I called bull on the ice cube trick for cold brew until a barista in Tulsa showed me her grind log
A barista at a shop in Tulsa told me she drops a couple ice cubes straight in her cold brew concentrate before it goes in the fridge, said it keeps it from tasting flat after day three. I rolled my eyes so hard, because in my head water is water, why would ice change anything. But she pulled out this little notebook where she tracked every batch for about 5 weeks, grind setting, bean age, all of it, and the ice batches were the only ones that stayed sweet past day 3. So I tried it at home with my usual 1:8 ratio, 16 hours in the fridge, and sure enough by day 4 it still tasted like coffee instead of wet cardboard. My guess is the slow melt tops off the oxidation or something, I honestly do not know the science. She used a medium coarse grind, one step coarser than what I was doing, and that alone fixed a bitter edge I kept blaming on my beans. Anyone else messed with ice in their concentrate, or am I just late to something everybody already knew?