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Ask Wine Wizard

Making Dry Muscat

TroubleShooting

Cesare Lerullo — Thornhill, Ontario asks,
Q

I am going to be making wine using fresh Canelli Muscat grapes from California. I do not want a sweet wine. My question is which yeast would you recommend, and how long would you leave the skins in contact with the juice before pressing? I live in the Toronto area and have access to Lalvin yeasts.

A

Sounds tasty to me! I love a dry (or even off-dry, maybe with residual sugar of around 5 g/L), crisp Muscat wine. Historically, Muscats have been used in many wine types, from sweet and desserty to fortified to dry. I’ve made a few myself in my career, starting with the infamous “Vin de Glaciere” dessert wine and Moscato Frizzante at Bonny Doon Vineyard to a dry Muscat blending component I make for many of my dry white table wine blends today.

Muscats (which also include variants like Orange Muscat and Muscat of Alexandria) are a special family of Vitis vinifera grapes in that they contain an aromatic class of compounds called terpenes that are largely responsible for their exotic aromas. Only “free” terpenes, that is, terpenes not bound to a sugar molecule in the form of a glycoside, are detectable in the aroma of a finished wine. During fermentation, most yeast cells produce an enzyme that will help cleave off the terpenes, essentially freeing them up to contribute chemically to the wine’s aroma. Some yeast strains do this better than others and for this reason; one of my very favorite yeast types for Muscat wines is Zymaflore VL1, which is made by Laffort. I also have had success using other strains that have this same “Beta-glucosidase” activity, including Steinberger Uvaferm (AKA DGI 228) and Lallemand’s QA23 (the latter two available through Scott Labs and other outlets).

No matter which strain you use, be sure that you read up on all the specifications from the manufacturer around ideal performance conditions. For example, on Laffort’s website there is a pdf fact sheet available that tells you its maximum alcohol tolerance, ideal fermentation temperature range and relative nitrogen requirements. By adjusting your juice and fermentation conditions to each yeast’s unique ideal parameters, you maximize the chance for a successful and complete fermentation. For example, Zymaflore VL1 can ferment up to 15% alcohol but has very high nitrogen requirements, so you must make sure you are starting with at least 300 ppm “YAN” (yeast available nitrogen). If you choose to use a “special needs” yeast like VL1 it can pay off to send a sample of juice into a wine lab to get the YAN number so that you make sure you’re not left with tons of stinky hydrogen sulfide from cranky yeast covering up all your gorgeously un-bound terpenes.

With regards to your skin-contact question, I rarely purposefully give my aromatic whites any skin contact time because I’ve run into browning, tannin-extraction and bitterness issues doing that. Frequently, the travel from vine-yard to my cellar (sometimes 60 minutes, sometimes a few hours) is enough skin contact for me.

Home winemakers that are using frozen grapes or grapes toted long distances from the source need to be aware that there will already have been a certain amount of maceration happening. Frozen grapes, especially, have had many of their skin cell walls burst during the freezing process already, and as they thaw and are pressed they will release juice (and potential browning components, tannins, etc.) that much more easily. Unless you are willing to do a fining addition of pvpp, protein and or both later (and you may be, I just find it an annoying extra step), I recommend getting your aromatics by using a yeast strain with Beta-glucosidase activity and forego any kind of skin contact regimen.

Response by Alison Crowe.