2010.guidelines.chilling-protocols by matis

8/3/2019 2010.Guidelines.chilling-Protocols by MATIS

1/31

Optimised Chill ing

Protocols for Fresh Fish

Bjrn Margeirsson

Hlne L. LauzonLrus orvaldssonSveinn Vkingur rnasonSigurjn ArasonKristn Lf ValtsdttirEmila Martinsdttir

Vinnsla, virisauk i og eldi

Skrsla Mats 54-10Desember 2010

ISSN 1670-7192


2/31

Titill / Title OptimisedChillingProtocolsforFreshFishHfundar / Authors Bjrn

Margeirsson,

Hlne

L.

Lauzon,

Lrus

orvaldsson,

Sveinn

Vkingurrnason,SigurjnArason,KristnLfValtsdttir,EmilaMartinsdttir

Skrsla /Report no. 54-10 tgfudagur/Date: December 2010

Verknr. / project no. 1682/1704/1852

Styrktarailar / funding: AVS R&D Fund of Ministry of Fisheries in Iceland, the TechnologyDevelopment Fund at the Icelandic Centre for Research, Universityof Iceland Research Fund and EU (contract FP6-016333-2)

gripslensku: Leibeiningarumklinguferskumfiski lsahrifamestukliaferum

llum

stigum

klikejunnar

me

herslu

hvtan

fisk.

Lst

er

hvernig

eigiabestaklinguogvihaldahitastigi tilessahmarkagiogryggi afura og minnka kostna og orkunotkun. skrslunni erubakgrunnsupplsingar fyrir leibeiningar iupplsingaveitunaKligttheimasuMats semsettareru framnotendavnanhtt slenskuwww.kaeligatt.is og ensku www.chillfish.net. Leibeiningarnar erutlaar fyrir sjmenn, framleiendur, flutningsaila og ara ailaviriskejunnar. Leibeiningarnar byggja rannsknum semframkvmdar hafa veri innan rannsknaverkefna eins og Chillon,HermunkliferlaogKlibtar. Helstukaflarfjallaumklinguumbor,vinnslu,vipkkun,flutningoggeymslufiski.

Lykilorslensku: Kling,fiskur, hitastig,vinnsla,pakkningar,flutningur,geymslaSummary in English The overall aim of the optimised chilling protocols is to describe the

mosteffective chillingmethods forany stage in the food supply chainwith emphasisonwhitefish.This comprisesoptimisationof thewholechain for lowering and maintaining low temperature with the aim ofmaximisingqualityandsafetyoftheproductsandminimisingcostsandenergy use. This report is the background for the protocols andguidelinespublishedwithopenaccessatMatswebsite inIcelandicandEnglish inauserfriendlyway:www.chillfish.net.Theseareprotocolstofollowaimedfortheuseoffishermen,manufacturers,transportersandotherstakeholdersinthefisherieschain.Theinformationisdividedintosubchaptersofdifferent links in the chain.How to chill fishonboard,during processing, packaging, transport and storage are the mainchapters.

English keywords: Cooling,fish, temperature,processing,packaging, transport,storage Copyright Mats ohf / Matis - Food Research, Innovation & Safety


3/31

Contents1 Introduction 1

2 Catching 1

2.1 Howtochillrightaftercatch 1

2.2 Precoolingbeforeicing slurryicevs.solidicechilling 2

2.3 Propertiesofslurryice 3

2.4 Icerequirement 5

2.4.1 Coolingwhitefish 5

2.4.2 Duringstorage 6

2.4.3 Calculationoficerequirement 8

2.5 Temperaturemaintenance 10

3 Processing 11

3.1 Chilledroombeforeprocessing 11

3.2 Liquid/slurryicecooling 11

3.3 CBCcoolingorsimilartechniques 13

3.4 Holdingtimeandairtemperatureinprocessingroom 14

4 Packaging 16

4.1.1 IcePacksandExpandedPolystyrenevs.CorrugatedPlastic 16

4.1.2 Importanceofprecoolingbeforepackaging 20

5 Chilledstorage 22

5.1 Dailyheatbalance 23

6 Transportpostprocessing 24

6.1 Interfacesbetweendifferentlinksinthecoldchain 24

6.2 Roadtransport 24

6.3 Seatransport 26

6.4 Airtransport 26

7 ACKNOWLEDGEMENTS 27

Nomenclature 28


4/31

1

1 IntroductionProperandsteadycooling isthekeytogoodquality, longshelf lifeandhighvalueofseafood.Caremustbetakentohandlethefishproperlyatallstagesduringprocessingtoensurethehighestqualityandthusmakethemostpossiblevaluableproducts.Theconditionoftherawmaterialisvitalforthequalityandutilisationofthefish.Factorswhichcanaffecttherawmaterialqualityarefishingseason,fishingarea,fishinggear,nutritionalstatusandageofrawmaterial,rigormortisandhandlingbeforeand after processing. Proper cooling during the whole value chain is a key factor in maintainingmaximumqualityaslongaspossible.Theoverallaimoftheoptimisedchillingprotocolsistodescribethemosteffectivechillingmethodsforanystageinthefoodsupplychainwithemphasisonwhitefish.Thiscomprisesoptimisationofthewholechain for loweringandmaintaining lowtemperaturewiththeaimofmaximisingqualityand

safety of the products and minimising costs and energy use. This report is based on theory andexperience within several national and international research projects and contains practicalinformationandcoverageoncoolingandhandlingoffishatallstagesofthevaluechainfromcatchtomarket.Thereportisthebackgroundfortheprotocolsandguidelinespublishedwithopenaccessat Matis website in Icelandic and English in a userfriendly way: www.chillfish.net. These areprotocols to followaimedat fishermen,manufacturers,transportersandotherstakeholders inthefisherieschain.Theinformationisdividedintosubchaptersofdifferentlinksinthechain.Howtochillfishonboard,duringprocessing,packaging,transportand storagearethemainchapters.

2 Catching2.1 HowtochillrightaftercatchOncethecatchisreceiveditisveryimportanttominimisetheholdingtimeandcoolitwithslurryiceassoonaspossible.Oncethefishhasbeenallowedtobleedinrunningseawater/wateritshouldbeprecooledfurtherdowntoatemperatureasclosetotheintendedstoragetemperatureaspossible.

The fishshouldthenbestored in theholdwithevenlydistributedslurry ice inwell insulatedtubs.Sincefishcanabsorbbothsaltandwaterwhenstoredinslurryiceforanexcessiveamountoftime,itisnotrecommendedtostoreitformorethan24hoursinslurryice.Ifprolongedstorageisnecessarytherawmaterialshouldbestoredincrushedplateice.

Another important factor is the temperature in theholdwhich shouldbe close to0C.Byhavinggoodcontrolovertheholdtemperature,bothiceandenergycanbesavedandtherateofspoilageisminimised.


5/31

2

2.2 Precoolingbeforeicing - slurryicevs.solidicechilling

Figure1:Meantemperatureoffishstoredininsulatedtubsasfunctionoftimefordifferenttypesoficecoolingmedia.

Figure1showsresultsfromacoolingexperimentconductedinordertocomparetwodifferenttypesofslurry ice(denotedasLIAandLIB)andcrushedplate ice(Fl+Fl,where+Fldenotestop icingwithcrushedplate ice).1 Therawmaterialwaspackedwithexcessiveamountof ice inallcasesandthe

temperatureinthefleshwasrecordedeveryfiveminutes.TheiceconcentrationandtemperatureoftheslurryicecoolingmediaarepresentedinTable1.Thefigureclearlyshowsthedifferenceincoolingratefordifferenttypesofice,whereLIBreaches0C in2030minuteswhilethesameprocesstakesapproximately4hoursand20minutesfortherawmaterialpackedincrushedplateice.Table1.Propertiesofslurryicecoolingmediausedforcoolingwholefishbyorvaldssonetal.(2009).1

Slurryicegroup Iceconcentration[%] Temperature[C]

LIA+FI 34 2.2LIB 47 2.4LIB+FI 34 2.2

Inordertoslowdownspoilagemechanismsandensurethequalityoftherawmaterialbyreachingoptimaltemperatureassoonaspossibleitisthereforerecommendedtocoolitwithslurryice.

However,thestudyalsoshowedthatfishcooledinslurryiceandstoredupto8dayshadsignificantlyhigherTVBN andTMA content.This couldbe causedby the conditions createdby the slurry iceenvironment(saltuptakeofflesh),causinganevenfasterfishdeteriorationprocesswithincreasingprolongedstorageperiod. Infact,aninsignificantbutmeasurablesaltuptakewasfoundinthefleshafter48hourswhileallslurryicemediasignificantlyincreasedsaltcontentoffleshafter48daysof

1

Lrus orvaldsson, Hlne L. Lauzon, Bjrn Margeirsson, Emila Martinsdttir, Sigurjn Arason. Comparisonof cooling techniques - Their efficiency during cooling and storage of whole, gutted haddock, and their effect onmicrobial and chemical spoilage indicators. Mats report 34-10.


6/31

3

storage(p


7/31

4

Figure3.Relationbetweenicepercentage,saltconcentrationandtemperatureofslurryiceforawiderangeofsaltconcentration.3

Thecoolingcapacity(enthalpy)oficeslurriesisshowninFigure4.

Figure4.Enthalpyphasediagramofsodiumchloridewater(slurryice)asafunctionofadditiveconcentration.4CIdenotesicemassfraction(iceconcentration)andthesaltcontent(additiveconcentration)isonthexaxis.

3 Melinder, ., Granryd, E., 2005. Using property values of aqueous solutions and ice to estimate iceconcentrations and enthalpies of ice slurries. International Journal of Refrigeration 28, pp. 13-19.


8/31

5

2.4 Icerequirement2.4.1CoolingwhitefishThemostimportantvariableswhenconsideringtheicerequirementforfishcoolingarestoragetimeandinitialfishtemperature.Orinotherwords:themostimportantfactorsindetermininghowmuchice isneededforacertainamountoffish, istheheatcontained in it,andtheheatabsorbedbythecontentsofthetubfromtheenvironment.In order to determine how much heat is contained in the fish the temperature dependent heatcapacityofwhitefishcanbeused.TheapparentspecificheatcapacitycfatanyspecifictemperatureisdeterminedbyinterpolatingthevaluesgiveninFAOtechnicalpaper340(Johnston,1985)andtheconductivityk, interpolatingdatafromZuecoetal.(2004).Table2.Thermodynamicpropertiesofwhitefishattemperaturerangingfrom 30Cto30C.5,6

T[C] cf

[kJ/kg/K]

k

[W/m/K]

30

2.055 1.872

20 2.595 1.67510 4.227 1.4796 7.744 1.4004 15.111 1.3613 26.539 1.3412 65.636 1.3221 102.72 1.3020 4.144 0.4305 3.641 0.43010 3.683 0.430

20

3.683 0.43030 3.683 0.430

Sincethespecificheatoffishisverytemperaturedependentitisnecessarytointegratethespecificheatoverthetemperatureintervalinordertofindtheenergyremovedfromthefishsuchthat

(1)

where the initial temperature of the fish is T1 and the final temperature after cooling is T0. ThisintegralissolvednumericallybyusingcubicinterpolationinbetweenthepointsdisplayedinTable2.

4 Melinder, ., 2010. Properties and other aspects of aqueous solutions used for single phase and ice slurryapplications. International Journal of Refrigeration XXX, pp. 1-7. In press.5 Zueco, J., Alhama, F., and Gonzlez Fernndez, C.F., 2004. Inverse determination of the specific heat of

foods. Journal of Food Engineering, 64(3), pp. 347-353.6 W.A. Johnston, F. N. 1985. Freezing and refrigerated storage in fisheries. FAO Fisheries Technical Paper-T340 , 143.


9/31

6

Figure5.Energy[MJ]requiredtolowerthetemperatureof100kgofwhitefishfromT1toT0.

Figure5showstheenergyneededtolowerthetemperatureofwhitefishfromT1toT0.Thecontours

clearlyshowthesteep increase inheatcapacityfrom 1Cto0Cwhich islargelyexplainedbythephasechangeofwaterinthefish.

2.4.2DuringstorageAccording to Fouriers law the heat flow between two points at a constant temperature in ahomogenousmaterialwith1Dgeometryfollowstherelation

A (2)

wherek isthethermalconductivityofthematerial isthethicknessof it,Atheareaandthetemperaturedifference. Fouriers law canbeusedas an approximation for theheat flow into aninsulated tubwitha lidwhereconvection isneglected.This isa reasonableassumptionas longas/ 1/,wherehistheconvectioncoefficientforeithersideofthetub.Assumingthatthetubhasouterdimensions theinnerdimensionsare

2 2 2(3)

whereisthethicknessofthewallsofthetub.Thetotalinnerareaofthetubisthen

2

(4)

whichcanbeinsertedintoFouriersequationwhichbecomes


10/31

7

(5)

where Te is temperature of the environment. A typical material which is used in such a tub is

polyurethanewhichhasthermalconductivitykofaround0.03W/m/K.

Bymultiplying withthestoragetimet,thetotalamountofheatputintothesystemisfound.Thetotalamountofenergyneededbothforcoolingandstoragecanthenbewrittenas

1

(6)

Convective thermalresistance,1/h,shouldnotbeneglected incaseofnowind,hereaconvective

heattransfercoefficientoutsidethetub,h=5W/m

2

/Kwasadopted.Theamountofslurryiceneededtofulfilthisenergyneedis

(7)

whereLiceisthelatentheatoficeandxiceistheiceconcentration(massratiooficeinthemixture)ofthe slurry ice. It shouldbenoted that the enthalpyof thenonfrozenpartof slurry icehasbeenneglected. This is reasonable for slurry ice temperature ranges between 3 C and 0 C and iceconcentrationabove10%,whichnormallyisappliedwhencoolingfreshfishwithslurryice.Figure4

canbeappliedifmoreaccuracyisneeded.


11/31

8

2.4.3CalculationoficerequirementAs can be seen from above, the most important variables when considering ice requirement forchillingfisharestoragetime,surroundingtemperatureduringstorageandinitialfishtemperature.

Figure6.Theratiompureice/mfishasafunctionofinitialtemperatureoffishfordifferentstoragetimeswithambienttemperature4C.

Figure7.Theratiompureice/mfishasafunctionofinitialtemperatureoffishfordifferentstoragetimeswithambienttemperature0.5C.


12/31

9

Figure6and Figure7and show the amountofpure ice required to cooldownandmaintain thetemperatureof fish fordifferent storage timesassumingambient temperatureof4 Cand0.5 C,respectively.Thetubisassumedtobemadeofpolyurethanewithconductivityk=0.03W/m2/Kanddimensions 123 cm 102 cm 58 cm.Therawmaterialisassumedtoreach0Cattheendofthecoolingprocess.

UsingFigure6theamountof icewithconcentrationrequiredtocoolacertainamountof fishwithmassmfishcaneasilybefoundoncethe initialtemperatureandstoragetime intubhavebeendetermined.Forexample,ificeof30%concentrationwastobeusedtocooldown100kgoffishwithinitialtemperature15Candstoredfor48hours,onecouldreadmpure,ice/mfish=0.33fromthechartwhichcouldthenbetranslatedintotheamountof30%slurryiceneededas

0.33

(8)

i.e.,

0.33 0.33100 kg0.30 110 kg

(9)

whichmeansthat110kgof30%slurryicewouldbeneededfor100kgoffishgiventheassumptionsabove.Table3andTable4showtheicerequirementforseveraldifferentinitialtemperaturesoffish,assumingstoragefor48hoursat4Cand0.5Cambienttemperature,respectively.

Table3.Icerequirementperkgoffishatdifferentinitialtemperatures(T0),assumingstoragefor48hat4C(msi,20%:massofslurryicewith20%iceratio)

T0

mpureice[kg]

msi,20%

[kg]

msi,33%

[kg]

msi,50%

[kg]

5 0.09 0.47 0.28 0.1910 0.15 0.74 0.45 0.3015 0.20 1.02 0.62 0.4120 0.26 1.29 0.78 0.5225 0.31 1.57 0.95 0.63

Table4.Icerequirementperkgoffishatdifferentinitialtemperatures(T0),assumingstoragefor48hat0.5C(msi,20%:massofslurryicewith20%iceratio)

T0 mpureice[kg] msi,20%[kg] msi,33%[kg] msi,50%[kg]

5 0.06 0.30 0.18 0.1210

0.11 0.57 0.35 0.23

15 0.17 0.85 0.51 0.3420 0.22 1.12 0.68 0.4525 0.28 1.40 0.85 0.56


13/31

10

2.5 Temperaturemaintenance

Figure8.Maintenanceoftemperatureasafunctionoftimefordifferenticetypes.

Figure8showshowtemperaturewasmaintainedintherawmaterialfordifferenticetypesinastudyconductedbyMatsinOctober2008.1ThesamenotationisusedinthisfigureasinFigure1above.Itcanbeseenthateventhoughthetemperatureofthecrushedplateiceisslightlyhigherthanthetemperatureoftheslurryice,it isbettermaintainedthroughoutthestorageperiod.Thereasonforthisisprobablyalargercontactareafortheslurryicebothwiththewallsofthetubandthefish.

Thisresultfurthersupportstherecommendationtoinitiallycooltherawmaterialwithslurryice,reicewith crushedplate iceafter24hours,and thenmaintain the temperatureafter thatwith thecrushedplateice.

Recommendations:

Allowthefishtobleedinrunningseawater(coolinginbleedingnotrequired). Coolthecatchinaprecoolingtubondeckassoonaspossibleafterbleeding. Forfasterprecooling,slurryiceshouldbeusedsinceitprovidesamuchfastercoolingrate

thansolidice(flakeice,plateice,tubeice).

Efficienticingoffishintubswilldependoneffectivemixingofslurryicewithfish. Ifslurryiceisnotavailableonboard,propericingcanbeachievedbyusingsolidiceaddedin

layersinthefishtub.

Iftherawmaterialistobestoredintheholdforaprolongedtimeperiod,atoplayerofsolidiceshouldbeaddedasneededtocovertherawmaterialinthetubindependentlyofthe

coolingmediumused.Thisisespeciallyimportantincaseofpoortemperaturecontrolinthe

hold.

Thetemperatureintheholdshouldbeclosetoorjustbelow0C. Goodcontroloverthetemperatureoftheslurryiceisalsorecommended.


14/31

11

3 ProcessingThemainpurposeofcoolingapplicationsinprocessingplantsistoquicklyandadequatelyreducetheenergycontentofthefishinordertomaximisetheproductsqualityandshelflife. Supercoolingthefishproducts (bringing the temperaturebelow its initial freezingpoint) canbe seen to result inapartlyfrozenstateofthefishmuscle;apartofthewaterinthefishmusclebeingfrozen. Theratioof

frozen water in the fish can be read from Figure 9, whichpresents the relation between energycontent,watercontent,temperatureandratiooffrozenwaterinthefish. Thewatercontentofcodandhaddockisaround8083%.7

Figure9. Enthalpy(energycontent,relativetotheenergycontent0kcal/kgat 40C)ofleanfishmuscleasafunctionofwatercontentandtemperature. Theratiooffrozenwaterinthefishmuscleisgivenby .8

3.1 ChilledroombeforeprocessingTemperaturecontrolinthereceivingchilledroombeforeprocessingisveryimportantandshouldbemaintainedcloseto0C. Preprocessing(suchasheadingandgutting)timeshouldbeminimisedinthis room, inparticular if the room temperature isnot strictly controlled. Thepreprocessed rawmaterialshouldbechilledassoonafterpreprocessingaspossible.

3.2 Liquid/slurryicecoolingLiquid cooling isaprecooling techniquewhich consistsof immersing the fresh fish into a cooled,lightly salted (1.02.5%)water.Slurry ice cooling isa similar techniqueexcept thata twophase

7 Rahman, M.S. 2009. Food Properties Handbook, 2nd ed., Boca Raton, FL, USA, CRC Press.8 Rao, M. & Rizvi, S. 1995.Engineering Properties of Foods, New York, USA, Marcel Decker, Inc.


15/31

12

slurryice(mixtureoficecrystalsandlightlysaltedwater)isusedasthecoolingmediumoftenwithatemperatureof1Cto 0.5C.Liquidorslurryicecoolingissometimesusedasastandalonesolutionwhile it ispreferabletohave itaspartofaCBCcoolingsystemorasimilartechnique.9WhenusedwithaCBC system itboth serves thepurposeof cooling the rawmaterialand to increase its saltcontentslightlyinordertoloweritsfreezingtemperatureintheCBCcooler.

Figure10.Temperatureinfilletsasafunctionoftimeinliquidcooler.10

Figure10showstemperatureprofilesofthreefilletsweighing400600gchilled ina liquidcoolerwithliquidtemperatureofca.1Cforapproximately6minutes.Duringthatperiodthetemperatureofthefilletscanbeseentodropby1 2C,whichdependsontheinitialtemperatureandsizeofthefillets,thetemperatureandflowofthecoolingmediumandthetimewhichthefillets/loinsspendinthe liquid cooling.The results from theaforementionedexperimentsandothersyield thegeneralruleofthumbthatthecoolingratecanbeestimatedas0.120.20C/minormorespecifically,ca.0.029 0.031 C/min per C difference between initial product and medium temperature. Thisimpliesthatwiththeinitialproducttemperatureof6Candmediumtemperatureof0Cthecoolingrate isca.0.18C/minbutamediumtemperatureof 2Cwouldgiveacoolingrateofca.0.24Cmin. Tochilltheproductfrom6Cto1Cwouldrequire5/0.18min 28minand5/0.24min 21minformediumtemperatureof0Cand 2C,respectively. Itshouldbenotedthatthesegeneralrecommendations for estimating the required cooling time only apply when the temperaturedifferencebetweentheproductandmediumismorethanca.1C. Figure11illustratesresultsfromanothercomparableprecoolingexperiment,11however,utilizingslurryicewithlowsaltcontent(0.5

0.8%)andtemperaturebetween 1and0C insteadof liquidwithno iceas inValtsdottiretal.(2010). Similar cooling ratewas yielded, i.e.around0.03 C/minper Cdifferencebetween initialproductandmediumtemperature.

9 Kristn Lf Valtsdttir, Bjrn Margeirsson, Sigurjn Arason, Hlne L. Lauzon, Emila Martinsdttir.Guidelines for precooling of fresh fish during processing and choice of packaging with respect to temperature

control in cold chains. Mats report 40-10, 37 pages.10

Valtsdttir, K.L, Margeirsson, B., Arason, S. 2009.A-3.2: Forkling fyrir pkkun vkvakli. Thermalmodeling of chilling and transportation of fish Mats project.11 D5.4.A. FISH Field Trial Scenario and Mapping Summary Report Chapter 3. Cod supply chain IS-FR (Opale) Liquid ice chilling. Chill on EU project.

0

1

2

3

4

5

6

1 3: 47 1 3: 48 1 3: 49 1 3: 50 1 3: 50 1 3: 51 1 3: 52 1 3: 53 1 3: 54 1 3: 55

Temperature[C]

Time

#463 #470 #484


16/31

13

Figure11.Temperatureduringcoolingofcodfilletsinaslurryicetub.11

No.170(658g),304(277g),317(263

g) and 457 (467 g) represent cod loin temperature and no. 1, 141 and 437 represent cooling medium

temperature. Massofloiningrams(g)isgivenforeachloin.

Figure 11 shows that the loin mass is not a dominating factor for the cooling rate. In fact, the

temperature difference between the cooling media and initial product temperature is more

important.

The iceconcentration ina liquidcoolershouldbe10%ormore,whichshouldresult inthedesired

coolingmediumtemperatureof2C(assuming3.5%salinity). Therelationshipbetweensalinity,ice

concentrationandtemperatureofslurryiceisshowninFigure2.

Despite

its

advantages

the

risk

of

cross

contamination

is

considerable

in

liquid

cooling.

In

order

to

minimisetheriskthefilletsshouldbekeptintheliquidforalimitedamountoftimeandthecooling

mediumshouldberenewedfrequently.

3.3 CBCcoolingorsimilartechniquesCBCcoolingisanewcoolingtechniquedevelopedbySkaginnhf.whereheatisextractedfromfillets

bothbyconductionthroughaTefloncoatedaluminiumconveyorbeltandbyconvection,wherecold

airissimultaneouslyblastedoverthefillets.12

Slurryicecooling,suchasdescribedabove,isapartof

theCBCcoolingprocess.ItisperformedbeforetheCBCcoolinginordertodecreasethetemperature

ofthefilletsandslightlyincreasetheirsaltcontent.

Liquid or slurry ice cooling of fillets can be used to lower the temperature in process prior to

packaging.Microbiologicalqualityof thecoolingmedium, itsrenewalandtemperaturecontrolare

necessary for success. Otherwise, high microbial load of specific spoilage organisms (SSO, namely

Photobacteriumphosphoreum, pseudomonads and H2Sproducing bacteria) in the cooling mediumwill lead to contamination of the fillets and rapid growth of SSO during storage of the products,

especially under temperature abuse. However, the impact of CBC cooling on the temperature

maintenanceofabused filletshasbeen found tobeconsiderablewhencomparedto liquidcooling

(LC) in process or untreated fillets. Abused CBC and LC fillets were found to have 100% and 25%

extendedshelflife,respectively,comparedtosimilarlyabusedcontrolfilletswithashelflifeof6days

12 Skaginn hf. 2003. Improved profitability in shore based processinghttp://www.skaginn.is/bindata/documents/__CBC_document_EN_03_00147_00012.pdf


17/31

14

fromprocessing.13 lafsdttiretal. (2006)also found thatCBC coolingcan lead to freshnessandshelf lifeextensionofcod fillets.14 It is thereforeanadvantageousmethod toprocess fillets tobeshippedasfreshproductssinceitwillhelpinmaintainingfreshnessandshelflifedespitebreakageinthe cold chain. Further, a bacterial growthretarding effect of CBC processing on SSO has beenobserved.

Figure 12 shows the temperature development of 5 different fillets weighing 400 600 g beingtransportedthroughaCBCcooler.Thetemperatureofthefilletscanbeseentodecreaseby2Cin10minutesduringthe liquidcooling.Therapidcoolingofthe fillets in theCBCcoolercanthenbeobserved where the temperaturedecreases by approximately 3.5 C in approximately 7minutes,

downtoatemperaturewheremostofthephasechangetakesplace.AnotherinterestingfeatureinFigure12isthatoncethefilletshavegonethroughtheCBCcoolerandarestored inanopenboxat14 C their temperature remains stable.The reason for this is thatalargepartofthecoolingenergyaddedtothefilletsintheCBCcoolerisintheformofphasechange,sothatthetemperatureremainsstableuntilmostoftheicehasmelted.

3.4 HoldingtimeandairtemperatureinprocessingroomTheholding time in theprocessing shouldbeminimised.ResearchconductedbyMatshas shownthatthetemperatureof filletscan increaseby3 4C foreveryhalfanhourtheyare leftwithoutcoolinginaprocessinghallat20C.9Theprocessinglineshouldbeleftclearandallrawmaterialkeptinchilledstorageduringcoffeeandlunchbreaks.

13Magnsson, H., Lauzon, H.L., Sveinsdttir, K., Margeirsson, B., Reynisson, E., Rnarsson, .R., Gujnsdttir,M., rarinsdttir, K.A., Arason, S., Martinsdttir, E. 2009. The effect of different cooling techniques andtemperature fluctuations on the storage life of cod fillets (Gadus morhua). Matis report 23-09, 37 p.14Olafsdottir, G., Lauzon, H.L., Martinsdottir, E., Kristbergsson, K. 2006. Evaluation of shelf-life of superchilledcod (Gadus morhua) fillets and influence of temperature fluctuations on microbial and chemical quality indicators.J.Food Sci. 71 (2), S97-S109.

1

0

1

2

3

4

13:50 14:00 14:10 14:20 14:30

Temperature[C]

Time

#A

#B

#C

#D

#E

CBCcooler

LiquidcoolerStoredinanopenbox

Figure12. Thetemperatureof5differentfilletsasafunctionoftime.10


18/31

15

Figure13.Fillettemperatureincreasingduringbreaksimulationinthetrimmingarea.9

Figure 13 shows the temperature increase in four fillets which were left without cooling in theprocessing room having initially been cooled in a liquid cooler. The temperature can be seen toincreasebyupto67Cforeveryhourtheyareleftwithoutcooling.Suchascenario isverylikelyforexampleifthefilletswereleftwithoutcoolingduringalunchbreakorifthetrimmingwouldbeabottleneckintheprocessingline.Itshouldbenotedthatthistemperatureincreasedependsheavilyontheambienttemperatureinthetrimming/processingroom.

Recommendations:

Maintainlowandstabletemperatureinthechilledroombeforeprocessing. Useliquidcooling,butavoidcrosscontaminationbylimitingtheamountoftimeeachfilletis

in thecoolingmediumandbesure tocirculateand renew thecoolingmedium frequently.Liquidcoolinghasbeenfoundtoextendtheshelflifeoffilletssubjecttotemperatureabuseby25%,comparedtosimilarlyabusedcontrolfilletswithashelflifeof6days.

Precoolfillets/loinsbeforepackagingtoaround 1.0to 0.8CwithCBCtechniqueorothersimilartechnique.FilletscooledwithCBCcoolinghavebeenfoundtohaveextra3daysshelflifecomparedtosimilarlyabusedcontrolfilletswithashelflifeof6days.

Minimiseholdingtimeduringprocessing.Makesuretheprocessinglineisclearduringbreaksandmakesuretherearenobottlenecksintheprocessingline.

Coolthewater,whichisusedinprocessing,to1 2Cifpossible. Minimiseholdingtime. Thisisevenmoreimportantforloinsandfilletsthanforwholefish.

FormoreinformationonprecoolingduringprocessingareferenceshouldbemadetoValtsdttiretal.(2010).9

0

2

4

6

8

10

12

14

16

18

20

22

24

13:00 13:30 14:00 14:30 15:00 15:30 16:00

Temperature[C]

Time

Fillet1

Fillet2

Fillet3

Ontopof

fillets

Ambient

temperature


19/31

16

4 Packaging4.1.1IcePacksandExpandedPolystyrenevs.CorrugatedPlasticSome studies15,16have revealed that temperaturecontrol in real fishcoldchains isquiteoften farfrom what is described in the ATP17 thereby altering product quality, shortening shelf life and

decreasing product value. According to Mai etal.

15

, the temperature regulation in fresh fishdistributionchainsisactuallymainlyaproblemforairfreight,butnotseafreight.

The negative impact of unsatisfactory ambient temperature fluctuations during distribution ofperishable products can still be dampened by thermal insulation of the packaging. Othercharacteristicsofpackaging,whichcaninfluencethequalityoftheproducts,includeitsstrengthandspace(bothinternalspaceforcoolingmatsoriceinordertomaintainlowproducttemperatureandspace required for storage). Here all focus is on the thermal insulation since that is the mostimportantpropertyfortemperaturecontrolincoldchains.

Inlargepartsoffreshfishdistributionchains,theinsideboxesofwholepalletsareprotectedagainstthermal load from the ambient air by the neighbouring boxes and therefore it is important tounderstandwellthetemperaturedistribution insidepallets. This is,however,notalways thecasebecause frequently, pallets are broken up before being loaded onboard airplanes in order tomaximisevolumeexploitationofthecargohold. Thus,results forbothsinglepackagesandwholepalletsarediscussedhere.

Thermalperformanceoftwotypesofwholesalefreshfishboxeshasbeeninvestigated,18,19onemadeof expanded polystyrene (EPS) and another made of corrugated plastic (CP). The packagingcontainedfreshwhitefishfillets,whilechallengedbyambienttemperatureconditionssimilartooreven more severe than Mai et al.15 reported. The ability of ice packs to maintain desiredtemperaturesduringtemperatureabusewasalsostudied.

15 Mai, N., Margeirsson, B., Margeirsson, S., Bogason, S., Sigurgisladottir, S., Arason, S. In press. Temperaturemapping of fresh fish supply chains air and sea transportation. Journal of Food Process Engineering, doi:10.1111/j.1745-4530.2010.00611.x.16 Giannakourou, M. C. and Koutsoumanis, K. and Nychas, G. J. E. and Taoukis, P. S. 2005. Field evaluationof the application of time temperature integrators for monitoring fish quality in the chill chain. International

Journal of Food Microbiology, 102(3), p. 323 336.17 ATP, 1970, "Agreement Transport Perishables,Agreement on the international carriage of perishable

foodstuffs and on the special equipment to be used for such carriage, United Nations Economic Commission forEurope, Geneva (1970). http://www.unece.org/trans/main/wp11/atp.html.18 Margeirsson, B., Palsson, H., Arason, S. 2009. Thermal Performance of Corrugated Plastic Boxes and

Expanded Polystyrene Boxes. Matis report 01-09.19Margeirsson, B., Gospavic, R., Palsson, H., Arason, S., Popov, V. Experimental and numerical modellingcomparison of thermal performance of expanded polystyrene and corrugated plastic packaging for fresh fish.

International Journal of Refrigeration. Published online (doi:10.1016/j.ijrefrig.2010.09.017).

Figure14. Freshwhitefishfilletsinwholesalefishboxes. Left: corrugatedplasticboxwithnoicepack. Right:

expandedpolystyreneboxwithanicepackontopofthefillets. Alsoshownareibuttontemperatureloggersusedformappingproducttemperature.


20/31

17

The twodifferentwholesalebox typesare shown in Figure14 and theirdimensions and thermalpropertiespresentedinTable5andTable6,respectively.

Table5.Dimensionsofwholesalefishboxes.

19

Type InnerLxWxH(mm) OuterLxWxH(mm)

EPS 355.5x220x85 400x264.5x135CP 370x230x80 395x247x85

Table6.Thermalpropertiesofwholesalefreshfishboxes.19

Type mass(g) (kg/m3) cp(kJ/kg/K) k(W/m/K)

EPS 181 22 1.280.05 0.0310.036CP 178 150270 1.90 0.0380.045

It was shown that expanded polystyrene wholesale boxes are more thermally protective thancorrugatedplasticwholesaleboxes18,19asisillustratedinFigure15.Furthermore,frozenicepacksareefficientforprotectingfreshfishfilletsagainsttemperatureabuse.

Figure15.Evolutionofambienttemperature(amb)andmeanproducttemperatureduringfourtemperatureabusetrialswithhaddockfilletsinfreestandingwholesalefreshfishboxes.19

Valtsdttiretal.(2010)showedthatdistributingthecoolingcapacityinsidetheboxesbyplacingicepacksbelowandon topof filletsprotects the filletsbetter thanonlyplacing themon topof thefillets. Thedifference in insulationperformanceof the twopackaging types isnot asobvious formultiplepackagesloadedonpalletsasforsinglepackages.18


21/31

18

ButeventhoughEPSboxesaremorethermallyprotectivethanCPboxes,ithasbeenshownthattheEPSboxescanstillbeimproved.20Theproducttemperatureatthemostvulnerableposition(bottomcorner)intwoEPSboxesisshowninFigure16:1)anewboxmanufacturedbyPromensTempraehf.(Hafnarfjrur,Iceland)withroundedcornersand2)anotherbox(referredtoasoriginal)withlessroundingofcorners,stillweighingaround11%more.Theenvironmental temperature fluctuations

causingtheproducttemperaturefluctuationsinFigure16areillustratedinFigure17.

Figure16.Meanproduct temperatureatthebottomcornersof theoriginal (O)and thenew (N)EPSboxesduring a dynamic temperature period. The mean product temperature was calculated from four bottomcornerpositionsintwoboxesforboththeoriginalandthenewboxes.20

Figure17.Meansurfacetemperaturefortheoriginal(O)andthenew(N)EPSboxesduringadynamictemperatureperiod.20

20

Bjrn Margeirsson, Hlne L. Lauzon, Kolbrn Sveinsdttir, Eyjlfur Sveinsson, Hannes Magnsson,Sigurjn Arason, Emila Martinsdttir. 2010.Effect of improved design of wholesale EPS fish boxes on thermalinsulation and storage life of cod loins simulation of air and sea transport. Mats report 29-10, 38 pages.


22/31

19

Asimplecorrelationforthewarmuptime(inhours)givenbyBASF21canbeusedinordertopredictwarmuptimeatsteadyambienttemperature:

,

,

1 / /ln

3.6fb amb mean init

p p

amb mean final

h R d k T Tt m C

A T T

+ + =

(10)

FromEqn.10, themean temperature (Tt)of fillets inwholesaleboxessubject toasteady thermalloadofdurationt(hours)canbeyieldedas:

TheinternalareaoftheboxisrepresentedbyA[m2]=2x(LxW+LxH+WxH),thefilletweightbym (kg), the specific heat capacity of the fillets by cp (3.85 kJ/kg/K), the convective heat transfer

betweenboxandambientairbyh(W/m2/K), thethermalresistancebetweenfilletsandboxbyRfb(m2K/W),thethicknessoftheboxbyd(m),thethermalconductivityoftheboxwallsbyk(W/m/K)and finally, the initial fillet temperature and ambient temperature by Tinit (C) and Tamb (C),respectively.

Figure18. Effectofambienttemperatureontheestimatedmeantemperatureofa3kgbulkofwhitefishfilletsstoredinanEPSbox(3kgcapacity)asinfluencedbytime.The initialfillettemperatureisassumedtobe1Candtheconvectiveheattransfercoefficientoutsidethebox isassumedtoequal5W/m2/K(representingnowind,i.e.naturalconvection).

21 BASF, Styropor Technical Information. 2001 [accessed 23 Oct 2008]; 2001 Edition:[Available from:http://www.plasticsportal.net/wa/plasticsEU~en_GB/portal/show/content/products/foams/styropor_peripor.

3.6exp

(1/ / )

amb init t amb

p fb

T TT T

At

mc h R d k

=

+ +

(11)


23/31

20

Figure19. Effectofambienttemperatureontheestimatedmeantemperatureofa5kgbulkofwhitefishfilletsstoredinanEPSbox(5kgcapacity)asinfluencedbytime.The initialfillettemperatureisassumedtobe1Candtheconvectiveheattransfercoefficientoutsidethebox isassumedtoequal5W/m2/K(representingnowind,i.e.naturalconvection).

TheestimatedwarmupoffreshwhitefishfilletsisshowninFigure18andFigure19forasingle3kgEPS box and a single 5 kg EPS box, respectively. The convective heat transfer coefficient (h) isassumed tobe 5W/m2/K, the thermal resistance inside thebox (Rfb) is assumed tobenegligibleaccordingtoBASFbutmaybetakenashighas0.05 W/m2/K.19Thesefiguresrevealtheimportanceofminimizingthetimethatpackagedfishfilletsarestoredinsinglepackagesataslowtemperatureas10CeventhoughtheyarepackedinwellinsulatedEPSboxes. Theyalsoshowthatfilletsin3kgEPSboxesaremorenegativelyaffectedbythermalloadsthanfilletsin5kgEPSboxes.

4.1.2ImportanceofprecoolingbeforepackagingThe importance of precooling white fish fillets before packaging is obvious when two thermallyabused5kgEPSboxesat15Cambienttemperaturearecompared,thefirstonecontaining5kgofprecooledfilletsdownto 1.0C,theotheronecontaining5kgoffilletsat1.0C.

Theenthalpyofcodat 1Cis307kJ/kgcomparedto337kJ/kgat0C.22 Thismeansthat30kJ/kgwillbetransferred intothepackagedfilletsbeforetheirtemperaturehas increasedfrom 1.0Cto0.0C. Theheattransfercanbecalculatedas

1(12)

where isthetemperaturedifferencebetweentheambienceandtheproduct, i.e.ca.15.5C inthiscase. TheRvaluecanbecalculatedas(seeEq.(11)):

22Rao,M.A.andRizvi,S.S.1995. EngineeringPropertiesofFoods. 2ndedn.MarcelDekker,Inc.NewYork.


24/31

21

1

15 0

0.0240.033 0.927

(13)

hence,

10.927/ 0.254 15.5 4.2 (14)

Themeltingtimefor5kgoffishfilletspackedinEPSboxandabusedat15C,i.e.thetimeittakesthemeantemperatureof5kgoffilletsinanEPSboxtoorisefrom 1to0Cisthus

0 1 30 54.2/ 35300 . 9.8

(15)

This implies thatbyprecoolingwhite fish filletsdown to 1 Cbeforepackaging inEPSboxes theproductsearnanextraprotectionagainstathermal loadof15Cforalmost10hourscomparedtoprecooledproductsto0C. ApplyingEq.(11)andFigure19showsthatfilletswithinitialtemperatureat1Cwouldhavethemeanproducttemperatureof6.6Caftera15Cthermalloadfor9.8hours.

Recommendations:

Minimisepackagingtimeandlimitthepackagingroomtemperatureaspossibleaccordingtoregulations.Thetemperatureoffilletswaitingonthe lineforbeingpackagedcaneasilyrise

from1Cto34Catpackagingroomtemperatureof20C.

Usewell insulated fishboxes. Expandedpolystyrene (EPS)boxesarepreferredratherthancorrugatedplastic (CP)boxes. CorrugatedfibreboardboxeswithEPSpanelsalsohavehighthermalresistanceandboxesmadeofpolyurethane(PUR)foamevenhigherthanEPS.23

Applyfrozenice/gelpacksontopoffishfilletsbeforeclosingthefishbox. Suitableicepacksizeis125250gfor37kgoffishfillets.

Useaslargepackagingunitsaspossible(e.g.5kginsteadof3kg),bearinginmindtheclientsrequirements. It should,however,benoted that larger temperaturegradients insideeachthermally loadedboxareexpectedastheboxgets larger, resulting indifferent fishqualityinsidelargerboxesassumingsufficientlygreatthermalload.

Loadpackagesonpalletsandput inachilledstorageassoonaspossibleafterpackaging inordertominimisethermalloadonpackages.

However, less insulated fishboxesareactuallypreferablewhen theambient temperature is lowerthan the product temperature. This applies when precooling in processing before packaging isinadequateresulting in fishfillet temperaturehigherthanca.23Candthechillchain fromtheprocessortothewholesaler/consumer isunbroken. Butsincethetemperature inmany(airborne)chillchainscanbequitedynamic,effectiveprecoolingbeforepackagingshouldbeemphasisedandthewellprecooledproductswellthermally insulated inEPS/PURboxes. Incontainerisedseaborne

23 Singh, S.P., Burgess, G., and Singh, J., 2008. Performance comparison of thermal insulated packaging boxes,bags and refrigerants for single-parcel shipments. Packaging Technology and Science, 21(1): pp. 25-35.


25/31

22

chillchainstheinsulationrequirementsonthepackagingaremuchlessandthusmorepossibilitiestouselessinsulatedpackagingmaterials.

Applyingdifferent typesof ice (e.g.plate ice, flake ice, crushedblock ice)or coolingpacks insidewholesaleboxescontainingsuperchilled(e.g.CBCchilled)filletstransported inproperlyfunctioning

mechanically refrigerated containers does not seem to be important with regard to optimisedtemperaturecontrol. Thisisduetothefactthattheproducttemperatureisbroughtdownto 1.0to0.5 C in the CBC cooling and the ambient temperature normally is very close to the producttemperature.

FormoreinformationoncoolingduringpackagingareferenceshouldbemadetoValtsdttiretal.(2010).9

5 ChilledstorageReference shouldbemade toColdStoreGuide (International InstituteofRefrigerationIIR,1993)24andInsulation

and

airtightness

of

coldrooms(IIR,2002)

25

forfurther informationoncoldstores, inparticulartheirconstruction,operationandsafetyaspects.

The importance of proper precooling before packaging should be emphasised because speciallydesignedprecoolingequipment,suchastheCBCequipment(seechapter3)coolstheproductsmuchfasterto thedesiredtemperaturethanstorage inachilledstoreafterhavingbeenpackaged. Thepurposeofthechilledstorageroomistomaintainlowtemperatureoffoodstuffforstorage,nottocoolthefoodstufftothedesirabletemperature.

Regardingthestoragetemperatureoffreshfishfillets,superchilledstorageisadvantageoustoextendthe freshness and shelf life period, while comparison of abused products, either CBC processed,

liquid/slurry ice cooled or uncooled in process, has shown the greater benefit of CBC cooling.

13

Temperatureabusecanbeextremelydetrimental inunprotectedoruncooledfishproductsor inthose cooled but produced with poor hygienic conditions and leading to high microbialcontamination. Decreasing average fillet temperature to 0.8 C or 1.3 C by CBC cooling andsuperchilledstorageinEPSboxeshasbeenshowntoincreasefreshnessperiodby2025%comparedtofilletsstoredat01Cwhileasmallergaininshelflifewasobtained.26

In general, temperature is more strictly controlled in chilledstorage rooms than frozenstoragerooms. This is inaccordancetothe fact thatthe temperature insidechilledrooms iscloserto thepointofinitialfreezinginfood,whichisgenerallycloseto 1C. Airtemperatureshouldbekeptascloseto0C,stillbearinginmindthedangeroficeformationonfloors. Inordertoobtainefficientheat transferbetweencoolingairand theproducts, freeair flowmustbesecured throughout theroom (seeFigure20)27andanaircirculationratioof40 iscommonlyused.25 This implies that thevolume of circulating air in the room in 1 hour equals 40 times the volume of the empty room.

24InternationalInstituteofRefrigeration(IIR),1993. Coldstoreguide. Paris,France.

25InternationalInstituteofRefrigeration (IIR),2002. Insulationandairtightnessofcoldrooms. Paris,France.

26MartinsdttirE,LauzonHL,TryggvadttirSV.2005.hrifroklingargifiskflaka.Rannsknastofnunfiskinaarins/IcelandicFisheriesLaboratories,Verkefnaskrsla/ProjectReport1005,50p(Icelandic).27Johnston,W.A.,Nicholson,F.J.,Roger,A.,Stroud,G.D.Freezingandrefrigeratedstorageinfisheries.FAOFisheriesTechnicalPaper.No.340.Rome,FAO.1994. Availableathttp://www.fao.org/docrep/003/v3630e/V3630E08.htm


26/31

23

5.1 DailyheatbalanceTheloadonthecoolingsystemofacoldstore,i.e.therefrigerationload,hastwosources:

a. coolingproductsdown,i.e.reductionoftheproductsenthalpyb. maintaininglowtemperatureofproducts,i.e.removalofincomingandinternallygenerated

heat.

Thedifferentcomponentsoftherefrigerationloadarethefollowing:1. removalofsensibleand/orlatentheatfromproducts(seea.above)2. heatconductedthroughwalls,floorandceilingofthestore3. radiationfromoutside4. heatconvectedfromoutside(bothsensibleandlatent)throughopendoorsetc.5. internalheatgeneration: lights,personnel, fans, fanmotors,othermachineryand the last

butnottheleastimportantheatproducedduringdefrostingofevaporators.

In order to estimate the aforementioned components of refrigeration loads, empirical, analyticaland/ornumericalmethodscanbeused.25,28,29

Recommendations:

Somegeneral recommendations foroptimalstorage inchilledstorage roomsaregivenbelow. Allthese advices aim at minimising heat gain and stabilising temperature of the room, therebymaximisingproductshelflife. Theinsulationoftheroomshouldbesufficienttolimittheheatflowrateperunit(inner)areato6to12W/m2.25

Monitor temperature at several different locations inside the room, especially close toentrancesand faraway from coolingunits (blowersor spirals),wherehigher temperatureandmoreseveretemperaturefluctuationsareexpected.

Equip the storagewithentrances/docking stations,whichminimiseairexchange,e.g.withautomaticpowerdoors/slidingdoors,protectivestripsandadjustableheightgangplanks.

Equipthestoragewithcoolingunitsofsufficientcoolingcapacity inorderto facethedailyheatgainsdescribedabove.

Limitlighting,e.g.byshuttingitoffduringnighttime. Avoidstoringproductswithin12mdistancefromthenearestentranceifpossible.

28Trott,A.R.,Welch,T.C. 2000. RefrigerationandAirConditioning,3rded. ButterworthHeinemann,Oxford,

UK.29Margeirsson,B.,Arason,S.2008. TemperaturemonitoringandCFDmodellingofacoldstorage.In:CCM

2008:The3rdInternationalWorkshoponColdChainManagement. 23June2008. Bonn,GER,p.215226.

Figure20. Airflowinacoldstoreequippedwithanaircoolingevaporatorwithafan(blastcoolingsystem).Left:restrainedairflowbecauseofoverloading. Right:Goodairdistributioninthesamecoldstore.


27/31

24

Restrictunnecessaryopeningsofthechilledroom. Securefreeairflowthroughoutthestoreandanaircirculationratioof40.

6

Transport

post

processing

ReferenceshouldbemadetoGuidetorefrigeratedtransport(IIR,1995)30foranindepthreviewonrefrigeratedtransport. Researchhasshownthatthetemperatureinseafreightismuchmorestablethan in air freight relying on the existence of various interfaces of the segmental air transportchains.15 Below, special consideration is given to interfaces,whichare found inmost chill chainssince they normally are discrete, i.e. made up of different transport modes. Advice is given ontransportbyair,roadandsea,separately. Thereader interested inrailtransport isreferredto IIR(1995).30

6.1 InterfacesbetweendifferentlinksinthecoldchainTheriskofacommonlyexperiencedtemperatureabuseatvariousinterfacesinthechillchainshouldbeminimised. Thiscanbedonewithe.g.technicalsolutionssuchaswelldesigneddockingstationswith door sealing cushions to minimise air flow and heat transfer to the packaged products.Satisfactoryinformationflow,bothupstreamanddownstreamthechain,isalsoessentialinordertominimiseunnecessarydelaysattheinterfaces.Animportantissueregardingcertainhandoverpointsincertainchillchainsisthatmasterpackagingiscommonlybrokenup,ofteninordertomaximisevolumeutilization. Thisisthewaylargepartofchilledfishproductsarehandledbeforebeing loadedonboardairplanesandtheprocessorshouldpreparehisproductwithadequateprecoolingbeforepackagingandinsulationofthepackaging.

6.2 RoadtransportRecommendations:

Checkproducttemperaturebeforeloading. Airtemperatureshouldbekeptbetweenascloseto 1Candnohigherthan4Cforoptimal

storage of superchilled fish products. The importance of maintaining actually as lowtemperature as 1 C is governed by the insulation performance of the packaging anddurationofthetransport.

Permitfreeflowofcoolingairaroundthecargo(similartowhatisshownforachilledstorageroominFigure20).

Utiliseforcedaircirculation,i.e.distributeflowofchilledairfromcoolingunitthroughoutthewholetruck/container(seeFigure21).31

30InternationalInstituteofRefrigeration(IIR),1995. Guidetorefrigeratedtransport. Paris,France.

31 Moureh, J., Flick, D, 2004. Airflow pattern and temperature distribution in a typical refrigerated truckconfiguration loaded with pallets. International Journal of Refrigeration, 27(2004), p. 464-474.


28/31

25

Monitortheairtemperatureinsidethecontainer,especiallyfarawayfromthecoolingunit.Since thecoolingunit ismostoftenat the front, themostsensitive location isat thebackclosetotheroof. Preferably,theperformanceofthecoolingsysteminsidethebodyshouldbestudiedbymappingthetemperaturedistributionunderrealcircumstances(withthetruckloaded) beforeadecisiononplacementofrecordingthermometers(temperatureloggers)ismade.

Mechanically refrigerated containers with overall heat transfer coefficient (K or Ucoefficient)equal toor less than0.4W/m2/Kareneeded inmostcarriageswith fresh fishproducts. However,iftheroadtransporttime isonlyafewhours,insulatedcontainers(i.e.equipmentofwhichthebodyisbuiltwithinsulatingwalls,doors,floorandroofsuchthatK


29/31

26

6.3 SeatransportThemainadvantagethatseatransporthascomparedtoairtransport iscontinuity inthetransport,i.e. the chain has few and relatively secure handover points regarding temperature control.Containers (refrigerated and nonrefrigerated) are multimodal equipment, which generally allowgoodstobeswitchedbetweenlandandseatransportwithouttheneedofbreakingupthecargo.

Recommendations:

Checkproducttemperaturebeforeloadingthecontainer. Permitfreeflowofcoolingairaroundthecargobynotoverloadingthecontainer. Airtemperatureshouldbekeptbetween 1Cand0C foroptimalstorageofsuperchilled

fishproducts. Thesuperchilledstorageconditionsduringseatransportare ingeneralmoreimportantthanduringroadtransportsincenormally,seatransportlastslonger.

There isnotadefiniteneed formelting iceon topof fresh fish filletswhen transported incontainerswithpropertemperaturecontrol. Ifusedthenmakesuremelted icewaterdoesnotstay incontactwith theproductsor thatcrosscontamination isnotcausedbymeltedwaterfromonefishboxtoanother.

6.4 AirtransportRecommendations:Temperatureduringair freight is ingeneralnotaswellcontrolledasduringsurface (landandsea)transport.15 However,theconsignor/shippercanfollowthefollowingrecommendations inorderto

minimisetheriskofundesirablethermalloadsontheperishablefreight:

Apply precooling before packaging as one step of the processing (see chapter 3). Fishproductspackagedat 0.5Csimplycantakemoretemperatureabusethanproductsat4Cwhenpackaged.

Usewell insulatedpackagingsolutionsandpackasdenselyaspossible,given theproductsrequirements(seechapter4).

Checkproducttemperaturebeforeshippingtheproducts. Shipproductstothedepartingairportaslateaspossible,especiallyifrefrigeratedstorageisunavailablethere. Still,theproductsmustbe intimeattheairportaccordingtothefreight

forwarders/transportersspecification. It followsthattemperaturecontrolledtransporttotheairportshouldbeused.

Protecttheproductsfromchallengingclimaticconditionssuchasrainanddirectsun. Thinpolyethylenefilmsprotectagainstrainbutnotsunshine.

Selectadirect flight tominimise thenumberof thermallyhazardous interfaces in thechillchain.

Makesurethatallnecessarydocumentationissentbeforehandtothecollectorofthecargoat thedestinationairport. Furthermore,makesure thatthe freight iscollectedassoonas


30/31

27

possible in a temperature controlled vehicle and no delays are in the transport to theclient/market.

Whenanew freight forwarder/airline is taking careof theair transport, the temperaturecontrolinthechillchainshouldbeinvestigatedinatleastthreeseparateshipmentswiththe

helpofca.46temperatureloggers. Thecostrelatedtosuchtestsisminimalcomparedtothevalueofthegoodsandthiscangivevaluableinformationonroomforimprovements inthechillchain.

7 ACKNOWLEDGEMENTSThisreportisbasedonresultsfromtheresearchoftheEUfundedIntegratedResearchProjectCHILLON(contractFP60163332),theChilladdon(SamttingklirannsknaKlibt)fundedbytheAVS research fund under the Ministry of Fisheries (project no. R 06106), the TechnologyDevelopment Fund at the Icelandic Centre for Research (project no. 061358006) and Thermal

modellingof chillingand transportof fish (Hermun kliferla) fundedbyAVS FundofMinistryofFisheriesinIceland(projectno.R03708),TechnologyDevelopmentFundoftheIcelandicCentreforResearch (project.no.081304508)andUniversityof IcelandResearchFund.The financingoftheseprojectsisgratefullyacknowledged.


31/31

2010.guidelines.chilling-protocols by matis

Documents