Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR MAKING BREADS
BACKGROUND OF THE INVENTION
The present invention relates to a method for making
breads, more specifically, by incorporating potassium
bromate as an oxidizing agent into a bread dough, wherein
the resulting baked breads are free from residual bromate.
Potassium bromate has been widely used in the world
since 1910s when it was recommended as a bread improves in
the United States. In Japan, there is a guideline for use
of potassium bromate, stating that "potassium bromate is
limited to use for yeast leavened bakery products in an
amount of up to 0.03 g (as bromate) per kg of wheat flour
(i.e., 30 ppm based on wheat flour) and should be
decomposed or removed before completing final products,"
that is, potassium bromate must not remain in the products
after baking.
In conventional techniques, prevention of residual
bromate in bakery products has been accomplished, either by
us ing suf f icient time f or f ermentation and baking of a
dough to ensure complete chemical reaction of bromate or by
incorporating a reduced amount of potassium bromate, or
both.
The inventors of the present invention have already
developed a method for prevention or reduction of residual
bromate in bakery groducts by incorporating ascorbic acid
(see, e.g., JP 8-11&857 A).
The limitation "bromate should be decomposed or
removed" or "bromate must not remain" in the Japanese
guideline is intended to mean that bromate cannot be
detected when measured by the most sensitive analysis at
the time of the measurement, i.e., that bromate is below
the detection limit. In view of this limitation, the
inventors of the present invention have attempted to
incorporate ferrous sulfate in the step of preparing a
dough using potassium bromate and have succeeded in
reducing residual bromate in bakery products to lass than
3 ppb, a non-detectable level as measured by their
developed ultra-sensitive HFLC (high performance liquid
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chromatography) analysis with a detection limit of 3 ppb
for bromate in the bakery products (see, e.g., Japanese
Patent No. 3131898).
However, the term "free from residual bromate" or
"prevention of residual bromate" as used herein is intended
to mean that bromate does not remain in amounts of 1 ppb
and more, the "detection limit for bromate°' as measured by
further improved state-of-the-art HPLC analysis at the
first filing of the present invention in Japan.
However, the above conventional techniques neither
confirm their efficacy for complete removal or significant
reduction of residual bromate in breads, nor disclose the
incorporation of potassium bromate as an aqueous solution.
Further, in these conventional techniques, ferrous sulfate
is incorporated in an amount of 50 ppm to 370 ppm based on
total wheat flour required to prepare a dough, which amount
significantly exceeds the range acceptable for the breads
of the present invention to maintain the loaf volume,
flavor and taste of breads.
SUMMARY OF THE INVENTION
There has been a need to develop a method for
preparing a bread dough which allows improvements in the
quality of baked breads by incorporating potassium bromate
into the bread dough and which provides breads completely
free from the incorporated bromate or with-a bromate
content reduced to less than l ppb, the detection limit for
bromate. It has also been desired to develop a method for
making breads using such a bread dough.
To accomplish the present invention, the inventors
modified the conventional techniques referred to above by
using ferrous sulfate in an amount reduced to be within an
acceptable range for maintaining a loaf volume, flavor and
taste of baked breads. Using the detection method
explained above, the inventors confirmed the following
facts .
When a desired amount of potassium bromate is
incorporated in a bread dough which is then baked in
uncovered baking pans to form open top breads, a tendency
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reduction or complete removal of residual bromate tended to
be less than that of Pullman-type bread baked in covered
baking pans.
The inventors of the present invention analyzed
difference in residual brornat~ between breads baked in
covered and uncovered baking pans, and discovered the
following findings. The findings led to the completion of
the present invention.
Namely, in the conventional techniques, potassium
bromate in powder form was incorporated into a bread dough.
Potassium bromate has a relatively low solubility in water.
In open top bread, water would be evaporated from the
uncovered (i.e., exposed) upper surface of the dough in an
early stage of the baking step, followed by upper crust
formation. As a result, potassium bromate could not be
completely dissolved into the bread dough near the upper
surface before the completion of baking and hence it would
remain near the upper crust upon completion of baking
because sufficient chemical decomposition of bromate would
not occur.
The inventors of the present invention found that the
above problems associated with conventional techniques
could be overcome by incorporating potassium bromate in the
step of preparing a bread dough such that the solubility of
the incorporated potassium bromate is increased in the
bread dough to facilitate chemical decomposition of bromate.
The present invention thus provides the following
methods aimed at incorporating potassium bromate in the
step of preparing a bread dough for open top breads such
that the solubility of the incorporated potassium bromate
is increased in the bread dough to facilitate chemical
decomposition of bromate. Namely, the present invention
provides a method for preparing a bread dough for open top
breads by the sponge and dough process, which comprises
incorporating potassium bromate as an aqueous solution, in
combination with ferrous sulfate and ascorbic acid in the
step of forming a sponge, so that the resulting baked
breads are free from residual bromate, and a method for
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making open top breads which comprises baking the bread
dough.
Also provided are a method for preparing a bread
dough for open top breads which allows improved oven spring
in the baking step and hence increased loaf volume, and a
method for making open top breads which comprises baking
the bread dough.
Further provided are a method for preparing a bread
dough for open top breads, which comprises incorporating a
significantly reduced amount of ferrous sulfate, so that
the loaf volume, flavor and taste of baked breads are not
affected by ferrous sulfate, and a method far making open
top breads which comprises baking the bread dough.
DETAINED DESCRIPTION OF THE INVENTION
The present invention is therefore directed to a
method for preparing a bread dough for open top breads by
the sponge and dough process, which comprises incorporating
potassium bromate as an aqueous solution, in combination
with ferrous sulfate and ascorbic acid in the step of
forming a sponge, so that the resulting baked open top
breads are free from residual bromate.
In the present invention, as stated below, it is
necessary not only to prepare a bread dough by the sponge
and dough process, but also to incorporate three
ingredients, potassium bromate in aqueous solution form,
ferrous sulfate and ascorbic acid, in the step of forming a
sponge.
First, potassium bromate is incorporated in the form
of an aqueous solution prepared by dissolving powdered
potassium bromate in water. This aqueous solution of
potassium bromate may be prepared by simple or ultrasonic
stirring of potassium bromate in water or by any other
technique for aqueous solution preparation.
For incorporation into a bread dough, potassium
bromate should be completely dissolved in water, but may be
set to any desired concentration. Potassium bromate has a
relatively low and temperature-dependent solubility in
water. It has a lower solubility at a lower temperature
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and its maximum solubility in water at 0°C is 3~. Water
temperature for bread dough preparation is usually higher
than 0°C and potassium bromate can be dissolved in an
amount of 3~ or more. However, an aqueous solution of
potassium bromate should have a concentration not higher
than 3~, and in particular not higher than 2~, in order to
avoid precipitation of potassium bromate during bread dough
preparation.
On the other hand, with respect to the lower
concentration limit for an aqueous solution of potassium
bromate, a lower concentration can be advantageous in
ensuring a higher solubility and more uniform dispersion of
potassium bromate in a bread dough as well as in ensuring
more accurate and easier metering of potassium bromate.
However, too low a concentration will affect handling and
suitability for bread making because there arises a need to
incorporate a large volume of such an aqueous solution.
The lower concentration limit may therefore be adjusted to
meet both requirements.
An aqueous solution of potassium bromate may
preferably be incorporated in an amount of 8 ppm to 15 ppm
(as potassium bromate) based on total wheat flour required
to prepare a bread dough. In the case of making open top
breads, it is more preferably incorporated in an amount of
8 ppm to 12 ppm, and even more preferably 10 ppm to 12 ppm.
This allows potassium bromate to sufficiently exhibit its
inherent oxidizing effect, and as a result, a bread dough
will have improved oven spring when baked. Using such a
bread dough achieves improved bread-making properties such
as increased loaf volume and improved flavor of baked
breads. Further, in the case of open top breads, baked
breads can be substantially free from residual bromate by
merely incorporating a significantly small amount of
ferrous sulfate .
Too small an amount of potassium bromate may fail to
achieve the improved bread-making properties mentioned
above, while too large an amount of potassium bromate may
also fail to achieve the improved bread-making properties.
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In the case of too large an amount, it is also necessary to
incorporate a larger amount of ferrous sulfate to achieve
prevention of residual bromate in baked breads,
particularly in open top bread. However, such a larger
amount of ferrous sulfate will affect the loaf volume,
flavor and taste of baked breads. Further, there still
remains a risk of residual bromate in baked breads even
when a larger amount of ferrous sulfate is incorporated.
Ferrous sulfate has the chemical formula FeS04 and
can be available in crystal (7-hydrate) or dry (1- to
1.5-hydrate) form, which are designated as ferrous sulfate
(crystal) and ferrous sulfate (dry), respectively. In
Japan, ferrous sulfate (crystal) was accepted as a food
additive in 1957, followed by ferrous sulfate (dry) in 1964.
They are collectively referred to as ferrous sulfate.
Ferrous sulfate is prepared from iron and dilute
sulfuric acid as follows:
Fe + HZSO4 + 7H20 -~ FeS04~7H20 ( crystal ) + HZ
The dry form is prepared by drying the crystal thus
prepared at 40°C to give powder. Although ferrous sulfate
as used herein may be in either crystal or dry form, the
dry form (FeS04~1-1.5H20) was used in the Examples because
of its higher purity.
When incorporated into a bread dough (including a
sponge dough), ferrous sulfate serves as a good iron
enrichment in relation to the bread dough, while it serves
as a reducing agent or its equivalent in relation to
potassium bromate to ensure complete chemical reaction of
bromate. The present invention was completed based on this
finding in principle.
Ferrous sulfate may preferably be incorporated in an
amount of 10 ppm to 20 ppm, more preferably 13 ppm to 17
ppm, and even more preferably 14 ppm to 16 ppm, based on
total wheat flour required to prepare a bread dough. On
the precondition that potassium bromate is incorporated as
an aqueous solution, such an amount of ferrous sulfate
successfully ensures prevention or reduction of residual
bromate in baked open top breads, without affecting bread-
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making properties or the quality of baked breads. An
amount of ferrous sulfate exceeding 16 ppm tends to
slightly darken the crumb texture of baked bread. An
amount exceeding 20 ppm will affect, to a greater or lesser
degree, the loaf volume, flavor and taste of baked breads,
depending on bread-making conditions. In contrast, an
amount of ferrous sulfate less than 10 ppm may fail to
ensure prevention or reduction of residual bromate in
bakery products, depending on bread-making conditions.
According to the present invention, in addition to
potassium bromate in aqueous solution form and ferrous
sulfate, ascorbic acid is incorporated in the step of
forming a sponge of the bread dough. Ascorbic acid as used
herein is intended to mean L-ascorbic acid.
When further incorporated into the bread dough,
ascorbic acid ensures not only greater prevention of
residual bromate in baked open top breads, but also greater
improvements in bread-making properties and in the quality
of baked breads. With respect to reduction of residual
bromate, the bread dough of the present invention appears
to contain Fe3+ generated from chemical decomposition of
bromate by ferrous sulfate added thereto. However, Fe3+ is
difficult to chemically react with bromate. Ascorbic acid,
when incorporated into the bread dough, serves as a
reducing agent not only to directly decompose bromate
through chemical reaction, but also to indirectly
contribute to additional chemical decomposition through
conversion of Fe3+ present in the bread dough (which is
difficult to chemically react with bromate) into Fez+ (which
is easy to chemically react with bromate).
Next, the improvements in bread-making properties and
in the quality of baked breads will be explained as follows.
Potassium bromate has very narrow optimal ranges for
amounts to be incorporated as well as for temperatures and
time for fermentation and baking to ensure that its action
in a bread dough is sufficient. However, addition of
ascorbic acid allows these optimal ranges to be extended,
easing the conditions for bread making. Although
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incorporating breads with potassium bromate is more likely
to cause caving, this phenomenon can also be blocked by
addition of ascorbic acid.
Ascorbic acid available for use may be uncoated
ascorbic acid, ascorbic acid partially or completely coated
with a fat, or ascorbic acid partially or completely coated
with a mixture of a fat and an emulsifier such as a mono-
glyceride fatty acid ester.
Ascorbic acid may preferably be incorporated in an
amount of 10 ppm to 50 ppm based on total wheat flour
required to prepare a bread dough. In the present
invention, a larger amount of ascorbic acid will be
desirable in view of ensuring prevention of residual
bromate in breads. More specifically, it is more
preferably incorporated in an amount of 20 ppm to 50 ppm,
and even more preferably 30 ppm to 50 ppm. In contrast, a
smaller amount of ascorbic acid will be desirable in view
of ensuring improvements in bread-making properties and in
the quality of breads by allowing potassium bromate to
exhibit its inherent oxidizing effect in a bread dough.
More specifically, it is- more preferably incorporated in an
amount of 10 ppm to 40 ppm, and even more preferably 10 ppm
to 30 ppm. Thus, the most desirable amount of ascorbic
acid used in the present invention can be 20 ppm to 30 ppm
in view of meeting both requirements.
Preferably, either or both (more preferably both) of
ferrous sulfate and ascorbic acid may be incorporated in
powder form, independently of the above aqueous solution of
potassium bromate. If ferrous sulfate is used as an
aqueous solution, the iron ion (Fez+) in ferrous sulfate,
capable of reacting with and decomposing bromate, would be
affected and hence lose its ability to decompose bromate.
Likewise, if ascorbic acid is incorporated as an
aqueous solution, potassium bromate would be decomposed
before exhibiting its inherent oxidizing effect in a bread
dough, which adversely affects improvements in bread-making
properties and in the quality of baked breads.
Ascorbic acid and ferrous sulfate may each be
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incorporated alone or as a mixture with one or more members
selected from yeast foods, enzymes, emulsifiers and other
dough conditioners. Preferably, they may be incorporated
as a mixture.
In the present invention, it is necessary not only to
prepare a bread dough by the sponge and dough process, but
also to incorporate three ingredients, potassium bromate in
aqueous solution form, ferrous sulfate and ascorbic acid,
in the step of forming a sponge.
The sponge and dough process refers to a technique
for bread dough preparation, which usually involves:
forming a sponge by mixing part of wheat flour
required to prepare a bread dough with yeast and water,
optionally in combination with one or more members selected
from dough conditioners (e. g., yeast foods, oxidants,
enzymes), emulsifiers, salt, and other materials or
additives;
fermenting the sponge under given conditions;
making a dough by mixing the fermented sponge with
the rest of the wheat flour, salt and water, optionally in
combination with one or more members selected from sugars,
fats, skimmed milk powder, arid other materials or additives,
to prepare a bread dough; and
fermenting (floor time) the bread dough under given
conditions.
In the sponge and dough process of the present
invention, the amount of wheat flour used to form a sponge
should be 50~ to 80~ by mass, preferably 60~ to 80~ by mass
of total wheat flour required to prepare a bread dough. If
a larger or smaller amount of wheat flour is used to form a
sponge, the resulting bread dough would lack fermentation
stability and mechanical tolerance, which are features of
the sponge and dough process.
In addition, the mixed sponge should be fermented at
a temperature of 26°C to 29°C, preferably 27°C to
28°C, for
4 to 6 hours, preferably 4 to 5 hours, If the sponge is
fermented at a lower temperature or for a shorter period of
time, a young sponge would be formed and the resulting
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bread dough would lack fermentation stability and
mechanical tolerance, which are features of the sponge and
dough process. Such a young sponge would not only affect
the quality of breads, but also give rise to insufficient
chemical reaction among potassium bromate, ferrous sulfate
and ascorbic acid. Likewise, if the sponge is fermented at
a higher temperature or for a longer period of time, an
overfermented old sponge would be formed and the resulting
bread dough would also lack the above features of the
sponge and dough process and affect the quality of breads.
Thus, the present invention requires an extended
period of time for the entire process, from start of mixing
(including sponge mixing) to completion of baking, and
accordingly a longer period of time will be provided for
chemical reaction among potassium bromate, ferrous sulfate
and ascorbic acid incorporated in the step of sponge mixing.
As a result, sufficient decomposition of bromate will occur
to ensure prevention of residual bromate in breads.
The present invention encompasses a method for making
open top breads, which comprises baking the bread dough
prepared by the method for preparing a bread dough
discussed above.
The term "breads" as used herein is specifically, for
example, intended to mean, but not limited to, breads
obtained by proofing and baking a bread dough placed in a
rectangular baking pan having a rectangular bottom and 4
side walls standing upright from and surrounding the bottom.
The method of the present invention can be used to
provide breads free from residual bromate, in the case of
open top breads. The method is particularly preferred for
use in making open top bread baked in an uncovered baking
pan.
Further, in the method for making breads of the
present invention, the bread dough may be baked at low
temperature, if desired. More specifically, this low
temperature baking may be carried out under an atmosphere
at 160°C to 180°C. In general, the baking temperature for
breads is around 200°C to 220°C. In the case of
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incorporating potassium bromate, in particular, it has been
believed that a higher baking temperature and a longer
baking time are desirable for further reduction of residual
bromate in breads. In contrast, the present invention
allows prevention of residual bromate in open top breads,
even at a baking temperature as low as 160°C to 180°C.
Further, the period of time required for baking at such a
low temperature may be set to any value as long as it is
not extremely shorter than that of conventional baking at
the temperature as mentioned above. However, for
prevention of residual bromate in baked breads, it can be
desirable to use a longer baking time than that of
conventional baking at the temperature as mentioned above.
Thus, the present invention is preferably adapted to
a method for making tender-type breads with an uncolored or
light-colored and/or tender crust. Of course, it is also
preferred for tender-type open top bread with such a crust.
If desired, the method of the present invention may
further comprise spraying an aqueous solution of ferrous
sulfate, an aqueous solution of ascorbic acid, an aqueous
solution of ferrous sulfate and ascorbic acid, or water
over the (upper) surface of the proofed bread dough before
baking.
The above aqueous solution or water may be desirably
sprayed in an amount of 3 to 7 g per 450 cm2. Too small an
amount per unit area results in a decrease in the reduction
of residual bromate in breads, such as in the case of
incorporating a larger amount of potassium bromate. Too
large an amount results in crusty breads with a hard
(upper) surface crust, like a baguette, losing their
characteristic soft texture. Likewise, even when sprayed
in a larger amount, the above aqueous solution or water
would not significantly enhance the reduction of residual
bromate in breads. A unit area of 450 cm2 corresponds to
the upper open area (internal area) of a normal baking pan.
Thus, the present invention allows greater prevention
of residual bromate in open top bread by spraying the above
aqueous solution or water over the surface of the proofed
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bread dough before baking, as compared to open top bread
baked without spraying. This embodiment is therefore
extremely effective in incorporating a relatively large
amount of potassium bromate.
As stated above, the present invention can provide
breads free from residual bromate, i.e., those with a
bromate content reduced to less than 1 ppb, the detection
limit for bromate as measured by improved HPLC analysis.
This HPLC analysis, which was developed by the
inventors of the present invention as stated above, is an
ultra-sensitive high performance liquid chromatography with
a detection limit of 1 ppb for bromate in breads. Details
of this analysis can be found on pages 221-224 of the
Journal of the Food Hygienics Society of Japan, Vol. 43,
No. 4 (August, 2002).
EXAMPLES
The present invention will be further described in
the following Examples and Test Examples, which are not
intended to limit the scope of the invention.
[Example 1] Making open top bread
The amount of each ingredient is expressed as ~ by
mass or ppm based on total wheat flour (the same applying
hereinafter).
(Ingredient composition}
Sponge Wheat flour (strong flour) 70~
Yeast 2~
Dough conditioner (e. g., yeast food, enzyme) 0.1~
including L-ascorbic acid (uncoated) 20 ppm
Emulsifier 0.3~
Water 40~
Aqueous potassium bromate solution (0.13 as
concentration)
(as potassium bromate) 11.7 ppm
Ferrous sulfate 15 ppm
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Dough Wheat flour (strong flour) 30~
Sugar 5~
Fat
Skimmed milk powder 2~
Salt
Water 25~
(Process steps)
Sponge Mixing Low speed 3 minutes,
High speed 2 minutes
Temperature of mixed sponge 24°C
Fermentation 4 hours
Dough Mixing Low speed 2 minutes,
High speed 3 minutes
,~ ( add f at )
Low speed 2 minutes,
High speed 4.5
minutes
Temperature of mixed dough 27C
Floor time 20 minutes
Dividing 520 g
Rounding
Bench time 20 minutes
Moulding (curl each sheeted dough into
a roll)
Panning (place two moulded rolls into a baking
pan)
Final proofing 38C, 70 minutes
Baking (uncovered) 170C, 30 minutes
Open top bread was made under these conditions. Low
temperature baking was carried out to give tender-type open
top bread with a light-colored tend er crust.
(Evaluation)
Content of residual bromate w as determined as
described in the Journal of the Foo d Hygienics Society of
Japan, supra.
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(Result)
The bread was evaluated for the content of residual
bromate as described above (detection limit: 1 ppb, the
same applying hereinafter), indicating that residual
bromate was non-detected (ND, the same applying
hereinafter).
This demonstrates that the present invention allows
prevention of residual bromate in open top bread by
incorporating potassium bromate as an aqueous solution, in
combination with a much smaller amount of ferrous sulfate
(about 10-fold less than that of the conventional
techniques) and an appropriate amount of ascorbic acid.
The open top bread thus prepared was found to show
improved oven spring and increased loaf volume in the
baking step, as well as having good loaf volume, flavor and
taste which were not affected by ferrous sulfate.
[Examples 2 to 6]
(Ingredient composition)
The same ingredients as shown in Example 1 were used,
except that an aqueous potassium bromate solution was
incorporated in an amount as potassium bromate of 8 ppm
(Example 2), 9 ppm (Example 3), 10 ppm (Example 4), 11 ppm
(Example 5) or 13 ppm (Example 6).
(Process steps)
The same steps as shown in Example 1 were repeated.
(Results)
The open top bread from each example was evaluated
for the content of residual bromate as described above,
indicating that residual bromate was ND in Examples 2 to 5
and 1.4 ppb in Example 6.
The open top bread thus prepared was found to show
improved oven spring and increased loaf volume in the
baking step, as well as having good loaf volume, flavor and
taste which were not affected by ferrous sulfate.
[Examples 7 to 9]
(Ingredient composition)
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The same ingredients as shown in Example 1 were used,
except that L-ascorbic acid was incorporated in an amount
of 30 ppm (Example 7), 40 ppm (Example 8) or 50 ppm
(Example 9).
(Process steps)
The same steps as shown in Example 1 were repeated.
(Result)
The open top bread from each example was evaluated
for the content of residual bromate as described above,
indicating that residual bromate was ND in each case of
incorporating L-ascorbic acid in an amount of 30 ppm,
40 ppm and 50 ppm.
This demonstrates that the present invention allows
prevention of residual bromate in open top bread when
L-ascorbic acid is incorporated in an amount of 20 ppm
(Example 1) to 50 ppm.
However, a larger amount of L-ascorbic acid,
particularly 40 ppm or 50 ppm, tended to give a stiff dough
because gluten was more likely to tighten up during mixing
in the presence of a larger amount of L-ascorbic acid, thus
slightly inhibiting oven spring in the baking step and
making breads tough.
[Example 10]
(Ingredient composition & process steps)
In Example 6 given above, where 13 ppm potassium
bromate was incorporated into the bread dough to produce
1.4 ppb residual bromate in the open top bread, an aqueous
ferrous sulfate solution (0.1~ as concentration, 5 g) was
sprayed over the uncovered upper surface (open area of a
baking pan: about 450 cmz) of the proofed bread dough
before baking.
(Result)
The open top bread was evaluated far the content of
residual bromate as described above, indicating that
residual bromate was ND.
As is evident from this result, the present invention
allows significant reduction, and hence prevention, of
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residual bromate in open top bread by spraying an aqueous
ferrous sulfate solution over the surface of the proofed
bread dough before baking, as compared to open top bread
baked without spraying. This embodiment is therefore
extremely effective in incorporating a relatively large
amount of potassium bromate.
[Examples 11 to 13]
(Ingredient composition & process steps)
In Example 1 given above, the following solution (5
g) was sprayed over the uncovered upper surface (open area
of a baking pan: about 450 cmz) of the proofed bread dough
before baking:
water (Example 11);
an aqueous L-ascorbic acid solution (O.lo as
concentration) (Example 12); or
a mixture of an aqueous ferrous sulfate solution
(0.18 as concentration) and an aqueous L-ascorbic acid
solution (0.24 as concentration)(Example 13).
(Result)
The open top bread from each example was evaluated
for the content of residual bromate as described above,
indicating that residual bromate was ND in each of Examples
11 to 13.
[Examples 14 to 15]
(Ingredient composition & process steps)
Tn Example 6 given above, where 13 ppm potassium
bromate was incorporated into the bread dough to produce
1.4 ppb residual bromate in the open top bread, the bread
dough was covered with a dome-type lid during baking
(Example 14). Example 6 was also modified to incorporate
14.3 ppm potassium bromate into the bread dough, which was
covered with a dome-type lid during baking (Example 15).
(Result)
The bread from each example was evaluated for the
content of residual bromate as described above, indicating
that residual bromate was ND in each of Examples 14 and 15.
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This demonstrates that the present invention allows
complete prevention of residual bromate in bread by using a
dome-type lid during baking, as compared to open top bread
baked in an uncovered baking pan. This embodiment is
therefore extremely effective in incorporating a relatively
large amount of potassium bromate.
[Examples 16 to 17]
The same ingredients as shown in Example 1 were used,
except that potassium bromate was incorporated in an amount
of 10.4 ppm (Example 16) or 7.8 ppm (Example 17), to make
open top bread in the same manner as shown in Example 1.
The open top bread from each example was evaluated for its
loaf volume and specific volume and also evaluated for an
extensogram of the fermented dough. Each result was
expressed as the mean of five samples for each example.
Table 1 shows the results obtained, along with the
results of Comparative Test 2 below.
Table 1
Comparative
Example Example Example Example
3 1 16 17
Potassium bromate (ppm)11.7 11.7 10.4 7.8
One loaf volume (ml) 1,155 1,173 1,122 1,109
Weight after baking 229.6 228.8 229.9 231.1
(g)
Specific volume 5.0 5.1 4.9 4.8
Extensogram of
fermented dough
F value (B.U.) 577 627 616 608
E value (mm) 94 97 95 96
F/E 6.1 6.5 6.5 6.3
[Test Examples]
[Comparative Test 1]
The open top bread samples prepared in Example 1
above and Comparative Examples 1 to 3 below were evaluated
and compared for the content of residual bromate by
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improved HPLC analysis as mentioned above (which was also
adapted to the following Comparative Tests).
(Ingredient composition for Comparative Example 1)
The same ingredients as shown in Example 1 were used,
except that potassium bromate was incorporated in powder
form and that ferrous sulfate and ascorbic acid were not
incorporated.
(Ingredient composition for Comparative Example 2)
The same ingredients as shown in Example 1 were used,
except that ferrous sulfate and ascorbic acid were not
incorporated. In this comparative example, potassium
bromate was incorporated as an aqueous solution.
(Ingredient composition for Comparative Example 3)
The same ingredients as shown in Example 1 were used,
except that potassium bromate was incorporated in powder
form. In this comparative example, ferrous sulfate and
ascorbic acid were incorporated.
(Process steps for Comparative Examples 1 to 3)
The same steps as shown in Example 1 were repeated.
(Result)
The open top bread from each example was evaluated
for the content of residual bromate as described above,
indicating that residual bromate was ND in Example 1. In
contrast, residual bromate was 20.2 ppb, 12.7 ppb and 6.2
ppb in Comparative Examples 1, 2 and 3, respectively. This
demonstrates that the present invention allows significant
reduction, and hence prevention, of residual bromate in
open top bread, as compared to Comparative Examples 1 to 3.
[Comparative Test 2]
The open top bread samples prepared in Examples 1, 16
and 17 and Comparative Example 3 were evaluated for their
loaf volume and specific volume and also evaluated for an
extensogram of the fermented dough. In Examples 16 and 17,
the same ingredients as shown in Example 1 were used,
except that potassium bromate was incorporated in an amount
of 10.4 ppm and 7.8 ppm, respectively. Each result was
expressed as the mean of five samples for each example.
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(Result)
Table 2 shows the results obtained.
Table 2
Comparative
Example Example Example Example
3 1 16 17
Potassium bromate 11.7 11.7 10.4 7.8
(ppm)
One loaf volume (ml) 1,155 1,173 1,122 1,109
Weight after baking 229.6 228.8 229.9 231.1
(g)
Specific volume 5.0 5.1 4.9 4.8
Extensogram of
fermented dough
F value (B.U.) 577 627 616 608
E value (mm) 94 97 95 96
FJE 6.1 6.5 6.5 6.3
As shown in Table 2, when potassium bromate was
incorporated in an amount of 11.7 ppm, both loaf and
specific volumes of the open top bread were larger in
Example 1 according to the present invention than in
Comparative Example 3. In other words, the present
invention requires a smaller amount of potassium bromate
than Comparative Example 3 to obtain open top bread of the
same loaf and specific volumes .
Likewise, when potassium bromate was incorporated in
an amount of 11.7 ppm (Example 1), 10.4 ppm (Example 16)
and 7.8 ppm (Example 17), both F (resistance) and E
(extensibility) values of extensogram were higher in these
Examples than in Comparative Example 3 (11.7 ppm). In
particular, the F (resistance) value was much higher in
Examples 1, 16 and l7 than in Comparative Example 3.
As is well known, potassium bromate serves as an
oxidizing agent to toughen and tighten wheat gluten in a
bread dough by its oxidizing action, so that the bread
dough attains elasticity and gas-holding capacity required
for great expansion during final proofing and baking. As
CA 02457739 2004-02-16
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is evident from the F (resistance) and E (extensibility)
values of extensogram given above, in all of Examples 1, 16
and 17 according to the present invention, potassium
bromate even in an equal or smaller amount than used in
Comparative Example 3 has a strong oxidizing effect on
wheat gluten in a bread dough and hence provides the bread
dough with great elasticity, gas-holding capacity,
extensibility and flexibility.
[Comparative Test 3]
Open top bread was made in the same manner as shown
in Example 1, except that the dough conditioner (including
L-ascorbic acid) and ferrous sulfate were added in the
dough mixing step rather than incorporated into the sponge
(Comparative Example 4). The open top bread samples
prepared in Example 1 and Comparative Example 4 were
evaluated and compared for the content of residual bromate.
(Result)
The content of residual bromate in the open top bread
was evaluated as described above, indicating that residual
bromate was ND in Example 1, but 10.4 ppb in Comparative
Example 4.
This demonstrates that in preparing a bread dough by
the sponge and dough process, prevention of residual
bromate in open top bread can be accomplished by
incorporating three ingredients, potassium bromate in
aqueous solution form, ferrous sulfate and ascorbic acid,
in the step of forming a sponge.
The present invention provides a method for preparing
a bread dough, which comprises incorporating potassium
bromate as an aqueous solution, in combination with ferrous
sulfate and ascorbic acid in the step of forming a sponge
such that the solubility of the incorporated potassium
bromate is increased in the bread dough to facilitate
chemical decomposition of bromate, so that the resulting
baked breads are free from residual bromate. Also provided
is a method for making breads, which comprises baking the
CA 02457739 2004-02-16
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bread dough.
According to the present invention, it is possible to
provide a bread dough which allows improved oven spring in
the baking step and hence increased loaf volume. Also, a
significantly reduced amount of ferrous sulfate can be
incorporated into the bread dough, so that the loaf volume,
flavor and taste of baked breads are not affected by
ferrous sulfate. The method of the present invention is
widely applicable to bread dough preparation.
