Smell changes

I've brewed tons of beers before, as well as a few ciders, but I'm currently fermenting my first mead and the one thing that's very different from every other thing I've made is the changes in smell. I'm not saying that the smell is different, because the smell is different for just about everything you could make, assuming the style is different. But when I make a cider or a milk stout, for example, the smell stays the same from the beginning to the end.

With my mead, the first day after fermentation started, it had a very light honey smell mixed with a light alcohol smell. The next day it had a strong alcohol smell with no sweet honey smell (unless I put my nose up to the airlock). The third day the alcohol smell was gone and there was a small to moderate sulfur smell (except when I put my nose up to the airlock) that permeated the whole room. The next day the sulfur smell was completely gone and replaced by a strong alcohol smell mixed with a yeasty smell. That smell has continued ever sense.

Anyone know the reason for the sudden changes in smell every day? None of them were bad smells, although I don't like the smell of sulfur and wonder about that one the most (particularly why it lasted for one day and only one day).

For reference, I'm using around 12 pounds of wildflower honey in a 5 gallon batch and have been using staggered nutrient additions (and have already put in my final nutrient addition). Fermenting with White Labs Sweet Mead Yeast between 66 and 72 degrees, mostly staying in the 68 to 70 degree range. As a side note, the OG was 1.072, which struck me as low for 12 pounds of honey, but I guess that's just what happens.

I'm basically just curious as I've been a fan of (drinking) mead for over 10 years now and am finally making my own.

Curious. One pound of honey has about the same amount of fermentable sugar as a pound of table sugar - In other words, it will raise the gravity by 40 points when dissolved to make up 1 gallon. So, 12 lbs in five gallons should have produced a must with a starting gravity of about 1.095. But I just started a very small batch of lavender mead last night and I dissolved 2 lbs of honey in water to make 1 gallon and the SG was about 1.070..
As for the changing smells , you say that you are feeding the yeast so close to the point when they need to be fed they may be producing more hydrogen sulfide as they stress out, and after feeding the production of that by product should be nil.

I'm curious: why staggered nutrient additions? I think I would agree with Bernard that your yeast is stressing. Probably also moving back and forth between respiration and fermentation stages as more nutrients are added. All of this could produce aroma changes. The ideal process for me is always to provide enough nutrient up front so that the yeast can ride from start to finish without my having to do anything. The only times I've found myself opening a fermenter is when something is wrong or I'm pulling a sample.

Bernard, that is interesting. I'm wondering what's the cause for that gravity discrepancy in your lavender mead and my mead.

BrewHound said:

I'm curious: why staggered nutrient additions? I think I would agree with Bernard that your yeast is stressing. Probably also moving back and forth between respiration and fermentation stages as more nutrients are added. All of this could produce aroma changes. The ideal process for me is always to provide enough nutrient up front so that the yeast can ride from start to finish without my having to do anything. The only times I've found myself opening a fermenter is when something is wrong or I'm pulling a sample.

Click to expand...

As for why:
http://www.homebrewersassociation.org/how-to-brew/improve-mead-staggered-nutrient-additions/

I did the first nutrient addition about 12 hours after fermentation started. The sulfur smell started between 2-3 days after that, but it disappeared by the next morning. Between 3-4 days into fermentation, I did my second (and last) nutrient addition. I mixed the must each time I added the nutrients, but I've left the fermenter closed since the last nutrient addition and don't plan on opening it until fermentation has 100% stopped.

I can't imagine why my yeast would be stressing. I pitched around 300-400 billion yeast cells, have kept the temperature in the optimal zone or slightly below it (White Labs says that 70-75 is the optimal temperature range and I've kept it mainly between 68-72), and I've been giving it optimal amounts of nutrients such as Fermaid K.

EDIT: At second look at Bernard's post, that may be right. I added the second nutrient addition very shortly after the very slight sulfur smell and there has been zero sulfur smell after that. It might be true that the yeast were just finishing up the last of the nutrient and might have been a little stressed by running low on yeast nutrient.

Your gravity discrepancy can be explained by variations in moisture content of the honey paired with incomplete dissolution of the honey in the must. Honey takes a fair bit of time to dissolve.

I looked again at compleat mead maker and Schramm doesn't advocate continued feeding of yeast strains. His belief is that "prolonged fermentation my produce off aromas and flavors, which may or may not diminish with age." He admits that he has no direct experience but the man knows his mead.
I may try this feeding technique on a small batch with a regular process mead going at the same time as a control and see what happens. In theory it's not a bad idea but I don't know the chemistry or yeast biology well enough to postulate what will be happening.
Post updates! I for one would like to follow how it goes!

skadalajara said:

Your gravity discrepancy can be explained by variations in moisture content of the honey paired with incomplete dissolution of the honey in the must. Honey takes a fair bit of time to dissolve.

Click to expand...

That could definitely be the case. When I added the honey water mixture to the fermenter, it was only about 4 gallons, so I added 1 more gallon of water on top. It's certainly possible that the honey could have been unequally spread out and the gravity sample that I took had less honey dissolved into it.

BrewHound said:

I looked again at compleat mead maker and Schramm doesn't advocate continued feeding of yeast strains. His belief is that "prolonged fermentation my produce off aromas and flavors, which may or may not diminish with age." He admits that he has no direct experience but the man knows his mead.
I may try this feeding technique on a small batch with a regular process mead going at the same time as a control and see what happens. In theory it's not a bad idea but I don't know the chemistry or yeast biology well enough to postulate what will be happening.
Post updates! I for one would like to follow how it goes!

Click to expand...

Well, the smell has changed once more. Now it smells VERY similar to white wine. If I put my nose up over the airlock, it has a smell that's a mixture of honey, mead, and white wine, though.

I would imagine this is pretty normal since most meads use white wine yeasts anyway and mead itself, in some ways, is similar to white wine. It's just that today is the first day that the mead has had that smell.

It's interesting since a beer's smell is essentially the same throughout the entire primary fermentation.