Pumpernickel Spiel
Pumpernickel is a magical bread consisting of only three simple ingredients – rye, water, salt. Yet the chemistry involved in this dense, dark, sweet and fragrant bread is anything but simple. Over the past three weeks I have dived deep into the world of pumpernickel to gain an understanding of how it really works. I’d like to share what I’ve learned so far with you.
Before doing so, I’d like to thank LinkedIn colleagues, who contributed
to the pumpernickel discussions in my last post. Your comments and feedback sparked ideas that
would not have come to me alone.
Finally, before moving on, I’d like to put out a disclaimer. I am a baker, not a scientist. My learnings are empirical and based on what
I believe to be true at this current time and place.
PREMISE
Imagine a 24-hour bake timeline. This timeline is divided into two zones. The first is labelled “Amylase”; here amylase enzymes (alpha and beta) are actively converting starches into sugars. The second is labelled “Maillard”; here sugars accumulated during the first zone interact with amino acids to create the dark color and rich flavor of this bread.
The event that separates the “Amylase” and the “Maillard” zones
along the timeline is the denaturing of amylase enzymes. This happens in the oven when the internal dough
temperature reaches the critical temperature at which amylase enzymes are no longer active.
A LinkedIn colleague and I both agree that this event takes place. However, we have opposing views of when this
event should or does occur. My
colleague believes this event takes place downstream, while I believe this
event takes place upstream. For the
purpose of this article, my premise is the event takes place upstream.
Tying this back to our timeline, the “Amylase” zone is short
(1-3 hours) and followed by a long “Maillard” phase (21-23 hours).
MIXING
Pumpernickel consists of predominantly coarsely milled flour. There are two critical aspects of mixing pumpernickel
dough – 1) all of the water must be binded, and 2) final dough consistency. The first is achieved via a long, slow
mix. As far as consistency is concerned,
the dough should be neither very hard nor very loose. Instead, it should be malleable.
SOURDOUGH
This is where things get interesting. There are two main methods employed in
traditional German rye bread baking to mitigate excessive starch hydrolysis that causes a gummy crumb. The first is a high percentage of rye sourdough - acids produced by LAB inhibit amylase
activity. The second is a high oven starting temperature - this enables internal dough temperature reach the
amylase deactivation point as quickly as possible.
With pumpernickel, it is the opposite! In fact, starch hydrolysis via enzymatic activity is encouraged. We want to accumulate sugars (Zone 1), which
are a necessary component for the Maillard action (Zone 2). Therefore, use of sourdough is actually counterproductive
to the goal.
Looking at dozens of pumpernickel formulas, the sourdough
percentage is consistently very low, mostly ranging between 5-7%. In some cases, no sourdough is used at all! When used, sourdough is considered an adjustment
to flavor profile.
SCALD
To scald or not to scald, that is the question. To scald flour, a best practice is to pour hot
water (just under the 100C boiling point) onto the grains and mix them
vigorously. The temperature of the
mixture is above the “kill point” for natural yeast, but below the “kill point”
for amylase enzymes. In science talk,
the amylase enzymes are isolated.
Therefore, the amylase enzymes can go about their job of converting
starches to sugars WITHOUT the normal subsequent fermentation activity of yeast
metabolizing those sugars.
To validate this hypothesis, I tested two doughs – one with
scald, the other without – baked in the oven at the same time under identical
conditions. The scalded dough turned out
significantly darker due to having more natural sugars.
PHOTO: the darker loaves contained 10% sourdough and 40% scald, the lighter loaf contained 20% sourdough and 0% scald.
STEAM
I cannot stress this enough.
Steam is imperative when it comes to pumpernickel. In fact, pumpernickel is technically a
steamed rather than a baked bread. With
steam, the crust remains supple and the crumb bakes evenly throughout. Without steam, the crust gets impossibly hard
and acts as a barrier to heat transferring to the center of the loaf resulting
in an underbaked loaf.
Referencing my previous post, I suspected Time,
Temperature, or Hydration as the culprits for an underbaked loaf. Well, the design of experiments suggested
otherwise, which eventually led to a separate mini trial of steam vs. no steam. Steam was the culprit and the solution.
Pumpernickel is traditionally baked in long loaf pans with
fitted lids. Bad news - steam escapes
from these lids. Other bad news - steam also
escapes from loaf pans wrapped in aluminum foil and silicone banded tight. IMO, the best method to bake pumpernickel is using
the Dutch oven concept, yet taken one step further. In fact, pumpernickel
bakeries in Germany use special ovens based on the “box inside a box inside a box” design to
generate and keep steam inside the chamber.
In a deck or home oven, this design can be imitated by placing
lidded loaf pans on plates inside a roasting pan filled with water. The entire ensemble is then wrapped/sealed shut
with aluminum foil.
You might be asking, “Why does he put his loaf pans on
plates?” This way the loaf pan is suspended, and all
sides (including the bottom) are heated identically with moist radiant heat. Otherwise, the bottom would be heated with a more
intense conduction heat and create a hard bottom crust.
BAKING
The standard baking temperature for pumpernickel is
100C. This is not an arbitrarily chosen
temperature. 100C/212F is, as we all
know, the boiling point of water. If the
temperature were lower, then there would be no generation of steam!
A higher starting bake temperature is often used to regulate the
amount of time the dough stays in Zone 1, the amylase activity period. The higher the starting temperature, the
faster the internal temperature rises to reach the denaturing temp, and vice
versa. The standard starting temperature
for pumpernickel is 150C. Once the
enzymes are denatured, the temperature is immediately set to 100C and the remainder
of the bake occurs in a falling oven.
After the bake, I recommend a full 48 hours before slicing thinly with a non-serrated knife.
FINAL THOUGHTS
As you can see, I have not shared any pumpernickel recipe here. Instead, I have shared only concepts
and techniques that might be applied to manipulating your own pumpernickel recipe
in aim of achieving a desired result. Finally,
I believe many of the learnings from pumpernickel can be correlated to
non-pumpernickel breads, e.g. application of steam with panned loaves, application
of scalded flour, and even starting temperature to optimize browning of our wheat
loaves.
Thanks for reading. I
look forward to your comments.
Peace,
Stephen
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