CA1154209A - Method and apparatus for stripping flesh from fishframes - Google Patents
Method and apparatus for stripping flesh from fishframesInfo
- Publication number
- CA1154209A CA1154209A CA000382411A CA382411A CA1154209A CA 1154209 A CA1154209 A CA 1154209A CA 000382411 A CA000382411 A CA 000382411A CA 382411 A CA382411 A CA 382411A CA 1154209 A CA1154209 A CA 1154209A
- Authority
- CA
- Canada
- Prior art keywords
- rollers
- fish
- pair
- squeeze
- squeeze rollers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
ABSTRACT
Method for stripping flesh from fish frames by a squeezing action of a pair of contra-rotating rollers between which decapitated and gutted fishes or fish portions are passed tail first, An apparatus for executing said method comprises at least two pairs of contra-rotatable rollers (209, 210 212, 213) having parallel upright axes and each having at least a resilient surface, the first pair (209, 210), as viewed in the direction of transport, being at a greater mutual distance than the second pair (212, 213).
Fig. 4
Method for stripping flesh from fish frames by a squeezing action of a pair of contra-rotating rollers between which decapitated and gutted fishes or fish portions are passed tail first, An apparatus for executing said method comprises at least two pairs of contra-rotatable rollers (209, 210 212, 213) having parallel upright axes and each having at least a resilient surface, the first pair (209, 210), as viewed in the direction of transport, being at a greater mutual distance than the second pair (212, 213).
Fig. 4
Description
~1 ~LS4~20~9 METHOD AND APPARATUS FOR STRIPPING ~LESH FROM FISH
FRAMES
Hithert~o ~flesh was strlpped from fish ~rames by a cutting action, ~either: manually ~ or mechanically~
Both methods are not~feasible for treating~s;mall~fishes.
Accordingly, s~mall fi~she~s were;previously comminuted~and ; 5 pressed through sleve~mean~s, thereby removing the bones but yielding an off-colour mince. The invention~provides~
a method and;~apparatus~for~reme~dylng~this~
The invention provlde~s a~ me;thod for sbripping~
- ~ 10 flesh from ~he frame ~and skin: of a :fish port,ion,~ in which proeess a decapi;tated and gutted~fish portion2~whleh~ls~
; unsXinned and still contàins~the~backbone, is~p~assed tail-first between~a~pair~;of contra-rota~ing~paralle~ squeeze rollers, the~nip between whi~eh~has~su~ch a width;~that;~the~
~ail and the~skin ~o~ said~fish~portion is~gri~pped~su-f;~
ciently tightly for~the~skin and~ackbone of the fish~-to be drawn betwe~en~the rollers~wlthout being significantly damaged, and~while~the fish portion is being drawn between the squeeze rolle~rs flesh is~expressed from the head end 20 thereof. ~ ;
:
The inventicn also provides an apparatus in which the above process can be conducted~ comprising a housing, feeding means for fish portions, treating rneans and dis-. , : ,.
, charging means, which apparatus is characterised inthat the treating means comprise at least two pairs of contra-rotatably~drivable parallel rollers having upright axes, the first pair of rollers, viewed in the direction of transport~ being at a greater distance than the second pair of rollers, at least the second pair being coated with a resllient material having a profiled surface.
Although not absolutely necessary, it is highly desirable to have a second pair of rollers situated immediately in front of the squeeze rollers and rotated in a similar contrary manner relative to each other such that these rollers firstly guide the fish into the nip between the squeeze rollers and secondly apply a light pre-squeezing action to the fish which loosens the bond between the flesh and the frame. This pre-squeezing fa-cilitates the action of the squeeze rollers in express-ing the flesh from the fish as already described. This second pair of rollers will hereafter be referred to as the "pre-squeezing rollers".
Although not essential, it is also desirable to have a further pair of rollers situated immediately behind the squeeze rollers and rotated in a similar contrary manner relative to each other, such that these rollers grip the tail of a fish emerging from between the squeeze rollers and assist in the passage of the skin and frame of the fish through the apparatus.
2i~
- 3 ~ " 2~
~ his further pairof rollers will hereinafter be referred to as the "discbarge rollers "~
An apparatus according to the invention can be provided with squeeze rollers plus pre-squeeze rollers, or with squee~ze rollers plus discharge~rollers or with a combination of all three types of rollers ?
as desired~
Although the~squeeze rollers can be mounted in any orientation, it is~nevertheless highly desirable~ ;
that the nip between the squee~ze rollers sh;ould~ e~
in a vertical, or~at lèast~su~stantially ve~r-tical,plane.
; This feature is beneficial in assisting the recovery of the flesh expressed from the fish because the ~'lesh will tend to drop away from the~rollers rather than~
; 15 being caught between~bhem. ;
:
A further~des~irable f'eature is a means for applying water eithqr continuousl~ or in-termittently~
to the various~palrs of rollers.
~; Application~of the water can be, for~example, b~ means of a j~et;o~r~spray. ~he~wat~er assists~in keeping the~rollers~clean~and~there~fore~maintaining~
their gripping~qualit~les. ~;It~is generally desirable ~ ~ -to ensure that excessive~ amounts o~ water do not become mixe~d :with -th~e Xlesh expressed from the ~ish~
and therefore the provislon of means for collecting and removing the water falling ~rom the rollers is advantageous~
~ he s~ueeze rollers must have a degree of resilience~suff~icient to accommodate the naturally- ;
varying cross-section of a typical fish and -to accommodate the~variations in~size ~rom one fish to another. We have found that in general the squeeze ' :
. :
.: ~
, .
FRAMES
Hithert~o ~flesh was strlpped from fish ~rames by a cutting action, ~either: manually ~ or mechanically~
Both methods are not~feasible for treating~s;mall~fishes.
Accordingly, s~mall fi~she~s were;previously comminuted~and ; 5 pressed through sleve~mean~s, thereby removing the bones but yielding an off-colour mince. The invention~provides~
a method and;~apparatus~for~reme~dylng~this~
The invention provlde~s a~ me;thod for sbripping~
- ~ 10 flesh from ~he frame ~and skin: of a :fish port,ion,~ in which proeess a decapi;tated and gutted~fish portion2~whleh~ls~
; unsXinned and still contàins~the~backbone, is~p~assed tail-first between~a~pair~;of contra-rota~ing~paralle~ squeeze rollers, the~nip between whi~eh~has~su~ch a width;~that;~the~
~ail and the~skin ~o~ said~fish~portion is~gri~pped~su-f;~
ciently tightly for~the~skin and~ackbone of the fish~-to be drawn betwe~en~the rollers~wlthout being significantly damaged, and~while~the fish portion is being drawn between the squeeze rolle~rs flesh is~expressed from the head end 20 thereof. ~ ;
:
The inventicn also provides an apparatus in which the above process can be conducted~ comprising a housing, feeding means for fish portions, treating rneans and dis-. , : ,.
, charging means, which apparatus is characterised inthat the treating means comprise at least two pairs of contra-rotatably~drivable parallel rollers having upright axes, the first pair of rollers, viewed in the direction of transport~ being at a greater distance than the second pair of rollers, at least the second pair being coated with a resllient material having a profiled surface.
Although not absolutely necessary, it is highly desirable to have a second pair of rollers situated immediately in front of the squeeze rollers and rotated in a similar contrary manner relative to each other such that these rollers firstly guide the fish into the nip between the squeeze rollers and secondly apply a light pre-squeezing action to the fish which loosens the bond between the flesh and the frame. This pre-squeezing fa-cilitates the action of the squeeze rollers in express-ing the flesh from the fish as already described. This second pair of rollers will hereafter be referred to as the "pre-squeezing rollers".
Although not essential, it is also desirable to have a further pair of rollers situated immediately behind the squeeze rollers and rotated in a similar contrary manner relative to each other, such that these rollers grip the tail of a fish emerging from between the squeeze rollers and assist in the passage of the skin and frame of the fish through the apparatus.
2i~
- 3 ~ " 2~
~ his further pairof rollers will hereinafter be referred to as the "discbarge rollers "~
An apparatus according to the invention can be provided with squeeze rollers plus pre-squeeze rollers, or with squee~ze rollers plus discharge~rollers or with a combination of all three types of rollers ?
as desired~
Although the~squeeze rollers can be mounted in any orientation, it is~nevertheless highly desirable~ ;
that the nip between the squee~ze rollers sh;ould~ e~
in a vertical, or~at lèast~su~stantially ve~r-tical,plane.
; This feature is beneficial in assisting the recovery of the flesh expressed from the fish because the ~'lesh will tend to drop away from the~rollers rather than~
; 15 being caught between~bhem. ;
:
A further~des~irable f'eature is a means for applying water eithqr continuousl~ or in-termittently~
to the various~palrs of rollers.
~; Application~of the water can be, for~example, b~ means of a j~et;o~r~spray. ~he~wat~er assists~in keeping the~rollers~clean~and~there~fore~maintaining~
their gripping~qualit~les. ~;It~is generally desirable ~ ~ -to ensure that excessive~ amounts o~ water do not become mixe~d :with -th~e Xlesh expressed from the ~ish~
and therefore the provislon of means for collecting and removing the water falling ~rom the rollers is advantageous~
~ he s~ueeze rollers must have a degree of resilience~suff~icient to accommodate the naturally- ;
varying cross-section of a typical fish and -to accommodate the~variations in~size ~rom one fish to another. We have found that in general the squeeze ' :
. :
.: ~
, .
2~1~
rollers should be made of a material having a hardness in -the range 20 to 40 on the ~hore scale. With this consideration in mind, the squeeze rollers are best made from natural or synthetic rubber having a hardness in this range.
~ he surface texture of the squeeze rollers must be such that sufficient fric-tion can be generated bet-ween the roller surfaces and the skin of a fish to draw the fish between the rollers, while not causing ~ny significant damage to the skin. A surface fea-t-uring a multitude of small closely-spaced inden-ta-tions or projections is very suitable. Alternatively, a multitude of grooves or ribs, arranged for example parallel to the cylindrical axis of the roller, can be used. ~hese surface fea-tures can be moulded into the ma-terial from which the bulk of the roller is constructed, or can be imparted -to the roller by means of a surface covering.
~he pre-squeeze discharge rollers can be constructed of similar materials wi-th similar surface properties. We have found, however, that a relatively more frictional surface on the discharge rollers is beneficial.
~he physical size of the squeeze rollers may be varied deperlding upon the physical size of the fish to be processed using -the invention. ~he process of -the invention can be readily adapted for small, intermediate or large fish. Clearly fac-tors such as the ph~sical size of the rollers, their positioning relative to one another, and the speed with which a fish passes between the rollers may need adjustmen-t according to the particular fish being handled.
' ;
llS4~D~
In general, we have found that the squeeze rollers should have a diameter in the range 30 to 90 mm and a length in the range 60 -to 250 ~m.
~ he pre-squeeze rollers ~hould ideally have a length the same as that of the squeeze rollers. ~he dia~eter of the pre-squeeze rollers is preferably substantiall~ greater -than that of the squeeze rollers, thus promoting maximum fish-roller contact. In general we have found that the pre-squeeze rollers should have diameters in the range 70 to 120 mm.
.
~ he discharge rollers should ideally have a length -the same as that of the squeeze rollers~ ~he - diameter of the discharge rollers, however, is preferabl~ substantiall~ less than that of -the squeeze rollers so that close proximity between the two pairs of rollers can be obtained. In general we have found that the discharge rollers should have diameters in the range 30 to 60 mm.
Ideally the apparatus of the invention should be constructed such that the distance between the cylindrical axes of the squeeze rollers can be adjusted readily, thus making the apparatus better able to be used in -the processing of a wide range of fish sizes~
Preferably, the pre-squeeze rollers and the discharge rollers are similarly adaustable.
Preferabl~, -the squeeze rollers should be in con tact with each other With roLlers of hardness 20-40 and preferably 30-35 on the "A" ~hore scale, and a diameter of 50 to 90 mm, the cylindrical axes can be set so that the rollers are just touching, the resilience of the s~05~
rollers then providing for passage of a fish between them~ The more resilient the rollers, the closer can be the cylindrical axes to produce an effective pressure on a fish passing between the rollers~
Preferably, there is a gap between the pre-squeeze rollers, thus ensuring that their action on a fish passing between them is merely a mild squeeze and does not cause any significant expression of flesh from the fish in the manner intended during subsequent passage between the ~ squeeze rollers. In genaral, this gap will be from about 2 to about 30 mm. ~he gap between the pre-s~ueeze rollers~ when small fish such as blue whiting are being processed, will generally be about 4 to about 14 mm. ~or substantiall~ larger fish, such as haddock, -this gap will generally be about 16 to about 26 mm.
~he discharge rollers should ideally be in contact with one ano-ther, to ensure that they grip adequately the tail of a fish emerging from between the squeeze rollers, thus drawing the spent skin and skeleton of the fish onwards through the apparatus.
~he speed with which a fish passes between the various pairs of rollers should be constant, or prefer-ably increasing slightly as the fish progresses through the apparatus. ~he speed of rotation of the rollers should be set accordingly. A typical throughput for small fish, such as blue whiting, fed continuously into the apparatus, can be up to about 100 fish per minute, but a throughput of 25 to 50 fish per minute would be more normal.
~ ~he extent to which relatively bone-free and skin-free flesh can be recovered from a fish by means of the invention depends to a considerable extent on the ~uality of the fish used and the manner in which the fish has been treated and prepared prior to rolling. It is obviously , L5D~O~
essential that the head and gut regions of the fish should be removed prior to rolling. It is also use~ul if the dorsal fins of the fish are cut off7 as we have found that thiS can res~l~ in ~ smoother passage of the fish between the rollers and a lower incidence of back-bone breakage. It can also be advantageous if the belly flaps o:~ the fish are removed prior to rolling.
In the case of small fish such as blue whiting, small haddock, whiting and codling, the whole fish (minus head and guts) can be processed as a single unit.
Due to their small size, such fish are difficul-t -to process economically by conventional filleting operations conducted either mechanically or by hand9 In the case of larger fish, for example cod, it can be advantageous to "halve" the fish into "top" (head) and "tail" por-tions. ~he top portion can be pro-cessed using conventional techni.~ues to yield high quality fillet material. ~he intact tail por-tion can be processed usin~ the invention~
~he invention will now be more particularly described with reference to the accompanying drawings, of which:
~igs 1, 2, and 3 i.llustrate diagramatically the passage of a fish carcass between a pair of contra-rotating rollers;
~ig 4 represents a general plan view of a fish processing apparatus in accordance with the invention;
and ~ig 5 represents a ~ertical cross-section of 3o the apparatus depicted in ~ig 4 taken on the line AA shown in ~ig 4.
~`Q' (3 Figs 1 to 3 show a pair of parallel contra-rotating squeeze rollers 101 and 102, preceded by a pair of contra-rotating pre-squeeze rollers 106,107, set at a wider nip distanGe, and illustrate the passage of a head-ed and gutted fish carcass 103 between the rollers. Tail104 of fish 103 is presented to the pre-squeeze rollers, and on being gripped between the rollers and thereby slightly pressed passes through in the direction indicated between the squeeze rollers 101,102. As the bulk of fish 103 contacts the squeeze rollers it is squeezed between them and the flesh 105 within the fish is expressed there-from tFig 2).
Fig 3 shows the final stage of the rolling proce-dure, with fish 103 (now comprising essentially merelythe skin and backbone structure) having passed completely between the rollers and the flesh 105 remaining in front of the rollers.
Fig 4 is a plan view showing the general lay-out of a fish processing apparatus according to the invention.
The apparatus comprises a rectangular chamber 201, of which side walls 202 and 203 can be seen in section. Ends 204 and 205 of chamber 201 are open. A horizontal floor 206 spans the entire width of chamber 201, and extends slight-ly over half' the length of the chamber from forward end 204.From the rear edge 207 of floor 206, a sloping chute 208 leads downwardly and outwardly from chamber 201.
Chute 208 also spans the entire width of chamber 201.
The apparatus is provided with a pair of parallel pre-squeeze rollers 209 and 210 mounted with their longi tudinal axes vertical, the pair of rollers being adjacent the forward end 204 of chamber 201, and being symmetrical-ly arranged on either side of the centre line AA runningthrough chamber 201. A narrow gap 211 exists between the pair of pre-squeeze rollers.
, .
~ 3~
_ g _ Immediately behind pre-squeeze rollers 209 and 210 are a pair of squeeze rollers 212 an~ 213, again mounted with their longitudinal axes vertical a~d similarly symmetrically axr~nged on either side of centre line AL Squee~e rollers 212 and 213 contact one another. ~he diameter of squeeze rollers 212 and 213 is less than that of the pre-squeeze rollers 209 and 210. Behind squeeze rollers 212 and 21~ are mounted a pair of discharge rollers 214 and 2159 again with t-heir longitudinal axes vertical and also symmetrically arranged on either side of centre line AA. Rollers 214 and 215 are also in contact with one another, and their diameters are less than those of squeeze rollers 212 and 213. Each roller is rotatable about its longitudinal axes in a contrary manner relative to its par-tner, and in such a manner that an object presented from forward end 204 of chamber 1 between the pre-squeeze rollers 209 and 210 will be drawn i~to chamber 201 and progressed in turn between the three pairs of rollers towards rear end 205~
A pair of water pipes 216 and 217 each termin-ating in a verticall~-aligned ~-jet spray head, lead into chamber 201 ~nd are directed respectively against pre-squeeze rollers 209 and 210 such that water from the jets will impinge on the rear of each roller (relative to forward end 204 of chamber 201).
further palr of water pipes 218 and 219 lead into the apparatus and are directed via similar ver-tically-~ ali~ned V-jet spray heads against -the rear of squeeze rollers 212 and 213. A third pair of water pipes 220 and 221 are similarly directed via similar spray heads against the rear of discharge rollers 214 and 215.
A rectangular aperture 222 exists in floor 206~ and lies symmetrically benea-th the pre~squeeze rollers 209 and 210, and the s~ueeze rollers 212 and 213 such that anything falling between the two pairs of rollers will drop below floor 206. ~eading edge 223 o~ floor 206 is provided with an up-turned lip 224 which runs the entire width of the shelf.
~nother up-turned lip 225 runs round the entire edge of aperture 222. Side edges 226 and 227 of chute 208 are also provided with up-turned lips 228 and 229 respectively.
Below floor 206 is a second chute 230 which leads dow~wardl~ and outwardly from the fron~ end 204 of chamber 201, commencing from the rear of aperture 222 such that an~thing falling through aperture 222 will land on chute 230 and be directed towards the front of the apparatus. Chute 230 is also provided with up-turned lips 231 and 232 along its side edges 233 and 234 respectively.
~he apparatus is also provided with a ~eeder mechanism 235 comprising an upper continuous belt 2~6 and a lower continuous belt 227 arranged in parallel one above the other along centre line AA
at the forward end 204 o~ chamber 201~ ~ower belt 236 extends further from the chamber than does the upper belt.
Referring to ~ig 5, which illus-tra-tes a vertical cross-section of the apparatus taken on centre line AA shown in ~ig 4~ rollers 209, 212 and 214 can be seen within chamber 201. Each roller is mounted on a ver-tical shaft 237, 238 and 239 respectivley, running through bearings 240, 241 and 242 respec-tively, situated in the roof 243 of chamber 201. ~he shaf-ts ~ `
. .
are connected to a motor means (not shown) capable of causing rotation of each roller in the manner already described in relation to ~ig 4. Water jet 220 playing onto the back of rollers 214 can also be seen.
~loor 2Q5 with aperture 222 and rim 225 can be seen, as also can the two sloping c~utes 208 and 230. ~he sloping chutes are depicted as leading down to trays 244 and 245 respectively, capable of catching any material sliding down each chute.
~he two continuous belts 235 and 2~6 comprising the feeder mechanism can also be seenO ~elt 235 runs round a pair of horizontally moun-ted rollers 246 and 247. ~el-t 236 runs round a similar pair of horizontally mounted rollers 248 and 249~
~he belts lead upwards into the open end 204 of chamber 201 adjacent the gap 211 between the pair of pre-squeeze rolle~ 209 and 210~ A narrow gap 250 exis-ts between the two belts along their entire adjacent length. The belts 235 and 236 can be driven via their respective rollers by a motor ~eans (not shown), such that they run in a contrary manner and any material placed between the belts will be drawn between them upwards into the apparatus.
~he whole apparatus is depicted as s-tanding on grou~d 251 by means of legs mounted one at each corner, only the farther two of which legs (252 and 253) can be seen in this cross-section.
In operation, the three pairs of rollers within the apparatus are set in rota-tional mo-tion and -the belts are also set running. Water is fed via -the inlet pipes to the jets and played onto the rear of each rollerO Headed and gutted but otherwlse who-e fish carcasses are fed -tail first between the two belts~ which con~ey the carcasses upwards into the gap 211 between the pre~squeeze rollers 209 and 210, which apply rela-tively gentle pressure to each fish carcass and soften up the muscle s-tructure. ~he continuous ro-tation of the pre-squeeze rollers progresses the fish carcass towards the pair of squeeze rollers 212 and 213 which tigh-tl~
grip the tail of the fish and draw the fish between them. A~ the tail of ths fish emerges from between -the squeeze rollers it is engaged between the discharge rollers 214 and 215 which actively con-tinue the progress of the carcass through the apparatus~ As the fish carcass passes between the squeeze rollers it is subject to considerable pressure, and the flesh within -the carcass is separated from the skin and bone stl~c-ture and is extruded from the head end of the carcass. ~he extruded flesh falls through aperture 222 onto forwardly sloping chu-te 230, and slides down into the waiting -tray 245, ~he spent skin and bone structure of -the carcass is discharged from the apparatus after passing between the discharge rollers by sliding down rea~wardly sloping ch~te 208 into the o-ther waiting tra~ 244. ~he continuous jets of water pla~ed onto the rollers help in keeping each roller clean of fish flesh and slime from the fish skin, and thereby ensuring tha-t the rollers maintain an adequate grip on each carcass and tha-t the ~aluable fish flesh collected in tray 2'~5 is not unduly co~ltaminated with unwanted low-grade material. ~he water from each jet cascades down each roller onto floor 206 and then down rear chu-te 208. ~`he up-turned lips 22l~ and 225 around the :Leading edge 22~ of floor 206 and around aperture 222 , z~
~ ~3 -help to prevent undue amounts of water becoming mixed with the valuable fish flesh.
An additional or alternati~e means of ensuring that the fish flesh collected does no-t ha~e an excessive water content, is to use a foraminous material, such as an expanded metal screen, as the floor of the chute 230. Water can fall -throu~h the holes while the fish flesh slides down the chute into the waitin~ tray 2450 ~ n apparatus according to the invention and basically as just described with reference to Fi~s 4 ~nd 5, was used to recov0r flesh from blue whiting~
The apparatus had the following technical specification~
The pre-squeeze rollers ~ere constructed of rubber having a hardness of 30 on the Shore scale, moulded onto 20 mm stainless steel shafts. Each roller had a length of 150 mm and a diameter of 90 mm. A textured surface, comprising a non-slip vinyl sheet ma-terial recommended for use as a deck covering for yachts, was bonded to each roller.
A gap of 5 mm existed between the pre-squeeze rollers.
~he squeeze rollers were of identical construction to the pre-squeeze rollers, except -that they had a diame-ter of 70 mm, and were just in contact with one another.
~ he discharge rollers were constI~Icted of rubber 1~L5~LZ~
having a hardness of 35 on the ~hore scale, moulded o~to 15 mm diameter stainless steel shafts. ~ach roller had a length of 150 mm and a diameter of 40 mm.
~he~ were covered with the same non-slip material and were just in contact with one another.
Gutted frozen-at-sea b~ue whiting were thawed,~
and headed manually. 200 kilos of fish were pro-cessed in the apparatus in ~ hour 45 minu~es,~and~
70 kilos o~ acceptable flesh reco~ered, giving a~
yield of 35%.
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rollers should be made of a material having a hardness in -the range 20 to 40 on the ~hore scale. With this consideration in mind, the squeeze rollers are best made from natural or synthetic rubber having a hardness in this range.
~ he surface texture of the squeeze rollers must be such that sufficient fric-tion can be generated bet-ween the roller surfaces and the skin of a fish to draw the fish between the rollers, while not causing ~ny significant damage to the skin. A surface fea-t-uring a multitude of small closely-spaced inden-ta-tions or projections is very suitable. Alternatively, a multitude of grooves or ribs, arranged for example parallel to the cylindrical axis of the roller, can be used. ~hese surface fea-tures can be moulded into the ma-terial from which the bulk of the roller is constructed, or can be imparted -to the roller by means of a surface covering.
~he pre-squeeze discharge rollers can be constructed of similar materials wi-th similar surface properties. We have found, however, that a relatively more frictional surface on the discharge rollers is beneficial.
~he physical size of the squeeze rollers may be varied deperlding upon the physical size of the fish to be processed using -the invention. ~he process of -the invention can be readily adapted for small, intermediate or large fish. Clearly fac-tors such as the ph~sical size of the rollers, their positioning relative to one another, and the speed with which a fish passes between the rollers may need adjustmen-t according to the particular fish being handled.
' ;
llS4~D~
In general, we have found that the squeeze rollers should have a diameter in the range 30 to 90 mm and a length in the range 60 -to 250 ~m.
~ he pre-squeeze rollers ~hould ideally have a length the same as that of the squeeze rollers. ~he dia~eter of the pre-squeeze rollers is preferably substantiall~ greater -than that of the squeeze rollers, thus promoting maximum fish-roller contact. In general we have found that the pre-squeeze rollers should have diameters in the range 70 to 120 mm.
.
~ he discharge rollers should ideally have a length -the same as that of the squeeze rollers~ ~he - diameter of the discharge rollers, however, is preferabl~ substantiall~ less than that of -the squeeze rollers so that close proximity between the two pairs of rollers can be obtained. In general we have found that the discharge rollers should have diameters in the range 30 to 60 mm.
Ideally the apparatus of the invention should be constructed such that the distance between the cylindrical axes of the squeeze rollers can be adjusted readily, thus making the apparatus better able to be used in -the processing of a wide range of fish sizes~
Preferably, the pre-squeeze rollers and the discharge rollers are similarly adaustable.
Preferabl~, -the squeeze rollers should be in con tact with each other With roLlers of hardness 20-40 and preferably 30-35 on the "A" ~hore scale, and a diameter of 50 to 90 mm, the cylindrical axes can be set so that the rollers are just touching, the resilience of the s~05~
rollers then providing for passage of a fish between them~ The more resilient the rollers, the closer can be the cylindrical axes to produce an effective pressure on a fish passing between the rollers~
Preferably, there is a gap between the pre-squeeze rollers, thus ensuring that their action on a fish passing between them is merely a mild squeeze and does not cause any significant expression of flesh from the fish in the manner intended during subsequent passage between the ~ squeeze rollers. In genaral, this gap will be from about 2 to about 30 mm. ~he gap between the pre-s~ueeze rollers~ when small fish such as blue whiting are being processed, will generally be about 4 to about 14 mm. ~or substantiall~ larger fish, such as haddock, -this gap will generally be about 16 to about 26 mm.
~he discharge rollers should ideally be in contact with one ano-ther, to ensure that they grip adequately the tail of a fish emerging from between the squeeze rollers, thus drawing the spent skin and skeleton of the fish onwards through the apparatus.
~he speed with which a fish passes between the various pairs of rollers should be constant, or prefer-ably increasing slightly as the fish progresses through the apparatus. ~he speed of rotation of the rollers should be set accordingly. A typical throughput for small fish, such as blue whiting, fed continuously into the apparatus, can be up to about 100 fish per minute, but a throughput of 25 to 50 fish per minute would be more normal.
~ ~he extent to which relatively bone-free and skin-free flesh can be recovered from a fish by means of the invention depends to a considerable extent on the ~uality of the fish used and the manner in which the fish has been treated and prepared prior to rolling. It is obviously , L5D~O~
essential that the head and gut regions of the fish should be removed prior to rolling. It is also use~ul if the dorsal fins of the fish are cut off7 as we have found that thiS can res~l~ in ~ smoother passage of the fish between the rollers and a lower incidence of back-bone breakage. It can also be advantageous if the belly flaps o:~ the fish are removed prior to rolling.
In the case of small fish such as blue whiting, small haddock, whiting and codling, the whole fish (minus head and guts) can be processed as a single unit.
Due to their small size, such fish are difficul-t -to process economically by conventional filleting operations conducted either mechanically or by hand9 In the case of larger fish, for example cod, it can be advantageous to "halve" the fish into "top" (head) and "tail" por-tions. ~he top portion can be pro-cessed using conventional techni.~ues to yield high quality fillet material. ~he intact tail por-tion can be processed usin~ the invention~
~he invention will now be more particularly described with reference to the accompanying drawings, of which:
~igs 1, 2, and 3 i.llustrate diagramatically the passage of a fish carcass between a pair of contra-rotating rollers;
~ig 4 represents a general plan view of a fish processing apparatus in accordance with the invention;
and ~ig 5 represents a ~ertical cross-section of 3o the apparatus depicted in ~ig 4 taken on the line AA shown in ~ig 4.
~`Q' (3 Figs 1 to 3 show a pair of parallel contra-rotating squeeze rollers 101 and 102, preceded by a pair of contra-rotating pre-squeeze rollers 106,107, set at a wider nip distanGe, and illustrate the passage of a head-ed and gutted fish carcass 103 between the rollers. Tail104 of fish 103 is presented to the pre-squeeze rollers, and on being gripped between the rollers and thereby slightly pressed passes through in the direction indicated between the squeeze rollers 101,102. As the bulk of fish 103 contacts the squeeze rollers it is squeezed between them and the flesh 105 within the fish is expressed there-from tFig 2).
Fig 3 shows the final stage of the rolling proce-dure, with fish 103 (now comprising essentially merelythe skin and backbone structure) having passed completely between the rollers and the flesh 105 remaining in front of the rollers.
Fig 4 is a plan view showing the general lay-out of a fish processing apparatus according to the invention.
The apparatus comprises a rectangular chamber 201, of which side walls 202 and 203 can be seen in section. Ends 204 and 205 of chamber 201 are open. A horizontal floor 206 spans the entire width of chamber 201, and extends slight-ly over half' the length of the chamber from forward end 204.From the rear edge 207 of floor 206, a sloping chute 208 leads downwardly and outwardly from chamber 201.
Chute 208 also spans the entire width of chamber 201.
The apparatus is provided with a pair of parallel pre-squeeze rollers 209 and 210 mounted with their longi tudinal axes vertical, the pair of rollers being adjacent the forward end 204 of chamber 201, and being symmetrical-ly arranged on either side of the centre line AA runningthrough chamber 201. A narrow gap 211 exists between the pair of pre-squeeze rollers.
, .
~ 3~
_ g _ Immediately behind pre-squeeze rollers 209 and 210 are a pair of squeeze rollers 212 an~ 213, again mounted with their longitudinal axes vertical a~d similarly symmetrically axr~nged on either side of centre line AL Squee~e rollers 212 and 213 contact one another. ~he diameter of squeeze rollers 212 and 213 is less than that of the pre-squeeze rollers 209 and 210. Behind squeeze rollers 212 and 21~ are mounted a pair of discharge rollers 214 and 2159 again with t-heir longitudinal axes vertical and also symmetrically arranged on either side of centre line AA. Rollers 214 and 215 are also in contact with one another, and their diameters are less than those of squeeze rollers 212 and 213. Each roller is rotatable about its longitudinal axes in a contrary manner relative to its par-tner, and in such a manner that an object presented from forward end 204 of chamber 1 between the pre-squeeze rollers 209 and 210 will be drawn i~to chamber 201 and progressed in turn between the three pairs of rollers towards rear end 205~
A pair of water pipes 216 and 217 each termin-ating in a verticall~-aligned ~-jet spray head, lead into chamber 201 ~nd are directed respectively against pre-squeeze rollers 209 and 210 such that water from the jets will impinge on the rear of each roller (relative to forward end 204 of chamber 201).
further palr of water pipes 218 and 219 lead into the apparatus and are directed via similar ver-tically-~ ali~ned V-jet spray heads against -the rear of squeeze rollers 212 and 213. A third pair of water pipes 220 and 221 are similarly directed via similar spray heads against the rear of discharge rollers 214 and 215.
A rectangular aperture 222 exists in floor 206~ and lies symmetrically benea-th the pre~squeeze rollers 209 and 210, and the s~ueeze rollers 212 and 213 such that anything falling between the two pairs of rollers will drop below floor 206. ~eading edge 223 o~ floor 206 is provided with an up-turned lip 224 which runs the entire width of the shelf.
~nother up-turned lip 225 runs round the entire edge of aperture 222. Side edges 226 and 227 of chute 208 are also provided with up-turned lips 228 and 229 respectively.
Below floor 206 is a second chute 230 which leads dow~wardl~ and outwardly from the fron~ end 204 of chamber 201, commencing from the rear of aperture 222 such that an~thing falling through aperture 222 will land on chute 230 and be directed towards the front of the apparatus. Chute 230 is also provided with up-turned lips 231 and 232 along its side edges 233 and 234 respectively.
~he apparatus is also provided with a ~eeder mechanism 235 comprising an upper continuous belt 2~6 and a lower continuous belt 227 arranged in parallel one above the other along centre line AA
at the forward end 204 o~ chamber 201~ ~ower belt 236 extends further from the chamber than does the upper belt.
Referring to ~ig 5, which illus-tra-tes a vertical cross-section of the apparatus taken on centre line AA shown in ~ig 4~ rollers 209, 212 and 214 can be seen within chamber 201. Each roller is mounted on a ver-tical shaft 237, 238 and 239 respectivley, running through bearings 240, 241 and 242 respec-tively, situated in the roof 243 of chamber 201. ~he shaf-ts ~ `
. .
are connected to a motor means (not shown) capable of causing rotation of each roller in the manner already described in relation to ~ig 4. Water jet 220 playing onto the back of rollers 214 can also be seen.
~loor 2Q5 with aperture 222 and rim 225 can be seen, as also can the two sloping c~utes 208 and 230. ~he sloping chutes are depicted as leading down to trays 244 and 245 respectively, capable of catching any material sliding down each chute.
~he two continuous belts 235 and 2~6 comprising the feeder mechanism can also be seenO ~elt 235 runs round a pair of horizontally moun-ted rollers 246 and 247. ~el-t 236 runs round a similar pair of horizontally mounted rollers 248 and 249~
~he belts lead upwards into the open end 204 of chamber 201 adjacent the gap 211 between the pair of pre-squeeze rolle~ 209 and 210~ A narrow gap 250 exis-ts between the two belts along their entire adjacent length. The belts 235 and 236 can be driven via their respective rollers by a motor ~eans (not shown), such that they run in a contrary manner and any material placed between the belts will be drawn between them upwards into the apparatus.
~he whole apparatus is depicted as s-tanding on grou~d 251 by means of legs mounted one at each corner, only the farther two of which legs (252 and 253) can be seen in this cross-section.
In operation, the three pairs of rollers within the apparatus are set in rota-tional mo-tion and -the belts are also set running. Water is fed via -the inlet pipes to the jets and played onto the rear of each rollerO Headed and gutted but otherwlse who-e fish carcasses are fed -tail first between the two belts~ which con~ey the carcasses upwards into the gap 211 between the pre~squeeze rollers 209 and 210, which apply rela-tively gentle pressure to each fish carcass and soften up the muscle s-tructure. ~he continuous ro-tation of the pre-squeeze rollers progresses the fish carcass towards the pair of squeeze rollers 212 and 213 which tigh-tl~
grip the tail of the fish and draw the fish between them. A~ the tail of ths fish emerges from between -the squeeze rollers it is engaged between the discharge rollers 214 and 215 which actively con-tinue the progress of the carcass through the apparatus~ As the fish carcass passes between the squeeze rollers it is subject to considerable pressure, and the flesh within -the carcass is separated from the skin and bone stl~c-ture and is extruded from the head end of the carcass. ~he extruded flesh falls through aperture 222 onto forwardly sloping chu-te 230, and slides down into the waiting -tray 245, ~he spent skin and bone structure of -the carcass is discharged from the apparatus after passing between the discharge rollers by sliding down rea~wardly sloping ch~te 208 into the o-ther waiting tra~ 244. ~he continuous jets of water pla~ed onto the rollers help in keeping each roller clean of fish flesh and slime from the fish skin, and thereby ensuring tha-t the rollers maintain an adequate grip on each carcass and tha-t the ~aluable fish flesh collected in tray 2'~5 is not unduly co~ltaminated with unwanted low-grade material. ~he water from each jet cascades down each roller onto floor 206 and then down rear chu-te 208. ~`he up-turned lips 22l~ and 225 around the :Leading edge 22~ of floor 206 and around aperture 222 , z~
~ ~3 -help to prevent undue amounts of water becoming mixed with the valuable fish flesh.
An additional or alternati~e means of ensuring that the fish flesh collected does no-t ha~e an excessive water content, is to use a foraminous material, such as an expanded metal screen, as the floor of the chute 230. Water can fall -throu~h the holes while the fish flesh slides down the chute into the waitin~ tray 2450 ~ n apparatus according to the invention and basically as just described with reference to Fi~s 4 ~nd 5, was used to recov0r flesh from blue whiting~
The apparatus had the following technical specification~
The pre-squeeze rollers ~ere constructed of rubber having a hardness of 30 on the Shore scale, moulded onto 20 mm stainless steel shafts. Each roller had a length of 150 mm and a diameter of 90 mm. A textured surface, comprising a non-slip vinyl sheet ma-terial recommended for use as a deck covering for yachts, was bonded to each roller.
A gap of 5 mm existed between the pre-squeeze rollers.
~he squeeze rollers were of identical construction to the pre-squeeze rollers, except -that they had a diame-ter of 70 mm, and were just in contact with one another.
~ he discharge rollers were constI~Icted of rubber 1~L5~LZ~
having a hardness of 35 on the ~hore scale, moulded o~to 15 mm diameter stainless steel shafts. ~ach roller had a length of 150 mm and a diameter of 40 mm.
~he~ were covered with the same non-slip material and were just in contact with one another.
Gutted frozen-at-sea b~ue whiting were thawed,~
and headed manually. 200 kilos of fish were pro-cessed in the apparatus in ~ hour 45 minu~es,~and~
70 kilos o~ acceptable flesh reco~ered, giving a~
yield of 35%.
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Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A. method of treating a fish carcass for separating the flesh from the frame and the skin, wherein fish is passed between at least one pair of contra-rotating rollers, characterized in that a decapitated and gutted fish carcass, which is unskinned and still contains the backbone, is passed tail first between a pair of contra-rotating parallel squeeze rollers, the nip between which has such a width that the tail and the skin of said fish carcass is gripped sufficiently tightly for the skin and backbone to be drawn between the rollers without being significantly damaged and while the fish carcass is being drawn between the squeeze rollers flesh is expressed from the head end thereof.
2. The method of claim 1, characterized in that the fish carcass is pre-squeezed between a pair of contra-rotating, parallel pre-squeeze rollers, the nip between these being wider than that between the squeeze rollers.
3. The method of claim 1 or 2, characterized in that the tail emerging from between the squeeze rollers is fed into the nip between an additional pair of contra-rotating rollers, the nip between which has such a width that the tail and backbone can be tightly engaged without breaking.
4. The method of claim 1 or 2, characterized in that the rollers during operation are kept wet by applying water to the rollers.
5. The method of claim 1, characterized in that the fish carcass is pressed between resiliently surfaced squeeze rollers.
6. The method of claim 1, characterized in that the dorsal fin and the belly flaps are removed prior to passing the fish carcass between the rollers.
7. An apparatus for treating a fish carcass for separating flesh from a fish frame and skin, comprising a housing, feeding means for a fish carcass, treating means comprising at least two pairs of contra-rotatably drivable parallel rollers and discharging means, characterized by at least two pairs of parallel rollers having upright axes, the first pair of rollers, viewed in the direction of transport, being at a greater distance than the second pair of rollers, at least the second pair being coated with a resilient material having a profiled surface.
8. The apparatus of claim 7, characterized in that after the second pair of rollers a third pair of parallel discharge rollers is situated, drivable in a similar contra-rotatable manner to the first and second
9. The apparatus of claim 7 or 8, characterized in that the rollers are only supported at their upper extremity.
10. The apparatus of claim 7 or 8, characterized in that water spray means are provided for directing water sprays onto the roller surfaces.
11. The apparatus of claim 7, characterized in that the nip between the squeeze rollers is adjustable.
12. The apparatus of claim 7, characterized in that the squeeze rollers have a diameter in the range of 30 to 20 mmm and the pre-squeeze rollers have a diameter in the range of 70 to 120 mm.
13. The apparatus of claim 7, characterized in that the squeeze rollers have a surface hardness of 20 to 40 and preferably 30 to 35 on the "A" Shore scale.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000382411A CA1154209A (en) | 1981-07-23 | 1981-07-23 | Method and apparatus for stripping flesh from fishframes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000382411A CA1154209A (en) | 1981-07-23 | 1981-07-23 | Method and apparatus for stripping flesh from fishframes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1154209A true CA1154209A (en) | 1983-09-27 |
Family
ID=4120517
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000382411A Expired CA1154209A (en) | 1981-07-23 | 1981-07-23 | Method and apparatus for stripping flesh from fishframes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1154209A (en) |
-
1981
- 1981-07-23 CA CA000382411A patent/CA1154209A/en not_active Expired
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