Hi. Here I go with my first post to this group. I've enjoyed following it for some time from the side lines.
Here's my question...
I am making about 3 gallons of an apple wine that I started with some lovely fresh apples. All was going exceedingly well until this week all seems to have stopped. I have been watching the batch carefully and there is definitely nothing going on inside that carboy. The spec.gravity has stopped at 1025, so it's not quite ready to finish just yet.
I have done some reading about re-starting the fermentation process, what I wanted was some opinions on what might be going on. I also want to be bold and just outright ask "What WOULD happen if I just added more yeast to the batch, obviously there is still sugar to feed the yeast, etc?"
I realize this is my ignorance showing and I appreciate what guidance can be offered in return.
hi chris & welcome... can you tell us please: what was yr starting SG & what yeast did you use? did you taking any other readings like TA or pH? also what else besides apples is in the 3 gals you've got going? You can always pitch more yeast...but that could just stall too. More info will allow your question to be answered more thoroughly. regards, bob
Well, first make sure it's warm enough, most yeasts work better from
20 to 30C. Just adding yeast to a stuck fermentation usually ends up in more wasted yeast. You are better off building a starter and feeding it into the batch a bit at a time (pull off some of the batch and add it to the starter, not the other way around).
Hi. The recipe is just a basic apples+water+sugar+yeast (+nutrient, campden, etc). I didn't take any extra readings when I put this one together, but the initial SG was at 1100. The batch is about a month and a half old and has been a very slow product so far - the slow bit I'm not at all worried with. It's being kept in my pantry, so it is at about room temperature all the time. Cheers Chris
Hi. Is there a special starter I should use to re-start this? Room temperature shouldn't be an issue - it's being kept in my pantry so it is always warm enough. In other news, I have a second lovely batch that is working out well; it is clearing now and I am looking forward to bottling it soon. Cheers Chris
Uhhhm, if the original SG was 1.110, then your in the potential alky-hol range of 20+ % , or as we like to refer to it, knockout juice! my cohorts & i 've been making KO-J for a couple of years.Being in that range suggests that yr yeasties gave it their all then gave up the ghost; if you're in that range, restarting the yeast is an option that will involve propagating a large, more alcohol tolerant batch to pitch & will take a few days to accomplish. Alternatively, have you tasted it yet? If your culture partyed itself into yeast-oblivion @ 20% potential alcohol, try it; it may have a pleasant sweetness to it before it sends you down tipsy street. If this is the case, fret no more- let it sit to clarify racking as usual, etc. We've bottled 4 batches of incompletely fermented KO-J w/o a bottlebomb to date. If that makes you nervous, then hit it w/ some potassium sorbate before bottling. If you want to ferment to dryness, then start your yeast in about a quart of non-sorbated juice. Once it gets going, add a cup of yr stuck wine, let it culture & keep adding stuck winein 1-2 cup increments until you get a vigorous & thriving gallon of yeast . Then pitch that... I like lalvin
Bobdrob, you might want to recheck your SG table. 1.100 SG is only going to give you 13.4% alcohol, and 1.110 is 14.9%.
Chris, I had a stuck fermentation with some Peach I did a couple years back. What I did to get it going was to prepare a new starter using apple juice. Once that was going strong I add small amounts of the stuck juice to this starter over the next three days until I had added in the all the juice from the stuck fermentation. For the stuck fermentation I used yeast that is good for restarting a stuck fermentation. Options are Red Star Premier Curvee, Lalvin 43, Lalvin EC-1118, Lalvin K1-V1116, etc. There are more listed at
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Also add some yeast energizer per package directions to ensure a strong starter. If you use dry yeast make sure to re-hydrate it properly before addiing it to your starter.
Steve's post already gave you great advice and the correct value of 'potential alcohol' for 1.100SG. (My tables came from NBS so I know they are right.) The only thing I would expand on is the amount of time to give it to get going. Starters need to get going really well before you add them to the total volume. I keep doubling the volume of the starter and let it get back to fermenting strongly.
9 or 10 % I might be happy with that. I show that as 1.022 to 1.029 S.G.
bobdrob, I show 1.115 as 19.3 % ABV; I have the book at home that probably takes them higher; I have spreadsheet I made on my work PC. I can email you the spreadsheet.
For future reference, over a month at room temperature is too slow for a healthy ferment, espically if there is still so much sugar left. Most likely cause is there is not enough active yeast in the batch, possibly also lack of nutrients. Definitely do a strong starter with a new strong yeast and restart the ferment.
Same here - don't have the tables on me but last couple of years we got some Zin and Petite Sirah grapes that were over 1.130. I remember checking the PA on those and even that was definitely under 20% - not that we fermented them that way!
As for the 0.990 vs 1.000 difference, basically, you can think about it as the table being designed so that instead of using the difference between the starting and final sg points, you're only using the starting point. In other words, the table is built with the assumption that your wine ferments completely to dryness (because that's what PA means) and gives you the PA values with that assumption.
I understand that PA starts with the potential. What I am getting at is that SG and PA are given a common correlation as being discussed in this thread. Yet, SG works on total movement (from initial to final SG). So, what is the difference between a wine with PA of 15 that finishes at SG 1.000 and a wine with a PA of 15 which finishes at
0.990?
That still *weirds me out* Many thanks and I hope this isn't too off topic.
Ray Calvert had a discussion on this point about a year ago with another poster. I don't think it was ever resolved.
In my calculations I use formulae that were developed by UC Davis. Of course, this does not mean that they are bullet proof.
In order to resolve this, I think someone (who actually cares enough - or is interested enough) to actually do an experiment and ferment a wine with a known initial SG and a final SG (both corrected for temperature - preferably with a high initial SG and a very low final SG) and send the finished wine to a certified lab for results of PA. The test is not all that expensive, especially considering all the controversy about the topic.
The final SG of a wine fermented to dryness has to account for the fact that the alcohol in the wine is less dense than water. That's why the dry wine has an SG less than 1.000. A wine at SG 1.000 is not quite dry.
Hi Paul, Yes, I'm sure to a rounding error. I have the book now. Baume (modulus 145) is what most people refer to as 'potential alcohol'. I show 34.3 brix =1.14985 S.G. .90 Baume 145 at 20C.
I really think the confusion comes from two places.
One, alcohol concentrations can be measured by volume (V/V or ABV) or weight ABW) . Most refer to ABV now and don't mention ABW. ABW is about 20% lower than ABV so maybe that is what your chart is calibrated to, weight, not volume.
More important, the potential alcohol scale is _exactly_ what it says it is. It is only a crude measuurement of potential alcohol. There in no way to measure density changes and categorically align them to actual alcohol content with precision. The type and quantity of yeast used, the temperature of fermentation and the storage conditions all play into final alcohol content. PA does not consider dry extract content either, most of which is acid and is variable to an easily measurable degree. It can't. Wine can have a little acetic acid and can have a whole lot, that affects the density too.
All that said, if you make the same wines the same way with the same materials you can probably predict pretty well what your final alcohol will be. I use those values as a rough guess of where things stand and that is it. As I see it, this scale is useful to monitor fermentation progress and very little else because then is a marginally relative measurement. Even then the acids are changing to a measurable degree and all my hydrometers measure is total density at a given temperature.
As to why it doesn't go below zero, I'm pretty sure Baume calibrated his scales with salt solutions so by definition they can't go below zero. The final gravity is much affected by dry extract content so where a dry wine will end up isn't just a matter of alcohol, it's the acid content and other dissolved solids too. The best relatively cheap way to measure alcohol is by distillation and hydrometry; that way you are measuring relatively pure components. The best cheap way to measure residual sugar is Clinitest tablets.
Physics is cool but I treat the PA scale like Myth Busters; I watch it but I don't lend a lot of weight to it... :)
Just curious, what does your book say the PA and SG equivalent to 22 Brix is?
Personally, I am not hung up on Alcohol. In fact I very much dislike the high Brix Central Valley California wines. I much more prefer the lower alcohol Mid Atlantic wines. They go a lot better with food. I guess that is why they are called "old style" wines.
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