Hello Home Baristars!

I am starting to cold brew coffee, and I have some questions because there are so many conflicting instructions on the interwebz...

What is the function of stirring other than to submerge the grinds? Can one actually overextract a cold brew by stirring too much?

I am going 5.5x brew ratio at room temp water/extraction for 12-16 hours. Grind is medium-coarse (think Kalita wave). Using a Lido 2, I manually sift out the fines so that I don't have to worry about them. I use home roasted beans at FC.

Any input would be helpful!

On a side note, I'm wondering if the implications of the relationship between agitation and extraction could mean that one could actually accelerate the cold brew process by means of shaking/stirring. Is there any literature or thought on this topic?

Hello, and welcome to HB.

Any time you agitate coffee while brewing you will accelerate the speed of extraction. Exactly how much of an increase depends on lots of factors like grind size and temperature in the case of cold brewing. Often times when cold brew is stirred during the brew process, it causes the fines to settle to the bottom and make decanting (when using a Toddy) very slow.

Agitation will most certainly accelerate the process. There was recently a discussion on using a blender and ultrasound to make cold brew in minutes as opposed to tens of hours. How taste compares I haven't experimented to know, but I would guess it would be brighter and more origin specific and less oxidized (generic old coffee flavor).

This thread is essentially discussing agitation and cold brewing, although it is taken to an extreme. "Emulsified" cold brew