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View Full Version : Yeast nutrient question. To add, or not to add?



chefguru
09-24-2010, 01:41 AM
Ok, this might be a dumb question, but I'm curious...

What will the difference be in a final product if the fermentation is "rushed" with yeast nutrient versus a slower fermentation?

I typically add a bit of yeast nutrient to the initial mix to get the process going, but what would happen if I periodically added a little more nutrient, or mixed some nutrient in with the water I use to top off the carboy when I rack it?

I assume adding more nutrient (versus the same recipe with NO additional nutrient) would cause fermentation to complete quicker, right? And if so, would the resulting product have much difference one way or the other?

Sorry if it's a dumb question, but I was wondering about that tonight.

Medsen Fey
09-24-2010, 09:10 AM
Fermenting a honey must without nutrients usually produces a protracted slow fermentation. Undernourished yeast may produce sulfur odors, and in a highly clarified must, more acetic acid. A really long fermentation may also contribute to increased acetic acid and volatile acidity, with accompanying odors. It can easily take 6-9 months for some fermentations to finish, and often they do not complete fermentation, but end with residual sweetness, the level of which may be unpredictable. Lack of nutrients was one of the main reasons why meads have historically been known as slow, difficult fermentations.

With proper yeast management, I find the results are cleaner, and the mead smells and tastes better, and they are done much sooner.

chefguru
09-24-2010, 09:32 AM
Thanks Medsen, but that didn't answer my question...

Will beefing up the addition of yeast nutrient, and adding more of it periodically, make the yeast work faster (compared to the same batch without adding extra nutrient) and create a faster fermentation than normal?

For instance, if a batch would normally take 6 months to finish fermentation, would I be able to add more nutrient and get the yeast to work faster and finish in 3-4 months instead. And if so, how, if at all, would this cause the flavor to differ?

The only thing I gathered from your answer was that a faster fermentation might produce less acid?

Medsen Fey
09-24-2010, 09:50 AM
A properly nourished and managed yeast can typically finish a fermentation in 1-3 weeks (rather than several months). We often stagger the nutrient additions during the first half of fermentation as that seems to produce yeast with the maximal alcohol tolerance and the best chance for complete fermentation.

Starving yeast can create sulfur odors which are just foul (try RC212 without nutrients sometime if you want to see how bad it can get). Volatile acidity is essentially vinegar, and often comes with an odor of nail polish. So a protracted fermentation (other than by low temp) may create many unpleasant odors and flavors that detract from a mead, and I find the meads I have made since learning to manage the fermentations better have been much better than my earlier attempts.

That is not to say that great mead cannot be made without nutrients - Brother Adam of Buckfast abbey preferred not to use them and made meads which are legendary. He was very particular with choice of yeast and honey, and fermented and aged in barrels for years. There are more modern mead makers such as Chuck Wettergreen who make "show meads" using only honey, water, and yeast who've made many award winning meads. Again, yeast choice and honey selection/blend become critical.

I generally prefer to make use of nutrients and get the fermentations done quickly and cleanly.

Medsen

P.S. I hope I am answering your question.
P.P.S. After reading your question again, it seems you are asking about adding nutrients very late (like after racking). Generally that does not have nearly as much impact as adding them early in the fermentation. As the alcohol builds the yeast cells are less able to take up and use the nutrients, especially DAP. This leaves it hanging around for spoilage organisms to feed on. If you use nutrients, it is better to get them in early.

manwithbeers
09-24-2010, 06:04 PM
In addition to the above... Using more nutrient than the yeast can use will leave residual nutrient in the mead. This alone will cause off flavors as well as provide food for spoilage organisms. I think this is the reason stepped smaller nutrient additions work better than a single large addition.

tycoon
09-24-2010, 11:16 PM
Here where I live, there are only two shops that I know of that sell supplies and equipment usable for mead-making (they are beer brewing shops), and I haven't found yeast nutrient available yet. In the 5 batches I have made, I used only honey, water, yeast and DAP, and at least the first two turned out very nice.

Having said that, fermentation has taken some three months to finish, so when I find yeast nutrient I will try using it, as Medsen recommends.

Next year, I will also try making melomel, with grape juice. I have read that that might help on the nutrient side....

fatbloke
09-25-2010, 03:04 AM
Here where I live, there are only two shops that I know of that sell supplies and equipment usable for mead-making (they are beer brewing shops), and I haven't found yeast nutrient available yet. In the 5 batches I have made, I used only honey, water, yeast and DAP, and at least the first two turned out very nice.

Having said that, fermentation has taken some three months to finish, so when I find yeast nutrient I will try using it, as Medsen recommends.

Next year, I will also try making melomel, with grape juice. I have read that that might help on the nutrient side....
Mail order is probably your way ahead. My local HBS does carry nutrients etc, but only a limited range ("normal" wines and beers etc), so for more specific types, I only use mail order. That is how I have to get my fermaidk and GoFerm......

regards

fatbloke

chefguru
09-25-2010, 03:29 AM
Thanks. The newer answers you've provided were more of what I was looking for.

I appreciate the help.

Nubster
09-25-2010, 11:40 PM
What nutrients are recommended? I have my first batch of mead fermenting away in the basement (started them this past monday) and I used DAP according the to the instructions which was 1 tsp per gallon and I added that when I mixed everything together. Should I add more at any point prior to racking?

Medsen Fey
09-26-2010, 08:15 AM
DAP provides only ammonia nitrogen. Another product like Fermaid K which provides essential vitamins, minerals, sterols, and amino acids is also beneficial. Generally, you want to add the nutrients/energizers during the first 1/3 of fermentation.

ken_schramm
09-26-2010, 10:14 AM
Medsen's answer gets to the issue I have railed about for years. The terms "nutrient" and "energizer" are arbitrary and don't exactly address the issues clearly. What you need are a nitrogen source and a source or sources of the other nutrients that Medsen mentions - biotin and potassium in particular are pretty critical.

Yeasts are just like any other organisms. They need vitamins and nutrients to run their systems. Over eons, yeast strains became acclimated to nutrient levels in the food sources that they we bound to in their environs. Most of the strains we use have generally been isolated from grape vineyards, and some from breweries. There aren't yeast strains that perform mead fermentations in nature, because honey is hygroscopic (absorbs water, even through cell membranes), and thus tends to kill off anything in it.

So when you refer to faster or slower than normal, you are talking about a fermentation that occurs in the presence of an adequate supply of nitrogen and micronutrients. They are best able to perform a fermentation of about 10-12% ETOH with nitrogen levels around 200-300 ppm. Wine musts and high gravity beer worts have levels in that range. Without adding nitrogen, mead musts have about one tenth that.

Fermentation in wines generally occurs in about 14-28 days, so that is what we strive for in mead. You can't really accelerate much faster than the yeast wants to go on its own. You can use too much nutrient, though, and that not only leaves the stuff there to mess up the mead's taste, it also leaves valuable resources around for other spoilage organisms (that might want it to screw with your mead) to thrive on after the yeast is done. That's a bad scenario.

You can also ferment hotter, which may go more quickly, and that will tend to create a different set of aromas and flavors. How you put value judgments on the results is up to you and the people who drink your mead. Many Belgian breweries ferment stuff at higher temperatures than, say, their German counterparts, but they both make beer I love.

The biggest issue I have is the production of higher alcohols from musts that do not have adequate levels of amino acids needed by they yeast. Montrachet and EC-1118 are very susceptible strains. They give the classic mead hangover, the edgy "rocket-fuel" profile, and don't tend to age out, even over long periods. That, to me, is the classic "tell" of a mead that has had a long and stressed fermentation. My value judgment on such meads is that I don't like the way they taste and smell, or what they do to me.

I have an article on honey fermentation in the blogs. I don't know if everybody can access that, or if you need to be a patron, but if you can get a look at it, it covers a lot of what you are interested in in more detail. I love detail.

Ken

tycoon
09-27-2010, 07:07 PM
I have just read Ken's blog entries on nutrients, and I have found them very interesting. I will try to get Fermaid K or some other substitute that increases the amount of aminoacids in my musts, as I have already found out (the hard way, of course :)) about the "higher alcohols" problem that Ken refers to. I am not happy to learn that they don't disappear with aging, as I had hoped they would...

I will also investigate in older posts whether there are "natural" sources of aminoacids and other nutrients that reduce the fermentation time (with 10 degrees centrigrade of ambient temperature, it has taken me some 3+ months to finish the two batches I have made).

I bought Ken's book in Amazon and it is probably one of the best book acquisitions I have ever made :)

Wassail!

Medsen Fey
09-27-2010, 08:01 PM
Fermenting at 10 C will give you a slow fermentation, even using Champagne yeast. At that temp, even with good nutrients it can take longer than 4 weeks. Slow fermentation due to cool temperature is not a problem (and may be beneficial).

Nubster
09-27-2010, 09:06 PM
So today I am at the one week mark of my fermentation. Is it too late to add something like Fermaid K and would it be recommended? I doubt I can find any locally so I would have to order it making it end of the week before I could add it to my must.

wayneb
09-27-2010, 11:17 PM
More important than the amount of time is the current SG (relative to your starting SG). As Ken and Medsen have both suggested, getting nutrients in while your yeast can still utilize them is the real driving requirement. What was your starting gravity, and what is the SG now?

Nubster
09-28-2010, 12:45 AM
More important than the amount of time is the current SG (relative to your starting SG). As Ken and Medsen have both suggested, getting nutrients in while your yeast can still utilize them is the real driving requirement. What was your starting gravity, and what is the SG now?

Well...in all honesty it seems I went in to my first mead making experience a little less then fully informed (thanks youtube) so I have no idea. I don't have a hydrometer though I was going to order one along with my Fermaid K. I guess since even if this first batch flops, I'll need the Fermaid K and the hydrometer with future attempts, I might as well order them now so I can at least have in the future.