Endogenous and exogenous enzymes in malting and brewing

The conversion of barley into beer is perhaps mankind's oldest and most complex piece of applied enzymology. Although for some companies brewing seems to be more art than science, the major brewing companies (and many of the smaller ones, too) have fine-tuned their operations based on the advances in understanding of the enzymology that underpins the process. And yet the absolute significance of all of the enzymes purported to be involved in the conversion of barley to beer is not rigorously established: c.f. just how important is lipoxygenase? Equally, there are almost certainly some enzymes whose role has been understated, e.g. esterases and peroxidases.