Author Topic: Fermentation terminated, cause?  (Read 255 times)

Offline Xoonz

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Fermentation terminated, cause?
« on: January 11, 2020, 08:12:05 PM »
Greetings,
I rarely ask for help but I am hoping the community can assist with discovering where my problem lies with my final gravity. On 12/28/19 I brewed the following Irish Red; yes I am a freak about measuring so i can be predictable and repeatable:

6lbs Maris Otter
2lbs Vienna
1lb Acid malt
4oz Roasted Barley
1.5oz EKG First Wort Hop
1/2 Whirlfloc @ 15min
1/2 tsp Wyeast Yeast Nutrient @ 15min
Dry English Ale yeast WLP007
Detroit Metro Huron pumping station Water 28Calcium, 10.4Magnesium, 4.5Sodium, 20Sulfate, 8.5Chloride, and 82Bicarbonate

I did a starter the night before with 1000ml of 1.040 wort on a stir plate. The next day I started the mash and it hit 160F so i immediately added ice to get it to 153F, which was close to my target. After 15min I measured the pH chilled to 60F and it was at 4.8 which was way below my target of 5.2. Beersmith said 1lb of acid malt would get it to 5.2? After 60min boil my SG was at 1.061. I then vorlaufed, drained and did a batch sparge. This hit 169F with a pH of 5.0. at a SG of 1.027. I ended up with a preboil volume of 6.75gallons and a 1.044PBG. After a 60 minute boil, then chill, i ended up at a 1.048OG with 6 gallons 5.5 gallons of which made it into the fermenter.

Fermentation started at 66F in my freezer w/controller. After fermentation slowed i moved it outside the freezer on 12/31/19 and noted a SG of 1.022. I left it to sit and do its thing until 1/9/20 when i discovered it was still at 66F and a SG of 1.022 so i moved it upstairs to warm it to 70F and performed a fast fermentation test with the 10g of Mango Jacks M42 i had on hand (expiration in June of this year) on a stir plate. After 48hrs i checked the test today and it was still at 1.022. Checked the beer now at 70F and it was still at a SG of 1.022. WLP007's attenuation is 70%-80% which would put me in estimated range of 1.014 - 1.009 so i feel like this beer's specific gravity should have gone lower.

So i understand that this is a process problem when i was brewing since the test revealed the same specific gravity. Could a screwed up pH really cause a problem?

Thanks for the assistance.

Offline majorvices

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Re: Fermentation terminated, cause?
« Reply #1 on: January 11, 2020, 08:20:27 PM »
pH shouldn't have anything to do with that. Plenty of sour beers start with a pH lower than that and reach terminal gravity. Might be a dumb question but have you calibrated your hydrometer? I've seen them off as much as 8 points before. That slip of paper can move.

Offline goose

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Re: Fermentation terminated, cause?
« Reply #2 on: January 11, 2020, 09:06:33 PM »
Majorvices is right that pH should have nothing to do with reaching terminal gravity.  I have had beers in the 4.8 range after chilling and they fermented out just fine.  I agree, check your hydrometer calibration.  You will need to make up a known solution of sugar or DME and verify what the hydrometer reads. Alternatively, borrow a fellow brewers hydrometer and compare the measurements.  They should be really close unless his is out whack as well.  If you are friends with the brewer a local brewery, you can also take a sample to the brewery and let them measure it to compare with what you get.  Most times they will be glad to help you out.

Looking at your recipe, I think that 1# of acid malt is a bit much for a 5 gallon batch since the only dark grain you have is 4 oz of roasted barley for color adjustment.  My reasoning is that I made a tripel last Sunday and used only 1/2# of acid malt to get the mash pH to 5.47 which is really close to the 5.5 pH that BeerSmith predicted.  Without the 1/2# of acid malt the mash pH was predicted to be around 5.8.  Try cutting the acid malt in half the next time and see if your mash pH gets in the desirable range.  I'll bet you'll get really close.
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Offline majorvices

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Re: Fermentation terminated, cause?
« Reply #3 on: January 11, 2020, 10:46:59 PM »
I just calibrate mine in distilled water. It should read 0.000. if it is above or below just add or minus accordingly. also agree, probably don't need any acid malt in that recipe. In fact few red ales should ever need acid malt (exceptions depending on your water).

Offline jeffy

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Re: Fermentation terminated, cause?
« Reply #4 on: January 11, 2020, 11:21:22 PM »
If you are measuring with a refractometer you need to adjust it for alcohol.
If not then perhaps it was mashed in hot enough to denature the beta amalize enzymes.
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Offline goose

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Re: Fermentation terminated, cause?
« Reply #5 on: January 12, 2020, 02:53:36 PM »
If you are measuring with a refractometer you need to adjust it for alcohol.
If not then perhaps it was mashed in hot enough to denature the beta amalize enzymes.

Jeffy is right with regard to the refractometer correction.  There is a lot of information out there about the correction factor.  You can also search the archives here to find the thread on this.

Regarding the beta amaylase enzyme being denatured, it is possible.  However, if you brought the temp down rather quickly there should still be enough active enzyme left to do the job.  I once made a batch that I mis-calculated the strike temp and ended up around 158-159.  I brought it down quickly and the mash converted just fine.  RDWHAHB.
That said, if thishappens again, I suggest that you do an iodine test of the wort to insure that everything converted.  If you are not familiar with the test, a drop of iodine in a small sample of wort will turn the wort black in the presence of unconverted starch.  If there is no color change, conversion has completed.  Be sure not to get any grain in the wort sample as this will give a false reading.

Another thought.  You can pitch more yeast into the batch and see if the fermentation takes off again.
« Last Edit: January 12, 2020, 02:56:36 PM by goose »
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Offline denny

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Re: Fermentation terminated, cause?
« Reply #6 on: January 12, 2020, 03:06:11 PM »
2 comments on mash temp.....

It is generally said that it takes 20 min. to denature enzymes

Most malts these days are so highly modified that the range of acceptable mash temps is much wider than it used to be
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Offline Xoonz

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Re: Fermentation terminated, cause?
« Reply #7 on: January 12, 2020, 09:08:55 PM »
Thanks everyone. I have a hydrometer so I can check that with some distilled water. The iodine would at least give me some peace of mind, so I will check that next brew.

Offline majorvices

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Re: Fermentation terminated, cause?
« Reply #8 on: January 12, 2020, 10:06:18 PM »
Thanks everyone. I have a hydrometer so I can check that with some distilled water. The iodine would at least give me some peace of mind, so I will check that next brew.

Be careful to leave any husk behind it will turn black/purple in the presence of husk everytime. I haven't done an iodine test in years. As long as you get you temp in the range fast there shouldn't be a need.

Offline denny

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Re: Fermentation terminated, cause?
« Reply #9 on: January 13, 2020, 02:42:38 PM »
Thanks everyone. I have a hydrometer so I can check that with some distilled water. The iodine would at least give me some peace of mind, so I will check that next brew.

Personally I find the iodine test so unreliable I quit doing it.
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Offline dmtaylor

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Re: Fermentation terminated, cause?
« Reply #10 on: January 13, 2020, 03:23:39 PM »
I see a combination of effects here.

1) You used WAY too much acid malt.  I wonder if you were supposed to use 1 ounce, or perhaps 0.1 lb, instead of 1 full pound?!  This is why your mash pH was so low.

2) The low mash pH could have inhibited proper breakdown of starches and complex dextrins, which are not as fermentable as normal wort.  And also...

3) The initial burst of temperature at 160 F might have killed some of your enzymes, depending how long it was up there.  And is it possible the initial temperature was actually even higher like 165-170 F, and only reached 160 F after several minutes?  In any case, some or maybe all of your beta amylase died here.

The combination of all these things together caused your high FG.  I think it's not just one thing, but at least 2 or 3 of the above.
Dave

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Offline Visor

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Re: Fermentation terminated, cause?
« Reply #11 on: January 14, 2020, 04:49:34 PM »
Thanks everyone. I have a hydrometer so I can check that with some distilled water. The iodine would at least give me some peace of mind, so I will check that next brew.

Personally I find the iodine test so unreliable I quit doing it.

   I've seen you say this before Denny, and I am curious about 2 things. 1st is unreliable in what way, and 2nd is what alternative method of testing for unconverted starches did you use to determine that the iodine test is inherently flawed?
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Offline denny

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Re: Fermentation terminated, cause?
« Reply #12 on: January 14, 2020, 05:17:54 PM »
Thanks everyone. I have a hydrometer so I can check that with some distilled water. The iodine would at least give me some peace of mind, so I will check that next brew.

Personally I find the iodine test so unreliable I quit doing it.

   I've seen you say this before Denny, and I am curious about 2 things. 1st is unreliable in what way, and 2nd is what alternative method of testing for unconverted starches did you use to determine that the iodine test is inherently flawed?

1) unreliable in that I've seenm people get readings that tell them conversion isn't done in 4-6 hours.  It's told me that I don't have conversion when a conversion efficiency table tells me I have

2) I almost never check to see.  I rely on science...appropriate time at appropriate temp means you WILL have conversion.  If I want to check, I check my conversion efficiency using Kai's chart
Life begins at 60.....1.060, that is!

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