I learned some things about mashing at the weekend.
1. I don't actually know the science of mashing that well
2. Grain has significant thermal mass -- I suppose that's why you get wheat pillows to warm beds and things lke that.
Because I didn't take the grain into account, my mash water wasn't hot enough and I had a few problems reaching the mash temperature I wanted; I was stuck in the low 60s and adding boiling water a litre at a time didn't seem to raise it much. But I checked with some iodine, and it didn't turn black, so I can only assume I did get conversion.
This made me think of a couple of posts I read about how brewers worked before they started using thermometers in the 18th century:
applied to lager decoction and
in general . You get all sorts of methods for judging how hot the water is, such as "When it has cooled enough that the steam has cleared and you can see your reflection in the water". Obviously brewers hundreds of years ago wouldn't know precisely how hot the water is, nor did they understand the science of why the sweet malt gave off a sugary liquid when mixed with hot water. But they still managed to make beer. But did it always work?
Well, there is still an expression in modern German: "Da sind Hopfen und Malz verloren". which means the situation is hopeless, and literally it means the hops and malt are lost, and that's a good description of what happens if you mash too hot. If that happens you destroy the enzymes which convert starch into sugar, and you're left with a starchy malt soup which will never become beer whatever you do. A lost cause, in other words.
I suspect that before the widespread use of the thermometer, this must have happened fairly often.
