Our pantry of sour is growing. We started with several liters of concord grape juice and a kombucha mother. The kombucha bacterias and yeasts converted the sugars in the grape juice into acetic acid. The result was sour concord grape juice. By fermenting kombucha instead of vinegar we are able to save a step to sour. Only one fermentation is needed. Kombucha allows us to sour almost anything. We have soured molasses and maple syrup. Also kombucha allows us to sweeten anything to eventually sour. Coffee is delicous. The potential for flavoring foods and drinks is tremendous.