Fermentation Not Complete

[Still Brewing]

I've followed the recipe for the lentil wash to the letter on more than one occasion but it never wants to ferment all the way down.

The sugar is always mixed in thoroughly and the temperature is kept constant with a heater but I can never get it down to below an sg of 1000. Never had a problem with getting the sg with winemaking but I struggle with this lentil wash.

What am I doing wrong, there has to be something. My latest wash has stuck on 1008 and even I can still taste sweetness in it.

My latest reading has been the same for four days, what am I doing wrong.

[chill]

My best guess is that the pH has gone lower than the yeast likes it. Try adding a tablespoon of baking soda (not baking powder!) and see if that results in any activity in 12 hours. If so, you will likely need to add more to get it to finish. That depends on how low it has gone and how much sugar is left. You might want to consider using a buffer to avoid this.

Chuck

[Mash]

Why do we have these pH problems with washes. I never suffer this with beer or wine.

[chill]

My guess is that the lack of, um, Other Things, to use the scientific term, is causing this. Wines and beers have a lot of other matter from the fruit or grains in them and this might help to buffer or stabilize the pH. With sugar, water, and a few nutrients there is not much to prevent swings. That is my guess.

Chuck

[RumJohn]

@ Still Brewing: What was SG prior to pitching your yeast? If it was too high, fermentation could have stopped due to high level of alcohol having been produced. That being the case, unfermented sugars will remain. You might be OK.

[Icefever]

+1 with RJ.

I read a book on yeast years back when I started brewing & wine making. I remember it said one thing to know about yeast....
"If all the sugars are gone, yeast dies"
"If the alcohol level is high, yeast dies"

I know this is a very simple way of looking at any problem we may have in this hobby, but it's very true. We walk a tight line when it comes to looking after this main ingredient, that gives us what we're after at the end of a wash.

I've since read a lot more about yeast, it's a fantastic but complicated little bugger...so do you have a SG for this wash ?? if so that may help.

Maybe it's time to try another type of wash??

[chill]

If he has followed the recipe to the letter as stated, he has used
Ingredients;
21lt water
5.5kg Sugar
400g Red Lentils.
50g Allinsons Bread Yeast


Which should not result in a terminally high alcohol concentration.

[Easydrinker]

I do not wish to argue with any replies here,but IMHO chill nailed it with PH issues.
A lentil wash is now my go to neutral.
These days I check PH after a couple of days,find it very low and add maybe a Teaspoon of Bicarbonate of Soda.
Sometimes I need to repeat this the next day.
For me,this ensures that the wash ferments out at around .990 in under 7 days.
I don't have the patience to just wait and see,but that may also work.

Robert.

[packapoo]

I've seen a school of thought elsewhere (don't believe it was this board) that suggests pH can be assisted by chucking a couple of suitably cleaned sea shells (cockles, whatever) into the mix.
Apparently it works.
Theory is over a period the calcium is consumed and gradually you find, next two please.
FWIW. I haven't tried it but I'm intending to.

[Mash]

+1 with RJ & Ice

Heres the detail.

By using the recipe [instead of the SG of the bucket] We can predict the outcome. Sorry to use BRIX but it is so much easier than SG.
https://en.wikipedia.org/wiki/Brix


FACT: 1˚ Brix = 1% sugar (ie 10 grams of sugar per litre)

FIND THE BRIX FROM THE RECIPE.
Therefore 5.5kg in 21l = 260 g per litre
=26% or 26 brix


FIND THE % ALC FROM THE BRIX.
FACT: Brix x 0.59 = % alcohol
So.
26 brix x .59 = 15.34% alcohol

Conclusion

15% alcohol is too much to expect from bread yeast. To be fair 15% is too much for some wine yeast strains

If the calculation above is sound, I would suggest, the PH swing is the NOT the cause - but the symptom of much sugar. It is the indicator that the yeast have drowned in the alcohol.

In short we are asking to much !!

[hampk]

I like that, Mashy.

As some of you will know from my slow fermentation posts, I've been playing with pH buffers and the wheat wash.

If I repeat Mashy's calculation with my current variation of his excellent recipe, I get an ABV of 12.98 ( I'm using 5.5 kilos of sugar in 25 litres of water) - my washes are currently getting to at least 0.990 SG.

So here is it worth trying lentils with 25 litres of water instead of 21, and chucking in the buffer to avoid pH issues as well?

Cheers

Hampk

[Mash]

Another thing to consider is how well (accurate) are we measuring the number of litres. I use the Young's wide mouth fermenters and calibrated them myself because the pre-printed gauge was nowhere near.

So is it 21 L or maybe only 19L ?

[hampk]

Another good point

Me, I'm sufficiently anal that I actually use borosilicate glass laboratory beakers in the brewhouse so I'm accurate to a few ccs!

[Still Brewing]

Wow, loads of info to take on board.

PH was bang on 5.2 like my previous two washes. Had to adjust with a little citric acid to bring my local water down a bit. Maybe my PH meteris out, its a new one, one of those yellow things from ebay.

SG of the wash before fermentation was 1082 @ 30 degrees. Temperature adjusted 1085 @ 20 degrees.

I never really had a problem with this before, especially when I wasn't adjusting the ph or adding half a campden tablet to my brewing water.

Might make the next one without these aditions.

[chill]

Is 5.2 the starting pH or the pH when it stalled? The pH will drop as the ferment proceeds unless you are using an adequate buffer. When it gets down around 3, things get pretty quiet on the fermentation scene.