Why Multi-step Mash Modified Grains?

[BrewerMikey]

Hi Everybody

I occasionally see recipes from companies like Castle Malting and Fermentis Yeast. In these recipes they give instructions to perform multistep mashing on modified grains(2-Row only). Anyone know why they would give these instructions? Are they trying to get you to produce a more fermentable Mash/Wort?

For example
Check recipe #16 Belgian Blonde Beer
http://www.fermentis.com/brewing/craftbrewing/tips-tricks/

 

[dgr]

Here are the steps. Ctrl-C broken?

Step 1. Mash in 75 litres at 45°C (113°C)
Step 2. Raise the mash temperature to 63°C (145°F) and rest for 55 minutes
Step 3. Raise the mash temperature to 70°C (158°F) and rest for 20 minutes
Step 4. Pump at 78°C (172°F) for 2 minutes

The mash-in is an acid rest. But they don't give a time which is odd. The chart shows about 5 minutes. I don't think you would get any acidification in that amount of time.The last step is the mash-out.

The two steps between - from braukaiser: "German brewers commonly apply a multi step saccharification rest to achieve better fermentability." http://braukaiser.com/wiki/index.php?title=The_Theory_of_Mashing

 

[JimRausch]

I agree, wierd instructions, which I'll bet they haven't changed for a decade or so.
Shouldn't need an acid rest, and the short length of time to heat up from 113* to 145* probably wouln't get you much done anyways(ie. I believe acid rests have to be loooong to get any benefit).
I don't have any problem with the 145>158 rests, except the 55 minutes at 145 will have probably completely converted all fermentables, so that the 20 minutes at 158 would be wasted. If I do a 2-step, I'll usually go 20 min at 145 and 40 min at 155-158. Think I read about that schedule in J.P.'s book.
Speculating that maybe because the recipe is a Belgian, they have a long 145 rest in order to get the driest beer possible. But still, I think the 158 rest would be wasted. Correct me if I'm wrong folks.