Poking Holes in Pumpernickel

I plan to make the pumpernickel recipe in George Greenstein's Secrets of a Jewish Baker. However, I have some questions about the following instructions, which appear when the round loaves have been brushed with a cornstarch solution and are ready to be baked:

[quote]Punch 5 times with an ice pick or skewer, 1 hole in the center and 4 holes in a circle around the center. With a wet finger push all the way down in the center hole, leaving a large indent in the middle of the loaf.[/quote]

Do these holes serve a specific purpose? Is this a traditional way to prepare this type of loaf? Something else? Thanks.

It's traditional and useful. Gets rid of big air pockets and allows steam to escape during baking.

PiPs has a recent example of what happens when you don't dock. He called it "losing the roof", which is what happens when you fail to dock some loaves, particularly ryes: a big air hole at the top of your crumb: http://www.thefreshloaf.com/node/25615/dark-rye-revisited-problem-solving-problem-finding

Also, this thread and Paul's response: http://www.thefreshloaf.com/node/21515/what-am-i-doing-wrong

Docking is just a matter of poking holes in the dough before it goes into the oven. You can use a wooden or metal skewer, or a thin knitting needle. The idea is to provide a path for the escaping steam and other gases during baking so that they aren't trapped under the crust. Since the crust will dry and harden first, it will contain the steam being generated by the still-raw dough in the inner part of the loaf. That often creates a big bubble at the top of the loaf. The folks at www.breadandbakingscience.com have this to say about rye breads: "When the proofing period is completed, the loaves are washed with corn starch wash or egg wash and a sharp object about the size of a pencil is punched about half way through the loaf about two inches apart the full length of the loaf."

Poking with a finger? Sounds kinda kinky sticky if you ask me and not very efficient. I would think it would tend to push bubbles aside instead of popping them. In a free from loaf, finger poking might spread the loaf flat.

I often make a line of docked holes using most of the length of a moistened standard wooden toothpick and then dock a pattern so there is about one little hole every inch in every direction across the top.

@ thomaschacon - Thanks for the comments and the links. Very informative. Looking again in Greenstein's book, he calls docking stippling.

@Mini Oven - I also thought that poking the risen loaf with a finger was overdoing it. Since I plan to make two loaves, I'll make one with the finger poke and one without. If there's any interest, I'll take some pictures and post them.