Yeast Colony Health at end of fermentation?

[Bmd2k1]

Is there any easy way to tell how healthy the yeast colony is at the end of a fermentation?

Cheers!

Brian

 

[Rice_Guy]

If the fermentation went well you should assume the yeast are healthy. If it was a stuck fermentation I would be concerned. In the beer industry reusing is normal for a few cycles. The concern to keep from doing it forebear is that mutations occurs and the flavor drifts from target.

 

[Raptor99]

If you are talking about the sediment from primary fermentation, I usually taste the gross lees. If the lees taste good, the ferment was healthy. Of course the lees will taste very yeasty, but there should not be any of flavors. Any off flavors in the wine will be much stronger in the lees.

 

[Bmd2k1]

If you are talking about the sediment from primary fermentation, I usually taste the gross lees. If the lees taste good, the ferment was healthy. Of course the lees will taste very yeasty, but there should not be any of flavors. Any off flavors in the wine will be much stronger in the lees.

Interesting!

Was actually referring to the still alive yeast in suspension....

 

[winemaker81]

If the fermentation went well you should assume the yeast are healthy.

This.

Once fermentation is done, the yeast become unhealthy as they starve to death.

 

[Bmd2k1]

This.

Once fermentation is done, the yeast become unhealthy as they starve to death.

So...

If ya cold crash....say at SG=1.01...there's still sugar in the must to feed the yeast as they go dormant...once the temp gets back to a happy range for the yeast...they will begin to eat again at their normal rate. I assume some yeast perish during the cold crash.

 

[winemaker81]

If ya cold crash....say at SG=1.01...there's still sugar in the must to feed the yeast as they go dormant...once the temp gets back to a happy range for the yeast...they will begin to eat again at their normal rate. I assume some yeast perish during the cold crash.

That's my understanding.

 

[BigDaveK]

So...

If ya cold crash....say at SG=1.01...there's still sugar in the must to feed the yeast as they go dormant...once the temp gets back to a happy range for the yeast...they will begin to eat again at their normal rate. I assume some yeast perish during the cold crash.

I transfer to secondary at 1.020ish. As a test I froze the pulp from 3 elderberry/blackberry batches and made a surprisingly good 2nd wine without adding more yeast. They laugh at the cold.

 

[Rice_Guy]

Any unit operation which forces metabolism to change will reduce the number of viable cells. Using a plate count method freezing translates to reducing from about 10,000,000 per ml to 1,000,000 per ml. @David Violante had a good graphic at post;
https://www.winemakingtalk.com/threads/yeast-life-span-and-nutrient-needs.76940/#post-855285
,,, There is a major risk of refermentation during the first few months after active growth stops.

 

[Bmd2k1]

In a Pet-Nat scenario where the yeast being used (D47) - which has an alcohol tolerance of 15% - ferments the must to .996 - yielding an ABV=12% - and you want to cold crash the wine and then rack it for bottling - in order to maximize the health of the yeast colony - would it be best to add the additional sugar before or after the cold crash? Realizing that D47 is temperature sensitive below 59F and tends to slow down considerably.

Cheers!

 

[Rice_Guy]

A gut feel answer is the nutrition needs to be good while the yeast is in suspension. if one adds nutrients after creating the paste adding an osmotic (water loving) sugar or salt will stress the cells pulling moisture out of them.

This post is eight “BOOK REVIEWs” on YouTube webinars related to fermentation microbiology. This is intended to let you know the good info is out there whether you just read summaries or watch as you need the vendor's answer. ~MY OPINIONs~ are in italic followed by the link to the webinar and the authors description. Warning!, some folks (me for example) may start binge watching YouTube since there are other pretty good webinars industrial suppliers have given about their wine making supplies.

In pre-pandemic time Scott Labs, (a US supplier) put on four hour long customer seminars. They were intended introduce important concepts to help folks make quality wines and familiarize us on which Scott Labs product would help. Suppliers have started creating webinars which are available on YouTube. The list in this post are a few fermentation topics that I like. They tend to be about an hour, and are college level information. Scott is by no means the only place for good technical info so I start with Lallemand and end with Bucher Vaslin (French supplier).
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An easy to follow, low tech guide for using dry yeast, 36 minutes
* Everything you need to know about dry yeast, Brittney Berg, Sales Manager for Lallemand answers many frequently asked questions about dry yeast ranging from production, rehydration to repitching. Questions that were covered: What is A.D.Y. (active dry yeast)? How is it made? What is Trehalose? Why are there not as many dry strains available compared to liquid? Do I need to rehydrate dried yeast? How do I go about doing that? How do I store dry yeast? and how once I have opened a packet? Do I need to aerate? Can I repitch another ferment with this yeast? What if I ignore the best by date?
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When you get down to it yeast are very hardy. This short video shows what a microbiology lab looks like and “sterile” technique in farming yeast, drying yeast. 4 minutes
* Virtual Tour: Lallemand Bio-Ingredients Salutaguse, Estonia plant
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Basic concepts one gets in a microbiology course as competitive cell populations going into a fermentation, plus practical details as nutrition/ pH as a fence/ use of metabisulphite/ sorbate/ filtration/ infection vectors/ microbial spoilage/ weaknesses of spoilage organisms/ always mix your yeast to prevent pockets of infection/ what if we dose with less than recomended yeast. (1) 1 hour; 12 minutes and (2) 1 hour, 19 minutes
Part 1: https://youtu.be/bFouHaECa94 * Budding Geniuses: Yeast Management & Selection to Maximize Wine Quality & Drive Wine Style, Scott Labs loves yeast! Yeast have a huge impact and yeast selection is an important tool for driving wine style. Proper nutrition and fermentation practices combined with strain selection are important to achieve a desired outcome. Join us for Part 2 of an exciting two-part episode of our webinar series where host Darren Michaels and guest speaker Dr. Nichola Hall explore the world of yeast, yeast selection, and fermentation outcomes. Budding Geniuses Part 2: Good Fermentation Practices - The Importance of Proper Yeast Rehydration - Nutritional Management - How to Use Nutrients to Drive Aromas
Part 2: * Budding Geniuses: Yeast Management & Selection to Maximize Wine Quality & Drive Wine Style: Scott Labs loves yeast! Yeast have a huge impact and yeast selection is an important tool for driving wine style. Proper nutrition and fermentation practices combined with strain selection are important to achieve a desired outcome. Join us August 6th for Part 1 of an exciting two-part episode of our webinar series where host Darren Michaels and guest speaker Dr. Nichola Hall explore the world of yeast, yeast selection, and fermentation outcomes. Budding Geniuses Part 1: Yeast Physiology and Selection - Basic Yeast Physiology and Growth Cycles - Yeast Nutritional Requirements - Selecting Yeast Using Our 2020 Winemaking Handbook
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Extra microbiology course info related to farming with yeast, as how to choose conditions where yeast out compete or what does sulfur dioxide do to bacterial cells. 1 hour, 24 minutes
* Taming the Beasts Within Your Wine: New & Old Ways to Prevent Microbial Spoilage: We are excited to announce a new Scott Labs Winemaking webinar series, hosted by our very own Darren Michaels. Join us for a short presentation and Q&A with Dr. Nichola Hall, where we discuss the following: - Wine hygiene theory - Methods to prevent and treat microbial spoilage - Low-to-no SO2 microbial control options1
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A microbiologist talks about requirements for growing yeast. Of note she is good at “off the cuff” answers of what is happening and fixes in the question session. 1 hour, 16 minutes
https://www.youtube.com/watch?v=S_Majzto54Q * Snap Out of It: Restarting a Stuck Fermentation: a quick review and live Q&A with Dr. Nichola Hall and Darren Michaels, where we will be discussing stuck wine treatments and how to get a restart going towards the best possible outcome. Topics Include: - Brief procedure overview - Critical control steps in building a successful starter - Treatment of toxins and competitive species - Optimal yeast and nutrient options.
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Malo Lactic fermentation; eleven slides with the basics and question & answer session, bacteria are inhibited above 7 gm/L malic acid, VA above 1.4g/L, limiting factors, free sulfur, slow below 68F, Lallemand scorecard for ease, ML restart process, 1 hour 2 min,
* Stuck MLF Diagnosis and Remediation, Wouldn’t it be great to finish malolactic before the holidays? Join Annamarie Howard and Darren Michaels as they have a quick discussion and live Q&A on how to deal with sluggish or stuck ML fermentations. From asking the right questions to deciding on the analysis to run, join us to try and get those wines to be bed before the holidays! Topics include: - Common diagnostic questions to answer - Should I use malolactic fermentation nutrients? - Calculating Success: Lallemand MLF Scorecard - Method to Restarting a Stuck ML Fermentation.
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Bucher Vaslin, a French company, authored this webinar focused on microbial control,,, some of the tools which are legal in other countries are new to us. (If you want to stay US centered the Scott Labs version of this subject is “ Strategies and Solutions for High pH Wine Making”. HACCP = prevent the issue before it bites you)
high pH winemaking * high pH winemaking. BucherVaslin pH is one of the most important parameters measured and used by winemaker as decision maker from grape picking and all along the winemaking process. pH, related to vineyard practices, indicator of grape ripeness, also affects wine stability and quality. High pH has historically been a difficult winemaking situation, where microbial stability and oxidative challenges can depreciate wine quality through fermentation and ageing. We will focus on the challenges associated to high pH grapes and the winemaking solutions available to winemakers. • Limit further increase of pH during grape processing • Oxidation management: from harvest to bottling • Microbial control during winemaking • Mouthfeel : tools available to balance high pH wines. www.bvnorthamerica.com/lamothe
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... To be continued as I binge watch