(Part I appeared in
the
March/April 2004 issue of GMC)
After a description
of the main types of preferments most often used
in baking, the second part of this article will
focus on the technical aspects of the preferment.
Our goal is to help bakers learn how to take full
advantage of the preparations and then decide
which preferment will work best with a specific
flour or dough. Before we get into this, let’s
look over the main advantages and the few
drawbacks of preferments.
Advantages
The main advantage
of the preferment is to bring all the benefits of
fermentation to the final dough. As discussed in
preceding articles, the fermentation process
produces gas, alcohol, and acidity in dough.
Gas, at this stage
of the baking process, does not have the same
importance as it does after mixing of the final
dough. Dough at the preferment stage is not used
to make the final product. It is used to make the
final dough that is used to make breads.
Alcohol reacts with
other substances during pre-fermentation to
generate esters. Esters are the aromatic
component of bread and are very important in
producing the flavor of the final product.
Acidity plays a more
important role than gas and alcohol at this
stage. It has three main effects on the dough and
final product. The first effect is in the
strengthening of the dough. Acidity tightens up
the protein and creates a gluten with higher
elasticity. Adding preferment to the final dough
decreases its pH which brings us to the second
effect of acidity: Lower pH increases the shelf
life of the bread by delaying the staling process
and inhibiting mold growth. Finally, as a result
of secondary fermentation, organic acids forms,
producing aromas in the dough. Those aromas will
be very important for the flavor of the final
product.
When the quality of
the flour is not optimal, the preferment can be a
great help to bakers. As noted later in this
article, some preferments can affect the strength
of the dough as well as the enzyme activity.
One additional and
important advantage of preferment is it
facilitates better work organization. By playing
with the quantity of preferment involved in the
formula, bakers can increase or decrease the
length of the first fermentation without
jeopardizing the quality of the final product. For
example, a longer first fermentation requires a
lower quantity of preferment while a shorter first
fermentation (which is usually more common in
bakeries) demands a larger quantity of
preferment.
The use of
preferment in production is definitely justified
by the longer shelf life, better flavor, improved
dough characteristics and a more efficient work
organization. However, this preparation also
presents certain inconveniences.
Drawbacks
The main drawback in
using preferment is the additional work required
before final dough mixing. In order to prepare
the preferment, additional mixing and scaling is
required either the day before or at least three
hours prior to mixing the final dough.
Extra space at ideal
conditions (room temperature or sometimes in the
cooler) is necessary to allow pre-fermentation to
happen. For heavy production, this can present an
important problem, especially if the production
area is small or the cooler space is limited.
In the designing of
a new bakery, it’s a judicious idea to plan for a
room reserved specifically for preferment. An
additional temperature control system would
certainly be even more beneficial in order to keep
the fermentation activity as consistent as
possible.
Another possible
drawback is the potential inability to plan the
exact amount of preferment needed relative to the
quantity of production. One way of bypassing this
obstacle is to require customers to place orders
at least a day in advance.
Even with all the
downsides, it remains worthwhile for bakers to
include preferments in their production especially
considering the increased quality of the final
product.
Having said this,
however, certain precise technical points in the
process have to be understood and respected in
order to obtain the full benefits from the
preferment.
Technical
considerations
Mixing
A very basic but
very important step in mixing is the precise
scaling of all the ingredients. The precision
allows the baker to regulate the fermentation
activity of the preferment to be the same everyday
and to get a very consistent final product.
Water temperature should be
generally around 60°
F but can be adjusted if the baker wants to
increase or decrease pre-fermentation time.
However, too cold a water temperature can have a
negative effect on the work of the yeast. It is
therefore preferable, when a longer
pre-fermentation is necessary, to decrease the
quantity of yeast involved in the preferment.
The main goal of the
preferment is to bring some acidity to dough. At
this point in the process, gas retention of the
dough is not important. Therefore, it is not
necessary to develop the gluten structure.
Mixing should be
long enough to fully incorporate the ingredients,
but not too long to over-oxidizing the dough. By
using faster mixers like the spiral mixers, the
mixing can be completed at first speed in 5 to 8
minutes depending on the size of the batch. For
slower mixers, like an oblique axis or vertical
mixer, 2 to 3 minutes at second speed can be added
to the mixing time after incorporation to insure a
full incorporation of all the ingredients.
For liquid
preferments, a paddle attachment is preferable to
achieve a perfect blend in a shorter period of
time. When making a poolish overnight (using a
very small amount of yeast), it is better to first
dilute the yeast in water in order to diffuse it
completely in the poolish.
Incorporation in
the final dough
Two points are
really important when adding preferment to the
final dough: timing and quantity.
Preferments are
generally added to the final dough at the
beginning or during the incorporation time of the
mixing process. However, it is sometimes
preferable to delay their incorporation.
Prefermented dough
coming from a prior batch (already fully mixed)
must be incorporated towards the end of the mixing
time to avoid a double mixing of the dough.
Double mixing could negatively effect gluten
structure, color of the crumb and flavor.
To make an autolyse,
the preferment should be added to the final dough
along with yeast and salt only after the resting
period of the autolyse. This is done in order to
avoid any incorporation of yeast in the autolyse.
Sourdough could be a possible exception to this
rule. Because of slower fermentation activity,
levain can be incorporated before the autolyse
starts. However, if the water temperature is very
cold, it’s better to incorporate the levain after
the autolyse to avoid delaying the culture’s
fermentation process.
The quantity of
preferment that the baker can include in his/her
formulas depends on the baking process. As a
general rule, anytime the first fermentation is
shorter, the quantity of preferment should be
increased to avoid penalizing the quality of the
final product. There are, of course, certain
limits. Preferment brings flavor, but also
strength to the dough. If an excessive amount of
preferment is added, the acidity level in the
dough may be too high thereby reducing dough
extensibility. A lot of factors such as the
strength of the flour, hydration, and the type of
preferment help to determine the quantity of
preferment to use in the dough.
Through a series of
baking tests, we can determine what is the right
percentage of preferment. Sometimes, practical
considerations like floor space and/or production
requirements are also part of the decision.
Average amounts are listed in part one of this
article.
It’s also
interesting to note that preferment can be used to
alter the water temperature. For example, a
prefermented dough coming from the cooler is a
good substitute to regulate dough temperature
instead of ice or cold water. On the other hand,
when using high quantity of poolish, the water
temperature has to be decreased. Sometimes at
least half of the water involved in the poolish,
needs to be at room temperature. In any case,
water temperature has to be adjusted depending on
the type and quantity of preferment used in the
final dough.
Secondary
effects of the preferment
When flour and water
get incorporated together, enzyme activity starts.
Some enzymes generate sugar degradation (amylase),
while others provoke protein degradation
(protease).
During the
pre-fermentation time, the yeast uses up a lot of
the flour’s sugar, especially during long
fermentation time at room temperature. When this
portion of flour is added back to the final dough,
the overall quantity of fermentiscibles sugar is
lower than what is usually available for the yeast
in a straight dough method. As a result of the
lower availability of sugar, it is difficult to
obtain satisfactory coloration of the crust. This
defect is sometimes noticeable when a high
percentage of overnight poolish or sponge is used
in the final dough or when the enzyme activity of
the flour is on the low side. To troubleshoot this
problem, 0.5% to 1% of diastatic malt (based on
the total flour) can be added to the final dough.
Preferments like
poolish or sponge, sometimes generate lower levels
of fermentescible sugars available at the end of
the pre-fermentation time. In certain cases, this
can be used to our advantage. A higher quantity of
preferment should be added to the final dough when
working with a high level of enzyme in the flour
(low falling number). By increasing the quantity
of preferment, we increase the portion of the
flour with less sugar available to the yeast. In
doing so we reduce a lot the fermentation activity
and the reddish crust color that is usually
obtained when too many enzymes are present in the
flour.
More liquid
preferments like poolish, because of their
liquid consistency, favor enzyme activity.
Amylase, but also protease, will be more active
during the pre-fermentation. As a result,
higher extensibility in the final dough is
obtained, reducing the mixing time of the final
dough and preserving it from potential over
oxidation. A better extensibility is also
noticeable at the shaping stage. Higher volume and
more open inside are also achieved in the final
product.
The same protease
effect also happens in preferments such as sponge
that do not have salt and ferment for a long time
at room temperature. Room temperature (versus
cooler temperature) favors enzyme activity. The
absence of salt in the preparation encourages a
higher rate of protease activity since protease is
very salt sensitive.
Sometimes we notice
that the inside of the preferment starts to
liquefy, especially at the end of the maturation
stage. This is due to an excess of enzyme
activity, and can eventually compromise the
characteristics of the final dough. To correct
this problem, 0.1% to 0.2% salt can be added
during the preparation of the preferment.
Cold doughs with
salt do not generate the same level of enzyme
activity. It is more useful to apply an autolyse
process when using prefermented dough than when
using a poolish. Flour with a tendency to generate
strong dough will give better baking performance
when used with a poolish process.
When using a poolish
or a liquid levain, autolyse are less necessary.
In fact, the preferments in those cases bring
strength, better extensibility to the dough,
flavor and shelf life to the final product.
Flavor wise, each
preferment generates different aromas depending on
its characteristics. Liquid or stiff, fermenting
at room temperature or in the cooler, salted or
unsalted, fermented with commercial yeast or wild
yeast, all those parameters will affect the types
of aromas produced and the final flavor of the
product. Although it is difficult to describe all
the flavors of each preferment, the poolish is
generally described as having a nutty flavor, the
sponge is sweeter with more acidity and the
prefermented dough is a little bit more acetic
without being sour.
The main factors to
take into consideration when opting for a specific
type of preferment are production and space
requirements, flour characteristics, and flavor.
Knowing all those parameters, the baker should be
able to decide what kind of preferment is best for
his or her production. Once the choice is made, it
is better to limit the type of preferment to two
or three kinds.
The use of
preferments is just one more example of how the
baking process can be simple and complex at the
same time. But once a baker understands how to
work with them, their usage remains the more
natural and traditional way of improving the bread
quality.
Didier began his baking career in the traditional way: at age 15,
with technical training at a regional French
professional school and an apprenticeship under a
local baker. But his love of bread and his desire
to see the world soon set him apart — and his
career on a very untraditional path.
After a few stints as staff baker in some exotic
places, Didier’s abilities caught the attention of
his employer, Club Med. He was assigned to the
clubs with the most sophisticated clientele. Then
Club Med noticed Didier’s organizational skills,
and assigned him the task of opening new or
remodeled bakeries at the company's resorts.
Included in his responsibilities was training
local bakers to work in these bakeries. In 1995,
Didier
returned to France to enhance his professional
skills at the prestigious Institut National de
Boulangerie-Patisserie in Rouen. After five months
of highly technical and business oriented
training, he was awarded a Brevet de Maitrise, a
degree that we would call a “Masters in Baking.”
While working on a private research project for
Bay States Milling Company in the United States,
Didier became unofficial trainer of the 1996
Baking Team
USA.
His expert advice and patient guidance were
important factors in the American team’s first
place finish in the bread category at the Coupe du
Monde de Boulangerie in Paris in February 1996. In
February 1999 under
Didier’s guidance the team
USA took home the gold medal of the competition
and in April 2002, the silver medal. He will be
the official coach for the 2005 Baking Team USA.
Didier has also contributed many technical articles for
newsletters and baking magazines His formulas have
been published in the professional press and are
considerate by the industry to set the standards
of quality in Artisan Baking.
When the
National Baking
Center
was created in 1996, Didier was selected to
develop and teach the Bread curriculum. His other
functions at the NBC included the supervision of
various research projects and consulting for
specialty bread bakers across the
United States,
South and Central America, Europe and Asia.
Since January 2002, he has been working as Head
Instructor for the San Francisco Baking Institute
where he continues to specialize in baking
education and consulting, nationwide and
internationally.
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