CEW, I am sure that someone will be able to give you a better answer because I have only used the Vintner's Harvest fruit bases in the primary fermentation to enhance a particular fruit flavor in a grape wine. For example, I just made a Barolo to which I added a can of VH Blackberry fruit base to give the wine a more pronounced blackberry undertone.
Since you are fermenting to dry and then back sweetening, if it were I, I would get the base, strain it to capture as much free run juice as possible and then squeeze the fruit as thoroughly as possible to extract all the juice possible. You could take the SG of this juice which will be very high and then calculate how much sugar is in the volume of juice that you have. I, however, am more of the Edisonian ("Trial and Error" or "Hunt and Try") school. I would start by adding a measured amount of the concentrated juice to about a gallon of the wine and take the SG. You are probably looking for something in the SG 1.015 -1.020 range, maybe more. When I reach that level in the gallon, I would scale up the addition to the remaining 4 gallons.
Since you are fermenting to dry and then back sweetening, if it were I, I would get the base, strain it to capture as much free run juice as possible and then squeeze the fruit as thoroughly as possible to extract all the juice possible. You could take the SG of this juice which will be very high and then calculate how much sugar is in the volume of juice that you have. I, however, am more of the Edisonian ("Trial and Error" or "Hunt and Try") school. I would start by adding a measured amount of the concentrated juice to about a gallon of the wine and take the SG. You are probably looking for something in the SG 1.015 -1.020 range, maybe more. When I reach that level in the gallon, I would scale up the addition to the remaining 4 gallons.
