ransycli" tuaot S 4-et,cee. Johnny Rlyrvik reb its. st, El?<c.mie y-t TRANSPORT OG LAGRING AV FERSK FISK. S 1-1A 4z.tA.

Transkript

1 ' 5.1- TRANSPORT OG LAGRING AV FERSK FISK Utdrag fra underskelser vedrrende cntainertransprt av imager fisk _ Jhnny Rlyrvik ransycli" tuat S 4-et,cee reb its El?<c.mie y-t ri ker,:rn d st, S 1-1A 4z.tA c)kylnl j0v.k. M0,1,..TeCinnit,à U11, te, ers;t--1 strett e,r

2 Innhld 1. Bakgrunn Side 1. Smacntainere sm lastenheter li 1 3. Frsksarbeidet Il 4. Temperaturbetingelsene under lagring ll 3 5. Vektutbyttet fra fangst tu l knsumferdig prdukt Filetprduktets kvalitet " 10 sensriske analyser " 10 kjemiske mâlinger " 1 7. Knklusjn " 13 REFERANSER " 13

3 Transprt g lagring av fersk fisk. Utdrag fra underskelser vedrrende cntainertransprt av mager fisk. 1. Bakgrunn. Transprtleddet fr fersk fisk mellm fangst g viderebehandling er prblematisk bâde p.g.a. den krte hldbarhetstiden g andre naturgitte betingelser under fiskeriene. Den stadig nesten enerâdende lastfrmen, kasser med kjling av is, er preget av tidkrevende manuelle arbeidsperasjner. Driftsknmien blir skadelidende, gsâ gjennm redusert râstffutnyttelse g prduktkvalitet. Prblemene innen ferskfisktrâlingen er illustrerende. Den tungvinte lastingen/ levere fangstene direkte ved fabrikkene. Fr à redu- lssingen lâser bâtepe til â sere tapene er det da naturlig at hver fangstperide strekkes til det ytterste. Tab. 1 peridene presses pp mt dgn, blir râstffkvaliteten sterkt redusert. Ca. halve lasten er ubrukelig til filetprduksjn. middel st.avvik viser bl.a. driftstid fr seks ferskfisktrâlere fra Vesterêlen. Nâr fangst- Antall driftsdgn Antall fiskedgn Antall turer Driftsdgn pr. tur (Dr.dgn - fiskedgn)/turer Fangstverdi pr. fiskedgn, kr Tab.l. Driftsstatistikk fr seks ferskfisktrâlere, Vesterâlen Med dette sm utgangspunkt ble det ved Institutt fr kjleteknikk, NTH, tartet underskelser med mâl â bidra tu l utviklingen av bedre hêndteringsmetder.. Smâcntainere sm lastenheter. Prinsipper g metder sm har vist sine frdeler ved andre transprtbehv mê, sâ langt mulig, gsâ utnyttes i hândteringen av fersk fisk. MAlet er â kmbinere effektiv g fleksibel frembrihelse av râstffetinnenfr akseptable investerinner. Ulike typer cntainerlast er stadig blitt mer vanlig der mekanisering skal kmbineres med smidig varedistribusjn. Tilpasset de naturgitte frutsetningene, synes denne lastfrmen gsâ â kunne gi de beste systemer fr transprt/lagring av fersk fisk. Fr stre deler av fiskeriene kan det bli aktuelt â skille transprten g selve fisket pâ ulike fartyer. Et effektivt cntainersystem kan gjre slik mlastin lnnsmt i mange tilfeller. Det kan synes rimelig â anta at riktig strrelse fr lastenheten blir ulik fr de ulike farty- g fangsttyper. Strst mulig grad av standardisering er imidlertid frdelaktig bâde av hensyn tu l investeringskstnader g tu l fleksibiliteten i transprtsystemene. Bl.a. ut fra denne tankegang er riktig cntainerstrrelse antatt â vœre ca. 1 m 3. Behlderene skulle da kunne tilpasses det meste av dagens fartyer g annet transprtutstyr. Fisken frutsettes frtsatt kjlt med is prdusert ved landanlegg. Dette blir billigste metde, frst g fremst frdi et strre landanlegg gir bedre utnyttelse av maskineriet. PA stre fiskebâter, sm f.eks. trâlere, blir lekkasjevarmen tu l lastermmet ftest tatt pp av installert mekanisk kjleanlegg, da dette er en relativ lav men jevn belastning. "Ferskfiskfrskriftene" angir 60 cm sm m'aksimal lastehyde ved isihg i binge.

4 at drenert stabling medfrer vekttap. Ved bruk av cntainere blir det aktuelt à fylle vann sammen med fisken g isen. Vannet har da tdelt funksjn: a Trykket utjevnes "6" Vannet kan bidra til varmeverfringen fisk-is ved knveksjn. Rkt kntakt- - flate mellm fisk g kjlemiddel (isvann) bidrar gsà til kt kjleeffektivitet. Valget stâr mellm ferskvann g sjvann (eventuelt ferskvann tilsatt salt). Sjvann blir selvsagt det lettvinteste ved fiske pâ havet. Ferskvann blir derimt det mest narliggende dersm cntainerene skal fylles pà land, eller ved fiske i urent farvann. FANGST SLOYING OG HODEKAPPING r_ TEMPERATUR- ' MALINGER 1 1 underskelsene er de t alternativene sammenlignet med rdinarkasselagrinp. Tre ffietder er altsà benyttet i parallell: VEIING IS + FERSKVANN LAGRING 1 cntainere NTEMPERATUR- i 3,6.9 g 'MALINGER 1 1 degn kg pr. parti * IVEIING 1 / VEIING IS + SJOVANN LAGRING cntainere EMPERATU ql.lagring 1 3,6.9 g 'MALINGER 1 1 degn kg pf-. parti VEI1NG IS VEIING smaka%spr smàkasser g 1 degn kg pr. parti VEIING II III Cntainere med kjling i is + sjvann (CSW). Cntainere, kjling i is + ferskvann (CFW chilled fresh water). Kasser med is (her kalt ICB - ice chilled bx). Isingen i kassene ble utfrt â rdinar, men relativt Ordentlig mâte. 3. Frsksarbeidet. F1LETERING Baader 189 SKINNING. Baader 47 VE1ING REINSKJKR: PAKK1NG VEIING INNFRYSING Platefrvs. 0REBEIN RYGGBEN SKINN AVKUTT, TYKKFISK BEIN VEIING VEIING VEIING F1LETERING Baader 189 SKINNING Baader 47 VEIING REINSKJ/11. PAKKING VEIING PROVER ca. 50 kg pr. parti OREBEIN RYGGBEIN SKINN SALG FILITERING Baader 189 SKINNING Baader 47 VEIING REINSKJFR. PAKKING VEIING Fig. 1 viser den vanlige behandlingen av hvedpartien mens fig. viser analyser utfrt med prvestykker. Arbeidet mfatter fire hele serier sm vist, fruten supplerende frsksser. de fleste knsentrert m kjleeffektiviteten. Underskelsene kan, sm figuren viser, deles inn i tre hved mrâder: a Temperaturbetingelsene under lagringen b Vektutbyttet fra fangst t knsumklart prdilkt c Filetprduktets kvalitet. Fig. 1. Behandlinen av hvedpartiene, skjematisk. 1 tillegg ble der gsâ utfrt mer spradiske

5 Cntai nerene TINE OG KOKE- FORSOF 1 veid tint veid kkt veid avdampet veid Fig.. PR 9 V E R ca. 50 kg pr. parti SENSORISKE ANALYSER - TO TESTMETODER I KOMBINASJON: A TRIANGELTEST B POENGBED1MMELSE Rangrdens test vha. t-vegs. variansanalyse. - IRE UAVHENGIGE TESTPANEL - CA. 15 DOMMERE I HVERT PANEL - TO TESTOMGANGER KJEMISKE ANALYSER - ANALYSER FOR: A TOT. FL. N B TMA C TMg0 D HYPOKSANTIN E SALT Analyser utfrt med prver fra frskspartiene. I de t frste seriene ble fr- det benyttet cntainere av kmmersielle merker tu l skslagring/transprt. De aktuelle typene er imidlertid uten termisk islering, fruten at utfrmingen gjrde dem ne uegnet tu l bruk pâ bât I de resterende seriene ble 1 derfr spesialbygde behldere benyttet tu l lagringen. DiSSE var utfrt i t versjner, en i glassfiberarmert plast, den andre i aluminium. Cntainerene var laget dbbeltvegget ME.5-3 cm plyuretan i mellmrmmet. Fr en fleksibelt anvendelig cntainer er islent en ndvendighet, selv- mrmest salgt mer j hyere rmtemperz turen er, g j svakere vannei sirkulerer i behlderen. Dette var den mest benyttede g den best islerte cntainer- Fig. 3 viser skisse av, glassfiber-cntaineren med pâmnterte termelementer fr temperaturmâlinger. typen. Det viste seg imidlertid at.aile behlderene, sm var prveutkast, varbeheftet med kuldebrer sm- reduserte i-slasjnsevnen. Glassfibercntainerene hadde hyt kulgjennmslag i bunnen ved beina, fruten ved dreneringsspunset. 4. Temperaturbetingelsene under lagring. Fiskens kvalitetsnid etter gitt lagringstid er nrmalt hvedsakelig bestemt av.temperaturhistrien. Sm beste temp.frlp regnes hurtigst mulig nedkjling g deretter lagring ved temperaturen fr begynnende utfrysin (frysepunktet). Fig. 3. Plassering av termelementer pâ glassfibercntainer. I nen frsk var hele 17 termelementer plassert pâ staven i sentrum. Nedkjlingstiden er bestemt a temperaturen ved innlasting kjlingens effektivitet. Hvest kjleeffektivitet kan ténkes. m fiskene kunne mgi av kjlemiddel med uendeli varmekapasitet. Da ble tempe raturfrlopet alene bestemt av varmeledningen i fiskekrppen. Denne teretiske ptimal-betingelse kan tilrermes m hver fisk pakkes finknust drenert is, vel â merke sâ lenge hele verflag

6 er i kntakt med isen. Fig. 4 A g B viser!winger ved kjling av t 4 kgs fisker i is (A) g i is + ferskvann (issrpe, B). Fig. A viser at der ved ising raskt ble dannet et islerende luftskikt ver fisken. Nedkjelingsfrlpet i sentrum av fisken ble imidlertid nksà likt i de t frskene, halvkjlingstiden (tiden fr halvering av temp.differansen fisk - is) er ne under en time. Sm kurve 0 i B er vist beregnet temp.frlp i sentrum av en sylinder med diameter lik bredden av fiskene, 10 cm, nâr denne kjles mmentant tu l O ct utvendig. Kurven bekrefter at det hvedsakelig er den indre varmpledningen sm bestemmer nedkjlingstiden i bâde A g B c ci.. i \ - _. c.14 dm ii a bx \ e 3 '... ' N...,. 3 Timer. h Fig. 4 A g B. Temperatur sm funksjn av lagringstid i t like fisker (trsk) A - innpakket i drenert is. B - kjelt i is + vann (issrpe). Slyd g hdekappet. Vekt hver fisk: 4.0 kg. Bredde g tykkelse ver tykkfisk sm vist. Omkrets - 40 cm, lengde - 70 cm. Màlepunkter: 1 - ved beinet - like under skinnet 3 - pâ skinnet 4 - ca. 5 mm ver fisken. Kurve 0 i B viser beregnet temperaturrespns i sentrum av sylinder med diameter 10 cm. Mmentant kjlt utvendig Termisk diffusivitet Beregnet etter it Kjleeffektivitet mtrent sm vist i fig. 4 kan ppnâs i et cntainersystem f.eks. dersm rikelig is fylles jevnt frdelt i lasten. Et system med findeling av isen kan gsâ bli anvendelig i praksis, se-lig der bâter g transprtkjeder planleages fra grunnen. Dersm transprtsystemet skal utfrmes med utgangspunkt i dagens vanlige bâtinnredninger, betyr imidlertid mulighet fr mer knsentrering av isen frenkling g/eller lettelse i arbeidet. Enklest blir_ systemet m all is kan ligge under fisken, da kan isen fylles i behlderene,ved mbrdsetting. Hvr langt fra det ideelle frlp sm j praksis mâ aksepteres, blir en avveining mellm praktiske/knmiske hensyn g kvalitetstapene. Slutningene sm trekkes i det flgende bygger pâ slike avveininger, men de er nksâ skjnnsmessige. Varmeledningsevnen i fisk (g i vann: er svak, strrelsesrden 0.5 W/mK. En frutsetning fr â ke transprtavstanden fr varmen (avstanden mellm islagene) er derfr at kjqlingen sikres ved knveksjn i vannet. Knveksjnen kan frârsakes av: a Differanser i spesifikk vekt i vannet sm flge av temperatureller saltgradienter (egenknveksjn), eventuelt supplert. av: b Pumping eller aaiterina.

7 Underskelsen har vist at dersm sirkulasjnen bare drives ved egenknveksjn, er tilrâdelig avstand mellm islagene sterkt begrenset. Fig. 5 g 6 viser malinger i h.h.v. CSW g CFW der isen var plassert i tre lag med avstand cm. Selv m innvirkningen fra aile tenkelige parametre fr temp.frlpet ikke er kartlagt, er likevel slutningen trukket at strste frsvarlige avstand mellm islagene ved nrmale starttemperaturer blir mtrent sm vist i figurene. 1,33 1 H, 10 0, 0,. 0-4,1 ehlb 110-leille ' t, 1 14.eOPPi 010 f it %. 0-4 _ Oh F..k Ftsk 10 C H ,8 0,6 0,4 0, is bee% >ems- isk IMRIZIW 3iiirea- me- _ nadilffl p is fisk `C II is Fig. 5. Temperaturprfilet ver hyden i cntaineren fr angitte timer etter frsksstart, CSW. Isfrdelingen ved start sm antydet, avstand mellm islagene ca. 30 cm nederst g 40 cm verst. Saltknsentrasjn i vannet ved pâfylling: 3.4%. âtarttemp. mdellfisk/vann/is, C: 11/6/-15. Mengder pâfylt fisk/vann/is, kg: 440/170/60. Antall mâlepunkter: 18. Fig. 6. Temperaturprfilet ver hyden i cntaineren fr angitte timer etter frsksstart, CFW. Mâlepunkter: 18, vertikalt sentrum i glassfiber-cntainere TempA ved innlasting fisk/vann/ is, 'C: 18/7/-15. Rmtemp.: Ca. 0 C. Mengder pâfylt mdellfisk vann/is, kg 400/80/165. Isfrdeling ved start mtrent sm antydet pa figuren. PA bâten bidrar sjgangen til kt mrring. I alle frskene pâ bât var hele ismengden plassert under lasten av ca..1 m hyde. I alle frskene unntatt ett ga dette effektiv sirkulasjn g gd kjling. I det ene tilfellet, mâlinger vist sm fig. 7, gikk nedkjlingen ne sakte p.g.a. sr1ig stille sj. Her ble derfr sirkulasjnen frsterket ved A blase luft inn til bunnen av behlderene, umiddelbart i ferskvannscntaineren g etter ca. 0 timer i sjvannsbehlderen. Systemet virket effektivt selv med enklest tenkelig utstyr. Det ekstra isfrbruket var gsâ minimalt, anslâtt MI ca. 0.5 kg/dgn. Bevegelsene i bâten er sm regel sammensatt av mange kmpnenter, fra lange I

8 6 16 «c Luf Item. breddg i meter g utslag 10-15v. Fr à mâle innflytelsen fra rullingen under kntrl lerbare betingelser ble en enkel vugge knstruert. Den svinget behlderene harmnisk m tyngdepunktet med regulerbart utslag g frekvens. 'c 6 4 '4 4 "C ra N "-- Ved bunnen cm. ver bunnen -e- 10cm. ver bunnen t. I I.«. _ Sjevannskjelt. sentrum cntine I.. t i.... :A S vnnskjelt. ved krtside. «.. Ferskvnnskje1L sentrum cntainer I 1 D,t e 9/8 30/8 pu FerSkvnnskjelt. ved krtside 31/6 V9 /9 4- Fig. 7. Temperaturelinger i serie 4, pâ trâler. I 4-1- Tvungen vannsirkulasjn v.h.a. luftinnblâsing. Innblâsingen startet umiddelbart i CFW, etter ca. 15 timer i CSW. Is ble etterfylt under lagringen. Fig. 8 g 9 viser frsk der behlderene er vinget med frekvens 6 min -1 (nrmal bredde av en ferskfisktrâler er ca. 10 m) g utslag 10'. Selv m det gsâ her er mange faktrer sm kan pâvirke temp.frlpet, synes ndvendig bevegelsesmengde â vfflre av denne strrel- - sesrden bâde i tilfelle CSW g CFW. Pâ grunn av vannets tettehetsvariasjn med temperatur g saltinnhld er det alltid viktig at der blir liggende is under fisken. Dette kan sikres ved at fisk fylles pà fr vann, eller ved bruk av f.eks. _en rist. Fr referansemetden, kasser me is, gjelder at temperaturfrlpene varierer sterkt, fra relativt gde betingelser ved msrgsfullt arbeid, tu l de: helt uakseptable. De âpne g uislerte kassene gir gsâ str mfindtlighet verfr lufttemperaturen, fig Vektutbyttet fra fangst til knsumferdig prdukt. Fig. 1 g viste prsedyren f utbyttemâlingene, fig viser mâleresultater fr fire av stadiene i fremstillingsprsessen. I figurene 1-14 representerer de âpne markeringene frsk der elever under ppl&ring utfrte reinskjœringen g pakkingen. Etter reinskjaribg er disse frskene tillagt mindre vekt enn de vrige, hvr betingelsene var helt realistiske (utfrt i rdinfflre prduksjnslinjer). Hvedknklusjnen er at fisken ved vannlagring ker i vekt. Vektkningen er strst I CFW, g kan bli av betydning allerede etter fê dager, fig. 11. Vannet sm taes pp sitter imidlertid lst bundet, slik at differansene i --frhld tu l innlastet kvantum blir mindre etterhvert i prsessene, fig. 15.

9 7 1,33 1. H, r.1. 4.iiii.1c0 i _. 140 to 0.8 0,6 0,4 rim- Irepkt. ca t a% - _ 1,33 1, H. ni 1,0 0,8 0,6 0,4 VIM/ WI 13 WAIF Ong PP1 f 0, 0, C10 0 u s. 0 _ *C14 s Fig. 8. Nedkjling av linefanget sel; CFW. Innfelt vises mâlinger i en enkeltfisk plassert ca. 15 cm under verflaten, vekt 4.1 kg. Starttemp. fisk/vann/is, C: 9/14/-. Rmtemp.: ca. 14 C. Mengder fisk/vann/is, kg: 480/155/190. Hyde is etter innlast.: Ca. 50 cm.. Rullebevelser i "blgesimulatr"1' - frekvens/utslag: 6 min /10. Fig. 9. Temperaturprfil ver hyden i cntaineren fr angitte timer etter frsksstart, CFW. Runebevegelsq, frekvens/ utslag: 6 min '/10". Starttemp. fisk/vann/is, C: 15/1/-0. Mengder pâfylt fisk/vann/is, kg: 490/170/154. Hyde is ver bunnen ved star. ca. 57 cm. Rmtemp. ca. 0 C.

10 8 u 16 'S> Iluftternperatur ls I_ I D Sj vann is (CSM) 0 Fe rshvnn is (CF4) --- Is i kasser (IC8) d./« Jell' 1) 3 e a 10 7' _ t. C a i 1 limer. h Fig. 10. Temp.mâlinger i fisk ppbevart i kasser med is pâ ukjlt râstffrm. Isen pâfylt sm det fte gjres i praksis: Et lag under g et lag ver fisken. Langs side- kantene blir fisken frt avdekket. flassering av mâlepunktene, tilsammen 4 kasser: 1- i verstâende kasse, ls ved sidekant. - i str fisk (5.5 kg), liggende ved sidekant. 3- midt i kasse, ls mellm fiskene. 4- ved krtside, ls mt veggen. 5- sm 4, mtsatt krtside, ls mt veggen. 6- ved langside, ls mt veggen. MAlingene er utfrt utenm de rdinre frskspartiene. IL r --- L " ---,. b --...e 's -t Mnn lve Fig. 11. Vektkning sm funksjn av lagringstidin. Utbyttet er regnet i frhld til innveid slyd g hdekappet rêstff. (

11 110 sl 90 A 110 :1100 -es e "",...-- A r- s a N ----b---. A - Lgret B - Filetert t C 1 C ' ID C - Renskôret, pkket g frsset D - Tint, kkt g avdmpet T>) C.I.1 - -> ''''. " 1 ' jr 8 I I sj " "-- C 4, - -r-- - D A - Lgret _ 8 -Filetert C - Renskôret, pkket g frsset D - Tint, kkt g vdmpet Dügn lgret e Otign lgr et Fig. 1. Utbytte sin funksjn av lagringstiden fr fisk lagret i sjvann + is (CSW). Utbytte i frhld tu l slyd g hdekappet râstff. Apne markeringer: --elever under pplering har renskâret partiene. Fig. 13. Utbytte sm funksjn av lagringstiden fr fisk lagret i iskjlt ferskvann (CFW). Utbytte i frhld tu l slyd g hdekappet râstff. Apne markeringer - elever unde pplering har rensuret partie 110.t N 1,- A 11 0 J..; "'" I.4 _...- 1,_ :A e 100 i I 90 e. Sjvann is : Ferskvnn is ----: Ksser m. is e -r- --- e --!----r 4- C. A - Lagret Filetert C - Renskeiret, pkket g frsset D - Tint, kkt g avdmpet t 1 50 I _ i 1 40 I I Tz...».. «30 A- Lgret 0 _ 8 - Filetert C - Renskôret, pkket g frsset 10 D - Tint, kkt g vdmpet Dügn lgret 0 I I IIII 0 à 4 i5 8 lb 14 Dgn lgret Fig. 14. Utbytte sin funksjn av lagringstiden fr fisk lagret i kasser med is (ICB). 15. Sammenstilling av kurvene i fig. 1-1A.

12 Filetprduktets kvalitet. Sensriske analyser. Filetprduktets kvalitet ble i frste rekke frskt bedmt ved hjelp av smaksprving i testpanel. Et mfattende arbeid er nedlagt fr med strst mulig sikkerhet à kunne pâvise eventuelle ulikheter i kvaliteten sm flge av de tre lagringsmetdene. Ved hjelp av tre uavhengige dmmerpanel, hvert bestâende av persner, ble prver fra hvert frsksparti smakt g bede ca. 40 ganger. Analysene ble utfrt ved kmbinasjn av triangeltest g penggiving etter karakterskala. Penatallene er benyttet bâde tu l enkel sammenligning av middelverdiene, g sm grunnlag fr differansetester (den sâkalte Tukey's rangrdenstest). Denne sammenligningen av t ulike diff.tester (triangeltesten g Tukey's test) var nskelig bl.a. frdi muliae kvalitetsulikheter innad i frskspartiene kunne vanskeliggjre analysene. Fr Trier utfyllende mtale av testene g de statistiske metdene henvises tu l ref. [1] - [3], her skal bare nen av hvedresultatene nevnes. Tab. viser utslag i differansetestene i en av frsksseriene (serie 3). I denne serien viste testene et av de klareste utslagene, ferskvannsfisk (CFW) er skilt nksâ systematisk fra CSW g ICB etter 9 (lan (se-mg hs dmmerpanel nr. 1). Lag- Dnnerpanel le. 1 Dmerpanel ni-. Lei-panel ci-. 3 rant- Rangrd.t lriangelt. Itangrd.t. Triangelt. Rangrd.t. Triangelt. tail Ongang ni-. *gang ci-. Paging Cr. Onganq Cr. C i nq ri-. Ongana ni-. Dann A/C 8/C B/C A/C A/B A/B A/B 6 NC A/C 8/C 8/C A/B A/8 A/B A/B A/9 A/9 9 A/C A/C 8/C 8/C 8/C B/C 8/C B/C A/6 1 A/C A/C B/C B/C 8/C Tabell. Signifikans ved differansetester. (rangrdenstest g triangeltest). Frsksserie nr. 3. A - fisk lagret i sjvann + is (CSW) B - fisk lagret i ferskvann + is (CFW) C - fisk lagret i kasser med is (ICB) Tre uavhengige testpaneler, 10 dmmere i panel nr., 15 dmmere i de t andre. T testmganger med filet sm var frsset g deretter kkt. Signifikansnivâ: 5% Markeringene viser tester der typene er pâvist ulike.

13 Fig. 18. Karakterer fra smaksprvinger av frsset g deretter kkt filet sm funksjn av laringstid fr râstffet. Frsesserie nr Fig. 16 viser midlere karakterer fra samme dmmerpanel g serie sm funksjn av lagringstiden. Fig. 17 g 18 viser resultater fra t andre frsksserier (serie 1 g 4). Det frste vi merker ss er at kvalitetsutviklingen med lagringstiden kmmer svakt frem, hvedvekten ble da gsà lagt à sammenligning mellm de tre lagringsmetdene fr samme lagringstid. Dessuten har dmmerpanelene ppfattet skalaen ne ulikt, smrlig skiller panel nr. 3 seg ut, fig- 18. L7 6 I I I Sjevnn is Ferskvnn is --- Is ika;ser I P. 7 r V - 1%. 5 4 _ '--- _.r. ss, lra tt 3 es -4. -', _ Odgn lgrel 16. Karakterer fra smaksprvinger av frsset g deretter kkt filet sm funksjn av lagringstid fr râstffet. Middelkarakterer fra dwerpanel nr. 1 i frsesserie 3. Sammenligninger mellm de tre alternative lagringsmetdene. 1 -D---- sjcivann i5? ferskvnn is u- --- is i ksser I I I I 0 3_ Th Orign lgret Fig. 17. Karakterer fra smaksprving( av frsset g deretter kkt filet sm funksjn av lagril tid fr râstffet. Frsksserie nr. 1, dminerpanel nr. 1. t Panel Panel nr ' I ---. Sjevann is. - - Ferskvnn is Is i kasser I Panel nt ' 6 Degn lagret 1

14 r Hvedknklusjnen etter smaksprvingene er at kvalitetsdifferansene sm regel var smà, sarlig var differansene smà innen 8-9 dgn sm mà regnes sm lengste frsvarlige lagringstid fr fullverdig rêstff. Den generelle tendens sm kan sees i scringsresultatene, er at sjvannslagret fisk fte fâr hyest pengsum, mens den ferskvannslagrede gjerne fàr lavest. Slik var gsà utfallet fr 9-dgns-frskene i serie 3, tab. g fig. 16. Sm det skal vises, gir imidlertid de kjemiske analysene ingen sterile tu l nedvurdering av CFWfisken. Det ble da heller ikke pâvist nen usmak i filetene, kmmentarene gikk i stedet i retning av manglende smak, en viss smaksfattighet. Tendensen tu l hyest pengsum fr CSW-fisken var nksâ generell innenfr de nevnte 8-9 dim. I t av seriene (serie g 3) var tendensen der ge etter de lengste lagringene, h.h.v. 10 bg 1 dgn. I de t andre seriene (serie 1 g 4) var imidlertid sjvannsfisken kmmet lengst i kvalitetsfall ved frsksslutt, 11 g 1 dgn. Selv m mulige pesie11e ârsakssammenhenger kan pâpekes (sà sm manglende/mangelfull islering), er likevel sluttinntrykket at lagring i sjvann utver de nevnte ni dgn er betenkelig. Nâr kvalitetstapene tfrysekjeden gsâ taes i betraktning, synes en uke â vare en rimelig vre grense fr lagringstilen uansett kjellemetde. I serie 1 ble gsâ smaksprvinger utfrt etter ett Ars fryselagring. Da ble ingen systematiske kvalitetsdifferanser pâvist. Kjemiske mâlinger. Verdien av kjemiske kvalitetsmâlinger, er selvsagt helt avhengig av sammenhengen mellm det valgte kriterium g varens samlede kvalitetsnivâ. I underskelsene _.0 CJ \*"... I Serie nr. 3.../4015 MOg 8 4 IIIIMMI. Fisk iagret i: Seri. 3 CI-- spivnn is 0 terskvann is v kasser med isiall MUM 1 Dean lgret \--...1"... Seri, U. sjvannet D fisk 1g,-et 1 sjvann is 0--- fisk lagret I ferskvann is O---: fist laret I kasser sd is. Serie nr. 3. Serie _...-_15_-r-_:_." T eliE. I 1 15 Dsin lagret Fig. 0. Mâlt saltinnhld sm funksjn av lagrinastiden, serie 3 g Fr ferskvannspartiene (CWF), kasser m. is (ICB) er partieng ikke adskilt.

15 e var mâlingene knsentrert m det vanligste kriteriet; spaltingen av flyktig nitrgen. Fig. 19 viser sm eksempel sammenstilling av malt innhld av trimetylamin (TMA) sm funksjn av lagringstiden. Selv m spredningen er str, kan enkelte tendenser spres. CSW-fisken ligger fte lavest i TMA-innhld. Da dette gsâ skulle brge fr beste kvaliteten, er dette resultatet annerledes enn utslagene I smaksprvingene. Inntrykket er at N-spaltingen ikke er helt gdt egnet sm kvalitetskriterium, i hvert fall ikke fr relativt fersk fisk. Fiskens saltpptak i sjvann er selvsagt pâvirket av vannets saltinnhld, g dermed av issmeltingen (frutsatt ferskv.is ). Fig. 0 viser mâlinger av saltknsentrasjn I serie 3 g 4. Den smule kning i saltinnhld sm gsa er mâlt i iset fisk (ICB), skyldes at vannet av praktiske hensyn ble tilsatt ne salt ved isprduksjnen (ppgitt tu l ca. 0.5%). Ved smaksprving ble kkevannet tilsatt.5% salt. Differansetestene viser at dette *var nk tu l à kamuflere ulikt saltinnhld i fiskekjttet. 7. Knklusjn. CSWHeller CFW i smâcntainere er lvende metder fr transprt/ppbevaring av ferskt fiskerâstff. Hvedfrdelen er at effektivitet kan kmbineres ma smidighet-i- râstff frembringelsen. Med et gdt planlagt system br penger kunne spares, samtidig sm ' fiskens midlere kvalitet ved ilandfring bedres. REFERANSER Franstâende er sammendrag fra flgende publikasjner 1 J. Ryrvik: Transprt g lagring av fersk fisk. Avhandling fr graden Institutt fr kjleteknikk, NTH, G. Lrentzen, A.M. Bredesen g J. Ryrvik: Lagring av fiskerâstff i cntainere med is eller is-vann-blanding. Institutt fr kjleteknikk, NTH, J. Ryrvik: Industriell filetprduksjn av râstff lagret i is eller is-vannblanding. Institutt fr kjleteknikk, NTH, 1977.

16 ISSN ( Canadian Translatin f Fisheries and Aquatic Sciences N. 57 Transprt and strage f fresh fish. Excerpts frm studies n cntainerizatin f lean fish J. Ryrvik Original title: Transprt g lagring av fersk fisk. Utdrag fra underskelser vedrrende cntainertransprt av mager fisk Frm: Institutt fr kjleteknikk, NTH Original language: Nrwegian Available frm: Canada Institute fr Scientific and Technical Infrmatin Natinal Research Cuncil Ottawa, Ontari, Canada KlA 0S typescript pages

17 - Secretary Secrétariat f State d'état / MULTILINGUAL SERVICES DIVISION TRANSLATION BUREAU DIVISION DES SERVICES MULTILINGUES BUREAU DES TRADUCTIONS Clients N. N du client Department Ministère Divisin/Branch Divisin/Directin City Ville DFO IPB Ottawa Bureau N. N1 0 du bureau Language Langue Translatr (Initials) Traducteur (Initiales) Nrwegian - English IEC TRANSPORT AND STORAGE OF FRESH FISH Excerpts frm studies n cntainerizatin f lean fish Jhnny R4yrvik Canadâ SEC 5-5 (Rev. 8/11)

18 w Cntents Page 1. Backgrund 3. Mini-cntainers as lad units 4 3. Experiments 6 4. Temperature cnditins during strage Weight yield frm catch t cnsumer-ready prduct The quality f the fillet prduct Taste test analyses Chemical measurements 6 7. Cnclusin 8 REFERENCES 9.

19 1. «I 3. (1) Transprt and strage f fresh fish. Excerpts frm studies n cntainerizatin f lean fish. 1. Backgrund The transprt stage f fresh fish frm time f catch t prcessing is a difficult prblem, bth because f the shrt time the fish will keep fresh, and because f ther natural cnditins that may ccur during fishing. The type f cntainer that is still used almst exclusively, i. e. bxes chilled with ice, is characterized by timecnsuming manual labur. The perating ecnmy als suffers, due t reduced utilizatin f raw materials and reduced prduct quality. The prblems fund in fresh fish trawling are a gd example. The heavy and clumsy lading/unlading frces the bats t deliver their catch directly t the factries. It is then nly natural that each catch perid is stretched t its limits in rder t reduce lsses. Table 1 shws the perating time, etc., f six fresh fish trawlers frm Vesterâlen. When the catch perids are pushed up twards days*, the quality f the raw material is drastically reduced. Abut half f the lad cannt be used fr fillet prductin. Based n these facts, studies were begun at the Institute fr Refrigeratin Engineering at the Technical University f Nrway, with the gal f cntributing t the develpment f better methds f handling fish. * Transi. nte: In t is dcument "day" always means 4 hurs.

20 Number f perating days Number f fishing days Number f trips Operating days per trip Operating days less fishing days/trip Value f catch per fishing day in Nrwegian crwns Mean Standard deviatin ,58.- 3,507.- Table 1 Operating statistics fr six fresh fish trawlers, Vesterglen, Mini-cntainers as lad units The principles and methds that have prved advantageus fr ther types f transprt, shuld as much as pssible als be applied t the handling f fresh fish. The gal is t cmbine efficient and flexible frwarding f the raw material with acceptable investment csts. Varius types f cntainerizatin are becming increasingly cmmn in areas where mechanizatin has t be cmbined with a smth distributin f gds. This type f carg transprt, when adapted t natural cnditins, als seems t ffer the best system fr transprt/strage f fresh fish. Fr a large part f the fishing industry it may be necessary t separate the transprt frm the actual fishing activity n different ships. An efficient cntainer system can make such a transshipping prfitable in many cases.

21 It appears reasnable t assume that the crrect size f the lad unit will vary with type f ship and catch. The highest pssible degree f standardizatin is preferable, bth with respect t investment csts and flexibility within the transprt systems. Based n these and ther ideas, the crrect cntainer size was assumed t be abut 1 m 3. The cntainers culd then be adapted t mst f tday's ships and ther transprt equipment. 5 It is assumed that the fish will cntinue t be refrigerated with ice prduced in plants n land. This will be the cheapest methd, primarily because a large land-based plant prvides better utilizatin f the machinery. On large fishing bats, e.g. trawlers, the heat leaking int the hld is usually absrbed by an installed mechanical refrigeratin unit, since this is a relatively lw but even lad. "The fresh fish regulatins" give 60 cm as maximum height fr icing in bins. Hwever, already at this height, the fish becme cnsiderably defrmed*, and drained stacking als results in weight lss. When () cntainers are used, a system f mixing water with the fish and ice will be suitable. The water will then take n a duble functin: a The pressure is equalized b The water can cntribute t the heat transfer frm fish t ice thrugh cnvectin. Mre cntact surface between fish and re- frigerant (ice-water) will als imprve the refrigerating capacity. * Transl. nte: Here it is pssible that ne line was cut ff during phtcpying, see nte n page 7.

22 6. The chice is between fresh water and sea water (pssibly fresh water with salt added). Sea water wuld, f curse, be the mst cnvenient methd during cean fishing. Fresh water, hwever, is the mst practical when the cntainers are t be filled n land, r fr fishing in unclean waters. In the studies these tw alternatives were cmpared t regular bx strage. Three parallel methds were als used: Cntainers chilled with ice + sea water (CSW - chilled sea water). II Cntainers chilled with ice + fresh water (CFW - chilled fresh water). III Bxes with ice (here called ICB - ice-chilled bx). 3. Experiments Figure 1 shws the nrmal treatment f the main prtins, while Figure shws analyses perfrmed n test pieces. The wrk includes fur full series, as shwn, plus additinal test series, mst f them cncentrated n refrigerating capacity. The studies can be divided int three main areas, as shwn by the figure: a Temperature cnditins during strage b Weight yield frm catch t cnsumer-ready prduct.9_ Quality f the fillet prduct

23 7. CATCH GUTTING AND DEHEkDING TEMPERATURE I MEASUREMENTS [WEIGHING [FRESH WATER WEIGHING [ ICE + SEA WATER ICE WEIGHING STORAGE cntainers 3,6 1 9 and 1 days kg per batch TEMPERATURE MEASUREMENTS STORAGE _ - cntainers 3,6,9 and 1 days kg per batch TEMPERATURE MEASUREMENTE STORAGE [ small bx s 3,6,9 and 1 days k per batch I WEIGH/ING!WEIGHING WEIGHING FILLETING Baader 189 SKINNING Baader 47 EAR BONES SPINE SKIN FILLETING Baader 189 SKINNING Baader 47 FI TING Baader 18 SKINNING Baader 47 WEIGHING PACKING UT-OFF 1"44THICK BO ZING Flatfrze IGHING SAMPLES _ - Abut 50 kg/batch SALE Figure 1 Diagram f treatment f main parts. In additin, mre spradic measurements were taken, e.g. measurements f bacteria befre and after...* * Transi. nte: Line(s) cut ff during phtcpying. Cmplete cpy f riginal nt made available t me.

24 8. (3) SAMPLES Abut 50 kg/batch THAWING AND COOKING TESTS weighed thawed weighed cked evaprated Vweighed TASTE TEST ANALYSES - NO TEST METHODS IN COMBINATION: A TRIANGLE TEST B SCORE EVALUATION RANKING TEST with the aid f tw-way analysis. - THREE INDEPENDENT TEST PANELS - ABOUT 15 JUDGES IN EACH PANEL - TWO TEST ROUNDS CHEMICAL ANALYSES - ANALYSES FOR: A TOT. VOLATILE N B TMA C TMAO D HYPDXANTHINE E SALT Figure Analyses perfrmed n samples frm the test batches. men. Figure 3* Lcatin f thermelements n fiberglass cntainer. In sme tests, as many as 17 thermelements were placed n the centre rd. * Transi. nte: Text n figure unreadable n my phtcpy.

25 9. The cntainers In the first tw series, cmmercial brand cntainers were used fr the strage/transprt tests. Hwever, these mdels d nt have thermal insulatin and their design made them smewhat unsuitable fr use n bats. Specially built cntainers 1* were therefre used fr the remaining test series. Tw versins f these were built: One was made f fiberglass-reinfrced plastic, the ther f aluminum. The cntainers had duble walls with.5-3 cm f plyurethane in between. If a cntainer is t be suitable in a variety f situatins, insulatin becmes almst a necessity, bviusly mre s the higher the rm temperature is and the slwer the water circulatin in the cntainer. Figure 3 shws a sketch f the fiberglass cntainer and where the thermelements fr the temperature measurements were placed. This was the mst used and best insulated cntainer type. It turned ut, hwever, that all the cntainers that were f an experimental design, had defects in the frm f thermal bridges, which reduced their insulatin prperties. The fiberglass cntainers had a high cld penetratin in the bttm arund the legs, and als arund the drainage utlet. 1* Transl. nte: This nte, which must appear n the riginal, was cut ff during phtcpying, see my nte n page 7.

26 Temperature cnditins during strage The quality level f fish after a given strage time is nrmally determined mainly by hw the temperature fluctuates. The temperature respnse that is cnsidered as mst favurable, is ne where chilling is as rapid as pssible, fllwed by strage at the temperature where freezing begins (the freezing pint). The chilling time is determined by the temperature at time f lading and the refrigerating capacity. The highest refrigerating capacity wuld prbably be achieved if the fish were surrunded by a refrigerant with an unlimited heat absrptin capacity. In such a case, the temperature respnse wuld be determined nly by the thermal cnductin in the fish bdy. It wuld be pssible t cme clse t this theretical ptimum cnditin, if each fish was packed in finely crushed, drained ice, prvided that its entire surface was in cntact with the ice. Figures 4 A and B shw measurements frm the chilling f tw 4 kg fishes in ice (A) and in ice + fresh water (ice-water, B). Figure A shws that during icing, an insulating layer f air was quickly frmed abve the fish. The chilling prcess in the centre f the fish, hwever, was fairlysimilar in the tw tests, the half-time fr chilling (the time it tk t reduce the temperature difference between fish and ice by half) was a little less than ne hur. The "0" curve in Figure B shws the calculated temperature respnse

27 k IIM A IIIIMI c" dm «IIIIIIIIIIII Figures 4 A and B Temperature as a functin A - packed in drained ice B - chilled in :ice + water Gutted and deheaded Weight f each fish: 4. kg f strage time in tw similar fishes (cd). Width and thickness f largest part f fish, as shwn in the figure. Circumference: 40 cm, length: 70 cm. Measuringnpints: 1 - at the spine - just belw the skin 3 - n the skin 4 - abut 5 mm abve the fish Curve "0" in Figure B shws calculated temperature respnse at centre f a cylinder with a 10 cm diameter. Instantaneus external chilling t 00C. Thermal diffusivity : 4.7 x 1O. Calculated accrding t (9). at the centre f a cylinder with a diameter similar t the width f the fishes (10 cm), when it was chilled instantaneusly n the utside t 0 C. The curve cnfirms that it is primarily the internal thermal cnductin that determines the chilling time in bth A and B

28 1. A refrigerating capacity similar t the ne shwn in Figure 4 can be achieved with a cntainer system, if, fr example, plenty f ice is evenly distributed in the lad. A system where the ice is finely distributed can als be useful in practice, especially if bats and transprt stages are planned frm the beginning. Hwever, in cases where the transprt system has t be develped t suit presently cmmn bat interirs, being able t cncentrate the ice mre, wuld mean easier and/r less heavy wrk. The mst cnvenient system wuld be ne where all the ice culd be placed under the fish. The ice culd then be filled int the cntainers when they are laded n bard. What level f the ideal prcess wuld be acceptable in practice, will have t be determined by balancing practical/ecnmical cnsideratins against lsses in quality. The cnclusins drawn further n are based n such evaluatins which are, f curse, fairly arbitrary. The thermal cnductivity f fish (and water) is pr, in the rder f 0.5 W/mK. Therefre, in rder t increase the heat transfer distances (the distance between ice layers), cling must be ensured thrugh cnvectin in the water. Cnvectin can be brught abut by: a Differences in the specific weight f the water as a result f temperature r salt gradients (gravity flw), supplemented by: 1 pumping r agitatin.

29 13. (5) The study shwed that when circulatin is prduced nly thrugh gravity flw, the recmmended distance between ice layers becmes very limited. Figures 5 and 6 shw temperature measurements in CSW and CFW, respectively, where the ice was placed in three layers separated by a distance f cm. Althugh the effects n the temperature respnse f all cnceivable parameters have nt been calculated, the cnclusin drawn was still that the greatest permitted distance between ice layers, at nrmal starting temperatures, wuld be apprximately as shwn in the figures. On a bat, the mtin f the sea results in increased agitatin. In all the n bard tests, the entire ice quantity was placed belw the lad, which had a height f abut 1 m. In ne case, the measurements shwn in Figure 7, refrigeratin was smewhat slwer due t particularly calm seas. Therefre, circulatin was increased by blwing air int the bttm f the cntainers, immediately int the fresh water cntainer, and after abut 0 hurs int the sea water cntainer. This system wrked efficiently, even thugh the equipment used was f the mst basic kind. Additinal ice cnsumptin was als minimal, estimated t abut 0.5 kg/4 hurs. The mvements n a bat are usually cmpsed f many elements, frm lng, pitching mvements t engine vibratins. The mst imprtant element, hwever, is * * width in meters and a deflectin f (6) In rder t measure the effects f rlling under cntrllable cnditins, a simple cradle was cnstructed. It swang the cntainers harmnically arund the centre f gravity with adjustable deflectin and frequency. * Transi. nte: Line cut ff in phtcpying?

30 ,. 1,33 1 H, in 10 O. 0, Is ICE '4,-. _ -- - IN 0h F kf eh eleillie 1 Is Ice \ 14jell 'ref Oh 0 il I s * f 0-0 Fisk FLsh 1 is Ice 10 C H ,8 0,6 0,4 0, >ee"pe _."4-eemeimigliglill tsk F EMU is lclkisial-li fisk 1 ift friall tp is lc... 8 IC 1 t ish ish Figure 5 Temperature prfile f the height in the cntainer at indicated hurs after test start, CSW. Ice distributin at start, as described; distance between ice layers abut 30 cm at the bttm and 4 cm at the tp. Salinity f water when laded: 3.4 % Starting temperature f sample fish/ water/ice in C: 11/6/-15. Laded quantities f fish/water/ice in kg: 440/170/60 Number f measuring pints: 18. Figure 6 Temperature prfile f the height in the cntainer at indicated hurs after test start, CFW. Measuring pints: 18, vertical centre f fiberglass cntainer. Temperature n lading f fish/water/ice in C: 18/7/-15 Ambient temp.: Abut 0 C Laded quantities f sample fish/water/ice in kg: 400/80/165. Ice distributin at start, apprximately as indicated in the Figure.

31 . c ulttem. Air temp " Ved bunnin At bttm cm. ver bunnen 60 cm a, ve bttml... 10cm ver bunren 1 ve bttm C - 'c I Sjvnnikjett. $entrum cntant* Mg MIZZIMBI t f cntainer( t sidp 0 4.C fg. Kt Time.\ WM illn. _..,.. Ferskvnnskjett. sentrum cntainer 4/8 30/ 8 VII lig Ill / g I e f cnamer rt side Figure 7. Temperature measurements frm series n. 4, n trawlers. ) Frced water circulatin with the aid f air injectin. Injectin started immediately in CFW, after abut 15 hurs in CSW. Mre ice was gradually added during strage.

32 16. Figures 8 and 9 shw tests where the cntainers were swung at a frequency f 6 min. width f a fresh fish trawler is apprximately 10 m) and a deflectin f 10. Even thugh, als in this case, there are many factrs that may effect the temperature respnse, the amunt f mvement necessary seems t be f this magnitude bth fr CSW and CFW. Due t variatins in water density with temperature and salinity, it is always imprtant that the ice remain belw the fish. T ensure this, fish can be laded befre water, r a grating r similar device culd be used. In the reference methd, bxes with ice, the temperature respnse varied greatly, frm relatively gd cnditins when the wrk was carried ut carefully, t cmpletely unacceptable cnditins. The pen and uninsulated bxes were als very sensitive t the air temperature, Figure Weight yield frm catch t cnsumer-readyr du c Figures 1 and shwed the prcedure fr the yield measurements. Figures represent the test results frm fur f the prcessing stages. In Figures 1-14, the unfilled markings represent studies where apprentices did the final trimming and packing. After trimming, these studies resulted in lwer weight than the thers, where the cnditins were cmpletely realistic (perfrmed in regular prductin lines).

33 17. The main cnclusin is that the fish increases in weight when stred in water. The weight increase is the highest in CFW, and can be significant alreay after a few days, Figure 11. The water that is absrbed, hwever, is nly lsely bund, s that the differences in relatin t the laded quantity becme smaller with each prcessing stage, Figure 15.

34 18. ( 7 ) 1,33 1, H. ifimr 1, ,6 A ma 10 _ x. re 1.m 1,33 1, H , ,4 0, / *:',.% % , 0 0 i L II?, h C10 O "C 14 Figure 8. Chilling f cal fish caught with lines: CFW. The inserted diagram shws measurements frm ne individual fish placed abut 15 cm belw the surface, weight 4.1 kg. Starting temp.: Fish/Water/ice in kg: 9/14/-. Ambient temp.: Abut 14 C. Quantities f fish/water/ice in kg: 480/155/190. Height after lading: Abut 50 cm. Rlling mtin in "wave simulatr", - frequency/deflectin: 6 min 1 /10. Figure 9. Temperature prfile f the height in the cntainer at indicated hurs after test start, CF. Rlling mtin, frequency/aeflectin: -1 6 min /10. Starting temp.: Fish/water/ice in 15/1/-0. Quantities f laded fish/water/ice in kg: 490/170/154. Height abve the bttm at start: Abut 57cr Ambient temp.: Abut 0 C.

35 19. (8) * O E 1 cd L. à. iezr- T 1 - : kil, al..,.. %am«. mm me r Hurs IL ** 11 %r I 10 r-i 0 s. r1 e : 4 5 s de i I I I a Sjr nn it (CSW) - - Fer skvrtn is (CF11) - -- Is i kesser (ICS)._ j,..../...,e4 e - 9 ye Days stred j #.-re: d "It e b' Dgn lgr et. q Figure 10. Figure 11. Temperature measurements in fish stred in bxes with ice in an unrefrigerated raw material hld. The ice was laded in the manner it is nrmally dne in reality: One layer belw the fish and ne abve. The fish becmes expsed alng the side very quickly. Weight increase as a functin f strage time. The yield is calculated in relatin t the recrded weight f gutted and deheaded raw material. Lcatin f measuring pints, 4 bxes in all: 1- In a bx at the tp, lse by side edge - In a large fish (5.5 kg) placed by side edge 3- At centre f bx, lse against the wall 4- By the shrt side, lse against wall 5- As 4, ppsite side, lse against wall 6- By the lng side, lse against wall These measurements were perfrmed apart frm the regular test batches.

36 0. (9) 10 Sl a).0 '" 90 >4 s TD- - ta B I e A -Lgret Stred s rile t ert Filleted C RenskrDret, pkket g fr sset D - Tint, kkt g vdmpet Thawec, lk and e pr ate Days stred Dgn lgret H 0 >4 immed, packed d frzen 11 0 'e g ,-...._ f g-...4 r4. ^ ic_i ,- B t C p all :. 0 e 0 A - L gr et Stred B-Fileert Filleted C - Rensk;ret. pa k k et g frsset - Tint. kkt g vdrnpet =awed, cked and evaprated 4 6 Days stred Drin lgr et Trimmed, packed and frzen Figure 1. Figure 13. Yield as a functin f strage time fr fish stred in sea water - ice (CSW). Yield in relatin t gutted and deheaded raw material. Unfilled markings - apprentices trimmed these batches. Yield as a functin f strage time fr fish stred in icechilled fresh water (CFW). Yield in relatin t gutted and deheaded raw material. Unfilled markings - apprentices trimmed these batches.

37 1. >, ri P-1 D se c e - f «... 1 *A _I._ pi il f,... 1 _., D A -Lgret Stred B -Filetert Filleted C Renskrpret, pkket g frssed immed, packed D - Tint, kkt g vdrnpet and frzen awed clked and prated Days stred Dtign lgret I e D I I g. Sjevnn is S a zte + ice : Ferskvrm is eh w:ter + ice Ksser tri. is th ice 70 " ] 0 0 _ A- Lgret Stred' B- Fileter! Filleted C - Renski;ret. pkket g i mmed,packed e frsset & frzen D - Tint. kkt g vdmpet.i. de wed, cked & -vaprated B Days stred Dn twel Figure 14. Yield as a functin f strage time fr fish stred in bxes with ice (ICB). Yield in relatin t gutted and* Figure 15. Cmparisn f the curves shwn in Figures * Transl. nte: Lines cut ff during phtcpying

38 . (10) 6. The quality f the fillet prduct Taste test analyses The principal attempt t determine the quality f the fillet prduct invlved taste testing by a test panel. Extensive effrts were made in rder t be able t demnstrate, with the highest degree f certainty, any pssible differences in quality resulting frm the three strage methds. With the help f three independent panels f judges, each cnsisting f persns, samples frm each test batch were tasted and judged apprximately 40 times. The analyses were perfrmed thrugh a cmbinatin f a triangle test and allcatin f pints accrding t a character scale. The scres were used bth t make a simple cmparisn f the mean values, and as a basis fr differential tests (the s-called Tukey's ranking test). This cmparisn f tw different differential tests (the triangle test and Tukey's test) was desirable partly because pssible differences in quality within each test batch culd jepardize the analyses. Fr a mre detailed discussin f the tests and the statistical methds used, we refer t reference materials 1 and 3. We will here nly mentin the main results. Table shws the results f the differential tests fr ne f the test series (series 3). In this series, the tests prduced ne f the mst clear-cut results: Fresh water fish (CFW) is fairly

39 3. systematically separated frm CSW and ICB after 9 days' strage (in particular by panel n. 1). Strage time Days Panel N 1 Rank. t. R Un d n. 1 Triangle t. Rund 1 n. Panel N. Rank. t. Run d n. 11 Triangle t. Rund 1 n. Panel N. 3 Rank. t. Tri ang le t. Run d n. Rôund 1 1 il n. 3 A/C A/C B/C B/C 6 A/B A/B A/C A/B B/C B/C A/B A/B A/B A/B A/B A/B 9 A/C A/C B/C B/C B/C B/C B/C B/C A/C A/B 1 A/C A/C B/C B/C B/C Table. Significance frm differential tests. (ranking test and triangle test). Test series n. 3 A - fish stred in sea water 4 ice (CSW) B - fish stred in fresh water 4. ice (CFW) C - fish stred in bxes with ice (ICB) Three independent test panels, 10 judges in panel n.. 15 judges in the ther tw. Tw test runds with fillet, frzen and then cked. Level f significance: 5 % The markings shw the tests where the types f fish were significantly different.

40 4. (11) Figure 16 shws mean characters frm the same panel f judges and the same series as a functin f strage time. Figures 17 and 18 shw the results f tw ther test series (series 1 and 4). The first thing we ntice is that the change in quality in relatin t strage time des nt stand ut clearly, but then, f curse, the emphasis was n a cmparisn between the three strage methds after equal strage times. The scale was als perceived differently by the panels f judges, in particular by panel n. 3, see Figure L7 6 t D Sjavnn is Seaufatea e. Fersk nn is sh we --- ts i kiser ICe in b] i -----"- A + ice ter + 'ice es 10 4.) a «7 Um 6 %. NI, _ le:::::\ N..,. 3 n Dign lgre1 Days stred Figure 16. Characters frm taste tests f frzen and then cked fillet as a functin f the strage time f the raw material. Mean characters frm panel n. 1 in test series 3. Cmparisns between the three different strage methds. sjeynn is S pa wat er+ice ferskvnn is -.$8.11- water+ice is i ksser Ice ir bxes I I I g n tgret Days stred Figure 17. Characters frm taste tests f frzen and then cked fillet as a functin f the strage time f the raw material. Test series n. 1, panel n. 1.

41 , 5. -p a c) td â 7 4:1 6 Panel I -- SplIVOnfl is Ferskvnn *is" Is i ksser Pne' i Sea water + ice Fresh water + ice Ice in bxes Pnet :...,.._ nr,1 ---; , ?6 9 1 Dgn 'egret Days stred 1 Figure 18. Characters frm taste test f frzen and then cked fillet as a functin f the strage time f the raw material. Test series n. 4. * The main cnclusin after the taste tests is that the differences (1) in quality were generally small; the differences were particularly small befre 8-9 days, which must be cnsidered the lngest acceptable strage time fr high quality raw material. The general tendency seen in the scring results is that sea-water stred fish ften gets the highest scre, while the fresh-water stred ften gets the lwest. Hwever, as will be shwn later, the chemical analyses d nt supprt the dwngrading f the CFW fish. Neither were these fillets fund t have a bad taste - the cmments made were rather abut a lack f taste, a certain tastelessness. * Transl. nte: Line(s) cut ff in phtcpying.

42 6. The tendency fr the CSW fish t btain the highest scre was fairly general within the 8-9 days mentined. In tw f the series (series and 3), this tendency persisted after the lngest strage times, 10 and 1 days, respectively. Hwever, in the ther tw series (series 1 and 4), it was the sea-water fish that had lst mst in quality at the end f the test perid, 11 and 1 days. Even if it is pssible t demnstrate particular cnnectins between cause and effect (such as lacking r unsatisfactry insulatin), the final impressin remains that strage in sea water, beynd the mentined 9 days, is nt advisable. If the quality lsses during the freezing stages are als taken int cnsideratin, it appears that ne week is a reasnable upper limit fr the strage time, regardless f the refrigeratin methd. In series 1, the taste tests were als perfrmed after ne year f freezer strage. At that pint, n systematical quality differences culd be fund. Chemical measurements The value f chemical quality measurements is, naturally, entirely dependent n the relatinship between the chsen criterin and the verall quality level f the prduct. In these studies, the (13) measurements were cncentrated n the mst cmmn criterin: The decmpsitin f vlatile nitrgen. Figure 19 shws, as an example, a cmparisn f measured cntents f trimethylamine (TMA), as a