Note: Descriptions are shown in the official language in which they were submitted.
METHOD FOR COLORING FISH FLESH
Background of the Invention
This invention relates to the field of processing
fish products and-more particularly to an improved method for
imparting color to fish flesh.
In the manufacture of lox, sides of salmon are
smoked and food coloring is added thereto to impart the char-
acteristic salmon red color. Coloring of the lox is conven-
tionally accomplished by immersion of cured fish slices in a
color bath containing the proper mixture of food colors,
followed by packing of the fish for shipment. Substantial
labor is required because the fish must be sliced before
immersion in the coloring solution.
There have been no suitable commercial processes for
coloring whole fish or sides of fish. Often salmon of excel-
lent flavor and texture has severely reduced market appeal
where it exhibits a white color rather than the salmon red
color which the consuming public has learned to expect.
Hatchery salmon in particular tend to have white flesh. Pale
to dark chums, caught late in the season, also suffer from
deficient color which adversely affects their ~arket value.
In order to render white or pale salmon attractive to the con-
sumer, it has been necessary to subiect slices of the fish to
the aforesaid immersion coloring process which, in this
instance also, affords only low productivity. Whole fish or
sides of fish cannot be satisfactorily colored by immersion
because the rate of diffusion of colorant through the fish
flesh is not adequate to produce an even hue within a reason-
able time.
Accordingly, there has been an unfulfilled need in
the art for improved processes for coloring fish flesh and for
introducing curing solutions into the fish.
Summary of the Invention
Briefly, therefore, the present invention is direct-
ed to a process for coloring fish flesh, in which an a~ueous
solution of a food dye is introduced into the flesh. Such
solution is injected into the flesh via an array of a plural-
ity of hypodermic needles and the fish flesh containing the
injected dye is aged for a period of at least about two days.
The dye is thereby allowed to diffuse through the flesh and
produce a substantially even hue therethroughout.
Other objects and features will be in part apparent
and in part pointed out hereinafter.
Brief Description of the Drawings
~ Fig. 1 is a schematic side elevation of an apparatus
useful in practicing the method of the invention, with some
parts broken away to better illustrate the operation of the
apparatus;
Fig. 2 is an enlarged detail view in section of a
valve mechanism for delivering food dye solution to the injec-
tion needle manifold of the apparatus of Fig. l; and
Fig. 3 is an enlarged detail view illustrating a
stop arrangement for preventing the injection needle stripper
plate of the apparatus of Fig. 1 from heavy impact on and dam-
age to a slab of fish that is colored in accordance with the
method of the invention.
Corresponding reference characters indicate corre-
sponding parts in the several views of the drawings.
Description of the Preferred Embodiments
In accordance with the present invention, it has
been discovered that fish flesh, particularly salmon, can be
`^S~9
colored effectively by controlled injection of an aqueous food
dye solution into the flesh using a plurality of hypodermic
needles manifolded to a supply of the dye solution. More
particularly it has been found that whole fish and sides of
fish can be colored at high productivity, so that division o~
the fish into small slices prior to ccloring is rendered un-
necessary. Although the injection of dye solution does not
immediately lead to uniform color distribution even where a
multiplicity of injection needles are employed, it has further
been discovered that aging of the fish flesh for a relatively
short period of two to three days while in cure results in
diffusion of the dye from the sites in which it initially con-
centrates upon delivery from the injection needles and thus
leads to the development of a very even and attractive hue
throughout the flesh.
- In particular, it has been found that highly satis-
factory results can be achieved using a Townsend model 1400
injector produced by Townsend Engineering Company, Des Moines,
Iowa for carrying out the injection process. This machine is
fully described in Townsend U.S. patent 3,687,058.
Illustrated in the Fig. 1 of the drawings is a sche-
matic depiction of the essential operating parts of the
Townsend machine. Shown at 98 is an endless chain belt hori-
zontal conveyor which receives slabs of fish 288 for position-
ing under a manifold 146 containing a supply of aqueous food
dye solution for injection into the fish. A multiplicity of
injector needles 174 are arrayed on the lower face of manifold
146 for penetrating the fish flesh upon lowering of the manl-
fold. Needles 174 are in communication with aqueous dye solu-
tion contained within the manifold.
Manifold 146 is supported on the outer ends of a~ms
80 and 82 which are pivotally connected at their opposite ends
to support plates 106 and 108. Arm 80 and plate 106 are on
the near side of the machine as depicted in Fig. 1, while arm
82 and plate 108 are on the opposite side and respectively
identical to, but obscured by, arm 80 and plate 106. At a
point intermediate manifold 146 and plates 106 and 108, each
of arms 80 and a2 is pivotally connected to the upper end of a
rod (76, 78 respectively). The lower ends of rods 76 and 78
are connected to eccentrics 72 and 74 of cranks that are
turned respectively on opposite ends of a shaft 64. Shaft 64
is turned by rotation of a pulley 66 connected by belts 62 and
68 via an intermediate pulley 58 to a drive motor 42. Rota-
tion of the crank causes rods 76 and 78 to move in phase in a
vertical reciprocal fashion. This in turn causes arms 80 and
82 carrying manifold 146 to reciprocate up and down and
needles 174 to be alternately inserted into and removed from
the slab of fish flesh 288 positioned on the conveyor 98 below
- manifold 146.
Another pair of arms 134 and 134a are each pivotally
connected at one end to eccentrics 74 and 76, respectively,
and connectea at the other end to a pawl and ratchet wheel
mechanism 120. This mechanism advances chain belt conveyor 98
as arms 134 and 134a reciprocate due to the cranking action of
the eccentrics. By virtue of their attachment to the same
eccentrics as arms 76 and 78, arms 134 and 134A reciprocate on
the same cycle as manifold 146. However, the pawl and ratchet
mechanism 120 is arranged for advancement of the conveyor to
be out of phase with the lowering of the manifold, whereby
slab 288 is held stationary as needles 174 are inserted into
the fish flesh. Mechanism 120 further provides for the
periodic advance of the conveyor to be less than the width of
the array of needles on manifold 146, i.e. the dimension of
the array in the direction of travel of the conveyor, so that
needles 174 penetrate each slab 288 more than one time.
Preferably, the conveyor is advanced between about one-eighth
and about one-half of the width of the array on each stroke.
Most preferably, an advance of approximately one quarter of
the width of the array is utilized~
A stripper plate 260 having a pattern of holes
therein in registry with needles 174 is positioned between
manifold 146 and conveyor 98. If the fish slab is lifted from
the conveyor on the upward -stEoke of the mani~old due to fric-
tional engagement with the needles, the stripper plate acts as
a barrier limiting the extent of such upward movement and
effecting disengagement of the needles from the flsh flesh.
In one embodiment of the invention, the stripper plate may be
fixed in position by rigid attachment to the conveyor support
frame while in an alternative embodiment, as illustrated in
Fig. 3, a yoke 301, driven by a pneumatic piston 303 and push
rod 305, may be utilized for driving of the stripper plate
downward in conjunction with the upward stroke of the mani-
fold. In the latter arrangement, it is desirable to provide a
fixed stop 307 on the frame aligned with and directly beneath
push rod 305 so as to limit the downward stroke of the
stripper plate and prevent damage to the fish. Stop 307 com-
prises a nut or collar 309 having a rubber stopper 311 in-
serted in the upper end thereof. Stopper 311 engages the push
rod and absorbs the impact of stopping the downward stroke.
Preferably, the needles are arrayed on one eighth
inch to one half inch centers most preferably approximately
3/16 inch. The bore of the needles if preferably in the range
of 0.03 inch to 0.06 inch.
- In order to conserve the dye solution and minimize
spraying of solution on the outside surfaces of the fish or
onto surrounding surfaces of the injection machine, the dye
solution is supplied to the manifold via the flow control
arrangement illustrated in Fig. 2. Thus, a valve 210 and a
supply line 206 are mounted on one end of the manifold and
vertically reciprocate therewith upon each stroke of arms 76
and 78. Valve 210 includes a valve member 230 normally held
121~
closed a~ainst valve seat 234 by the force of a spring 224 on
a vertically oriented valve stem 220 attached at its upper end
to valve member 230. Stem 220 has a piston 222 attached to
its lower end and is positioned vertically above a pin 259
that is mounted on the frame adjacent conveyor 98. On each
downward stroke of`arms-76 and 78, piston 222 engages pin 2~9,
thereby restraining the downward movement of stem 220 and
causing valve member 230 to separate from seat 234 and open
the valve for delivery of dye solution through pipe 206, the
interior of manifold 146 and needles 174 into the fish flesh.
Upon the reciprocal upward movement of arms 76 and 78, piston
222 disengages from pin 259, thereby allowing spring 224 to
close the valve and terminate supply of dye solution to the
manifold. The bore of needles 174 is small enough so that
atmospheric pressure prevents drainage of dye solution from
the manifold when valve 210 is closed. The height of pin 259
is adjustable to provide for control of the period in which
the valve is held open Qn the downward stroke of the manifold
on arms 76 and 78. As shown in detail in patent 3,687,058, a
pressure surge system may be provided on the inlet side of
valve 210 to produce a surge of fluid flow during the period
in which valve 210 is open.
In carrying out the method of the invention, a slab
288 of fish flesh is delivered to the conveyor, a supply of
dye solution is placed in communication with the inlet side of
valve 210, and motor 42 is started. Operation of the motor
advances the conveyor by operation of arms 134, 134A and pawl
and ratchet mechanism 120, thereby advancing the fish to an
injection station immediately underneath manifold 146. Opera-
tion of arms 76 and 78 alternately moves manifold 146 down-
wardly, so that needles 174 penetrate the fish flesh, and up-
wardly so that the needles are removed from the flesh with or
without the aid of stripper plate 260.
lZl~
On the downward stroke, piston 222 engages pin ~59,
thereby restraining stem 220 and opening the valve. Under
pressure from the supply of dye solution (and preferably with
the aid of the pressure surge system illustrated in patent
3,687,058) dye solution flows through needles 174 and into the
fish flesh while the needles are in the flesh. Upon the
return stroke of the manifold, spring 224 causes the valve to
close and solution flow to cease.
To provide optimal distribution of dye solution
through the flesh of the fish, needles 174 preferably extend
to within about 1/16 inch, most preferably about 1/32 inch of
the upper surface of conveyor 98 at the extremity of the
downward stroke of the manifold.
A variety of dye solutions may be used to impart a
desired hue to the fish flesh subjected to the process of the
- invention. For imparting the salmon-red color desired for lox
and other salmon products, it has been found that a suitable
dye solution contains between about- ?5 and-about 80 parts by
weight F, D & C Yellow No. 6 and between about 20 and about 25
parts by weight F, D & C Red No. 40, solids basis. Most pref-
erably, the colorant is comprised of 77.3 pbw yellow and 22.7
pbw red. To obtain the desired suffusion of natural appearing
color throughout the flesh, the coloring solution should con-
tain between about 0.6 and about 0.7 ounce total color solids
per sallon of water. A lesser concentration of colorant may
result in inadequate distribution of color while a greater
concentration may lead to an artificial appearance.
After injection of the fish with the dye solution,
the fish slabs are removed from the discharge end of conveyor
98 and placed in a conventional cure solution for a period
that is preferably at least about three days. This step
serves a dual role, providing a cure for the fish and causing
the color to diffuse and be evenly distributed throughout the
fish flesh. As a result, a highly attractive, even hue is
achieved in an overall processing time of only two to three
days. Moreover, by coloring whole fish or sides of fish prior
to slicing a significant reduction is achieved in the labor
required for processing and packing the fish.
It has further been discovered that the same type o~
machine utilized for injection of coloring solution into the
fish flesh may be also utilized for injection of a cure. Such
an operation minimizes the need for soaking in a cure bath but
an aging process of two to three days is still desirable for
full diffusion of the food dye and development of the overall
apPearance of which it is attractive to the consumer.
In order to inject cure, it has been discovered that
conventional cure material may be dissolved in the dye solu-
tion so that cure and dye are injected into the fish in a
single operation.
In view of the above, it will be seen that the
several objects of the invention are achieved and other advan-
tageous results attained.
As various changes could be made in the above
methods without departing from the scope of the invention, it
is intended that all matter contained in the above description
or shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
