Wierd plum ferment. Ideas please ?

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Wierd plum ferment. Ideas please ?

Postby Pikey » Sun Sep 10, 2017 10:35 am

I have three plum washes of 25 Litres each. They were started within a few days of each other and 2 have fermented out to 0.997 ish. I didn't actually use the hydrometer to check them - just tasted and sure enough - bitter !

The third one has started to clear, but when I took a sip - Sweet notes ! still on the dry side but a pleasant sweetness in there.

That is when I got the hydrometer out and sure enough 1030 !
Checked the other 2 and 0.997 !

Now these are all sugar heads containing whatever fruit I had picked when I made them.
The first has 11 lb fruit and 5 kg sugar in 25 litres
The second I think 7kg fruit (15.5 lb) and 5 kg sugar in 25 litres
And what I assume is the wierd one - 7 kg fruit brought to boil and simmered for a while, 5 kg sugar in 25 Litres water.

All have been fermented on the pulp and this afternoon, I was straining out the pulp ready to run them, when this anomaly appeared.

I know we have discussions about heat producing unfermentables when mashing beer - Is there any way that the fructose in the plums could be turned into unfermentables by the boiling / simmering process ? :?
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Re: Wierd plum ferment. Ideas please ?

Postby Pikey » Sun Sep 10, 2017 12:51 pm

OR have I released the pectin (setting agent in jam) which has pushed the Gravity up ?
But then - is Pectin sweet ?
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Re: Wierd plum ferment. Ideas please ?

Postby Pikey » Sun Sep 10, 2017 1:57 pm

I'm thinking - it's the pectin :shock:

Apparently pectin is a polysaccharide (therefore sweet ?) released from the cell walls of the organism by boiling.

I didn't come across any mechanism for the conversion of pectin to Methanol in my travels - anyone got a convincing link ?

[Edit - thing is this tastes GOOD - even with the yeasty stuff still in suspension - I'm thinking to save a gallon or so for real wine !]
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Re: Wierd plum ferment. Ideas please ?

Postby thecroweater » Sun Sep 10, 2017 6:48 pm

Pectin would affect your gravity for sure, be sweet tasting I'm not so sure. Pectinase will beak down the pectin but not significantly into fermentable saccharides in the way amylase breaks down starch, that would probably require a further step using a cellulase enzyme so I'm thinking probably wouldn't make it seem sweeter.
Elevated levels of pectin can metabolise into methanol but under normal conditions this should be in the range of ppm and not be of concern. Pectinase has benifits in that breaking down the pectin it really liquifies the fruit releasing my flavour and making the wine much more susceptible to clearing. Would that result in an increase in methanol production? Not necessarily but potentially. From what I understand there are a few things going on for that to happen.
Firstly wild yeasts can be a increased risk as certain strains can metabolise more methanol and the other risk factor is open ferments or ferments subject to infection as at least half a dozen strains of the clostridium bacteria are know to convert certain polysaccharides to methanol. I'm not sure why you taste a sweetness but I had a friend that attempted to ferment some sour wild plums without adding sugar and after getting something like 3 or 400 mls out of 80 litres he refermented it with added sugar. Being that it was bacically stewed in the still kettle it was a quite different result, I guess you could say kinda sweet.
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Re: Wierd plum ferment. Ideas please ?

Postby Pikey » Mon Sep 11, 2017 1:29 am

Thanks crow - I was beginning to think "Everyone has me on ignore " :lol:
If I remember right, in one of the discussions on the failure of the starch to metabolise into fermentables, der wo had said that it was metabolised into a polysaccharide ("dextrinous sugars" ? - something like that) which had some sweetness but much less than "Proper" sugar.

This wash definitely has some sweetness, which is why I tested it, but from the taste I was surprised that the gravity was as high as 1030.

In a lifetime of winemaking, I have rarely cooked fruit. Banana I always cook and PArsnip, whilst not really a fruit, definitely takes on a slight "sweetness" when boiled. Both of these make delicious wines which have sweetness, but I always make them sweet anyway. Never have I had a wine which finished with sweetness although fermented dry, although this appears to be what has occurred here. Perhaps the "Noble rot" in grapes does something similar ?
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Re: Wierd plum ferment. Ideas please ?

Postby der wo » Mon Sep 11, 2017 2:22 am

I don't think it's pectine. Perhaps because you boiled the bad ferment, you had not much oxygen in it? And the fermentation had a bad start because of that? Or you used too much sugar by mistake? Did you measure the SG? Whatever. Strip it.
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Re: Wierd plum ferment. Ideas please ?

Postby Pikey » Mon Sep 11, 2017 2:48 am

Thanks for your input der wo
- Not oxygen starvation. Always between 1/2 and 1 hour on airstone and aquarium pump.
Too much sugar ? always possible, but I take my sugar to the must in a carrier bag. I would have put 5 kg in the bag and taken it to the must. It is possible (remotely) that I took 6 kg out there, but I was on Gervin High alcohol yeast which a friend whom I trust has managed to ferment to over 20% - So an extra kg in 25 litres, would have been no problem to it.

Why are we discounting Pectin ?

[Edit - I rarely measure starting Gravity, because I "just know" that 1 kg sugar to 5 Litres wash will be fine with a decent yeast. - I just dump the granular sugar in the wash and the yeast sorts it out, so a SG would not be accurate.

ALl 3 ferments were standing on the same pallet in the same fermenters, so temperature and other environmental factors were the same for all three. ]
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Re: Wierd plum ferment. Ideas please ?

Postby der wo » Mon Sep 11, 2017 5:56 am

Pikey wrote:Why are we discounting Pectin ?

For more than one reason:
- Plums don't have so much pectin.
- You did a fruit sugarhead with only little fruit content. Less fruit means less pectin.
- Pectin is not sweet. Only small sugars are sweet.
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