I have often wondered whether the word 'mash' was applied to the brewing process because ye olde cottage brewers simply soaked and drained barley grains for a time until they sprouted and the grains were soft and mashable. That is, the grains could be squashed with something like an over-sized potato masher.
We're getting into some pretty speculative history here. I presume the early association with bread making and the fact that the earliest brewers, the Sumerians, made little cakes out of their grain before mashing them indicates some sort of cooking/malting process occurred right from the start. (Though maybe in the expectation that fresh grains would be added too later in the process). But anyway, someone with more knowledge of the historical records will have to explain that one to us.
The English word is
mash. It could be related to mashed potatoes, and I used to think it was related to the very common German verb
machen (to make) and, indeed, the relatively common English verb
make. Actually the relevant German word is
maisch, so that would seem to indicate the English brewing term and the German brewing term both came from a common root, way back in the early Dark Ages/late Ancient period when the two languages split. That is, it was a common idea even then.
At any rate, the word has a very old history in our culture and while I don't entirely disagree with the idea of old cottage brewers mashing the stuff up with a large spurtle or whatever they used to mash stuff with then, it's best to be careful when dealing with such old terms and old concepts as the meanings can change over long periods of history in quite unexpected ways.
http://etymonline.com/index.php?allowed_in_frame=0&search=mash
Etymology online says:
mash (v.)
Old English mæscan, "to mix with hot water," from same root as
mash (n.). Meaning "to beat into a soft mass" is mid-13c. Related: Mashed; mashing. For romantic sense, see
masher.
mash (n.)
"soft mixture," late Old English *masc (in masc-wyrt "mash-wort, infused malt"), from Proto-Germanic *maisk- (cognates: Swedish mäsk "grains for pigs," German Maisch "crushed grapes, infused malt," Old English meox "dung, filth"), from PIE *meik- "to mix" (see
mix (v.)). Originally a word in brewing; general sense of "anything reduced to a soft pulpy consistency" is recorded from 1590s, as is the figurative sense "confused mixture, muddle." Short formashed potatoes it is attested from 1904.