Well well, what do you know? That’s a question I’ve never been asked before in all my years of writing this column!
The spirit of the vintage laws for commercial wine is that the year on the label, if one is listed, reflect the year that the fresh fruit was grown. This is so consumers can, presumably, tell if it was a good year, or can help keep track of it in their cellar for aging. For blended wines like Port, some sparkling wines, and others, where a consistent house style is more important than the exact vintage date, the year is frequently not listed and is not seen as needed as a quality indicator. However, it is possible to see a “vintage” Port or Champagne where the producer thinks that the single vintage was so good as to make a special bottling from that year alone.
In your case, since it’s hard to tell the year of canned fruit, frozen fruit or concentrate, it’s impossible to give you a recommendation on vintage. Next time you use shelf-stable products for fermentation, check out the expiration date. I would hazard a guess that most frozen fruit had been picked the ripening season closest to your purchase date. Be sure to check the hemisphere of origin, however — the fresh fruit harvest in Chile, for example, is during our Northern Hemisphere winter. Grape concentrate should be pretty easy to source; because the question often comes up in winemaking many suppliers list the vintage year on the container. Canned fruit is a different matter as these items can last years on the shelf and your average pear canner in the US probably isn’t worrying about persnickety winemakers . . . they’re just concerned with the expiration date. In your case, I would think that you could just take your best guess on a date and no one but you will be the wiser, or you could go with the month or year when you started your fermentation, which is sort of like adding disgorgement dates on sparkling wine labels.