Note: Descriptions are shown in the official language in which they were submitted.
METHOD OF PRODUCING TEXTURED F~OD
The present invention relates to a method of produc-
ing a textured food. More particularly, the present inven-
tion pertains to a method o~ producing a processed food
having a meat-like texture from soy-beans.
In conventional methods of producing meat-like tex-
tured foods from soy-beans, extruders have heretofore been
employed to obtain ground, meat like, granular or fibrous
fragmentary food materials which give the sensation of
eating real meat. In another conventional method, soy-bean
protein is dissolved in an alkaline solution and is then
fiber-spun by an ex~ruder into a product with fibrous tex-
ture similar to muscular fibers. HoweverJ the product
obtained by this process is not satisfactory and must be
further processed to obtain the consistency necessary to
give the sensation of eating real meat. The products
obtained by these conventional methods are able to give the
sensation of eating real meat when they are granular or
fragmentary, but fail in giving that sensation when they
are in the shape of a relatively large lump. This is
because the extruders employed are of the single-screw type
and the water content of the materials must be relatively
low. Researches into the application of twin-screw ex-
truders have recently advanced, and this type of extruder
has been introduced into the food industry to process raw
~9~
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materials having relatively high water contents. Certain
methods have already been proposed for texturing proteins
such as defatted soy-bean flours having relatively high
water contents by utilizing twin-screw e~truders. With
these proposed methods, the degree to which the proteins
are textured is so small that the texture o~ the products
is far from the desired meat-like consistency~
In view oE the above-described circumstances, it is a
primary object of the present invention to provide a method
o~ producing a heterogeneously textured meat-like processed
food from soy-beans, particularly a soy-bean flour and/or
okara (by-product from the making of soy-bean curd or soy
milk~, using a twin-screw extruder.
The present inventors made various studies and have
successfully found that, when an extruder having an orifice
and provided with a cooling die is used, a meat-like tex~
tured food can be obtained when the protein and fat contents
of a soy bean material are specified such that they respec-
tively fall within predetermined ranges, thus accomplishing
the present invention.
The present invention, therefore, provides a method
Eor producin~ a textured food characterized in that a soy-
bean flour and/or ~ having 8 to 38 wt%, preferably 16 to
30 wt% protein and not greater than 7 wt%, preferably not
greater than ~ wt~ fat is processed by employing a twin-
screw extruder having an orifice and provided with a cooling
die.
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The present invention will be described hereinunder
in detail.
The present inventors first carried out a texturing
test by employing a soy~bean flour (12.5% water, 35.3~
protein, and 19.0% ~at) and a twin-screw extruder having an
orifice and a cooling die, at a barrel temperature of 170C,
and found that it was difficult to obtain the required
texture. Since the fat content in the soy-bean flour was
seen to be too high, the present inventors continued the
examination employing defatted raw materials. More speci-
fically, a soy-bean flour and okara (80.3% water, 6.5%
protein, and 4.0% fat) were dried and defatted to prepare
a defatted dry okara (11.1% water, 36.1~ protein, and 1.8%
fat) and a defatted soy-bean flour (12.9% water, 46.3%
protein, and 2.1% fat). Various amounts of water were added
to these raw materials and mixed together to produce five
kinds of raw-material sample respectively having final water
contents falling within a range from ~5% to 70~, as shown in
Table 1. Then, a texturing test was carried out on these
samples by employing the same machine as that in the case of
the first soy-bean flour at various barrel temperatures,
i.e., frcm 150 to 210C.
As a result, the defatted soy-bean flour containing
46.3% protein was transformed into a lump having no linear
fiber or fibrous property in any of the aforementiopned
conditions.
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From the results shown in Table 1, the present inven-
tors have found that a heterogeneous meat-like extruded
product can be obtained having a water content o~ 55~ when
the barrel temperature is 180C and a water content of 50 to
60~ in the case of barrel temperatures of 190C and 200C.
Next, the conditions of a barrel temperature of 180C
and a water content of 55~ which showed excellent results
in the aforementioned test were further examined. More
specifically, various amounts of soy oil were added to, and
uniformly mixed with, the defatted okara as shown in Table
2 to prepare raw-material samples, and a texturing test was
carried out on these samples in a manner similar to the
above. As a result, it has been found that heterogeneous
meat-like properties can be obtained when the Eat content
is not greater than 6%, preferably not greater than 4~.
Table 2
Fat content (%) Fiber condition of extruded product
0.5 heterogeneous meat-like lump
1.0 ditto
2.0 ditto
4.0 ditto
6.0 ditto
7.0 low directional property
8.0 crumbly lump without directional property
Next, a vegetable Eibrous material was mixed with
dried Q~E~ containing 55~ water and 1.2% fat at various
rates to prepare raw-material samples differing in protein
content as shown in Table 3, and these samples were
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subjected to a test similar to the above at a barrel temper-
ature of 190C. Table 3 shows the results of the test.
Table 3
~rotein content (%~ Fiber condition o~ ext,ruded produc~
7 no fibrous aspect
heterogeneous meat-like lump
16 ditto
21 d.itto
24 ditto
ditto
34 ditto
38 slightly linear fibers
41 linear fibers
From the results shown in Tahle 3, it has been found
that extruded products can possess the characteristic prop-
erty of exhibiting a meat-like texture when the protein
content is between 10% and 34%, preferably 16% and 30~.
Finally, a test was carried out on the protein
aspect. ~ vegetable fibrous material was added to a
defatted soy-bean powder such as to obtain a specified
protein content o~ 25%, and this powder was subjected to a
heat treatment to prepare raw-material samples differing
in NSI (nitrogen solubility index), the water content of
these samples being adjusted to 60%. The result of this
test showed that when the NSI was no greater than 64, the
desired physical properties were obtained.
As has been described above, the present invention
provides a method wherein a soy-bean material having a
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specified protein content of 8 to 38 wt~, pre~erably 16
to 30 wt~, and a specified fat content of 7 wt~ or less,
preferably 4 wt% or less, is processed by a twin-screw
extruder having an orifice and a cooling die at a barrel
temperature of 175 to 205C, preferahly 180 to 200C,
whereby it is possible to obtain an adequately textured
meat-like processed food. Thus, it is possible, accord-
ing to the method of the present invention, to obtain a
processed ~ood containing textured vegetable protein which
has characteristic toughness and flavor in a single step
using a twin-screw extruder by specifying the protein and
fat contents of the material.
The following Examples are provided for further
illustration of the present invention.
Example 1
An extrusion experiment was carried out by employing
a twin-screw extruder having an oriEice and provided with a
cooling die. As the raw material, defatted and dried okara
(10.9% water, ~8.1~ protein, and 2.2% fat) was employed and
supplied to the extruder from a feeder. As to the water
content, water was supplied by a peristaltic pump .so that
the water content eventually reached 55~. The barrel tem-
perature was set at 1~0C, and the screw speed at 60 rpm.
The temperature oE water for cooling the die was 2 to 6C.
The extruded product obtained under this set of conditions
had heterogeneous properties which were extremely similar
to those of real meat.
Example 2
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An extrusion experiment was carried out by employing
completely the same material and apparatus as those employed
in Example 1 except for the water content, which was set at
60% in this Example. The barrel temperature was set at
200C, and the screw speed at 120 rpm. The product thus
obtained had physical properties similar to those of real
meat.
