Hops and bittering algorithms – rec.crafts.brewing | Google Groups: “First, IBUs are not mg of isomerized alpha acid/1 ml of beer. That’s a commonly-given definition (including in how to brew), but it’s not right. IBUs take a measurement of the acids in beer and run it through a formula designed to align with empirical bitterness data. That measurement includes not only isoalphas (humulone, cohumulone, adhumulone) but also oxidized beta acids (lupulone, colupulone, adlupulone).”
No fixed plans. Not intent upon arriving.