Sorbitol in Crab Apples?

[Adam]

We pressed a few Crimson Gold crab apples this year and several independent fermentations from different pressings (and using different strains of yeast) have all stopped dead at SG 1.005 despite significant time and prodding whereas nearly everything else we run gets down at or below SG 1.000 as expected.

I've learned from basic online research that Crimson Golds are actually Applecrabs, meaning a hybrid between crab apples and domesticated apples.

Curious if anyone here has had similar experience and/or knowledge of potential sorbitol content for this variety or other crabs as a point of reference?

Thanks!

AC

[Wes Cherry]

My Manchurian crab sticks at 1.015 to 1.022 every year.    I'm pretty sure the remaining isn't sorbitol.  

 I have tried a number of procedures to get it to restart, all failed except diluting it to approx 10%.    

Adding it 50:50 to an active ferment stopped the other ferment dead in its tracks, overnight.

I used 71b or Lalvin C yeast and fed with nutrients.

Andrew had some theories as to why it sticks.   Should be easy to find in the archives.

-'//es Cherry

Dragon's Head Cider

Vashon Island, Wa US

www.dragonsheadcider.com

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[Jonathon Bowman]

My Dolgo crabapple batches stuck at 1.010, with DV10. Tried restarting with K1V-1116 but to no success. I'd assumed it was due to a combination of the screaming levels of acid in combination with the alcohol that had been produced. Interestingly, the one batch that I did with 71B-1122 has continued to ferment, presumably as the yeast metabolizes the malic acid.

[Andrew Lea]

On 17/01/2017 22:02, Adam wrote:

>
> Curious if anyone here has had similar experience and/or knowledge of
> potential sorbitol content for this variety or other crabs as a point of
> reference?

I have never seen any specific data for sorbitol in "crab" apples
(whether true Malus species crabs or just Malus domestica dessert
hybrids).

However, the best modern data I've seen on sorbitol in dessert apples
show maximum levels in the region of 1.6%. This would be sufficient to
raise the SG by about 5 degrees, and could explain what you are seeing.

Residual SG levels higher than this are hard to explain. The only way to
find out if they are due to unfermentable sugars eg pentoses or other
polyols eg inositol would be by chemical analysis. To get any sensible
answers you would probably need to team up with a University or College
Food Science Department who can do this sort of work by HPLC. It's not
inherently difficult in the 21st century, but somebody needs to be
inspired to do it / pay for it!

Andrew

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near Oxford, UK
Wittenham Hill Cider Portal
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[Claude Jolicoeur]

Le mardi 17 janvier 2017 17:02:14 UTC-5, Adam a écrit :

We pressed a few Crimson Gold crab apples this year and several independent fermentations from different pressings (and using different strains of yeast) have all stopped dead at SG 1.005 despite significant time and prodding whereas nearly everything else we run gets down at or below SG 1.000 as expected.

How about acidity?
I have never tested it, but I would think that a solution of malic acid would have a SG higher than 1.000.
Hence a high acid juice (such as procuced by crabs) would have part of its SG coming from the malic acid.
Claude

[Andrew Lea]

On 18/01/2017 14:24, Claude Jolicoeur wrote:

>
> How about acidity?
> I have never tested it, but I would think that a solution of malic acid
> would have a SG higher than 1.000.
> Hence a high acid juice (such as procuced by crabs) would have part of
> its SG coming from the malic acid.

Good point. It could contribute. The SG of a 1% malic acid aqueous
solution is around 1.004 according to the literature. So if you assume a
'typical' cider is 0.5% acid, it would add an extra 2 degrees of gravity
above what you'd normally expect at dryness.

[Claude Jolicoeur]

Le mercredi 18 janvier 2017 09:44:06 UTC-5, Andrew Lea a écrit :

Good point. It could contribute. The SG of a 1% malic acid aqueous
solution is around 1.004 according to the literature. So if you assume a
'typical' cider is 0.5% acid, it would add an extra 2 degrees of gravity
above what you'd normally expect at dryness.

That is certainly a good contribution.
For example, Dolgo crab typically tests at a TA of around 25 g/L malic. This would be 2.5% and such acidity level could thus contribute approximately 10 points of SG...
This would correlate quite well with the SG reported by Jonathon with his Dolgo.
Claude

[Andrew Lea]

Oh I hadn't really caught up with the fact that people are fermenting high acid ornamental crabs as single variety ciders. Where I come from, they would normally only be fermented as part of a blend. Obviously in such an extreme situation the acid could indeed be a major contributor to SG. Maybe the sorbitol issue is a "red herring" in this case and the high SGs can all be explained by high acid. 

Andrew

Wittenham Hill Cider Portal
www.cider.org.uk

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[Barrett Froc]

I tried this last year Andrew, and the resulting cider had to be dumped due to the calamitous bitterness of the resulting cider (at least to my tastes). This year I blended 15% dolgo into 85% of some unknown species cooking apple with a really low TA. We'll see how well it turns out. Hopefully it's better, as I've got 35 Litres of it in carboys. I'm looking to bottle in March I think. unfortunately I had a very fast ferment that didn't slow much upon racking, so I'm not too enthusiastic, but we'll see.

[CiderSupply.com]

I wonder if high pectin levels in some crabs. Possibly do a alcohol-pectin test on a few crab juices to see if the ones with high pectin also are associated with the SGs not dropping all the way down?

Best regards
Chris Rylands

[Adam]

this is a great read, thank you for the input.

My crimson gold crabs are fairly acidic, but nowhere near a Dolgo, mine are around 10-11g/l with SG approaching 1.070 on a good batch. They are actually quite pleasant to eat (and conveniently sized for lunch boxes)

Sounds like 10g/l malic this could start to explain the ending 1.005 gravities i'm seeing consistantly.

Will do a pectin test and report back as well, thanks Chris.

Also very possible I'm bunging up the fermentation somehow.

Best,

AC

[Jay Kenney]

I found this thread interesting and wanted to add our data to it. We fermented a large batch of Dolgo Crab juice with WLP775. It began at an SG of 1.074, pH 3.01, and an estimated MA of 24 g/l (I say estimated because it was an Accuvin test, not a formal lab test). Two months later (Feb), the cider was stuck on SG 1.012 and has not moved from there since. We sent it off for testing to ETS and it came back at 20.4 g/l and 7.1% ethanol. When we did a small bottle-test blend with several other batches, which had all fermented to complete dryness, fermentation within the bottle resumed and produced an interesting bottle conditioned cider. The Dolgo was approximately 15% of the total volume of the BC blend. I'll leave it to others to speculate about the role the acid played in all of this, but suspect there were both fermentable and unfermentable sugars in the Dolgo cider when it quit fermenting in primary. Without the fermentable sugars in the Dolgo there would have been nothing to encourage bottle conditioning. Further, that combination of beginning SG and final SG predicts ABV of 8.14%. The lower actual ABV value suggests the presence of unfermentable sugars which did not convert to ethanol. I'll post more as I learn more.

[Claude Jolicoeur]

Jay, this is very interesting.

You wrote:

We fermented a large batch of Dolgo Crab juice with WLP775. It began at an SG of 1.074, pH 3.01, and an estimated MA of 24 g/l (I say estimated because it was an Accuvin test, not a formal lab test). Two months later (Feb), the cider was stuck on SG 1.012 and has not moved from there since. We sent it off for testing to ETS and it came back at 20.4 g/l and 7.1% ethanol.

This might indicate it ran out of nutrients and the fermentation got stuck there

 

When we did a small bottle-test blend with several other batches, which had all fermented to complete dryness, fermentation within the bottle resumed and produced an interesting bottle conditioned cider.

This would indicate that there were nutrients left in the dry ciders used in the blend, and this has permitted some fermentation to restart.

 

The Dolgo was approximately 15% of the total volume of the BC blend. I'll leave it to others to speculate about the role the acid played in all of this, but suspect there were both fermentable and unfermentable sugars in the Dolgo cider when it quit fermenting in primary. Without the fermentable sugars in the Dolgo there would have been nothing to encourage bottle conditioning.

I would suggest you try just one bottle of your Dolgo cider, add some DAP and a bit of yeast, and leave at room temperature under an airlock until completely fermented. This test would give you a much clearer indication of how much fermentable sugar there is in there.

 

Further, that combination of beginning SG and final SG predicts ABV of 8.14%. The lower actual ABV value suggests the presence of unfermentable sugars which did not convert to ethanol. I'll post more as I learn more.

Don't forget that there might be some measurement imprecision, both from your measurements of SG and in the lab's results. 

Claude

[Jason Mitchell (Ashridge Cider)]

I may be missing the point here, so apologies if I am, but I thought the whole thing about sorbitol was that it wasn't readily fermented by "wild yeasts", and that's why you always tend to get a residual amount after "normal" fermentations, and the SG stops at an unusually high level. This is the sorbitol. The yeasts simply cannot use it all. 

I certainly found this when making sparkling perry from UK perry pears. 

But, when you use a much more vigorous champagne style yeast as I did for making sparkling perry, the secondary fermentation carried on fine as the champagne style yeast managed to use much more of the sorbitol. A much more complicated sugar. 

So to arrive at the correct final pressure and "fizz", you do need to take the "unfermentable" sugars into consideration, otherwise bombs etc etc as discussed many times here. 

Jason

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[Andrew Lea]

Jason,

Sorry but I think you are mistaken. Long received wisdom has it that sorbitol is not fermentable by any yeast, neither wild nor cultured. But if you can point me to the science that says otherwise, I'd like to see it. Perhaps there is new knowledge out there?

Sorbitol isn't a complex sugar. It's a simple sugar alcohol. It just isn't fermentable, not even by champagne yeasts AFAIK. 

Andrew 

Wittenham Hill Cider Portal
www.cider.org.uk

[Jason Mitchell (Ashridge Cider)]

Well that's good to know. I haven't any evidence about this. I was told about this ages ago by a reputable cider maker, and took it as read. I guess this happens a fair bit. So I appreciate this being cleared up. 

I never actually measured the resulting pressure in the sparkling perry or any other measurements like final sugars etc. 

That would have shown what was really going on. 

On a very different note:

Blossom is early in Devon this year. 

Jason Mitchell

[Trevor FitzJohn]

Here is an interesting article showing normal oral microbes including bacteria and yeasts cannot easily metabolise sorbitol. http://www.apjtb.com/zz/2011s2/24.pdf

	Trevor FitzJohn
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[Jay Kenney]

Good points. I'll round up some DAP which we do not typically use and run a test bottle with a bit of yeast and see what happens. Thanks for helping me think this through

[Jay Kenney]

I am resurrecting this thread to add some 2018/19 data to that of 2016/17. I fermented another large batch of Dolgo Crab juice last fall using White Labs ECY. It began at an SG of 1.072 and a pH of 2.95. At first racking, SG was 1.011, a month after pitching, December 6, 2018. I've been checking the SG ever since and have gotten consistent readings between 1.009 and 1.011. Lab testing in early March, 2019 revealed malic acid at 17.7 g/L and ABV at 7.91%. I tried to find a local lab which would measure (for free hopefully) the unfermentable sugars, which I believe (from earlier parts of this thread) are pentoses and polyols. I was hoping to tease apart the relative contributions of malic acid and the unfermentable sugars. Sadly, the local university could only measure simple sugars, as follows: Glucose: <.01 mg/mL; Fructose: .15 mg/mL; and Sucrose: .03 mg/mL. Without being able to follow Andrew's suggestion above to measure the unfermentable sugars, there are few conclusions to draw from the data about the relative contributions of malic acid (which in this case would suggest a malic acid contribution of 7 SG points) and sorbitol, etc. I'll keep looking for a lab that can run the tests.