Cold brewing at varying temperatures - How does steeping temperature affect extraction?

Question

I've always cold brewed at ambient temperatures (typically in the 68-74F range). I've recently been speaking with people who say that they only cold brew at refrigerated temperatures, stating that it enhances the flavor and smoothness of their final product.

Question is, is there a scale or ratio that relates TDS to brew time and brew temperature? I know this might not be completely linear because the ratio and grind type will also play into this, but given a consistent ratio and consistent grind, is there a somewhat predictable result?

For example

Brew at 75F for 12 hours yields TDS of 1.75
Brew at 65F for 13 hours yields TDS of 1.75
Brew at 55F for 14 hours yields TDS of 1.75
...
Brew at 35F for 16 hours yields TDS of 1.75

Answer 1

Okay, so what if I told you, that I sell a lot of cold brew at my shop, and have had success with 4-hour steeps.

I've tried a bunch of stuff, and I've realized that since the temp is really low (mild to cold), it barely makes a difference in TASTE. The biggest factor is oversteeping (like, 48hours up brew), as it can make your cold brew sour. But as a rule of thumb and for sanity of the production team, I go for cold water and steep for 8-15 hours, depending on the time of day it's made.