Awhile back I listened to a Sunday Session podcast with Shea Comfort (from 11-23-08.)If anyone reading this hasn't listened to it I *highly* recommend it! They cover two different topics, both of which are quite helpful. The first deals with using wine yeast in beer.
Most wine yeast is incapable of digesting maltotriose which is one of the complex sugar chains present in malt. Since there's no malt in wine/mead/cider, this normally isn't an issue. Comfort talked about an enzyme called Convertase AG-300 which, when added to the fermenter in very small amounts, breaks up all the complex sugar chains into simple sugars that are easily fermentable. This will completely dry a beer out though unless a tiny, tiny, tiny amount were added.
Wine yeasts are interesting creatures to use in beer fermentation because they can impart some great fruit flavors and big mouthfeel (even in drier beers, since it isn't coming from residual sugar like most homebrewers are used to) to the final product. Ale and wine yeast strains are all members of Saccharomyces Cerevisiae, as opposed to Saccharomyces Pastorionus (lager yeast) and Brettanomyces strains. Some Sacch C. strains are killer, some are neutral, and some are susceptible. The way this breaks down is that killer strains secrete compounds which will completely kill off a susceptible strain within about 12 hours. However, they will not affect neutral strains. Neutral strains and susceptible strains will coexist fine. Pretty much all standard ale strains are susceptible.
The problem in using wine and ale strains in the same batch becomes that the wine yeast will kill off the ale strain, but won't be able to digest the maltotriose, thus the need for AG-300 enzyme to break down the maltotriose into simple sugars. Other approaches include adding the wine strain later in fermentation, after you've gotten what you want from the ale strain, or blending from a split batch using 2 or more different strains of yeast.
They discussed several different wine strains on which I took notes. White wine yeasts tend to impart either apple/pear, or tropical/citrus flavors. Red wine yeasts tend to impart cherry or berry flavors. I will outline some of the notes on specific strains here:
Susceptible, white, general fruit salad
Killer, white, champagne yeast, relatively neutral flavor, general background winey (fruit/grape, not alcohol) Useful for Belgians, etc. Good for bottle conditioning a finished beer due to its strength.
Killer, white, peach and stone fruit flavors
Killer, red, fresh berry. (Comfort suggested Stout, Porter, Kriek, Lambic as possible uses)
Killer, red, cherry, big mouthfeel (won't get broken down as it dries out). Comfort suggested 1/3 this yeast, 2/3 ale yeast in split batch. Cold crash a lot and re-yeast to bottle.
Killer, red, berrylike flavor
suggested dosage of .08-.28ml/gallon
I ordered some Convertase AG-300 to play around with and brewed a batch as an experiment. I decided to do a split batch and ferment part with WY3711 French Saison strain. (I had several packs of this in the fridge, and I really like it. I chose it for this simply because it was onhand and I was hoping the spiciness would complement the fruitiness of the wine yeast.) I opted for BM-45 for the rest to see how much cherry flavor and mouthfeel it produces.
I stuck with an extremely simple grist since this was an experimetn, adding only a small amount of Crystal malt to an otherwise all base malt bill.
Wine Yeast Experiment I
brewed on: 4/30/10
expected OG: 1.044
Expected IBUs: 31
mash temp: 152F
8 lb Maris Otter
1 lb Crystal 40L malt
2 oz Willamette @ 4% - 60 minutes
0.6 oz Kent Golding @ 4.8% - 15 minutes
1.5-2 gallons - BM45 Brunello
4 gallons - WY3711 French Saison yeast
The BM45 batch finished very early after just a couple days and I added .25ml of Convertase. Within 12 hours the fermentation picked back up again for several more days!
6/13 - The 3711 batch finished at 0.002, not unexpectedly as this yeast is a monster. The BM45 (w/ Convertase) batch completely dried out to 0.000! I have to admit I was disappointed in the lack of overwhelming cherry flavor I was hoping for from this batch. However, as I sipped the sample I did begin to pick it up. However, being bone dry obscures it a little. I blended the 2 batches together in a secondary. While I'm not expecting anything amazing from this blend, I do think the spice and fruit will complement each other well still. I need to decide if I want to augment this somehow to add some residual sugar, or possibly brett and something for it to nibble on. We'll see when I taste the blend soon, given some time to actually blend together completely.