axlq wrote:

> I wonder if the difference can be tasted?

Depends on how much concentrate is used. A little, used to
add color, will have less impact than a lot (used to add
sugar).

> For two reasons:
>
> 1. Wine is made from raw grapes, whereas concentrated grape juice is
> (as far as I know) made from heated grape juice, which effectively
> pasteurizes it and changes the flavor. Sort of like the difference
> between fresh-squeezed orange juice and frozen concentrated orange
> juice; the latter has been cooked, and tastes that way.

Of course.

> 2. Concentrated grape juice (at least the frozen kind you buy in the
> grocery store) is made from Concord grapes, which have a decidedly
> different flavor than most wine varietals.

One can concentrate any kind of grape juice, including varietal grapes.

> Maybe the concentrate is used only in blended wines? I can't see a
> winemaker using it for varietal wines.

I can think of several examples of where concentrate (aka condensed
grape must) has been used in varietal wines. If you're adding just
a little for color and/or to raise residual sugar, it won't change
the varietal flavor, at least not much. Think of red wines that
are a bit "light", for example...

Dana