I have an Oatmeal Stout and want to add Butterscotch flavoring extract. I researched quite and found a butterscotch extract that is gluten free and sugar free. Is there a formula available for figuring out how much extract to use for 5 gallons of beer?
There is no formula per se, but I would start, right before bottling, pour a measured amount. and use a syringe to measure out extract, and start with very little and add it in. taste, then decide to add more or less. and then scale it up by five gallons.
each extract, is different, and you cant really come up with formula, since each one will be more or less depending on flavors.