All the procedures described so far are termed indirect methods of
testing flours made from bread cereals. But only baking tests that show the
complex interaction of all the ingredients give real information on baking
characteristics. Carefully conducted baking tests are the only reliable way to
predict the properties of the dough and the baked products. Like the indirect
methods, the baking tests should be standardized, i.e. human influence on the results
should be excluded as far as possible. But standardization also means that the conditions
under which the tests are carried out must be reproducible, so that the result
is the same if the same flour sample is used again.
As long as these requirements are met it does not matter whether a
baking test for flour is carried out as suggested in the standard methods or
whether a special baking procedure is used to reflect the conditions at a
particular plant. The main criterion is that it must be possible to describe
the properties of the flour.
The structure of the baking test must be suitable for the raw material
and reflect the usual production process. In the case of wheat flours the mixing
system used in production must also be taken into account. For rye flours the
company's own sour dough should be used. Only then is it possible to assess the
quality of the flour accurately and make any changes to the process to
compensate for changes in the raw materials.
1. Baking Tests to Determine
the Quality of Wheat Flours
A method permitting comparability throughout the world is the baking
test with wheat flour described in ICC Standard 131. For the European region
the baking tests for pan bread and rolls and the test using wholemeal flours
for pan bread have proved very satisfactory. The following section describes
examples from Germany that can be modified for specific applications in other
countries.
2. Standard Baking Test for Pan
Bread
Made with Wheat Flours of the German Classified Types This baking test
is suitable for all wheat flours of the types classified according to their ash
content. The method reveals the baking properties of the flours from the point
of view of bread-making. The results yield information on the baked volume that
can be achieved, the texture, and the characteristics of the crumb. To permit
comparability the score can be calculated.
Even more than with the indirect methods, it is important to check the
raw materials and mechanical equipment before the baking test is performed to
ensure that it takes place under standardized conditions.
Before the dough is prepared, the moisture content of the flour must
be determined, the weight corrected to a level of 14% and the water absorption
determined in the Farinograph at 350 FU. The amount of water determined in this way, 3% fresh yeast and 1.2% salt are made up into
a dough with 500 g of flour in a laboratory mixer (arm mixer), taking the dough
development time shown in the Farinogram into account. After a resting time of
30 min and 60 min the dough is worked with 15 strokes of the mixer in each case.
When the fermentation gases have been expelled for the second time, the dough
is divided into two pieces of equal weight. This results in dough pieces that
contain 250 g of flour each.
After being made into a round shape in the ball homogenizer the dough
pieces are put in a special container to prove. The proving time is determined
on the basis of the baker's experience. The first piece of dough is placed in
the oven with the container when the normal level of proving has been reached.
The second piece of dough is used to ascertain the effects of over-proving, so
the fermentation time is extended by 20%. After baking for 30 min at 240 °C,
the loaves are brushed with water and stored in such a way that they cannot dry
out. The evaluation is made after 15 to 24 hours (Association of Cereal
Research, 1994).
3. Standard Baking Test for
Bread Rolls Made with Wheat Flour Type 550 – Rapid Mix Test
Bread rolls are made almost exclusively from wheat flour of the type
550. The Rapid Mix Test (RMT) was developed to establish the suitability of
flours of this type for making bread rolls. The name is derived from the quick
method of mixing and making the baked product. The principle of the method is
to have as many activities as possible performed by machines in order to limit human
influence on the results. Using a portion of wheat flour of the type 550 corrected
in weight to a moisture content of 14% a Farinogram is made in which the water absorption
is determined at a consistency of 500 FU. The flour must previously have been adjusted
to a Falling Number of 250 ±25 s by adding malt flour. No malt flour is added
to flours with high enzyme activity (Falling Numbers below 200 s).
The dough is prepared from 1,000 g of flour with 5% yeast, 1.5% salt,
1% each of sugar and peanut fat and 0.002% ascorbic acid (only if the flour is
untreated). The temperature of the dough should be between 26 and 27 °C. The calculation
of the water temperature should be based on the sum of the flour and room temperature.
The water temperature is the difference between this sum and key figures stated
in the comprehensive instructions for the test. The temperature of the mixing
bowl should be adjusted before the dough is prepared. The doughs are made up in
a rapid mixer with a special mixing paddle. The mixing time is only 1 min; after
20 s the sides of the bowl should be scraped.
When performing the test it must be ensured that the dough pieces are
placed in the oven no more than one hour after mixing is finished, so the dough
has to be kneaded and shaped within the resting times. The dough pieces are divided
and rolled into balls in the divider. The elongated shape is produced by a
moulder after brief intermediate proving. The machine settings are prescribed.
The rolled dough portions are placed on tilting trays with the open
side downwards and set in a precisely adjusted fermentation cabinet for 25 min
to prove. Before baking, the dough portions should be left to stiffen for 2 min
at room temperature, exposed to a fan. They are then baked at 250 °C in a deck
oven with the open side upwards. The baking time is 20 min.
4. Standard Baking Test for Pan
Bread Made with Wholemeal Wheat Flour
To test wholemeal flours a baking test can be used in which the
consistency of the dough is set at 500 FU (14% moisture content). The doughs are
made from 600 g of flour in a laboratory mixer. 10% of the flour is soured in a
one-stage sour-dough process. To prepare the dough, ascorbic acid (60 mL of a
0.1% solution) is added besides sugar, fat, salt and yeast (1.5% each).
The mixing time is based on the dough development time determined in
the Farinograph. After a resting time of 30 min the whole of the dough is put in
a rectangular loaf tin, then placed in the oven after the appropriate proving
time. The oven temperature should be 210 °C. Evaluation is carried out 15 to 20
hours after baking. The rating criteria are much the same as those for the
pan-loaf baking test with classified white flours.
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