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Freezing Grape Must

TroubleShooting

Tamara Patrick — Wilder, Idaho asks,
Q

I just finished harvesting my Merlot and Syrah today and found out I have more Merlot than I can handle at one time. If I stabilize the rest with SO2, can I freeze the must for use later?

A
If you have the freezer space I say freeze, freeze away! It’s actually somewhat common (for those grape producers who specialize in it like Brehm Vineyards, Vino Superiore, or Wine Grapes Direct) for growers to freeze grapes and ship them to areas of the country where they don’t grow so well naturally. I myself used to send Muscat grapes to a commercial food freezer in Watsonville, California to make Bonny Doon’s famous “Vin de Glaciere” dessert wine in which we pressed semi-frozen grapes to extract concentrated juice. A difference you might notice when your frozen grapes are thawed for fermentation is that the grapes will be softer and may give up their color and tannin more easily. This is because the grape skin cells, where all the color resides, get pierced by ice crystals. Maceration might be easier and fermentation might in fact be faster because compounds within the grape, including sugar and nutrients, will become available more quickly. This may mean that you will want to especially watch your fermentation temperature and keep things a little cooler if possible.
Response by Alison Crowe.