"Stuck fermentation" for newbies

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Scientific hippie

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Aug 8, 2018
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Greater Philadelphia
How long should one be seeing bubbles coming from the airlock? When is fermentation over, and when is it "stuck"? I have five separate gallons of elderberry must, with different yeasts. The four (with and without raisins) I have with Lalvin 1122 or Montrachet are bubbling; the one (just a couple of days older) with Lalvin 1116 has stopped bubbling. All the musts are in my basement, which is about 80 degrees. the older one's SG is > 0.99. I added the contents of a packet of Montrachet after transferring it to a gallon jug from the primary fermenter. Am I on the right track?
Sorry, but bubbles are baubles and really tell you diddly squat about the fermentation. If the seal between the bung and the airlock is poor or if the seal between the bung and the carboy or bucket lid is poor then CO2 will use that poor seal as the route of least resistance and so you will see no action in the "bubbler". Conversely even after there is not a gram of sugar left in the wine or mead but the ambient temperature rises or the air pressure increases then CO2 still absorbed in solution will be forced out and if the line of least resistance is through the airlock then you will witness bubbles.

The only real effective method of determining whether a fermentation has ended or has stalled is to take a sample of the wine and measure its gravity. If the gravity across a number of readings is falling then fermentation is still ongoing. If it is rock hard stable across a few readings then it has stopped or stalled.

When the SG hits either your target low or it shows a gravity of 1.000 or less (could be as low as 0.996 (+/-) then for all intents and purposes you can assume that fermentation has ended. If , on the other hand, the gravity is at , say 1.015 and stays there for several readings over several days that would suggest - all other things being equal - that the fermentation has stalled (It COULD mean that if your starting gravity was in the stratosphere your yeast has reached its tolerance for alcohol - so while that might look like the fermentation has "stalled".. it really has ended...
Thank you , Bernard; that is so helpful. The few little books and booklets I have never tell you when fermentation is supposed to stop. The SG IS < 1, so things are pointing to it having stopped, but to be sure I will substitute a cork for the screw top with the opening for the airlock; maybe I will put in the cylindrical airlock I am used to from the primary fermentation. I guess now it has entered the aging and racking stage?
No, it's probably ready to be racked (siphoned) to a new vessel off of the lees, topped up to have no headspace, and allowed to clear. After that, generally it should be racked after 60 days if there are any lees present, or whenever there are 1/4" or so of lees accumulated. It should be kept under airlock for quite a while longer, so that the wine can degas.

80 degrees is very warm for fermentation, and fermentation is exothermic, meaning it creates even more heat. So if your basement is 80 degrees, the fermenting wine could actually be over 90 degrees! At that temperature, the yeast go crazy and can ferment out a must in just a day or two. Ideally, you'd have it much cooler. I suggest those stick-on thermometers (like on aquariums) to monitor the temperature and take action to always keep the wine under 75 degrees, ideally even a bit lower.
Thank you, Yooper. Y'know, I finally got a book on Amazon (Home Winemaking for Dummies) so I finally understand the difference between the first fermentation and malolactic fermentation; I had not understood how soon the first fermentation ceases. I have thermometers on all my buckets; unfortunately, we are having a massive heat wave and I am just hoping for the best, being very busy (freelance job, jury duty [not picked, thank God], Jewish holidays coming up, etc.); I think it is going to break tomorrow. I did siphon the wine I was asking about; the SG was < 1 when I measured it yesterday. There is a layer of dead Montrachet on the bottom of the bottle; should I rack it again right away or can it wait?

At least this wine is from dried berries or concentrate, practice for when I get my elderberry bushes and they begin to bear fruit next year (though it smells wonderful and the little bit I taste tasted great). Before I make wine from them, I will set up either a beverage cooler or our old refrigerator in the basement to avoid heat waves like this.
You can wait on racking- just make sure you do rack if the lees get 1/4" thick or more. Some yeast strains make some terrible flavors if the lees break down, but you have plenty of time to rack if the lees get that thick. Winemaking is a great hobby for procrastinators. I finally bottled my 2013 apple wine last year- it was behind a chair in my living room for more than 4 years, with no ill effects!

What I did for temperature control was simply a bin of water with frozen water bottles added to the water every other day surrounding the fermenter. It's redneck, but it sure worked well!
That's a great idea, not "redneck"! Fortunately, the heat wave is breaking, but if we suffer another one I will definitely consider it. This is typical of me when I take up a new interest; I throw myself wholeheartedly into it without enough attention to detail. At least I have learned not to invest too much up front; some hobbies have taken off (knitting, gardening/permaculture) and some have fizzled (sewing, making crystal radios).
So, two very quick thoughts in response to what you and Yooper have mentioned.

1. At higher temperatures yeast tend to produce all kinds of compounds when they ferment, some of which you might like but many of which are likely to produce outcomes that you won't. One such outcome is that higher alcohols - fusels are produced and fusels tend to taste unpleasantly "hot" (and may be the cause of hangovers).
2. Malo-lactic fermentation, while not considered "primary fermentation" is not routinely initiated. Your wines need to have malic acids - not all fruit has malic and even fruit with malic may not have enough of that acid to make MLF worthwhile. Malic tends to be a harsh acid and so when bacteria are introduced to transform malic into lactic acid the lactic acid is much smoother and so the wine will taste less sharp.
So, while there is "primary fermentation" that term is usually applied not to the fermentation itself but to the vessel in which the fermentation takes place - and that vessel will tend to be larger than the volume being fermented, will have lots of headroom (to prevent volcanoes of froth and foam from overflowing) and may not need to be sealed. The "secondary" refers to the vessel (NOT the fermentation itself) and THAT vessel will have the same volume as the wine , be filled right up into the neck and be sealed with a bung and airlock.
Thank you for explaining that, Bernard. I understand what you mean about higher temperatures; it is probably why my usual favorite California wine now tastes like prune juice from sitting in a warm cabinet. I now keep it in the fridge.

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