Cold brew concentrate went sour after 4 days in the fridge and I think I know why

Made a big batch of cold brew last Sunday with my French press. Used a 1:4 ratio like the internet says. Let it steep 20 hours at room temp. Drank some Monday and Tuesday. Thursday I pulled it out and it smelled like vinegar. Tossed the whole thing. I think the room temp steep made it go bad faster plus I didn't strain it right away. Anybody else had their cold brew turn on them after a few days?

3 comments

3 Comments

ryanburns22d ago

You let it steep 20 hours at room temp" is your problem. Cold brew is supposed to be made in the fridge for a reason. Leaving coffee sitting out that long gives bacteria a chance to grow. Room temp is the danger zone for anything wet and sugary. I've made cold brew the same way you did for years and never had it go sour because I always steep it in the fridge for 24 hours max. Straining it right away would help too but the steep temp is what really matters. Try it again but keep it cold the whole time and you should get a week out of it easy.

laura_wright22d ago

Oh man @ryanburns, I heard someone's friend lost a whole batch that way and it smelled like a science experiment gone wrong.

miles_sanchez15d ago

Actually I gotta push back a little on the fridge thing. I've seen food safety people say steeping at room temp for 12-18 hours is totally fine as long as you're starting with clean equipment and clean water. The bacteria thing is more of a concern if you're going past 24 hours or leaving it out in a warm kitchen. The fridge method works but it also takes longer to extract and you end up using more beans to get the same strength, right? As long as you're not leaving it out for two days straight, room temp steep is pretty standard for most recipes I've seen.