Note: Descriptions are shown in the official language in which they were submitted.
s
1 BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for de~aturing the
flesh of an a~uatîc animal with a h~drophilic organric solvent.
2. Description of the Prior Art
. . ~
U.S. Patent No. 4,060,542 (corresponding to Japanese
Patent Application (OPI) Nos. 70846/76 and 151360~76) discloses a
process which comprises contacting the flesh of an aquatic animal
with a hydrophilic organic solvent such as an alcohol to defat
and dehydrate the flesh and simultaneously to moderately denature
the protein of the flesh and to coagulate the flesh. However,
only an insufficient defatting of the aquatic animal flesh is
achieved in this process, and the inherent fishy smell cannot be
fully removed from the flesh.
SUMMARY OF THE INVENTION
Initially, in investigations it was found that the
inherent fishy smell of the flesh of an aquatic animal can be
removed almost completely by treating the flesh with a hydrophilic
organic solvent at about 20~C to the boiling point o~ the solvent.
However, the flesh of an a~uatic animal treated with an alcohol
at such a high temperature was excessively denatured and was
different from meat in texture. Further investigations made with
this background led to the accomplishment of the present invention.
An object of this invention is to provide a method for
denaturing the ~lesh of an aquatic animal, which can impart a
meat-like texture to the aquatic animal flesh and which can
almost completely remove the inherent fishy smell of the ~lesh
of an aquatic animal.
According to this invention, there is provided a
method for denaturing the flesh of an aquatic animal, which
1 comprises contacting the aqu~tic an~mal ~Lesh with a hydrophilic
organic solvent maintained at a temperature of 0C to less than
20C to impart a meat-like texture to the flesh, and then contact-
iny the flesh with a hydrophilic organic solvent maintained at
a temperature of 20C to the boiling point of the solvent to defat
and deodorize the flesh.
DET~ILED_DESCRIPTION OF T~E' INVENT'ION
This invention is applicable to all marine and fresh-
water aquatic animals such as fish, for example, marine or salt-
water fish such as ~laska pollack, mackerel, coa, shark, horse
mackerel, croaker, atkea mackerel, white croaker, sardines,
hake, etc., mollusca such as cuttleEish, octopus, etc.,
fresh-water fish such as grass fish, silver carp, big head carp,
carp, crucian, wels, etc., and all aquatic mammalia, etc. The
invention, however, is not to be constured as being limited to these
exemplified species. Herein, the term "aquatic animal" is used
in a broad sense to collectively describe aquatic mammals, fish,
etc.
Alcohols are the preferred hydrophilic organic solvents
used in this invention. Suitable alcohols are lower alcohols
having 1 to 4 carbon atoms. Non-toxic alcohols such as ethanol and
isopropanol are especially preferred hydrophilic oryanic solvents.
~ere there is noconcern relative to -toxicity or complete solvent
r~moval on or after drying where residual solvent might yive rise
to toxicity problems, methanol can be used as the hydrophilic
solvent.
In performing the method of this invention, the
flesh of an aquatic animal is prepared by removing bones
and viscera. The flesh is chopped (if necessary), and
optionally, soaked in water and the water removed. Then,
salt (sodium chloride) or/and a atty acid ester
B
of sucrose, and sodium bicar~onate and/or sodium polyphosphate,
etc. r are added. The sodium chloride or the fatty acid ester
of sucrose serves to dissolve actomyosin in the flesh and
impart moderate texture to the proteins when they are denatured
with the solvent. The sodium bicarbonate or the polyphosphate
is ~lseful or increasing the ~ater-retention properties of the
proteins in the final product. As stated before, it is the
action of the sodium chloride or the fatty acid ester of
sucrose which serves to dissolve actomyosin in the flesh and
to impart moderate texture of the proteins. Thus, it is
essential for at least one of sodium chloride or a fatty acid
ester of sucrose to be added to achieve the desired results.
Similarly, as stated before, it is the action of the sodium
bicarbonate or the pol~phosphate which increases the water-
retention properties of the Proteins and thus, it is essential
for only at least one of the sodium bicarbonate or the
polyphosphate to be added. The flesh is kneaded with a kneader
to render the flesh paste-like. Then, it is placed in a tank
containing a hydrophilic organic solvent maintained at 0C to
less than 20Cr preferably at 0C to lO~C, and contacted with
the solvent preferably for about 5 to about 20 minutes to
denature the flesh. During the denaturing process, the
proteins of the flesh are moderately coagulated and have a
meat-like texture, i.e., the te~ture of meat obtained from
livestock. The denatured flesh is taken out of the tank and
the solvent is preferably removed from the flesh. The
flesh is then placed in a tank containing a hydrophilic
organic solvent maintained at 20C to the boiling point,
preferably 40C to the boiling point, of the solvent, and
contacted ~ith the solvent for about 5 to about 20 minutes
~B
1 to defat and deodorize the flesh su~ficiently. This defatting
and deodorizing step can be used to completely remove the fish-- -
like smell of not only Alaska pollack, but also fish containin~
a large amount of fat such as mackerel and sardines whose
deodorization has heretofore been difficult. This treatment
with a hydrophilic organic solvent at a hi~h temperature does
rot make the flesh too hard nor result in the flesh losing a
meat-like texture.
A suitable amount of the hydrophilic organic solvent
used is at least about 2 times by weight of the aquatic animal
flesh in each of the two contacting steps in this invention.
The amount of the hydrophilic organic solvent used will differ
dependin~, of course, upon the fat content of the aquatic
animal flesh. ~s the fat content of the aquatic animal
flesh increases, the amount of the hydrophilic organic solvent
used will increase. rJith aquatic animal flesh with high fat
contents, a suitable amount of the hydrophilic organic solvent
used is about 6 times by weight to the total amount of the
aquatic animal flesh in the two steps of this invention.
While the treatment of the flesh of an aquatic
animal with a hydrophilic solvent at a high temperature usually
makes the flesh too hard and different from meat, the process
of this invention does not cause this disadvantage to occur.
This is presumably because the pre-treatment of the flesh with
a hydrophilic solvent maintained at 0C to less than 20C
imparts a livestock meat-like texture to the flesh and fixes
the flesh in a state that is d~fficult to change.
~he defatted and deodorized flesh of the aqua-tic
animal is preferably treated to remove solvent, e.g., by
centrifuging, and dried, e.g., to an extent oE ahout 25~ by
~ .
'`:"
1 weight of water or less, by passing aix over the flesh to Eorm
flesh proteins~ When the resulting flesh proteins are to be
used as a food, they are swollen with water, and cooked
while adaing seasonings, etc., thereto. Thus, for example,
a product similar in texture to a hamburger obtained Exom
nleat can be produced.
The following Examples are given to further illustrate
the pxesent invention in greater detail. Unless otherwise
indicated, all parts, percents, ratios and the like are by
weight.
Example l
160g o~ sodium chloride and 40g of sodium bicarbonate
~ere added to 8 kg of the chopped flesh o~ Alaska pollack (crude
fat content: about 3~S to 5.5~ converted to a dry basis), and
the mixture was kneaded with a kneader to render the flesh
paste-like.
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E~ .
:
1 The paste-l~ke mlxtuxe was d~vided lnto four e~ual parts and
subjec~ed to Trea~ments Al to A4 descri~ed below, respectivel~.
Al
The first part was extruded from a chopper having a
die orifice diameter of 3 mm into 4 liters of 95 w~w~ ethanol
maintained at 5C, and, after standing for 10 minutes, taken out
using a bamboo basket to remove the ethanol. The treated mixture
was again put into the chopper, extruded into 4 liters of 95
w/w% ethanol maintained at 5C, and stirred for 15 minutes. The
mixture in the ethanol was then placed in a centrifugal filter
to remove the ethanol, and dried by passing air thereover.
A2
The second part was subjected to Treatment ~1 in which,
however, the first treatment was performed in 95 w/w~ ethanol
maintained at 5C, and the next treatment, 95 w/w% ethanol
maintained at 40C.
A3
The third part was subjected to Treatment Al in which,
however, the first treatment was performed in ~5 w/w% ethanol
~ maintained at 40C, and the next treatment was performed also in
95 w/w% ethanol maintained at 40C.
~4
The fourth part was kneaded by hand in 6 liters of
95 w/w~ ethanol maintained at 5C, and, after standing for 15
minutes, was centrifugally filtered to remove the ethanoll after
which the product was dried by passing air thereover.
The crude fat contents of the dried solids obtained
using Treatments Al to A4 above were found (on a dry basis) to be
0~36% for Al, 0.03% for A2, 0.04% for A3 and 0 19% for A4,
respectively. It can be seen ~rom these results that more
de~atting was achieved usiny the me-thod o~ the pr~sent invention
~A2~ than was achieved ~n conventlonal met~od tA~1.
Patties were made from the dried proteins obtained
using Treatments Al to ~, and the ~ishy smells and textures o~
the patties ~ere sensually evaluated.
Sample Preparation
Dried protein (200 g) was immersed for 30 minutes in 2
liters of water, and then the excess water was removed by centri-
fugal filtration until the weight of the protein became 800 g.
The water-swollen protein (800 g) was mixed with 350 g of minced
beef, 250 g of beef tallow, 250 g of onion, 150 cc of bread crumbs,
80 g o butter, 10 cc of salt, 0.5 g of pepper. 0.5 g of a sodium
glutamate seasoning, and 5 g of beef extract. The mixture was
fried in a frying pan to make fried patties.
Sensual Test _A)
The fishy smell was evaluated by a panel of 20 persons
on a scale of five grades in which 5 represents the absence of a
fishy smell and 1 represents the presence of a fishy smell.
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I~rea~tment
Pane-list ~1 ~2 - ~3 ~4 Total
Pl 3 5 5 4 17
P2 4 5 5 ~ 18
P3 3 5 5 3 16
P4 3 5 5 3 16
P5 4 5 5 3 17
P6 4 5 S 5 19
P7 3 5 5 4 17
1 P8 3 4 4 3 14
P9 2 5 4 3 14
P10 4 5 5 5 19
Pll 4 5 5 4 18
P12 3 5 5 3 16
P13 4 5 5 4 18
P14 3 5 4 4 16
P15 2 .5 5 3 15
P16 2 4 ~ 2 12
P17 3 5 5 3 16
P18 4 5 4 4 17
P19 3 5 5 3 16
P20 2 5 4 4 15
Total 63 98 94 71 326
Average 3.15 4.90 4.70 3.5S 4.08
~7-
~8~5
1 Pispersion ~nal~s~ Ta~le
Degrees of Dispersion
Factor FluctuationFreedom D~spersion Ratio
... .
Sample 44.0 3 14.66 63.74**
Panel 1~.5 19 0.76 3.30**
Error 13.0 57 0.23 --
Total 71.5 79
** Statistically significant at the 1% risk level
Reliability Region ~5~ risk level) + 0.21
There was no statistically significant difference
between samples produced by Treatments A1 and A4 and
between the samples produced by Treatments A2 and A3
There was a statistically significant difference between
Al A4 and A2 A3.
It can be seen from the results shown in the above
table that a considerable fishy smell remained in the protein
obtained by the conventional method (A~), whereas the protein
obtained by the method of the invention (A2) was almost co~plete~
ly free from a fishy smell.
Sensual Test ~B)
~ = _ . .
The textures of the samples were evaluated by a panel
of 20 persons on a scale of five grades in which 5 represents
a texture similar to that of meat and 1 represents a texture
different from that of meat.
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T~e~ tmen*
Panelist Al . A2 ~3 ~4 Total
Pl 5 S 3 5 18
P2 5 5 3 5 18
P3 4 5 4 5 18
P4 5 4 4 5 18
PS 5 4 3 S 17
P6 5 5 2 4 16
P7 5 3 ~ S 17
1 0 P8 5 4 3 4 1
P9 5 4 2 5 16
P10 4 5 2 4 15
Pll 3 4 ~ 5 16
P12 . 5 5 3 5 18
P13 5 5 2 5 17
P14 5 5 4 4 18
P15 4 ~ 4 4 16
P16 4 5 ~ 4 17
P17 5 5 3 5 18
P18 5 5 3 4 17
Pl9 4 5 3 5 17
P20 S 5 4 5 19
To~al 93 92 64 93 342
Average 4.65 4.60 3.20 4.65 4
~9_
1 Dispers~on ~n~l~sis T~bl~
- Degrees.. of Dispersion
Factor ~lu-ct~ation~xe-edom Dispersion Ratio
. _ _ . . . _ . . ~ _ ~ . . _ _
Sample 30.9 3 10.30 24.52**
Panel 5.0 19 0.26 0.62
Error 24.1 57 0.42 --
Total 60.0 79
** Statistically significant ~t the 1~ risk level
Reliability Region (5% .risk leve~ .29
There was no statistically significan-t difference amon~
Al, A2 and A4 , but ther~ was a statistically significant
difference between Al A2 A3 and A3.
It can be seen from the results shown in the above
table that the protein obtained b~ the method of this invention
(A2) has a meat~like texture equivalent to that obtained using
conventional method (A4).
Example 2
12 liters of water at 5C was added to 4 kg of the
chopped flesh of mackerel ~crude fat content: about 25 to 55~
converted to a dry basis). The mixture was stirred for 5 minutes
and then water removed~ Then, 60 g of sodium chloride and 45 g
o sodium bicarbonate were added to the flesh, and the flesh was
kneaded with a kneader to render the flesh paste-like. The
paste-like mixture was divided into two equal parts and sub-
jected to Treatments Bl and B2, respectively, described below.
Bl
The first portion was extruded from a chopper wi~h a
die orifice diameter of 3 mm into 3 liters o~ 95 w/w% ethanol
maintained at 5C, and, after standing for ].0 minu~es, taken ou~
with a bamboo basket to remove the ethanol. The treated ~lesh
~10--
1 ~Yas again put into th~ chop~er, and e~truded into 3 liters of 95
w/w~ ethanol maintained at 5C. Tfie m~xture was st;rred for
15 minutes, and the ethanol was removed using a centrifugal
filter. Then, the product was again put into 3 liters of 95 w/w%
ethanol maintained at 5~C, stirred for 15 minutesr centrifugally
~iltered, and dried by passing air thereover.
B2
The second portion was extruded ~rom a chopper having
a die orifice diameter of 3 mm into 3 liters of 95 w/w~ ethanol
maintained at 5C, and, after standing for 10 minutes, taken out
with a bamboo basket to remove the ethanol. The treated ~lesh
was again put into the chopper, extruded into 3 liters of 95 w/w~
ethanol maintained at 5C, and stirred ~or 15 minutes. With
continued stirring, the ethanol was heated to 75C, and at 75C
the ethanol was stirred for 15 minutes. The mixture was
immediately filtered centrifugally to remove the e-thanol. The
flesh was again put into 3 liters of 95 w~w% ethanol maintained
at 75C and stirred for 15 minutes. The mixture was immediately
filtered centrifugally to remove the ethanol, and dried by passing
~ air thereover.
The crude fat contents of the dried solids obtained by
Treatments Bl and R2 were found (on a dry basis) to be 10~3% for
Bl and 0.1~ for B2, respectively. It can be seen ~rom these
results that a ~ish having a large amount of fat such as mackerel
was difficult to defat even by repeated treatment with an alcohol
at low temperature, whereas defatting to a marked extent was
achieved with the method of this invention (B2).
Patties were made from the dried proteins obtained by
Treatments Bl and B2, and the presence of fishy smells and their
textures were sensually evaluated.
--11--
Sensual Test (C ~
The fish~ smell ~as evaluated in t~e same manner as in
Sensual Test (A~ given hereinabove,
Treatment
Panelist Bl B2 Total
Pl 2 4 6
P2 3 4 - 7
P3 2 5 7
P4 2 5 7
P5 2 4 6
P6 3 4 7
P7 3 5 8
P8 2 5 7
P9 2 5 7
P10 3 . 5 8
Pll 3 4 7
Pl~ 2 4 6
P13 2 5 7
P14 3 5 8
P15 3 5 8
P16 2 5 7
P17 2 5 7
Pl~ 2 4 6
Pl9 3 5 8
P20 3 5 8
Total 4 9 9 3 14 2
Average 2 . 45 4 . 65 3 . 55
--12--
~g38q~f¢~;
1 Dispexsion Anal~is Ta~le
- Degrees of Dispersion
FactorFluctuationFreedom DispersionRatîo
. .. _,
Sample48.4 1 48.40 201.66**
P~nel 4.9 19 0.26 1.08
Error 4.6 19 0.24 --
Total 57.9 39
** Statistically significant at-the 1~ rick level
The product obtained by Treatment Bl had a ~trong fishy
smell and was unfit ~or ~ood. In con~rast, the product obtained
by Treatment B2 had an extremely weak fishy smell and could be
used sufficiently as a meat substitu-te.
Sensual Test ~D) f
. . ~
The textures of the products were evaluated in the same
manner as in Sensual Test (B) given hereinabove.
Treatment
Panelist 1 - 2 Total
Pl 5 4 9
P2 5 4 9
2~ p3 5 5 10
. P4 5 4 9
P5 4 5 9
P6 3 5 8
P7 5 5 10
P8 5 5 10
P9 4 4 8
P10 4 3 7
Pll 4 3 7
P12 ~ 4 8
P13 4 4 . 8
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1 ~e~ual T~S~t (Dl ~ continu~d
Treatment
Panelist Bl B2 Tot-al
. _
P14 5 5 10
PlS 5 5 10
P16 5 4 9
P17 3 4 7
Pl~ 3 5 8
P19 5 . 5 10
1 C~ P20 5 5 10
Total 88 88 176
Average 4~40 4040 4,40
There was no statisticall~ significant difference in
texture between the method of this inven-tion (B2) and the con-
ventional method IBl).
While the invention has been described in detail and
with reference to specific embodiments thereof, it will be
apparent to one skilled in the art that various changes and
modifications can be made therein without departing from the
spirit and scope therof.
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