Producedby:FisheriesandAquacultureDepartment

Title:Planningandengineeringdata.2.FishCanning... Moredetails

4.PROCESSING

4.1TechnologicalProcesses4.2ProcessingOperations

4.1TechnologicalProcessesThemainobjectiveofcanningistoobtainashelfstableproductthatcanbestoredinsuitablecontainersforaconsiderablelengthoftime(atleasttwoyears)withoutundergoingfoodspoilage,whileretainingdesirablenutritionalandsensoryqualities.

Toachievesatisfactoryshelflifethefollowingconditionsmustbeobserved:

i. Thecontentsofthecansmustbecommerciallysterilized.ii. Theinsideofthecanmustberesistanttoanddamagingeffectsfromthecontentsandtheoutsidemustberesistantto

corrosionunderreasonablestorageconditions.iii. Thecanendsmustbesealedtopreventingressofwaterand/orairoranyformofcontamination.

4.2ProcessingOperations

4.2.1General

Fishshouldbechillstoredatatemperaturebetween0and2C,orsortedfrozeninfreezersattemperaturesbelow28C.

Whenfrozenfishisused,itmustbethawedbeforegradingand/ordressing.

Inthefollowingdescriptionsoftheprocessingstagesforvariousproducts,operationswhicharesimilararedescribedinChapter4.2.2"Descriptionofcanningtunainbrine",andsubsequentlyonlymentioned.

4.2.2Descriptionofcanningtunainbrine

Thedescriptionisrelatedtocanningplantwithacapacityof20tonswholerawfish(bluefinoryellowfintuna)per8hours.Theoverallyieldisapproximately5055%whichgivesapproximately10000450g(1pound)cansor20000225g(1/2pound)cansper8hours.SeeFigure4"Layoutfortunacannery".

Simplifiedflowsheetsforcanningtunainbrine,tunaflakeswithvegetablesandtuna.petfoodareshowninFigures5,6and7respectively.

Sequentialprocessingoperationsforcanningtunaaredescribedasfollows:

a. Frozentunaisthawed,preferably,bymeansofrunningwateratatemperatureof1015C.Lossduringthawingis0.51.0%.

Holdingoffrozentunaforlongperiodsbeforethawingmayleadtooxidationoffatresultinginayellowtoorangediscolourationonthesurfaceofthecookedloins.Usuallythissurfacediscolourationcanberemovedwhenthefishiscleaned.

b. Longitudinalcutsarecommonwithlargesizedtunaandthevisceraareremovedfromthefishonboardfishingvesselspriortofreezing.Bonitoandskipjackarefrozenwithviscera.Oncethawed,thetunaiswashedandinspectedforspoilage.Iftunaisnotevisceratedonboardvesselsthismustbedoneintheplant.Thesplittingandeviscerationprocedureistheonlybutcheringoperationperformedonthetunawhileitisintherawcondition.Allothercleaningisperformedafterthetunahasbeencooked.Lossofweightisapproximately2427%.

Figure4Layoutfortunacannery

Figure5Flowsheetforcanningtunainbrine

Figure6Flowsheetfortunaflakeswithvegetables

Figure7Flowsheetfortunapetfood

c. Thetunaisgivenaprecookbyheatingatatemperatureinrangeof102to104C.Thisoperationisnecessarytomakeitpossibletohandpickthelightmeatfromthecarcassandalsotoremovesomeoftheoilfromoilyfish.

Thefishisplacedinbasketswhichareplacedonracks.Theracksofbutcheredfisharerolledintothecookerswhichareusuallyofrectangularcrosssectionandmadeofreinforcedsteelplatewithadoor,ordoors,atoneorbothends.Theprecookingisabatchtypeoperation.

Steamisadmittedthroughasteamspreaderonthefloorofthecooker.Steamventanddrainvalvesareprovidedtopermitremovalofairandcondensate.Precookingmayalsobecarriedoutinboilingbrine.

Theprecookingtimeforindividualbatchesvarieswidelyaccordingtothesizeoftuna.Forexample,thecookingtimemayvaryfrom11/2hoursforsmalltunato8to10hours,ormore,forlargertuna.Lossofweightisapproximately2226%.

d. Tunaiscooledthoroughlytofirmthefleshbeforethemanualcleaningoperationcanbeperformed.Lossofweightisapproximately35%.

e. Aftertheprecookingandcoolingoperations,tunaisindividuallycleaned.Theheadisremovedandthefishisskinnedandsplitintohalvesbeforeremovingthetailandbackbone.Theloinsareproducedbysplittingthehalvesofthefishalongthemedianline.Redmeatisthenremovedfromeachlointhebloodanddarkmeatarescrapedawayandtheloins,edibleflakesandwasteproductsareseparatedoftheseportionsapproximately15%isflaketuna.

f. Theproductionofsolidpackswasformerlyahandpackingoperation,butisnowcarriedoutbymachines.Thismachineproducesacylinderoftunaloinsofuniformdensityfromwhichcanbecutcanzisedsegmentsofuniformweight.

Chunkpacksareproducedfromloinswhicharecutonamovingbeltbymeansofreciprocatingcutterblades.Thecutloinsarethenfilledintocansbytunafillermachines.

Flakesandgratedtuna,whichisproducedfrombrokenloinsandflakes,areJpackedinthesamewayaschunkpacks.

g. Theopencansnextpassthelinewhereadditivessuchassalt,vegetablesandfinallyeitherwateroroilareadded.Oilshouldbeaddedslowlyoverasufficientstretchofthelinetopermititsthoroughabsorbtionbythetunameat.Whenoilisnotaddedanequivalentamountofwaterreplacesit.Theoiltemperatureisrecommendedtobe80C90C.

h. Smallcansmaybeclosed,withoutavacuum,andprocesseddirectly,whereaslargeronesmustbevacuumsealed.

Asthepressureinthecanincreasesconsiderablyduringheatprocessing,thevacuumisnecessarytominimizethepressureincreaseinordertoreducethechanceofdistortion(peaking)anddamagetothedoubleseam.

Afterprocessingandcoolingtheformationof.thevacuumcausestheendsofthecantoassumeaconcaveprofilewhichischaracteristicofvacuumpackedandhermeticallysealedcans.Thevacuumalsoreducestheresidualoxygencontentinthecanandthereforetheextentofinternalcorrosion.

Inordertoformavacuum,cansareseamedbyusingeithervacuumseamersoranexhaustsystem.

Whenusingtheexhaustingmethodthelidsofthecansarefirstclippedorclinchedontothebodyinsuchawayastoallowfreepassageofgasesandvapoursoutofthecan.Thecanandcontentsarethenheatedbypassagethroughanexhaustbox.Thelidisseamedtothecanimmediatelyitemergesfromtheexhaustbox,sothatwhenthecontentscoolavacuumisobtained.Thusthesystemreliesonsealingthecanwhilethecontentsarehotandallowingproductcontractiontocreatethevacuum.

Analternatemethodofachievingavacuuminsealedcansisbyusingvacuumseamers.Thesemachinesclosethecansandwhilesodoingdrawtheairoutthuscreatingavacuum.

i. Thedoubleseamingmethodisusuallyusedtosealmetalcontainers.Theseamiscreatedintwooperations.SeeFigure8."SeamingOperationDoubleSeam(CAC/RCP101976).

Thecan,withthelid(canend)placedorclinchedontop,standsonabaseplatewhichisraisedsothatachuckfitsintothecountersinkpartofthelid,holdingbothinposition.

Thecanendwhichislinedwithaplastisolsealingcompoundiscrimpedintoplacesothatitformsthesocalled"coverhook"aroundthelipofthecontainerbody.

The"coverhook"andtheenclosedlipofthecontainerarefoldeddownagainstthecontainerandinterlockaboutthe"bodyhook".Bothhooksoverlaptoformastrongjointwhichactsasahermeticseal.

Thesealingcompoundrenderstheseamairtight(hermetic).Arounditscircumferencethedoubleseamconsistsoffivelayersofmetalthreelayersofthecanendandtwolayersofthecanbody,howeverattheintersectionwiththesideseamtherearesevenlayersofplate,theextratwobeingduetosideseamoverlap.

Theseamingoperationmustbemonitoredthroughouttheprocessingandvisualinspectionsshouldbecarriedoutatleastevery30minutes(Warne,1993).

Goodmanufacturingpracticeindicatesthatthe.overlapshouldbeatleast45%oftheinternalseamlenghttoensurethattheseamwillfunctioncorrectlyandresisttominorabuse.

Figure8Seamingoperationdoubleseam

j. Thesealedcansaretransferredbyaconveyorthroughacanwasherwhichcleansthecansindetergentandwaterbeforedischargingthemintoretortbaskets.Theretortbasketsaretransferredintotheretortandthecanssterilized.

Table7Examplesofretortingtemperaturesandtimesforcannedtuna

Nominalcapacityofcans

Alternative Processingtemp.(C)

conditionstime(min)

1.8kg(4pound) I 116 230

II 121 190

450g{lpound) I 116 95

II 121 80

225g(l/2pound) I 116 75

II 121 45

112g(l/4pound) I 116 65

II 121 40

Allcannedfishproductsaresterilizedattemperaturesabove100C.Sterilizationtakesplaceinretorts,withorwithoutwater.Overpressureisbetween23kg/cm.Processingconditionsshownaresuitableforthosecanneries,operatingunderconditionsofgoodmanufacturingpractice.Individualcanneriesmayselectdifferentprocessingtimesand/ortemperaturestosuittheirmanufacturingrequirements.

Thesimplestandmostcommonretortstodayarehorizontal,orvertical,batchretorts.

Thefollowinggeneraldescription.appliestoprocessinginbatchretortsusingsaturatedsteamastheheatingmedium.

Aftertheretortisloadedthedoororlidisclosedandthesealischeckedtoconfirmthatallthelugsarefastenedsecurely.Thetemperaturerecorderischeckedtoensurethatitisworkingcorrectly.Followingthistheventsandbleedersareopenedandthedrainandoverflowareclosed{unlesstheoverflowisusedforventing).

Theretortisnowreadyforoperationduringwhichthefollowingoperationalproceduresshouldbeadopted:

Steamisadmittedbygraduallyopeningthecontrollerandthesteambypasslines.Whenthecorrectventingtemperatureisreached(>100C)and/orthespecified,venttimehaselapsed,theventsareclosed.Itisbadpracticetoventlessthantherecommendedtimenorshouldreliancebeplacedonagreementbetweenthemercurythermometerandpressuregaugereadingsasacriterionforcompleteairelimination,asthisisnotnecessarilyatrueindicationoftherequiredcondition.Ifthepressuregaugeisreadinghighwhilethetemperatureisreadinglow,thereisstillairintheretortandventingshouldbecontinueduntilagreementbetweenpressurereadingandthecorrespondingretorttemperatureisreached.Graduallyclosethebypassastheretortapproachestheprocessingtemperature.Thiswillpreventasuddendropintemperatureasthesteamsupplyiscutwhentheretortingtemperatureisreached.Whentheretorthasreachedtheprocessingtemperature,checkthetemperatureindicatedonthemercuryandrecordingthermometers.Whileitisnotseriousifthethermographindicatesatemperatureslightlylower(say1C)thanthemercurythermometer,itismostimportantthatitneverreadshigher.Atalltimesthemercurythermometershouldbeusedasthereference,forindicatingtrueretorttemperature.Atthestartoftheprocess,recordontheproductionrecordsthetime,themercurythermometerreading,thepressure,andthetemperatureindicatedbytherecordingthermometer.Keeparecordofthecomeuptimetomakecertainithasbeenlongenoughto.allowsufficientventing.Maintaintheretorttemperatureattherecommendedprocessingtemperature.Throughouttheprocess,checkthatthespecifiedtemperatureisbeingmaintained.Leaveallbleederswideopenduringtheentireprocess.Whentherecommendedprocessingtimehaselapsed,turnoffthesteamandimmediatelystartthecoolingcycle.

k. Whenprocessingmediumsizedorlargercans(saygreaterthan250g)inretortsusingsteamitmaybenecessarytocoolthecansunderpressuresothattheendsdonotpeakduringcooling.Steammaybeusedtomaintainthepressurebutcompressedairismoreusual.Thecoolingtimedependsontheprocessingtemperature,thetemperatureofthewaterusedforcooling,thecansizeandthenatureofthepack(i.e.,liquidtosolidratio).

l. Ifnecessarythecansshouldbewashedbeforetemporarystorage,howeverundernoconditionsshouldtheprocessedcansbemanuallyhandledwhilewet.

4.2.3Descriptionoftheprocessingoperationsofanautomaticcanninglineforskipjack

Thedescriptionsarerelatedtoaplantwithacapacityof10tonswholefishper8hours.Theoverallyieldis5055%andapproximately900010000450g(1pound)cansareproducedper8hours.SeeFigure9"Layoutporskipjackcannery".Theweightofthefishtobeprocessedisapproximately2to5kgperfish.

a. Fromthechillroomthewholefreshskipjackisbroughttoabulkelevatorwhichtransportsthefishtoaguttingmachinewhichconsistsofasemiautomaticmachineinwhichthefishisplacedwithitsbellyupermost.Arotatingknifeopensthefishandremovestheviscera.

Thefishisconveyedtoarotatingnylonbrushunderwhichitiscleanedbywaterspraynozzles.

Aftereviscerationthetunaisconveyedtoaninspectiontablewherethefinalcleaningiscompletedmanuallyorwherethosefish,toolargefortheguttingmachine,canbebutchered.Atthedischargeoftheguttingmachinetheoffalisdirectedtoarotatingfilterdrumforseparationsofwatertheretainedoffal,ispneumaticallypumpedtocontainers.

Figure9Layoutforskipjackcannery

b. Inspectorsexaminethefish,whileitpassesontheconveyor,toensurethatishasbeensatisfactorilycleaned.

c. Fishareautomaticallysizegradedtoassistinfeedtotherotorcookerandregulationofcookingtime.

d. Rotorycookersarefrequentlybuiltwithcounterflowanddischargebelts,andacapacityofapproximately1.3tonsperhourwithvariablecookingtimesofupto2hours.

Thecookerisdividedinto16cellsintowhichthefishisfed.Thebottomofthecookerisseparatedbyaheavymeshplate,andunderthisareplacedheatexchangersforindirectsteamheating.

Aftercookingthefisharetransportedonacontinuousbelttothecounterflowcooler(astainlessvesselwithfreshwatersupply)andthenontothecleaningstations.

e. Typicalcleaningarrangementsconsistof:

OneworkingtableforcleaningthetunaaftercoolingOnerotatingtablefittedwithholders/cupsforloinsOnedischargeelevatorfortransportationofloinportionsfromtherotatingtabletothepackingmachineOneoffalconveyormontedbeneaththecleaningstationtocollectand"dischargeoffal.

Theoperationsareasfollows:

The1stoperatorremovesthefishfromtheconveyorandtransfersittoaworking.tablewheretheskinandthehead

areremoved.The2ndoperatoropensthefish,removesthebackboneanddividesthefishinto4loins.Simultaneouslythemajorityofdarkmeatisremovedandsingleloinsareplacedinthecupsontherotatingtable.The3rdand4thoperatorscleantheloins,removingtheremainingdarkmeat.Thecleanedloinsarethenremovedautomaticallyfromtheircupstoarubberbeltconveyorwhichtransportsthemtoanoverlyingconveyor.

f. Theloinsthenpasstoanautomaticscaleforcontinuousweighingwhichmakesitpossibletomonitorproductionyields.AfterweighingtheloinspasstoanIaccumulationstationpriortopassingtoapackshaperwhichpackstheloinsintocans.

Thefilledcanspasstoanoil/brinefillingmachinebeforethevacuumseamingmachine.

Descriptionofthesubsequentoperationsandtheireffectsonyieldaresimilartothosedescribedforcanningtunainbrine.

4.2.4Descriptionofcanningsardinesinoil

Themethodforcanningsardinesinoilisoftencalledtherawpackagingmethodwhichcontrastswiththemethodinwhichthesardinesarethermallytreatedbeforepackingintocans.

Theprocessingplantrelatedtothedescriptionhasacapacityof15tonsrawfishper8hours.Theoverallyieldsisapproximately50%oftheweightofrawfish.SeeFigure10"Layoutforsardinesinoil,cannery"whichshowsaplantofthiscapacity.

Figure10Layoutforsardinesinoilcannery

Onetonofrawsardinesisrequiredtoproduce5200(5263)1/4clubcans,packedinto52casesof100canseachor5800(5882)1/4dingleycanspackedinto58casesof100canseach.

Figure11shows"Flowsheetforcanningsardinesinoil".

Theoperationsafterthethawingofthefrozenfishoraftertransportingthefreshfishfromthechillstoreareasfollows:

1. Thesardinesaresizegradedbyanautomaticgradingmachinewhichselectssardinestosuitthesizeofcansusedintheplant.

ThenumberofsardinespercanpermittedforvariouscantypesisgiveninTable8

Table8.Numberofsardinespercanpermitted*forvariouscantypes

Typeofcan Numberofsardines

Minimum Maximum

1/4dingley1layer 6sardines 12sardines

1/8 6sardines 12sardines

1/16oblong2layers 8sardines 14sardines

1/4club1layer 4sardines 8sardines

*Permittedby?

Thesmallestsizeofsardinesallowedforcanning(inNorway)is9.5cm.

2. Aftergrading,thesardinesaredischargedontoaconveyorfortransportationtothenobbingmachinewheretheheadandgutsofthefishareremoved.Onatypicalnobbingmachine,thefishareplacedoncontinuousbeltswithonefishineachcompartment.Thebeltfeedsthefishtoacuttingwheelwhichcutsthehead,andtogetherwiththeguts,drawsitawayfromthebodywithrollers.Ifnecessarythetailsarecutinthesameoperation.

Thepackersexaminethefishtoensurecompleteremovalofguts.Lossofweightduringnobbingisapproximately21%.

Nowadaystherearealsonobbingmachineswithgreatercapacity,servedbyfourormoreoperators,whichcancompletefollowingoperations:

RemovaloftheheadEviscerationRemovalofthetailWashingthefishPackingthefishintocans

Theautomaticnobbing/packingmachinehasacapacityof3580cansperminuteandrequiresapproximately50%ofthemanpowerrequiredbyatraditionalcanningline(Perovic,1983).

Figure11Flowsheetforcanningsardinesinoil

3. Afternobbingthesardinespassthroughawashingprocesstoremovebloodandsurfaceslime.Washingmachinesofmanytypesmaybeused.Washingshouldbewithpotablewaterorseawaterofsimilarquality.(Forcertainspecieswithhardandinediblescales,suchaspilchard,specialwashingmachinessuitableforremovingscalesareused).

4. Thesardinesarethentransported,usuallybyaconveyor,toabriningmachine.Thebriningcaneitherbeabatchoracontinuousoperation.Thespeedoftheprocessandtheconcentrationofthebrinecanbecontrolled.Thefishareloadedintothebriningunitinoneendwheretheyareimmersedinconcentratedsaltsolution,andthenscrewedthroughtheunitandsimultaneouslybrined.Thefisharethendischargedattheoppositeendoftheunit.

Saltisabsorbedbythefleshasaltcontentofabout12%offishweight,wheninboxesisacceptable.Thebriningmachineisequippedwithafiltertoscreenparticlesfromthebrine.

Inadditiontogivingtheproductthedesiredsaltcontent,brininghasotherbeneficialeffects.Theprocessbrightenstheappearanceofthefishbyremovingremainingslimeandalsotoughenstheskinwhenunbrinedfisharecannedmuchoftheskinadherestothecan.

Afterbrining,thefishareallowedtodrainbeforebeingtransportedtothepackingtable.

Thebrinemustbepreparedfromsaltwhichdoesnotcontainlargequantitiesofmagnesiumchloride,acommoncontaminantinunrefinedsalt.Thebrineshouldbereplacedregularlyasotherwiseitbecomesasourceofcontamination.

5. Afterthebriningprocessthesardinesarepacked(manuallyorautomatically)intoprewashedcans.

Amanuallyoperatedpackinglineisequippedwithconveyorbelts,thespeedofwhichcanbealteredinordertoensureasmoothsupplyofsardinesandcanstothepackers.Thefilledcansandwasteareremovedbytheconveyorafterpacking.

Incommonsardinelinesthefilledcanspassoveraweightcontrolunittoacanalignerandthentoacanpusher,whichautomaticallyfeedstheconveyortransferringthemtotheprecooker.

Changeofyieldduringthepackingprocessdependsonthequalityofrawmaterial,butonaverage5%lossofweightisexpected.

6. Atypicalflashcookerforsardinesconsistsof2sections,oneforcooking(insteamatabout95C)andonefordrying(inhotairatabout130C).Thecanswiththeopenendupwardsareautomaticallytransferredtocrates,whicharehangingoncrossbarsmountedonacontinuouschainconveyorrunninginslingsupawardsintothecookingsection,andintoslingsdownwardsinthedryingsection.

Betweenthetwosectionswaterisdrainedfromcansasthecratesareturnedthrough360aroundatumbler.Theheatinthecookingsectionisobtainedfromsupplyofdirectsteamwhiletheheatinthedryingsectionisindirectlysuppliedfromaheatexchanger.Afanlocatedonthetopofthesectioncirculatestheheatedair.Weightlossduringthisoperationisapproximately25%.

7. Fromthecookerthecansareautomaticallytransferredontoaconveyorwhichtakesthentotheoildispenserandontotheseamingmachinewheretheyaresealed.

8. Beforetheretortingprocessthecansarewashedtoremovefishresiduesandoilfromtheoutsideofthecontainers.

9. Furtheroperationsasforcanningtunainbrine.Seechapter4.2.2..

Table9Examplesofretortingtemperaturesandtimeforcanningsardines

Cantype Temp.(C) Retortingtime(min)

1/4club 115116 55

1/4dingley 115116 65

4.2.5Descriptionofcanningpresmokedsardinesintomatosauceoroil

Mostoftheoperationsinthisprocessaresimilartothosedescribedforcanningsardinesinoil.

Thedescriptionisrelatedtoaplantcapacityof5tonsofrawfishper8hours.

Theyieldfromcanningofsardinesandotherpresmokedsmallfishesapproximatetheyieldsobtainedwhencanningsardinesinoil.

SeeFigure12"Flowsheetforcanningpresmokedsmallfishintomatosauceandoil",andFigure13"Layoutforpresmokedsmallfishcannery"whichshowsaplantofthecapacitymentionedabove.

Thevariousoperationsaredescribedbelow.

1. Gradingissimilartotheoperationdescribedforcaninesardinesinoil.

2. Briningissimilartotheoperationdescribedforcanningsardinesinoil.

3. Thefisharerodded,i.e,hungonrodsthroughtheeyes.Thisoperationcanbedoneautomaticallyormanually.

Theautomaticroddingbeingacomplicatedprocessisonlypractisedinlargeplants.Theroddedfishareplacedintoframeswhicharefittedtothesmokingracks.

Theframeshaveusuallyaccommodatefor30rods,eachwith30fish.

4. Thefisharesmokedforapproximately1hourattemperaturesuptol30C.Themainpurposesofthesmokingistoenhanceflavourandtolowerthewatercontentofthefish.

Usuallytunneltypesmokingkilnsareusedinwhichthereisacontrolledtemperaturegradientbetween30and125130C.

Theairpassesthroughaheatexchangerwhilesmokeadded.Thesmokeisproducedbyasmokegeneratorusingsawdustfromhardwoods(oakorsimilar).Lossduringsmokingisapproximately25%.

5. Aftersmokingthebodiesofthefishareseparatedfromtheheadswithanautomaticcuttingmachine.Theheadsarethenremovedfromtherodswithanautomaticrodstrippingmachine.Lossofweightduringthedeheadingoperationisapproximately1012%.

6. Thepacking,thefillingofsauceoroilandthedoubleseamingoperationsaresimilartothosedescribedforcanningsardinesinoil.

Whenpreparingtomatosauce,pureeofgoodqualitymustbeusedandtothisisaddedoliveoilorfishoil,etc.

Typicalmixturescompriseonepartoilandtwopartstomatopuree(20%concentration).

7. Allsubsequentoperationsaresimilartothosedescribedforcanningsardinesinoil.

4.2.6Descriptionofcanningfishpasteproducts

Thedescriptionisrelatedtoafishpastecanningplantwithacapacityofl0tonswholerawfishper8hours.Theproductionisbasedoneitherdeheaded,guttedfishwithanaverageweightof1.5kgorsmallerindustrialfish.SeeFigure14"Layoutforfishpasteproductscannery"whichshowsaplantofthecapacitymentionedabove.

Overallyieldwhenmanufacturingcannedfishpasteproductsdependsonspeciesinvolved,however,approximately4565%ofrawfishweightcouldbeusedforplanningpurposes.

Theoutputfromaplantproducingmeatballsisapproximately25000/850mlcansper8hoursalternatively8000/850mlcansoffishcakesor15000/850mlcansofmeatballscouldbeproduced.

Figure12Flowsheetforcanningpresmokedsmallfishintomatosauceandoil

TheflowsheetforcanningfishpasteproductsisshowninFigure15.

Thevariousprocessingoperationsaresummarisedasfollows.

Therawmaterialhastogothroughagrinding/choppingandmincingprocess.

1. Thefisharewashed,descaledwhennecessary,evisceratedanddeheaded.

2. Accordingtoskinthicknessandsize,thefishwillhavetobesplitintohalvesfromheadtotailalongthebackbone.

3. Thesplitandopenedfisharewashedandcleaned.

4. Thewashedsplitfishisseparatedinameatboneseparator.Accordingtothetypeoffishonewillgetanacceptablemincedproduct,andoffal,bonesandskin.

5. Iftheminceisunacceptable,(i.e.,discolouredbecauseofbloodetc.),itmaybenecessarytohaveitwashedandthendewateredbymeansofascrewpress

6. Themincedfishismixedinabowlchopperormincerwiththeotheringredients.itisimportanttoaddthesaltfirstandtoallowthemincertoworkforafewminutesbeforeaddingtheremainingingredientstothemixture.

Thiswillimprovethebindingpropertiesofthefish.SeeFigure16"Processinglineforfishmeat".

Figure13Layoutforpresmokedsmallfishcannery.

Figure14Layoutforfishpasteproductscannery.

Figure15Flowsheetforcanningfishpasteproduct.

7. Starch,spicesand,ifnecessary,onions,fat,etc.,areadded.

8. Liquidmilkisaddedandaccordingtothetypeofmincer,itwilltake1012minforthematerialstoreachasoftandformableconditions.

9. Thefishballscanbeformedinmachines,byhandwithspoon,orbyhandsonly,anddroppedintoa11/2%solutionsofsaltwateratapproximately90C.

10. Aftercookinginthesaltsolutionforapproximately58minthefishballsarefilledintocans.

11. Hotbrineorfishbouillonisadded.

12. Afterseamingtheproductgoesimmediatelytoretorting.

Figure16Processinglineforfishmeat

Figure17Layoutforsalmoncannery

SeveralalternativesforretortingtemperaturesandtimesareshowninTable10.

Table10Examplesofretortingtemperaturesandtimesforcannedfishpasteproducts

Alternative Initialproducttemp.(C) Preheating Heating

temp.(C) time(min)

temp.(C) time(min)

Fishmeatballsinbrine/bouillon

850ml(99x119mm)cans

I 20 105 20 120 15

II 20 105 20 115 40

425ml(99x63mm)cans

I 20 108 20 120 13

II 20 108 20 115 35

Fishcakesinbrine/bouillon

850ml(99x119mm)cans

I 30 100 30 120 25

450ml(99x63mm),cans

I 30 100 30 120 20

Furtherdescriptionsareasforcanningtunainbrine.

4.2.7Descriptionofcanningsalmon

Thedescriptionisrelatedtoaprocessingplantwithacapacityof8tonsofrawfishper8hoursthiscapacityhasbeenbasedonusingwholefishweighing4kgeach.SeeFigure17"layoutforsalmoncannery".

Theoverallyieldwhencanningsalmonisbetween55to60%,dependingonthesizeofthefish.Withayieldof55%,1tonofrawsalmonwillgive3400(3437)225g(1/2pound)cans.

Theprocessingoperationsaredescribedbelow.SeeFigure18"Flowsheetforcanningsalmon"

1. Thefisharetransportedtoasortingtableandsortedbyspecies.

2. Thesalmonareevisceratedwithanironchinkmachinewhichremovesthehead,finsandviscerafromthesalmon(seeFigure19).Thelossofweightisapproximately3540%

3. Theeviscerated,deheadedfishisnextconveyedtotheslimingtable.Slimingconsistsofremovingfins,visceraandblood,etc.notremovedbythebucheringmachine.Duringtheslimingoperationthefishisthroughlywashed.Thelossofweightisapproximately35%.

Figure18.Flowsheetforcanningsalmon.

4. Fromtheslimingtablethecleanedfishisconveyedtoafishcutterfittedwithrevolvingsknifeswhichcutthefishintoslices.Theslicesarethen.fedintoanautomaticfillingmachine.Thelossofweightisapproximately0.51.0%.

5. Thefillingmachinefillsthecanswiththesalmonafterwhichsaltisadded.

6. ThefilledcanspassthroughanautomaticscalewhichsortsforunderWeightcans.

7. Fromthescalethecanspassintoavacuumseamingmachine.

8. Thefilledandsealedcansarethendischargedfromtheseamingmachinethroughacanwasher.

9. Afterseamingtheproductgoesimmediatelytoretorting.Retortingconditionsofapproximately115Cfor100minareusedfor450mlcans.

10. Furtherdescriptionsareasforcanningtunainbrine.

4.2.8Descriptionofcanningshrimps

Headless,peeledshrimpsaregradedaccordingtonumberofshrimpsper100gofdrainedproduct.SeeTable11(CodexStan371981).

1.HEADERKNIFE2.FISHINPOSITIONFORHEADING3.BULLRINGWHICHCARRIESFISHTHROUGHTHEMACHINE4.BACKPINCERS5.TAILPINCERSADVANCEDANDGRASPINGFISH6.TAILCUAOFFSAW7.BELLYFINNINGKNIFE8.BACKPINCERSADVANCEDANDGRASPINGFISH9.BACKFINNINGKNIFE10.BELLYSLITTINGSAW11.GUIDETOOPENBELLYFLAPSFORGUTTINGREEL12.GUTTINGREELTOREMOVEVICERA13.KNIFEANDREELTOSLITKIDNEYMEMBRANEANDTOREMOVEKIDNEY14.BRUSHTOREMOVEBLOODANDMEMBRANES15.ROLLERTOSUPPORTBULLRING16.FISHRELEASEDASBACKANDTAILPINCERSRETRACT17.CONVEYORTOREMOVEBUTCHEREDFISH

Figure19Ironchinkfordressingsalmon

Table11Numberofshrimpper100gofdrainedproduct

SizeDesignation Conventional Cleaned

Extralargeorjumbo lessthan12.3 lessthan13.4

Large 12.3to17.7inclusive 19.4to19.1inclusive

Medium morethan19.1butnotmorethan31.8 morethan19.1butnotmorethan34.6

Small morethan31.8butnotmorethan60 morethan34.6butnotmorethan65.3

Tinyorminuscular morethan60.0 morethan65.3

Figure20Layoutforshrimpcannery

Itisusualtocanonlythoseshrimpwhichfallinthemediumtoverysmallsizerange.

Thedescriptionisbasedonaprocessingplantcapacityof3.6tonsrawshrimpper8hours.Thiscorrespondstoproductionof1200014000cans,eachcontaining75gshrimp,in8hours.

Theoverallyieldfromcanningshrimpisbetween25to30%ofrawweight.SeeFigure20"Layoutforshrimpcannery"whichshowsaplantofthecapacitymentionedabove.Thedescriptionisbasedonusingicedrawshrimpastherawmaterial.Theshrimpsareusuallygradedbeforedeliverytothecannery.SeeFigure21"Flowsheetforcanningshrimps".

Theoperationsinthecanningprocessaresummarizedbelow:

a. Onarrivalatthecannery,iceisremovedbeforewashingtheshrimps.

b. Theshrimpsarethroughlywashedwhilebeingconveyedintotheplant.

c. Afterwashingtheshrimpsareinspectedandforeigndebrisremoved.

d. Theshrimpsarethenconveyedtoapeelingmachine,whichseparatestheshellsandheadsfromthebody.Thisoperationcanalsobedonemanually.Aproximately46%ofthetotalweightislostduringthisprocess.

e. Afterpeeling,theshrimpspassthroughtoawasteseparator,whichremovesfragmentsleftafterpeeling.

f. Thecleanedshrimpsareloadedintobasketsandplacedintoaboilingsaltsolutionforcooking.Averagesaltconcentrationinthesolutionis1113%.Thecookingtimevariesfrom610minutesdependingonthesizeoftheshrimps.

g. Aftercookingtheshrimpsareinspectedandanybrokenonesand/orpiecesareremoved.Theshrimpsarethendriedbyfans.

h. Theshrimpsareweighedandhandfilledintocans.Theweightoftheshrimps.shouldbe64%ofthecontentofthecan.Aluminiumcansarepreferablyusedforshrimpcanning,howeveriftinplatecansareused,layersofparchmentpapershouldbeplacedbetweentheshrimpsandthecantopreventcorrosion.Hotorcoldbrineisfilledintothecans.

Table12Exampleofmixtureforbrine

Salt 2kg

Sugar 1kg

Citricacid 0.9l

Water 100l

i. Thecansareautomaticallyclosedandtransferredtoretortsforprocessing.

Figure21Flowsheetforcanningshrimp

Table13Examplesofretortingtemperaturesandtimesforcanningshrimp

Alternatives PreheatingConditions ProcessingConditions

temp.(C)

time(min)

temp.(C)

time(min)

I 104 50 116 22

II 108 60

j. Furtheroperationsareasforcanningtunainbrine