A lot of Acid
Posted in: Tech Help, Tips, Tricks, Techniques
You're quite likely not doing anything wrong; what you're seeing is the result of fermentation, which generates lots of organic acids - and may have been left to go longer than it probably should have. Remember that there's no 'right' way to ferment beans - this farm you're working with may very specifically be targeting acidic beans, as that may be what someone has directed them to do in the past for a specific flavor profile, be it alone or in a blend. Or it could be that they screwed up. Hard to say w/o more details. You've got a few options you could try, i think:
1) Roast at a lower temperature, for a longer period of time. You might even consider wetting the beans a bit and trying to steam off the acetic acid by azeotroping it. I probably wouldn't start with that, but it might be something to try at a later time of other approaches don't give you what you want.
2) Take the lid off your melanage, and let it melange for 3x as long. Acetic is a fairly low molecular weight organic acid - you can tell this because you can smell it. If it wasn't, you couldn't smell it. It wants to go away. You're trapping it in by keeping the lid on, and the longer you let the cycle go, the more opportunity it will have to escape. Also consider heating environment (keep it below 160F) as heat has a direct impact on volatility.
3) Try adding a little bit of baking soda to your batch. Baking soda (sodium bicarbonate) is a very weak base. You've got some acid present. Give the two a chance to dance and neutralize one another. You'll have to play with the levels, but i'd start very low.
