Black Oak Brew Tips: Fix a "sour" coffee taste when brewing
Sourness in coffee can be a side effect of a light roasted coffee brewed in conditions that don’t extract enough sugars from the roast. We don’t want our coffee to taste sour; however, we do want to preserve the acidity to give the coffee finish, structure and complexity.
A coffee plant uses its organic acids as defense system from pests. The variety of those acids will vary based on soil type, variety, altitude and many more factors. It is this acidity which makes each coffee unique. In the roasting room, we try to develop the sugars during the roasting process to balance the acidity from the plant so that we don’t notice it as a prominent flavor.
All that digression is to say that if you are getting prominent sour flavors, try a finer grind, longer brew time and make sure your water is HOT.