Wanna make better wine?

[seth8530]

Because once the yeast are a certain percent through the fermentation ( which equates t a cycle of their activity) they quit accepting nutrients. They can use organic ammino nitrogen longer than say DAP. However, you still want to be careful about how late in the game you use it. Somewhere I found that with fermaid O and other ammino nitrogen you are actually good up to the 2/3 sugar break.. However, I have been unable to find the reference in which I found that. So I might drop back to using the 1/2 sugar break as my last nutrient addition.

 

[francois_du_nord]

Anybody know the difference btw Fermaid K and Fermaid O? I bought some Fermaid K to help with a mead that wasn't going off, so I've got that in my stash.

Thanks, Fran

 

[Deezil]

I guess my question is how do the yeast know when 50 percent of the sugar has been consumed or when 30 percent has been. If your starting gravity is 1.090 then 50 percent will be at a gravity of 1.045. If your starting gravity is 1.060 then 50 percent will be 1.030. So what precisely is the mechanism and the chemistry that compels us to add nutrients at the fifty percent point? Thanks

To answer this, you have to know more about the life cycle of the yeast colony during fermentation. I'm no pro, so I dont have this down step-by-step, but from my understanding..

You do all the steps pre-fermentation.. Fruit/flavor, acidity, sugar levels, etc... The yeast are stored, in their package, in a dehydrated sort of coma, and we rehydrate them. At this point, they intake water and swell back to 'normal', but during this rehydration process you're only bringing back to life one age-group of yeast. They're all in the 'same grade in grade school', for lack of a better analogy. This swelling, is the ONLY point at which these yeast, and their successors, have the opportunity to intake particular vitamins and minerals.

I do know, that when this first generation of cells rehydrates, they soak in particular vitamins and minerals (which are escaping me right now) that determine the thickness of their cell walls. This is important when you understand that yeast dont give birth to new yeast, they divide. Everything. 1 yeast cell uses nutrients to double up itself and splits into 2. The cell wall included. There's no more opportunity for these yeast to intake those minerals, when they come up short and start having thin or failing cell walls. This is why Go-Ferm is so important for rehydration - it contains these particular vitamins and minerals, allowing that first generation of yeast to divide further because of the thicker cell walls taking longer to thin out, ending with a larger and healthier yeast colony.

So you rehydrate the yeast, and they've taken in what they could - so they begin to divide rapidly... We know this as the 'lag phase', or the time in between when you've pitched the yeast and when the cap forms. The original generation splits to create a second generation, and then (if i remember right) both generations split to create even more generations. When does the colony know its big enough to handle the sugars? I dont know.. Or do they just keep splitting until they go almost-terminal? I dont know.

But when the lag phase is over, the whole colony pretty much 'switches gears' into consuming sugars and creating alcohol. At this point, the colony you have is the colony you get. They are either healthy enough to finish the job, or we end up with a 'mysterious' stuck fermentation.

And like us, when these yeast start to age, and change their diet due to exhaustion of nitrogen, minerals, vitamins, etc., they can begin to burp/fart/off-gas or become unhealthy.

Eventually, they dont want DAP anymore. They dont want the sugary cereal for breakfast, the Coke/Pepsi for lunch and the fast food for dinner. But they'll still eat a home cooked meal with a glass of wine.

To sum this up, it's not that the yeast know when 50% of the sugar has been consumed, but instead more along the lines of us using those terms to gauge the age of the yeast colony.

Somewhere I found that with fermaid O and other ammino nitrogen you are actually good up to the 2/3 sugar break.. However, I have been unable to find the reference in which I found that. So I might drop back to using the 1/2 sugar break as my last nutrient addition.

It was in that 'talk with the fermaid people' conversation we had.. Somewhere

Anybody know the difference btw Fermaid K and Fermaid O? I bought some Fermaid K to help with a mead that wasn't going off, so I've got that in my stash.

Thanks, Fran

Fermaid-K contains DAP, while Fermaid-O is strictly organic forms of nitrogen. I think they differ slightly on the vitamins and minerals they contain too, but thats kinda hazy.

 

[seth8530]

I remember saying in the thread that it is good up to the 2/3 sugar break. I was just wanting to confirm where I got that. I wonder if that came from my reading or from the oral communication I had with scott labs.

I am pretty sure fermaid O does not include vitamins and minerals. If I am wrong I would like to know though.

 

[Deezil]

Wasn't sure if it was your reading, your phone call, or my reading.. Somewhere in there though

 

[Geronimo]

I guess my question is how do the yeast know when 50 percent of the sugar has been consumed or when 30 percent has been. If your starting gravity is 1.090 then 50 percent will be at a gravity of 1.045. If your starting gravity is 1.060 then 50 percent will be 1.030. So what precisely is the mechanism and the chemistry that compels us to add nutrients at the fifty percent point? Thanks

IMO they are all voodoo approximations because we aren't microbiologists with a complete lab and a complete understanding of every strain. A more accurate statement is that yeast will not assimilate as much YAN as the alcohol toxicity rises. The fact is, they do continue to consume some YAN right up to (about) 75% of their alcohol tolerance level (which varies a lot by strain). The reasoning of drawing a line for vintners is to be safe about having any left over DAP in the finished product.

When I first started to make wine, I saw a lot more RC212 yeast in kits. This might actually have been part of the issue know as "kit taste" because few people knew the nutrient requirements of various yeasts and the kit producers didn't include any. Sticking with EC1118 in wines at or below 14% ABV with one conservative feeding at inoculation will produce consistent results. This is one of the main reasons hobbyist wine makers rarely deviate... unlike hobbyist beer makers which change yeast more often then they change underwear. EC1118 is so voracious (and cheap) that it's perfect for newbie kit makers. I remember a thread where someone was buying low end kits and making them as 5 gallon batches to improve the body and bump the ABV. With any other yeast, that might be just plain crazy.

 

[BernardSmith]

The microbiology of the yeast is really useful and quite fascinating but sorry, I am still skeptical about using the "sugar break" as the measure of when to add nutrient. Given the accounts offered here it would seem to me that a more useful measure ought to be the length of time the yeast has been in the must since rehydration or since their osmotic activity has begun. Surely the yeast are unable to "know" how much sugar or alcohol is in solution but they are likely to bud (reproduce) after they have reached a certain maturation /length of life (or am I way off base in making these assumptions) simply because of the amount and kinds of of activity taking place through their cell walls. If they have the nutrients they need, and the oxygen etc then they will work on reproducing, No? So why is our focus on the balance between alcohol and sugar and not the length of time it takes a colony of yeast to double or quadruple in size?

 

[Geronimo]

They are single celled plants... they don't "know" anything. However their chemistry is inhibited at certain alcohol toxicity levels (dependent on strain).

They go through 3 phases; the aerobic "lag" phase where they mainly reproduce, the anaerobic phase of mainly consumption and conversion, and finally the clean up phase (assuming they haven't dropped out do to alcohol toxicity, temp, or other straining factors).

 

[Deezil]

The microbiology of the yeast is really useful and quite fascinating but sorry, I am still skeptical about using the "sugar break" as the measure of when to add nutrient. Given the accounts offered here it would seem to me that a more useful measure ought to be the length of time the yeast has been in the must since rehydration or since their osmotic activity has begun. Surely the yeast are unable to "know" how much sugar or alcohol is in solution but they are likely to bud (reproduce) after they have reached a certain maturation /length of life (or am I way off base in making these assumptions) simply because of the amount and kinds of of activity taking place through their cell walls. If they have the nutrients they need, and the oxygen etc then they will work on reproducing, No? So why is our focus on the balance between alcohol and sugar and not the length of time it takes a colony of yeast to double or quadruple in size?

I think as winemakers, we place importance on how much sugar is left because we want the wine to finish the way we intend it to, but when it comes to yeast nutrition, it's more about how much sugar has been, and can be consumed.

If you use a yeast that has a 14% ABV tolerance, it's only has the potential to burn through ~103 Specific Gravity points [(1.103 - 1)/.735 = 0.14014 or 14% ABV).

But two different yeast strains that both have 14% ABV tolerances, will have two different lag phases; similarly, two different batches of wine using the same strain of yeast, will have different sugar, acidity, and temperature parameters, leading to different lag times within the same strain.

The only thing we can measure for sure, without a microscope, as far as the yeast go, is how much sugar they're supposed to convert to alcohol. Being the only concrete measure we have of how far along the fermentation is, it's our only measure for when to add nutrients.

But if you know how much potential the yeast has, and you know you want to spread the nutrition additions out, and you know the yeast will begin to select away from inorganic nitrogen as the fermentation progresses (and towards organic nitrogen), its enough information to outline a rough nutrient addition schedule when paired with the amount of sugar that the yeast strain is capable of converting.

It's only fair to note that companies such as Lallemand have sunk a lot of time and money into researching yeast, their nutrient products and how to get the most for your money out of the product, while having the best fermentation their products can offer.

On a side note, lag phases are paid due attention, and are important, although not so much for yeast nutrient but instead for wine health and properly assessing the ability of the yeast to build up and out-compete any native yeasts or spoilage organisms. So there is information out there about lag phases on different yeast strains, but they're more along the lines of "short, medium or long" and not "2 hrs, 4 minutes and 39 seconds". And the short-medium-long is merely a comparison between that strain and the length of the lag phase of other strains; they dont make it easy enough to say 'short' = 1-2 hrs, medium = 2-3 hrs, long = 3-4 hrs.

 

[BernardSmith]

Deezil, Does that not suggest that the metric should then be less based on the amount of sugar in the must and more on the particular strain of yeast? If I am fermenting a must with a maximum potential ABV of about 11% but my yeast is quite capable of fermenting 16% then should I be as concerned about adding nutrients at an ABV of around 5.5 % or around 8 % ABV, and if my yeast was known to be good for a brew of around 8 % (ale yeast) but not much more, then should I not be more concerned when the ABV is closer to 4%

 

[seth8530]

Deezil, Does that not suggest that the metric should then be less based on the amount of sugar in the must and more on the particular strain of yeast? If I am fermenting a must with a maximum potential ABV of about 11% but my yeast is quite capable of fermenting 16% then should I be as concerned about adding nutrients at an ABV of around 5.5 % or around 8 % ABV, and if my yeast was known to be good for a brew of around 8 % (ale yeast) but not much more, then should I not be more concerned when the ABV is closer to 4%

That might be something worth following up on with some experts.