Note: Descriptions are shown in the official language in which they were submitted.
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Process for producin~ fish meat materlal
The present invention relates to a process for produclng a
deboned, water washed, fish material, usually called Surimi.
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Surimi is a Japanese term for mechanically deboned fish meat
that has been thoroughly washed with water and then mixed wLth
additives, i.e. so-called cryoprotectants, for improved frozen
shelf life.
Surimi is used as an intermediate product for a variety of
fabricated seafoods~ such as flakes and crab legs. The aim of
washing with water is not only to remove fat and undesirable
matter, such a~ blood, plgments and odorous substances, but,
more impor~antly to increaae the concentration oE myoelbrillar
protein (actomyosin) thereby improving gel strength and elas-
ticity, essential properties for Surimi-based products.
Surimi has a great potential as a functional protein ingredient
which can be substituted for a variety of traditional animal
and vegetable proteins. The virtually unlimited resources of
underutilized fish species will ensure a sufficient production
of Surimi at a reasonable cost to meet the need for base
material for Surimi-based products.
In Japan, Surimi has been produced for several hundred years.
Traditionally, Surimi was freshly prepared from fresh fish and
immediately processed into a variety of products.
30 ` The technique evolved around A.D. 1100, when Japanese fishermen
discovered that they could keep the product longer if washed
minced fish was mixed with salt, ground up, and steamed or
broiled. The traditional Surimi production was run on a day-
to-day basis, depending on the supply of fresh fish. Conse-
quently, the Surimi industry could not expand to any great
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extent and remained in a limited capacity. However~ in 1959 atechnique to stabilize frozen Surimi was discovered. It was
found that an additive, i.e. a cryoprotectant, kept the Surimi
from freeze denaturation during frozen storage. This discovery
was the starting point for a rapid growth of Surimi production.
For additional information about the development of the conven-
tional process for production of Surimi, see Chong M. ~ee,
Surimi Process Technology , Food Technology, pp. 69-80
(November 1984).
Basically, Surimi is produced by repeatedly washing separated
fish ~eat with chilled water (5-10C) until it becomes odor-
less and colorless - that is to say, until most of the water-
soluble protein is removed. The temperature o~ the wash water is
determined by the species of fish utilized. Warm water fish can
tolerate a higher water temperature than cold water fish wlthout
a reduction in protein functionality. Originally, Suriml was
made in a manual batch process, with at least three washing
steps. Later, a commercial continuous process was developed. See
Fig. 1. The fish is headed, gutted and minced to a particle size
; of about 3-4 mm. The minced fish is mixed with the appropriate
amount of water in a ratio tank, and the mixture is pumped to a
washer, that is to say, a tank with an agitator, and is then
pumped to a rotating screen rinser, which comprises a cylindri-
cal mantle having holes of about l mm diameter. Water is sprayed
from the outside, and a flow of washed fish meat comes out of
the rinser. Water which passes through the holes of the screen
is discharged as waste. Usually there are three sets of washing
tanks and rinsers. The washed fish meat, with a dry solids
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(D.S.~ content of about 10-18 %, is then refined in a strainer
;having holes of about 1/2-1 1/2 mm, diameter in a cylindrical
mantle. Horizontal shaft rotating blades drive the Incoming fish
meat toward the mantle, and pieces larger than the holes form a
re~ect fraction, whilst the refined fish meat passes through the
holes and is then dewatered in a screw press to a D.S. content
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of about 20-27 %. Thls dewatered cake is then blended with the
cryoprotectant additive, 4 % sugar, 4 % sorbitol and 0.2 % poly-
phosphates and is then frozen and packed as Surimi product.
This conventional Surimi process i8 still rather old fashioned,
even if it is continuous. There are many drawbacks inherent in
the process. The overall yield of valuable fish protein is qulte
low, as the losses in the rather inefficient washing steps are
large. The amount of water needed for washing is large. The fish
protein is exposed to air for a long time, which results in a
great amount of hydrolysis and deterioratlon of the Eish pro-
tein. The pLant for carrying out the process requires a large
floor area.
Accordingly, there i8 a need ~or an efELcLent process for pro-
ducing Surimi, which overcomes the above mentioned de~iciencies.
It is therefore an ob~ect of the present invention to provide a
continuous process, to produce Surimi in an efficient way, using
smaller amounts of washing water and exposing the fish protein
to air for shorter periods of time. It is a further object of
the present lnvention to provide a compact plant, requiring but
a small amount of floor space, for carrylng out the continuous
process.
In the process of the invention, the minced fish material is
mixed using in-line mixer means, e.g. a static mixer or a pump,
and is washed by using a centrifugal decanter, e.g. a centri-
fugal clarifier having a horizontal axisO The process according
to the invention increases the yield of Surimi by up to 50 %,
requlres the use of 25-50 % less washing water, requires a
shorter amount of time (about 1.5 mlnutes as compared to 15
mlnutes for the conventional process), requires less staff and
less space to perform, requires fewer components and results in
a higher quality product~, havlng hlgher gel-strength, lower
water content and~appearing whiter in color than product
produced by the conventional process.
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The present invention relates to a process for producing a
deboned, water washed fish meat material, more commonly called
Surimi, in which the raw fish material is headed, gut~ed and
minced to a particle size of about 3-4 mm. The minced material
is washed with chilled water tmtil it becomes odorless and
colorless, and the washed material is then dewatered to a fish
meat having a D.S. coatent of about 18-22 %, which could then
be blended with additives such as sugar, sorbitol and poly-
; phosphates, frozen and packed.
10Fig. 1 illustrates a conventional process of making Surimi
(such as that described in the above-cited article from Food
Technology).
Fig. 2 depicts a process according to the invent:Lon wherein
minced fish is mixed with water and washed in ln-line ~ixer
means and separated in a centrlfugal decanter into a first
fraction of fish meat which is strained and further dewatered in
a screw press.
Fig. 3 depicts another process according to the invention where-
in minced fish is mixed with water and washed in in-line mixer
means and separated in a centrifugal decanter into a first frac-
tion of fish meat having a high dry solids conteat of 22-27 %
which is then straiaed.
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Fig. 4 depicts another process according to the invention where-
in miaced fish is strained to remove bits of bone, tendon, skin
and other impurities, mixed with water and washed in in-line
mixer means and thereafter separated in a centrifugal decanter
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;~ ~ into a first fraction of fish meat which is further dewatered in
a screw press.
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Fig. 5 depict~ another~process according to the invention where-
in minced fish is strained, mixed with water and washed In in-
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llne mixer means and separated in a centrifugal decanter into
a first fraction of fish meat having a high dry solids content
of 20-27 ~, to which fraction is added cryoprotectants and other
additives.
According to the invention the improvement over the conventional
process lies firstly in the washing of the minced fish material,
which is carried out by mixing a flow of minced material with
washing water in efficient in-line mixer means, such as a static
mixer (e.g., a pipe provided with internal baffles to create
turbulence) or a pump, and secondly in the dewatering of the
mixture so obtained in a centrifugal decanter with horizontal
axis~ to separate the mixture into a first fractlon of fish rneat
and into a second eraction of waste water, containing i~purltLes
and proteln losses which can be recovered Lf desired.
The second fraction of waste water can be further separated in a
high speed centrifugal clarifier into a third fraction of
recovered protein material and a fourth fraction of waste water.
The third fraction of recovered proteln material can be blended
with the first fractlon of flsh meat or can be handled in an
independent process line to yield a debonedJ wat~r washed fish
meat materlal.
