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-   -   Low pH -stuck @ 1.045 (http://www.homebrewtalk.com/f30/low-ph-stuck-1-045-a-151559/)

GNBrews 12-12-2009 04:47 AM

Low pH -stuck @ 1.045
 
I started a traditional mead, using 15lb of honey with Lalvin 71B-1122, on 11/20. I pitched 15g of the 71B, re-hydrating at 104F for the recommended 20mins before pitching, but did not use Go-Ferm as my LHBS was out. The must was oxygenated right after pitch; 2mins @ 1.5L/min flow rate.

The original gravity was 1.117. I used Hightest's honey calculator (http://home.comcast.net/~mzapx1/) for the staggered nutrient additions of 4.1g DAP/4.1g Fermaid-K initially, 2.5g DAP/2.5g Fermaid-K @ 1.108, and 1.6g DAP/1.6g Fermaid-K @ 1.059.

However, in my research about proper mead making, I didn't read much about how important pH control is to proper yeast health. I noticed that the fermentation was going quite strongly for the first 5 days, but has now petered-out to just over a point per day or so. At this rate, it's not going to finish like a mead managed with SNA should. So, I checked the pH, and it's around 2.8, which I've read is quite low (should be 3.7-4.6) and is probably causing my slow fermentation.

Now, the question is whether I add a bit of potassium carbonate/bicarbonate to adjust the pH and just let it go with the yeast already in suspension, or should I also add another 5g of yeast and a bit of nutrient? My guess is that the yeast already in suspension are quite stressed, and could maybe use some backup? ;)

fatbloke 12-12-2009 11:54 AM

If it were mine, I'd be trying the basics first and try the potassium carb/bicarb to bring it up to above 3.2, then it would get aerated, then possibly a bit more nutrient.

Poobah58 12-12-2009 12:15 PM

Just bring the pH up. I wouldn't aerate or feed at this point however. Stir gently to wake them up after adjusting. What is your ferm temp? How are you checking SG? Hydrometer or refractometer?

DarkStar 12-12-2009 02:54 PM

wine ph shouldn't be above 3.5, thats were most of the stability comes from compared to beer. 2.8 is little low and have had wine ferment out just fine at that level.

Adding more of the same yeast wont help, getting close to the limit for alcohol tolerance, would need to make a starter and get it acclimated to the alcohol level, ec-1118 is a good one for stuck ferments. If you make the starter stir the yeast back into suspension then add the acclimated starter to the mix.

fatbloke 12-12-2009 06:37 PM

Quote:

Originally Posted by DarkStar (Post 1736991)
wine ph shouldn't be above 3.5, thats were most of the stability comes from compared to beer. 2.8 is little low and have had wine ferment out just fine at that level.

Don't forget, this threads about mead. Mead is only "sort of" like fruit or grape wines. Yes, yeasties do like an acid environment, but "acid" is less than 7.0pH and if you dig around in the "mead world" you'll find that there's a lot of commentary about what the best pH level might be. There are those who feel that it's best between 3.5 and 4.2, there're also those who say that you shouldn't add any acid to mead musts period. Though looking into that, it seems that it's about the fact that with mead musts, the pH can leap around quite a lot, and is related to the production and stabilisation of gluconic acid compounds during fermentation. So that you just mix the must so that as longs as it's showing acid on a pH meter (don't see why litmus paper shouldn't do as well) and then fire it up to ferment. Only adding acid at the end, after the ferment has finished. The acid being calculated out as TA value. It's then up to the maker as it can then be modified "to taste"......


Quote:

Adding more of the same yeast wont help, getting close to the limit for alcohol tolerance, would need to make a starter and get it acclimated to the alcohol level, ec-1118 is a good one for stuck ferments. If you make the starter stir the yeast back into suspension then add the acclimated starter to the mix.
I didn't bother to "crunch the numbers" with any specific accuracy, but from 1117 to 1045 is a drop of 72 points, which equates to just under 10% - miles away from the tolerance quoted by Lallemand (maker of Lalvin range) of 14%. Hence if it didn't turn out to be a pH thing, I wouldn't use EC-1118 to restart, I'd try K1-V1116.

Now GNBrews didn't say if the honey was a varietal one, so moving away from 71B, which Lallemand say "enhances varietal character", to K1-V1116 which produces esters (while EC-1118 is listed as "neutral") it might be the better option..... personally I've found that EC-1118 is good but does tend to blow a lot of esters and other subtle flavours/aromas straight out through the airlock. As I say, it's good but it's like using a very blunt instrument (sledgehammer and walnut analogy comes to mind).

Besides, yeast does get very stroppy if the environment is too acid - as indicated by GNBrews original post. Hence I'd still be thinking along the lines of increase pH - 2.8 is painfully low, if it shows some sign of movement then, it'd be time to aerate and nutrient. If it did require a restart, I'd just follow the usual practices but using K1-V1116 - which is tolerant to 18% according to Lallemand (but 16% according to some independent sources). Either way, a drop of 117 points (taking 1000 as finished) is still just under 16% so well within it's ability.....

Oh, and Lallemand also list 71B as "sensitive" for a competitive factor so I'd bet it's the low pH that's an issue

hightest 12-12-2009 09:06 PM

IMO, the appropriate corrective actions would be (in order):
1) Add 5-6 g potassium bi/carbonate to reduce the must acidity.
2) Stir-up the yeast layer
3) Based on the gravities noted I would not add more nutrients or DAP
4) Try to keep the must in an area whose ambient temp is ~70F
5) Give the must yeast time to adapt and recover - 7-10 days
6) Then, recheck the SG & pH

Based on those new values you may need to consider adding another 5 g of K bi/carbonate and implementing actions for a stuck must (see the FAQ).

Lastly, yeast competitive factor is related to it's ability to protect itself from "contamination" from other yeast strains - maintaining the purity of its strain over that of an intruder - and not pH... ;)

GNBrews 12-13-2009 03:57 AM

Thanks guys. It's not quite a stuck fermentation yet, as the gravity is still going down; albeit quite slowly now. I'll bring the pH up, give the must a thorough degassing, and see where I'm at after a few days.

As for the honey, it's an orange blossom, sourced from a fellow in Florida. From what I've read, it seemed like a good honey to start-out with. I'll move on to the avocado and carrot honeys once I get the basics under control. ;)

Gravity was read with a refractometer, using the spreadsheet caluclator to bias for the presence of alcohol. I've often found my hydrometer and the corrected refractometer reading to be ~3points different, but in this case we're talking a significant amount of sugar still present, so there's not much need for picking nits.

Edit: I'm fermenting @ 65F. I'll warm 'er up a bit too if the pH doesn't sort things out by itself.

fatbloke 12-13-2009 10:08 AM

Quote:

Originally Posted by hightest (Post 1737459)
IMO, the appropriate corrective actions would be (in order):
1) Add 5-6 g potassium bi/carbonate to reduce the must acidity.
2) Stir-up the yeast layer
3) Based on the gravities noted I would not add more nutrients or DAP
4) Try to keep the must in an area whose ambient temp is ~70F
5) Give the must yeast time to adapt and recover - 7-10 days
6) Then, recheck the SG & pH

Based on those new values you may need to consider adding another 5 g of K bi/carbonate and implementing actions for a stuck must (see the FAQ).

Damn! I wish I could answer in such a clear and straight forward way - Brilliant!

Oh well, brevity is better than rambling on like I do, but I don't suppose it matters as long as the message gets across (though hightest does a better job than I ever could :rockin: ).
Quote:

Lastly, yeast competitive factor is related to it's ability to protect itself from "contamination" from other yeast strains - maintaining the purity of its strain over that of an intruder - and not pH... ;)
no, I understood that, but also whether that meant it might be sensitive to other factors as well i.e. whether a "sensitive" yeast might also "fall over" in the presence of other oppressive factors like low pH (the 100lb weakling getting sand kicked in his face on a beach analogy i.e. he gets knocked over by waves as well as the sand in the face thing......)

Obviously it was an incorrect presumption then.... not to worry :drunk:

GNBrews 12-13-2009 08:29 PM

Thanks again guys! I added 5g potassium carbonate (didn't have bicarbonate) last night, which raised the pH to 3.5. I woke up this morning to the mead happily bubbling away again! I'll have to make a note in my logbook about 71B and it's sensitivity to pH for future batches. :)

hightest 12-13-2009 09:21 PM

Quote:

Originally Posted by GNBrews (Post 1738916)
...I'll have to make a note in my logbook about 71B and it's sensitivity to pH for future batches.

It's not just 71B. Might I suggest you read the Honey Fermentation Concerns FAQ... ;)


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