I have 3 separate gallon wines going as of now. 1.Blueberry strawberry Nanking Bush cherry, 2. Golden Raspberry 3. Red Raspberry /Blackberry. #1 tasted great at racking. #2 SOUR. Not off but sour. #3 yet to be determined. What's the best way to back sweeten after a month with potassium sorbate. Cane sugar, corn sugar or some juice. These are 1 gallon batches. Thanks