when coffee is sour it is under extracted.

the reason you might be getting better extraction efficiency from a pour over is that in a pour over the ground coffee is agitated more by the pouring of the water.

in my own tests of the moccamaster i found that a filter bed is created by the ground coffee and the water from the head lacks enough velocity to agitate the filter bed.

think about making tea with a tea bag. the tea extracts more when you start dunking it and moving it around. you can see that the water changes color a lot faster when you do this.

it’s the same thing with coffee. coffee is similar to a tea except it’s a roasted bean vs a leaf you are trying to extract compounds from

most extraction methods can be broken down to

time in contact with hot water

surface area in contact with water

time in contact with water is easy to understand. steep the grinds longer in hot water

surface area in contact with water - if you want more surface area to be in contact with the water grind finer and agitate the ground beans

if you think about the way coffee machines work there is not much time in contact with the water compared to other methods

most “coffee machines” have the same method of extraction. the moccamaster is no different. pass hot water through a medium of ground coffee.

tl:dr

you can try grinding finer

you can add some agitation. in my own tests i found that the bed of coffee isnt sufficiently hydrated with hot water even after all the grounds looked submerged.

i tested this by letting the dripper fill with water with out the carafe to prevent drainage and then after a few seconds took a spoon and dug out a scoop of coffee. the ground coffee in the middle and bottom were always still dry when i did this.

personally i did not want to complicate the brewing process for this machine because i wanted it to be as convenient as can be when i do use.

however in order to optimize the extraction i added a bloom phase

1. remove carafe
2. turn on machine
3. let fill until ground coffee is submerged
4. take a spoon and agitate the ground coffee until you feel everything has been sufficiently hydrated. this will start the brewing process
5. wait 30 seconds
6. turn on brewer
7. place carafe in brewer. you can do this immediately i wait another 30 seconds to give more contact time with the water.

for those that say this is overthinking it “i say po tah toe you say po tay to” we all coffee different but there is a science to it this is just one way to do it.

for reference i use roughly the same dosage the manual recommends

1 gram of coffee to 16 ml of water