Yeast Nutrients

I would follow the manufactures mid range value - unless you want to send out some must for an analysis which I doubt seriously if most posting here do that.

I actually use the minimum suggested and smell the must the first few days for 'stink'. If i don't smell anything it's OK. A good rule of thiumb is to stuip up the must before adding the yeast to get some oxygen in there; the yeast like it early on.

Joe

It is possible to have a lab test for YAN (yeast assimilable nitrogen) ... but that is costly and time consuming, not something most home winemakers do. Quite a few commercial wineries don't do it either.

I err on the side of caution. I add DAP (diammonium phosphate) and nutrients at the outset of fermentation. There are numerous sources on how much to add; I use apx. 20 to 40 g of DAP per 10 gallons of must, and 20 g of superfood per 10 gallons of must. If I'm dealing with grapes that have previously been prone to H2S, or if I suspect low nitrogen (growing conditions), Imight add more DAP.

I don't seem to get H2S issues (knock on wood), but in the last 2 years or so, since we started getting high sugar premium grapes from California, the red ferments seem to last forever, 3 weeks and more, and that with regular nutrient doses (Fermaid K) added and at typical temperatures. Some of those batches also developed noticeable levels of VA. My theory at this point is that the YAN levels are too low on those grapes, leading to sluggish ferments.

So my recommendation for Wayne's situation - this being his first grape batch and a big one at that (was it 1400 lbs?) - actually would be to have the YAN levels measured in a lab and adjust the nutrients based on the result, especially if the grapes come in with high sugar levels.

Pp

The timing of nutrient addition is also worth mentioning. I've had the best results by adding nutrients (DAP and Superferment) in 2 aliquots rather then all at once. The first half is added once fermentation is started and the second at about 12 - 15 Brix. Waiting until fermentation is underway may help avoid encouraging growth among other microorganisms that you don't want to flourish.

RD

Purely out of interest for those of us with lesser experience in this field ... :)

Could you enlighten me as to how quick the turnaround is on a lab analysis, how much juice should be required, how you'd find a company to carry it out and how much it costs?

Sorry if this is a dumb question... Many thanks...

Jim

I also subscribe to the practice of incremental yeast nutrient additions (two or three smaller aliquots) rather than all at once at the start of fermentation.

Adding all the yeast nutrient at once at the start of fermentation encourages a very active fermentation (observed as heavy foaming). Highly active fermentations encourage carbamate production.

I try to minimize carbamate production... it's not good for us healthwise and is largely avoidable. I get all the carbamates I 'need' from french fries and other fried foods, so I like to avoid them in my wine.

Carbamates in wine are naturally occurring metabolic byproducts of wine fermentation, originating from the amino acid arginine. We can't eliminate arginine from the naturally occurring amino acid 'soup'; we can only minimize its conversion into carbamates by adding DAP in the minimum incremental amounts needed to prevent stinky/stuck fermentations.

Gene

Besides the active fermentation, the number of yeast cells multiplies to such a big number that it may cause H2S problem later on in the fermentation resulting from not enough nutrients for the yeast population. I add the dap/fermaid in 1/3 increments with the total adding up to the recommended dose per gallon.

Bob

Now I'm getting worried. I've been making fruit wines for 30 yrs on an off and on basis and never had H2S or a stuck fermentation without ever using any nutrients. Is this a grape specific problem? I may have enough grapes for some wine this year.

Dick

AxisOfBeagles wrote:

Sorry Jim, haven't done this through a lab myself so can't comment on this. Lab tests are really only practical if you live in a wine region

- don't you live in England? We're lucky because a member of our club went through the trouble of making up some test kits for YAN, so last fall we ran some tests ourselves. It's finicky but doable within about

Pp

I have made fruit wines from all sorts of random frozen juice concentrates from the grocery store (including 100% grape juice, but many others -- apple, apple + random other juice blend, pomegranate-blueberry, kiwi-orange-strawberry, or whatever else they have: so many to choose from!), and none of them has seemed to *need* yeast nutrients. I never smelled H2S and never had a stuck fermentation. Without the nutrients, some of them do ferment quite slowly, however (as in still bubbling after 2-3 months).

Utopia in Decay -- The future is coming to get you.

Kevin Cherkauer

Our local brewing supply store originally only had Montrachet and I got used to it. I understand that it is known to cause H2S but I've never had any problems. Recently, I noticed that they have several new yeasts but I haven't tried any yet.

Dick

snipped-for-privacy@hotmail.com wrote:

I never used DAP or any sort of fermentation aids early on and rarely had an issue. Hydrogen Sulfide is pretty stinky, you will know it's forming. If you add a minimal amount of any available yeast food initially and stir up your must prior to adding yeast chances are excellent you will be fine.You need to break up the cap at least once a day anyway so would notice an issue. if you had one prior to fermentation completion you could add some DAP and rack with splashing so it's easy to address.

Joe

Thanks anyway PP. Yes I am in England, it's just interesting to know :)

Jim

Coincidentally, The May/June 2008 edition of Practical Winery & Vinyard has a lead article on Nitrogen Management (pg 6)

I am still reading it, and at least some of the referenced research is still in the conceptual stage, but it is an interesting article.

Bascially, it addresses my original point of measuring nutrients rather than just blindly adding 100-200mg/L of DAP.

To be honest, much of this is a bit over my head, but I thought I would pass on the reference.