2 sources
Does grind size matter for cold brew?
Depends what you measure. Caffeine barely cared. In a filter bag, coarse grounds extracted about twice as much as medium. The bean mostly changed acidity.
Lab
Cold brew questions, answered from the data.
Each file takes one question, finds the research that measured it, re-plots the numbers, and says where the evidence runs out.
2 sources
How long should cold brew steep?
Caffeine levels off around 6–7 hours at room temperature. Everything else keeps dissolving, and in one tasting, 14 hours beat 22.
1 source
What actually changes between cold brew and a French press?
At room temperature, 8 hours matched the French press for strength and caffeine, with higher pH and less titratable acid. The fridge brew came out weaker.
4 sources
How long does cold brew last in the fridge?
No study sets a safe limit for home cold brew. In sealed lab bottles, bacteria stayed out for 6 weeks while sour, stale flavors crept in.
3 sources
Is cold brew actually less acidic?
By pH, barely: within about half a unit of hot coffee. By titratable acidity, yes: lower in every coffee tested, in both studies.