Step VS Single Infusion Mash

What is the essential difference between doing a single infusion in the upper 140s as opposed to a two-step beginning in upper 140s and finishing in upper 150s? Are you ensured a more complete conversion with the latter?

 

The second, higher temp step is an alpha amylase rest. It will cleave off some longer chain sugars (dextrin) that are unfermentable, giving the beer a bit more body.

Beta amylase, which operates at lower temps, clips off simple maltose molecules which are easily fermentable. But it can’t chop off the bigger chains.

Doing both is similar to what’s called a Hochkurz mash. Usually it’s at the extremes - 145°F and 160°F for example.

Alpha works quickly but beta is slow. So you balance the rest durations according to your desired balance.

 

I’m confused about your term “cleaving off”.

 

Cleave means to cut off or break apart.

 

The biggest difference I notice is getting complete conversion. I'm sure that a lot of brewers with poor efficiency (and a medium to coarse crush) would improve efficiency by having a rest around 160F. I'm not sure if it's necessarily conversion that's so much faster at this temp, or extraction of starch from the grain, but things move MUCH faster towards completion than they do at lower mash temperatures.

 

Right. It refers to how the starch is converted to different types of sugar. A simple way to understand it is that alpha chops off big pieces, beta snips little ones.

A cleaver is a big a$$ knife.

 

I was trying to keep it simple. But that’s great detail, Doug, thank you!