"Silent" fermentation

Worthewait · Oct 11, 2016

Years ago I assisted my father in making wine (commercially), but he was the Winemaster and I was primarily cheap labor. Of course, I learned some of the processes and am now trying to brush away cobwebs and apply that knowledge to making mead. My lovely wife and I are very excited about venturing into mead making. We don't have alot of space to work with so we aren't looking to generate any real volume right now. Next year will be a different story. Right now we are just beginning and we have two 1 gallon batches (our first) going and both presented the same odd quality during fermentation. I am hoping someone here can shed some light as to why. Before I go further, here are the details:

18 SEP 16 - Semi-Sweet "Show" Mead
3 lbs. Hawaiian "Rainbow Blossom" Honey... I have no idea how bees can harvest from Rainbows... We currently live in Hawaii and I can never quite get up close to them, no matter how much I stand on the gas pedal. Sorry, officer...
3.25 liters of mineral water
1/2 tsp yeast nutrient (DAP) (I know now that this was too little)
1 gram Fermaid K
Approx 1/2 packet of Red Star Premier Cuvee yeast (same as Lalvin EC-1118 )

All equipment sanitized using sodium metabisulfite and air dried.
Heated honey in 1L water 160 degrees for 5 minutes. The water actually got up to 180 degrees F (hotter than we wanted but the gas stove got away from us) and allowed to cool.
We added the 2.25 L of cool water to the primary fermenter along with DAP. Then added the Honey/water mixture.
SG at this time 1.095
Reconstituted the yeast (15 minutes) and pitched it when the must was at 82 degrees F and whisked vigorously for approx 8 minutes. The yeast can handle temps up to 95 according to packaging and literature.
Ambient temperature during this time was generally between 82-85 at the hottest time of day and goes down into the low 70s at night. The stick-on thermometer on the side of the bucket seldom reads lower than 82F however. The primary fermenter is a 3 gallon bucket with lid and fermentation lock. There is considerable air space inside since it's a 1 gallon batch in a 3 gallon container. I put on a fermentation lock from the beginning, and I am not sure why since even in wine the primary gets agitated at least once daily and is left open (for the most part).
30 SEP 16 - SG now 0.992 but there has been no real visible signs of fermentation. The primary fermenter bubbled maybe once every 2-5 minutes since starting on the 18th. We racked over to a 1 gallon glass jug with the expectation that a fair volume of yeast are still in suspension. At this time we added more honey, to be honest I lost track of the volume but once added the SG was 1.016. We added 1 gram Fermaid K and 3/4 tsp DAP simply because I wanted to try to restart the process so we could hopefully see some visible signs of fermentation (other than the SG dropping). The color is a yellow/brown and quite cloudy.
7 OCT 16 - SG 1.006, but still no visible signs of fermentation (rarely any bubbling in the fermentation lock). At this point I just went ahead and degassed the batch and just let nature take it's course.
10 OCT 16 - the SG has risen to 1.012 (which leads me to believe that 3 days ago the mead in the neck of the 1 gallon jug, where I pulled the sample, was lighter than the whole). The color is a very nice amber and is translucent. At this time we have racked again, added 1/4 tsp sparkolloid powder (reconstituted) and 1/2 tsp potassium sorbate, then put in the fridge to cold crash. It took a bit of doing to get the SG since it was semi-effervescent, but the fermentation lock was not indicating much pressure seeking to escape. This brings us to the present.

Please provide any advice or criticism on our process (we acknowledge a myriad of errors), as we have a thirst to learn that parallels our thirst for mead. What I really am seeking is an answer to is why the fermentation appeared so "silent" yet processed the sugars so effectively. The yeast is advertised as being "aggressive" and the SG readings support that claim but where were the bubbles?!? Don't get me wrong, bubbles are not the goal by any means but how better to visually assess progress then confirm with SG reading?

**************
We started another gallon batch on 1 OCT 16, same essential recipe (incl same yeast, the other 1/2 of the packet) but no heating of the honey/must and corrected the mistake of inadequate nutrient & energizer. Original Gravity of 1.104. Still no visible signs of fermentation, and on 7 OCT, the SG was 1.042 (calling that a 2/3 break), added 1/4 tsp DAP and 1/2 tsp Energizer and added honey (volume unknown - repeated that mistake) to bring SG to 1.056. On 10 OCT the SG 1.024, quite effervescent so took a bit to get a reliable SG, but calling this the 1/3 break . Added 1/4 tsp DAP and 1/2 tsp Energizer. At no time has there been any vigorous bubbling, but when adding the DAP and energizer to the mix it began to foam on the surface prior to wisking the mixture.

bernardsmith · Oct 11, 2016

Hi Worththewait, I am sure others with far more knowledge and experience than I have will happily weigh in but I can offer one possible explanation. The CO2 that the yeast produce will bubble through the airlock if that is the only escape route it has but if there are poor seals between the bung and the carboy (or bucket) or between the airlock and any grommet then those routes offer a far easier egress for the buildup of the gas. The only real effective - and simple - indicator of the activity of the yeast is the change in specific gravity.
That said, the temperature at which you are fermenting the sugars seems to me to be a little high. Is there any way that you can ferment in some kind of hacked refrigerator that allows you to ferment around 60 -65 F? That the yeast may be able to do its thing at far higher temperatures does not in fact mean that the flavors the yeast will produce at those temperatures will be flavors that you will find entirely pleasant...

Squatchy · Oct 11, 2016

So the activity you encounter when adding the mead is nucleation points from the granules allowing the suspended gasses to grab a hold of them. This often times ends up with foam rolling over the top of your carboy. Less so when you use buckets due to the added head space. To counter this: take a small amount of you must from your vessel, add your food to this and stir until it becomes desolved. Now you can add it back with very little eruption.

Your post is a great proof to why we tell people to by and use a hydrometer. Way too often people come on here and telling us this or that about how many bubbles. Bubbles don't really give us enough info to ever give good advice, as you can see. Benard said it perfectly.

Even if you don't have anything to really lower your temps try at least to place your stuff somewhere where you won't get such a great swing in temps. Lower would be better for sure but a steady temp will help a good bit as well.

Worthewait · Oct 12, 2016

bernard and Squatchy, thanks for the input. If the gasses were escaping from some other route I would expect to be able to catch the scent of fermentation in proximity to the bucket. There is none. In fact, I couldn't be sure fermentation was even taking place by odor until I took the lid off the bucket. All seals are well in place. I do have several years experience in making wine (albeit many years ago) so the processes are not new to me, although I am new to making mead. I have a hydrometer and understand well how it is used. If I didn't I would not have been able to provide that list of Specific Gravity readings along the way. From your response I should assume then that the excess (2 gallon volume) headspace remaining in the bucket has provided enough empty space for the CO2? This would conflict with distinct memories of stirring primary fermenters while making wine and the subsequent reaction resulting in significant release of an impressive volume of CO2, unless the meadmaking process is more different than I would expect. Perhaps the higher temperatures are suppressing the yeast to some extent, but then I am at a loss to explain how quickly and effectively the yeast have converted the sugars to alcohol. I am satisfied that the yeast have been effective; the SG readings make that readily apparent. I am simply trying to understand how that's possible without any detectable signs of off-gassing?

This summer, after my wife and I move to our new home, I'll have most of an entire cellar dedicated to the purpose of making mead. We'll also have 3 hives of bees (to start with) to produce our own honey. At that time we'll be in a position to better regulate temperatures during fermentation. For now, we'll make the most of what we have.

bernardsmith · Oct 12, 2016

Not sure I understand. Higher temperatures make the yeast worker harder so they produce more CO2 and more alcohol but they also produce what are called fusels and those spoil the taste of the wine (or mead). So you always want to ferment at the lower end of the yeast's tolerance for heat.
Stirring the primary has several purposes - 1) it ensures that any fruit is always kept moist (the CO2 will tend to lift the fruit to the surface and the surface of the fruit will tend to dry out and as it does become moldy). 2) stirring enables you to remove CO2 gas - The gas if left can increase the pH and if the pH increases too much that may stress the yeast and indeed stall the fermentation. 3) stirring ensures that the yeast is thoroughly mixed in the liquid. Yeast seems to have a preference for staying at particular levels in the fermenter. Not sure that a 1-5 gallon size fermenter makes much difference but certainly with larger sized fermenters the yeast will prefer a particular height and that can create problems if you are trying to ferment a batch of wine or mead. 4) stirring also assists in the degassing of the wine. That is to say , there will be less gas to remove come the time to bottle if you stir frequently during the active period of fermentation.

HeidrunsGift · Oct 12, 2016

bernardsmith said:
Not sure I understand. Higher temperatures make the yeast worker harder so they produce more CO2 and more alcohol but they also produce what are called fusels and those spoil the taste of the wine (or mead). So you always want to ferment at the lower end of the yeast's tolerance for heat.

I generally agree, but think its a little more complex than that. There is the temperature range for a yeast's tolerance, and within that, an ideal temperature range that the yeast will create the best flavor. I think its safe to say to keep the temperature range (if possible) always within the ideal temp range. The question becomes, within the ideal range, whether to ferment at the lower or higher temp range. There are pros and cons to both, so I think thats why the answer is yeast dependent.

Higher temps will create faster fermentation as you said, and the more vigorous fermentation will blow off more bad aromas like sulfuric aromas. It will also produce more fusels (not good), esters (sometimes good) and acetaldhyde (sometimes good, at least in beer).
Lower temps produce less fusels so that immediatley makes it an attractive option since in theory should make a better tasting mead. But it can also mean a slower, more sluggish fermentation which in the long run mean more stressed out yeast and more off flavors. The more gentle fermentation at this lower temp would also mean less of these off aromas are blown away during fermentation compared to a higher temp (but also less good armoas, which is a good thing).

So based off yeast strain, I would consider what the strengths and weaknesses of the yeast strain are. If it is known to start quickly, produce little to no sulfur, and ferment strongly/quickly, then I think going lower temp makes sense (again, the lower range within the ideal range). If you are worried about a sluggish fermentation, and its going to be an uphill battle for the yeast (for example maybe an extremely high SG, with step feeding) maybe helping out the yeast a little with a higher temp within the ideal range is better--risk a little bit of fusels that may age out rather than a lot of other off flavors caused by a prolonged fermentation.

What I do is consider the temperature in 3 stages: pitch, fermentation and then the diacetyl rest. Morewine making's Making white wine Manual (page 29, http://morewinemaking.com/public/pdf/wwhiw.pdf) suggests starting at slightly warmer temps, then cooling it down as fermentation gets underway. For diacetyl rest, yeast can "clean up" at higher temps (Yeast: The Practical Guide to Beer Fermnation).

So... for a yeast strain with ideal temp 57-64 degrees (and lets assume Im not worried about it getting started or producing sulfur) what I would do is start at 61 at pitch, bring it down to 59-60 until primary fermentation is over, then bring it up to 62-63 for diacetyl rest. Overall, this is primarily in the lower range but I'll change it as needed according to the phase of fermentation. BTW a cooling jacket can get temp control to within a degree so this is possible

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"Silent" fermentation

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