mabrungard wrote:...what I found is that we do need to understand how much of the original volume we end up boiling off from each batch of beer. That is where percent is worthwhile...
I can see both your points. I need to know my system for sure. Part of that is knowing how much I normally boil off (volume) to get the proper O.G. But at the same time, Fix is talking in percentages which is a ratio of starting to ending volume...what Martin is talking about and what I'm trying to understand as it relates to flavor development...especially OFF-FLAVOR development.
I posted this question on HBT and received some helpful input. One thing that became clear upon closer reading is that Fix is talking about EXCESSIVE THERMAL LOADING which he defines as long boil times or high-temperature/high-pressure boils. The evaporation rate isn't the issue. He's using the evaporation rate as an INDICATOR of excessive thermal loading. I can hear him saying, "15%? If you're boiling off that much...you've got a really hot boil or your boiling too long." But that's without him knowing where MY volumes started or even without knowing what my boil looked like.
Also, at another place in Fix he says, "On the other hand, excessive thermal loading (e.g. uncontrolled high-temperature [...] boils) can transform the simple melanoidins into less desireable heterocyclics...Nevertheless it is excesive heat treatement - not inadeqate boiling - that is responsible for their formation."
It seems to me that the HIGH HEAT applied during a boil is the cause, not the concentration...to a certain extent. The "extract twang" that extract brewers get is related to the formation of maillard reactions during the extract production process and the continued darkening of the extract that occurs over time. So when extract brewers boil very, VERY high gravity worts for 60+ minutes, it will occur more.
In my case, I'm not doing that. I'm boiling a lower gravity wort down to an "average strength" wort, not boiling a high gravity wort and then diluting it down to an average strength wort.
Martin I have a question for you. I'm using v.3.4 of the Supporter Edition of your spreadsheet. How would you recommend I use it to calculate mineral additions? Since I'm using BIAB and full volume mashing, should I just keep the sparge water at 0 or is there something else you would recommend? Thanks!