WHITE Grape Concentrate - 1 liter package Package. Winexpert Grape Concentrate comes in a 1 liter oxygen barrier resealable package. It can be added to wine to increase color, flavor, & sweetness & does not contain any stabilizers. The concentration is three times regular juice & the Brix is 68. Can be added to wine any time during the fermentation process but is usually used after fermentation is complete. When used after fermentation has completed, stabilizer (potassium sorbate) will need to be added at a rate of 1/2 of teaspoon per gallon of finished juice to inhibate re-fermentation. These products are NOT for making wine but for adding body and sweetness to wine. They can be used in any recipe that calls for grape concentrate also.