The first time I mashed my own grain, I was honestly surprised when wort started to flow from the mash tun’s ball valve. I understood that, yes, in theory, given enough time at the right temperature, enzymes would reduce starches in the malt to fermentable sugars. But the whole thing just seemed too…well…easy. Dare I say, magical, even?
Most of what happens when we brew beer takes place at the microscopic level, so it’s easy to forgive the writers of the 1516 Reinheitsgebot for neglecting to add yeast to the list (the first modern microscopes were at least 50–100 years away). How, then, could anyone even begin to fathom that enzymes, which are far too small for ordinary light microscopes to resolve, are responsible for the conversion of starch to sugar? For early brewers, it just sort of happened.
Fortunately, we know much more today and make substantially better beer than did sixteenth-century brewers. There are many, many enzymes at work in a typical mash, but for the vast majority of beers brewed by the vast majority of homebrewers, only two enzymes require much thought: alpha and beta amylase.