What is a phenolic acid rest?

[BVilleggiante]

I'm reading, "Brewing with Wheat" and it talks occasionally about phenolic acid rests. Can someone please explain what phenolic acid is and what are it's characteristics?

Cheers!

 

[dwarven_stout]

Not exactly sure, but I imagine they're talking about a rest at ~110 degrees F for 20min or so. It's supposed to develop the precursors that yeast turn into clove-like phenols.

 

[rockfish42]

It's a ferulic acid rest, it increases the precursor chemical for 4-vinyl-guiaiacol which is the clove phenol produced by weizen yeasts. It's conducted at ~110F and >5.7 pH and there is some debate about it's usefulness as well as the proper duration. I usually prefer to use a clove heavy yeast like wlp380 instead of wlp300 and that seems to give me plenty of the clove character.

 

[BVilleggiante]

Thank you Rockfish, that's very helpful.

 

[944play]

Apparently, 4VG degrades into vanillin. Pretty cool.

 

[bwomp313]

Apparently, 4VG degrades into vanillin. Pretty cool.

Interesting