just bottled a grape concentrate

Consider saving it and use as a blending wine at a later date - or a cooking wine.

That is a sign that the wine is just young. If you want to make a quick drinking wine use less acid, aim for the low end 0.5 - 0.6% TA (or even a bit less depending on how bad you want to drink it). Also aim for a lower alcohol % (8-9%). And consider making the wine fairly sweet.

The wine you have will want to age for a year or more. The acidity levels drop over time and the alcohol mellows. Just a note, if you use Jack Kellers recipies he develops them with the assumption that the wine will be topped up with water over several rackings. So his recipies have more sugar and acidity than other recipes.

Here is another suggestion, try making it into a wine cooler with the next bottle. Just pour half a glass and add some ginger ale or Seven Up (or whatever local lemon lime soda is available).

It sounds young and high in acid but that is one way to mask that. I know a lot of old time winemakers who drink wine I might consider next to vinegar that way. A little sweet soda goes a long way.

Another option is a base for sangria, just grab whatever fruit is in season and have at it.

Joe

If your wine is made from a Welch's or Seneca note that these concentrates have acides already added to them. Adding more might make it too acidic. Use a Ph strip.