you make wine correctly from the start. Good winemaking sure shows in the this wonderful glass of 2007 Wellington Marsanne I'm enjoying right now. Was enjoying, the bottle is empty.



I just love this site

"The power of accurate observation is commonly called cynicism by those who have not got it."

– George Bernard Shaw, author (1856-1950)

otolith


quality posts: 24 Private Messages otolith
wombativ wrote:Touche! Epic Bobo-style on my part. What can I say, when I decided to bail on the biopharma industry, my two dream careers were 1) winemaker or 2) get a PhD in Microbiology or Virology and become a CDC Virus Hunter.

In real life I usually know when to stop talking by all the blank stares. Its a little harder on here . . .



Keep it up! So I take it you chose #2?

Micro was one of my more favorite classes in undergrad. We even went on a tour of one of the local microbrews. It's still my favorite beer.

"When we try to pick out anything by itself, we find it hitched to everything else in the universe."
--John Muir

maddprofessor


quality posts: 5 Private Messages maddprofessor
wombativ wrote:Touche! Epic Bobo-style on my part. What can I say, when I decided to bail on the biopharma industry, my two dream careers were 1) winemaker or 2) get a PhD in Microbiology or Virology and become a CDC Virus Hunter.

In real life I usually know when to stop talking by all the blank stares. Its a little harder on here . . .




I'm working on a PhD in Cellular and Molecular Biology which a focus on virology (hep C in particular) I love the microbiology discussion. So can I get a job at a winery doing microbiology work and get free wine? Maybe I out to switch my focus from virus to bacteria. Wine is tastier than liver.

otolith


quality posts: 24 Private Messages otolith
maddprofessor wrote:I'm working on a PhD in Cellular and Molecular Biology which a focus on virology (hep C in particular) I love the microbiology discussion. So can I get a job at a winery doing microbiology work and get free wine? Maybe I out to switch my focus from virus to bacteria. Wine is tastier than liver.


Just figure out a cure for Hep C first.

"When we try to pick out anything by itself, we find it hitched to everything else in the universe."
--John Muir

ddeuddeg


quality posts: 35 Private Messages ddeuddeg
ScottHarveyWines wrote:That's because you make wine correctly from the start. Good winemaking sure shows..



This must be the reason why Wellington and Scott Harvey wines are the 2 best represented wineries in my cellar.

"Always keep a bottle of Champagne in the fridge for special occasions. Sometimes the special occasion is that you've got a bottle of Champagne in the fridge". - Hester Browne


Ddeuddeg's Cheesecake Cookbook