development/reduction of acids in roasting

[Freddo]

I have a batch of Samoan beans (first use of them) on the go which has a nasty acidic aftertaste. I thought a long conch might drive the acid out but the batch has been running for 96 hrs now and the acid has remained the same for the last 24 hrs.
I will keep it running but it seems rather unusual from what I have read on this forum and my experience with other beans.
Just wondering if I have a way of changing the acidity witht he roast on the next batch.

I read a white paper titled "Optimization of cocoa beans roasting process using Response Surface Methodology based on concentration of pyrazine and acrylamide" awhile ago which explained that Pyrazines are developed with roasting but also acrylimides, pyrazines = good, acriylimides =bad. They suggested the trick is to find the optimum temperature and time that the pyrazines develop without too much acrylimide. Their experiments concluded 116degC at 23min was optimum, the beans they used were Indonesian.
So i have been using this as a starting point.

Though they used nibs, not beans. and didnt explain if the nibs were held at that temperature for that time or if they were introduced to that temperature cold and left for the duration.

So one question I have is, if a roast is said to be "130degC for 30mins" does that imply putting the beans in an oven at 130degC for 30mins or get the beans up to 130degC and hold them for 30mins?

I read on this forum somewhere that a longer roast can smooth out acidity.

So in terms of my Samoan beans I am currently churning, does anyone have a suggestions on what to do with the next roast?

cheers

[anish]

Hi Freddo, Adding a pinch of common salt may hide acidity, cautious not too much....

[Sebastian]

The paper's not a very useful one, as there are so many other variables that they did not control. Bed depth, starting moisture, air flow, initial nib temperature, thermal mass, etc are all left to ones creativity. I'd suggest forgetting about that paper, and as previously noted - your acids are always a function of your fermentation. Control it there. If you don't have the abilityt o do that, and conching isn't getting rid of your volatiles, then you've got non volatile acids - which can only be chemically removed by combining them with a base. See previous note for details.

[Freddo]

Thank you Sebastian. Your learned comments are always appreciated