How far can I push Gervin D?

[oldbloke]

Just started a mixed berry melomel and a coffee wine and want them as strong as possible.
The only really suitable yeast I had was Gervin D.
Anybody know hown high I can push it?
And the best way to achieve that?

[Pinto]

Data on Gervin-D

Name: S.cerevisiae, strain 71B (or 71B-1122 or boulardii SD-1120)
Producer: Gervin (Varietal D (red-on-white label)), The Wine Lab, Lalvin 71B-1122 (Narbonne)
Origin: Selected in Narbonne at the Institut national de recherche en agriculture (INRA) by J.Maugenet
Used style: professionals, used for eg vin nouveau
other: long lived fresh, fruity character, native North American grapes, apples, gooseberries, rhubarb
Ferment: rapid start, moderate
Temp.s: 15ø and 30øC (59ø and 86øF)
Alcohol tolerance: 14%
Foam: low
Sediment:
SO2 tolerance:
Low nutrient tolerant: no (low nutrient needs)
Malolactic tolerant:
H2S production:
Flavour:esters
Other: sensitive competition factor; fine bouquet, can metabolise 20-40% of malic acid, rounder, smoother, quick to mature (due to low phenol extraction); very suitable for blush and residual sugar whites; excretes no urea, so the ethyl carbamate potential is extremely low

Best way I know to optimise yeast is to use it with nutrient - dont think there's a lot more you can do

[oldbloke]

Alcohol tolerance: 14%

Oh well.
I had hoped to get up to about 18.
Never mind.

[Pinto]

Thought about doing a two stage ferment ? gervin do a yeast strain that will push to 21%

http://www.brewstore.co.uk/gervin-white ... 1944-p.asp

I'd ferment it out until the activity drops and then repitch with the stronger yeast made as a starter to give it a head start

[oldbloke]

It's worth thinking about. Maybe.

[DeadFall]

Thought about doing a two stage ferment ? gervin do a yeast strain that will push to 21%

http://www.brewstore.co.uk/gervin-white ... 1944-p.asp

I'd ferment it out until the activity drops and then repitch with the stronger yeast made as a starter to give it a head start

I do that with high gravity wines and meads. start them out with a yeast for flavour and then finish up with a hg yeast. I find it gets much better results than the HG yeast on its own. Most years I make a port style elderberry wine like this, starting with a burgandy yeast.

[Benson_JV]

Give it a go anyway! I managed to push a wine yeast to 20 odd % a couple of times so I can't see any reason for not being able to get a couple more % out of it, hopefully!

[oldbloke]

Well I got hold of some of the Gervin high alcohol yeast.
I suppose I make a starter and put it in when the other yeast gives up?

Re the progressive sugar addition, do I wait until everything's nearly stopped before adding, or doesn't it matter that much?

Just added 1/2lb to the coffee wine, so that now has 2.5lb in it. I'd like to get at least another 1/2lb in if poss, and then I might want it sweet anyway so a bit more once the yeast(s) give up completely.
The berry mead is bubbling nicely and hasn't much headroom so I'll hold off adding more honey for a while - there's room for a bit more, after which I'll rack to lose the strawberry pulp and add the remaining honey.

[Pinto]

The advice i was given was to monitor the sg and add each sugar dose when the gravity reached 1.010, although without a refractometer i could see this presenting issues

[oldbloke]

Well, today I added the last 250g of honey to the melomel. It's now had enough sugars, between the fruit and the honey, to reach 19 or 20%. The Gervin D is still plugging away, but oh so slowly. I haven't taken a gravity reading so I can't tell how much sugar is still sugar, but when all the pulp has settled (there's a lot) and the yeast seems to have given up I'm going to rack it, and chuck in a starter made with Gervin's high tolerance yeast and yet more honey. I don't mind if it ends up a bit sweet, in fact it may be preferable, but I want to give it every chance to get very strong.
I also added another half pound of sugar to the coffee wine - same yeast, working a little quicker, total sugars in there now 3lb. Again I don't know how much is still sugar, and again I'll wait until the Gervin D gives up then rack and pitch a starter of the high tolerance yeast, but grown on (probably) brown sugar for this one. And bung some vanilla in it. I'll be trying to get to 4lb of sugar, all fermented, in this one.

[Pinto]

Hows this one going ?

Postie delivered into my little clutches 2 sashets of Gervin GV4 (the 21% stuff) today, all ready for my attempt at "Sui-cider" - im formulating the recipie right now and working out how much sugar will be going in to bring it to the 20% level (its frightening - in the region of 1.5kg of dextrose in a 5l batch !!) I found a useful little table HERE that gives g/l of sugar to accheive set ABVs so I plan to make up a straight TC, subtract the SG of the natural sugars and add the rest in dextrose to get max fermentation.

Carbonation could be an issue tho - maybe hold back the last 100g of dex and add it just before bottling ?

[oldbloke]

That's the table I like to look at. So much I downloaded it...
The coffee and melomel are still going, slowly (esp the melomel) on the original GervinD.
The coffee's had 3.25lb of sugar, which is only about 16.5, IF it goes to dry. So it wants another pound... Only the demi is full and I'm going to lose some when I rack, so, um, if what's left is x% and I want, oh I dunno.
The melomel has 2kg of honey, 1kg strawbs, 1kg rassies, for about 1730g usuable sugars, giving about 18.3 IF it goes dry. So when I rack I'll give it a bit more honey...