Note: Descriptions are shown in the official language in which they were submitted.
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The present invention concerns a method of manufacturing
yeast-incorporated doughnuts and, more particularly, a method
of manufacturing yeast-incorporated doughnuts with low oil
content suitable for serving just after frying them in a shop
front.
Yeast-doughnuts have heretofore been manufactured in
accordance with procedures, which are individually specified
in respective stores, by blending raw materials, kneading
them while controlling temperature, humidity, time etc.,
applying punching and fermentation, followed by frying.
The continuous performance of these operations requires
skilled persons in each store who are tied exclusively to
such operations. In addition, control of the timing of
-frying is difficult since it is desirable to serve customers
with doughnuts just after frying to enjoy the delicious
taste.
The present invention provides a method of manufacturing
yeast-incorporated doughnuts with low oil content by first
preparing frozen doughnuts by blending, mixing, punching and
freezing raw materials in a factory and, subsequently,
storing them in dough-conditioners or refrigerators installed
in each individual shop and then thawing and frying them
quickly as required.
More particularly, the present invention provides a
method of manufacturing yeast-incorporated doughnuts which
comprises blending raw material powder with a predetermined
amount of water and live yeast, mixing said powder, water and
yeast to prepare dough, conditioning said dough for a
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predetermined period of time, extruding said dough at a
predetermined thickness and shape under pressure, punching
extruded dough in a predetermined shape, rapidly freezing the
punched dough by freezing so that the temperature at the core
portion of said dough is lowered to about -12C, storing the
frozen dough in a dough-conditioner, thereafter, arranging
the frozen dough on a screen and applying thawing,
fermentation and dehumidification in a thawing box, followed
by quick frying.
The dough is prepared in the absence of fat or oil, and
does not undergo fermentation prior to freezing.
Utilizing the method of the present invention, the
blending, kneading and punching of the raw material in each
shop is no longer necessary. The time for such operations
can be eliminated and coupled with the automation of the
thawing box procedures, workers are necessary for only the
quick frying operation.
The present invention will become more apparent by
reading the following description of the preferred
embodiments in conjunction with the appended drawings,
wherein:
Figure 1 is a flow chart for the steps conducted in a
factory;
Figure 2 is a schematic plan view for a pressing
extruding machine, as well as a punching machine;
Figure 3 is a schematic side elevational view thereof;
Figure 4 is a view illustrating the shapes of respective
kinds of yeast-incorporated doughnuts;
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Figure 5 is a view showing the arrangement of doughnuts
on a screen; and
Figure 6 is a perspective view illustrating the state of
frying doughnuts.
The present invention will be described more
specifically by way of a preferred embodiment with reference
to the drawings.
Figure 1 shows the production step for frozen doughnuts
in a factory. The starting material, yeast-incorporated
doughnut powder mix, is weighed and charged into charger 1 in
the ratio of 100 parts by weight of the powder mix with 46
parts by weight of water and 6 parts by weight live yeast.
The mixture is blended and kneaded in a mixer 2.
In this mixing step, the ingredients are mixed in a
vertical type mixer at first at a low speed, for example, 25
rpm for about 3 minutes and then at a high speed, for example
at 75 rpm for about 20 minutes. In this case, the kneading
temperature is controlled to about 20C. After preparing
dough by such mixing it is aged in a room at about 20C for
about 30 minutes of floor time. The dough is transported on
a conveyor 3 as a shaping line and extruded at a
predetermined thickness. In this case, the extruded dough is
provided with viscosity by adjusting the pressure and the
speed to a predetermined level thereby preventing unevenness
and then extruding and shaping so that there is no shrinkage
in the dough (deformation of the dough). The pressing
extruding device 4 comprises rollers (four in the drawing)
disposed at a predetermined interval and, by passing the
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dough through the rollers, pressure is applied to the dough
to provide viscosity and prevent shrinkage thereof.
Then, the thus extruded and shaped dough is sent into a
punching machine 5 and punched into a predetermined shape.
The predetermined shape depends on the kind of the yeast-
incorporated doughnut, which may be a well-known shape in the
relevant field such as circular, elliptic, stick-like or
annular (perforated disc), or small spherical shape, as shown
in Figure 4. A punching die is spiked from above the shaped
dough, by which the inside of the die is filled with the
dough, which is lifted and moved forwardly. Then, air is
blown into the die to release the punched dough onto a
conveyor 6. Residual dough after the punching is returned to
the mixer 2 for re-mixing as described later.
The punched dough is sent to a freezer, for example, a
tunnel type freezer 7 and frozen. The temperature of the
freezer 7 is controlled at -38 to -40C such that the dough
can be frozen rapidly. For example, the temperature of the
dough core portion is lowered to about -12C during passage
for about 10 minutes to prepare a frozen dough. Excessively
slow or rapid freezing is not desirable. The frozen dough is
discharged from the freezer 7, transferred to another
conveyor 8, and checked for weight by a weighing means 9 to
eliminate those not having a predetermined weight. The
products with the predetermined weight are packed into
freezing and moisture resistant packaging bags and, after
checking for foreign objects, such as metal, by an inspection
device 10, packed into carton boxes, etc., depending on their
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shapes, and then stored in a refrigeration chamber 11, at a
temperature of about -15C.
The residual dough after the punching is re-mixed as
described above. In this case, fresh dough prepared by
lending 100 parts by weight of the powder mix with 46 parts
by weight of water and 6 parts by weight of live yeast is
further mixed with the residual dough. In this case, from 60
to 70 % of the fresh dough is mixed with from 40 to 30 ~ of
the residual dough. After mixing only the fresh dough in the
vertical mixer at a low speed (25 rpm) for 3 minutes and then
at a high speed 75 (rpm) for about 6 minutes, as described
above, the above-mentioned residual dough is charged and
mixed at a low speed for about 2 minutes and at a high speed
for about 10 minutes to prepare a secondary dough and mixed
at a kneading temperature of 20C. Then after the elapse of
a floor time of 30 minutes, the mixture is transferred to the
shaping line described above, extruded under pressure and
punched. The residual dough formed in this step is also
returned to the mixture to prepare a third dough and such
procedures are repeated subsequently.
During mixing, aging for the floor time and punching of
the first fresh dough, that is, during preparation of the
secondary dough by mixing with the residual dough, the same
procedures of mixing, aging for the floor time and punching
the fresh dough with the identical blend as in the first step
are conducted to reduce the step loss in order to save time
and improve efficiency.
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The frozen dough thus produced in the factory is
delivered on a refrigerated vehicle or the like to each store
and then stored in a dough-conditioner provided in each
store.
S During storage in the dough-conditioner, the inside
temperature is kept at about -15C and the frozen doughnuts
are stored in carton boxes while being classified depending
on the types of products as described above. In this case,
arrangement of the products in the dough-conditioner is
properly determined depending on the shapes of the products.
If the storage temperature is higher than -5C, the frozen
doughnuts are thawed and deformed, as well premature
fermentation of the yeast begins and inactivates the
fermentation after the complete thawing. On the other hand,
if the storage temperature is lower than -20C, the yeast die
and subsequent fermentation no longer takes place.
Prior to the description of the steps taken in each
store, the temperature in the kitchen of each store is
controlled at about 20 - 25C. If the temperature is lower
than 20~C, elevation of the temperature during thawing is
slow and thawing is insufficient during fermentation which
results in the doughnut product having undesired hardness,
poor taste, failed fermentation, etc. On the other hand, if
the temperature is higher than 25C, thawing prematurely
2S proceeds in the screening step, as well as condensation on
the doughnut surface, resulting in overweight, coarse
texture, excessive oil absorption or imprinting of screen
marks. Frozen doughnuts are removed from the carton box,
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arranged on the screen 12 and placed in a dough-conditioner
having a refrigerating function. In a case of arranging a
plurality of various products simultaneously in the dough
conditioner, it is preferable to arrange them in the upper
and the lower stages depending upon their shapes. It is
necessary to take into consideration the effect of humidity
in the subsequent steps so that those shapes requiring less
humidity are set at the upper stage and circulation of air in
the conditioner is improved. For instance, it is desirable
to arrange the doughnut products from the lower stage to the
upper stage in the order of their shapes such as elliptic,
circular, stick-like, annular and small spherical shape.
Since fermentation proceeds even at the time of removal
from the box or arrangement on the screen, such procedures
have to be conducted rapidly. The frozen doughnuts set in
the dough conditioner are successively thawed and then
fermented and dehumidified. Thawing is conducted at a
temperature of 20C in the dough-conditioner for 60 minutes.
Subsequently, fermentation is conducted while gradually
raising the temperature in the conditioner from 20 to 40C by
means of a toaster and at a relative humidity of 70 % for
about 30 minutes. Successively, dehumidification is
conducted while drying the surface of the doughnuts by a
blower at a temperature of the conditioner from 20 to 25C
and with a lapse time of about lO minutes.
For the dough-conditioner, time, temperature and
humidity are set such that each of the steps for the storage
under refrigeration, thawing, fermentation and
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dehumidification, are conducted successively and
automatically. If the temperature inside the conditioner is
excessively high during thawing, moisture condenses on the
thawed doughnuts to cause excessive wetness. On the other
hand, if the thawing is not complete, insufficient
fermentation may result. Upon fermentation, by gradually
raising the temperature by means of a toaster, yeast in the
thawed doughnuts become activated to evolve gaseous carbon
dioxide thereby causing the doughnuts to expand.
Predetermined temperature and humidity are necessary for the
fermentation, in which temperature contributes to the
vertical expansion of doughnuts, while humidity contributes
to lateral e~p~n~ion thereof. Since condensation of moisture
is not desired and, on the other hand, insufficient
fermentation results without appropriate moisture, control of
the temperature and the humidity is important. Expansion by
fermentation is conducted to about 80 % of the finished
state. Dehumidification is applied to the doughnuts after
fermentation for stabilizing gases envolved inside and drying
of the surface. Since excess moisture increases the amount
of oil absorbed upon frying, it is necessary to completely
remove moisture. The doughnuts, after sufficient
fermentation and drying in the dough conditioner, are rapidly
fried in the frier 13 while being placed side by side on the
screen 12.
The temperature for the oil in the frier 13 is adjusted
to about 185C. The screen 12 taken out from the dough
conditioner is put between a holder 14 and horizontally
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immersed in the oil. Then when the doughnuts float upwardly,
they are fried quickly (setting frying time).
Although the frying time varies depending on the types
of the products, they are fried quickly, for instance, frying
is applied in 40 seconds for the surface and, after turning,
in 40 seconds for the rear face in the case of annular or
circular doughnuts, in 30 seconds for both surface and rear
faces each time immersed for 30 second in oil in the case of
elliptic doughnuts, in one minute and 30 seconds, being
immersed in oil in the case of stick-like doughnuts, in 45
seconds in oil in the case of small spherical doughnuts.
Doughnuts are removed from the frier after frying resulting
in just fried yeast-incorporated doughnuts of low oil
content.
The present invention is not restricted to the single
embodiment as described above. For instance, the blending
ratio between the powder mix and water and living yeast can
be changed as from 45 to 50 parts by weight of water and from
5 to 7 parts by weight of living yeast based on 100 parts by
weight of the powder. Further, mixing can be conducted in a
horizontal mixer, large or small mixer. Mixing is not
limited only to the two stage mixing. In addition, the
kneading temperature and the aging time may also be varied so
long as they do not adversely affect fermentation after the
thawing. The preferable freezing temperature is such that
the temperature for the core portion is about at -12C. If
the temperature is lower or higher than noted above, the
yeast die or the fermentation proceeds too fast. However, an
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appropriate temperature range can be set within such an
extent as to not cause such undesirable effects. However,
too rapid or too gradual refrigeration is not preferred as
has been described above.
Furthermore, it will be apparent that the values for
temperature, time, moisture, arrangement, etc. in the dough
conditioner, as well as the frying time in each store are not
limited but can be controlled in various manners.
According to the method of the present invention,
material powder is mixed with predetermined amounts of water
and live yeast, and then mixed into dough, the dough is
spread at a predetermined thickness under pressure and
extruded, the shaped dough is punched out and then rapidly
frozen such that the temperature for the core portion is
about -12C to prepare frozen dough (frozen doughnuts).
These frozen doughnuts are stored in the dough-conditioner in
each store, and then subjected to cold storage, thawing,
fermentation and dehumidification while being arranged on the
screens in the dough conditioner. Thereafter, they are
quickly fried, so that the operation steps in each store can
be conducted automatically in the dough conditioner resulting
in the reduction procedures conducted by skilled persons,
easing the difficulty for securing manpower and reducing the
preparation time in each of the stores. In addition, the
time for the procedures in each store is reduced and workers
can engage in other procedures during the automatic
processing in the dough conditioner. Further, by properly
setting the time for starting the thawing in the dough
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conditioner, since the cold storage can be automatically
conducted even during night and the thawing can be started at
a predetermined time, over-time labour of workers is no
longer necessary. Furthermore, since the frying time is
S extremely shortened, doughnuts of low oil content can be
quickly obtained so that the intended purpose of the
invention is attained easily.
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