Merki: Geymsluþol

Skýrslur

Þróun gæðastuðulsaðferðar og geymsluþol á þíddum makríl (Scomber scombrus) / Development of Quality Index Method and storage life of thawed mackerel (Scomber scombrus)

Útgefið:

01/07/2010

Höfundar:

Kolbrún Sveinsdóttir, Patricia Miranda Alfama, Aðalheiður Ólafsdóttir, Emilía Martinsdóttir

Styrkt af:

AVS rannsóknasjóður í sjávarútvegi, UNU Sjávarútvegsskóli Háskóla Sameinuðu þjóðanna

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

Þróun gæðastuðulsaðferðar og geymsluþol á þíddum makríl (Scomber scombrus) / Development of Quality Index Method and storage life of thawed mackerel (Scomber scombrus)

QIM aðferðin (Quality Index Method) er hlutlæg, fljótleg og áreiðanleg skynmatsaðferð sem þróuð hefur verið til að meta ferskleika fisks. Markmið rannsóknarinnar var að útbúa QIM einkunnaskala fyrir þíddan makríl (Scomber scombrus) sem geymdur var í ís við 0°C og prófa notkun hans í geymsluþolstilraun. Makríllinn var metinn með skynmati eftir QIM og DA aðferð (generic descriptive analysis), einnig voru taldar örverur (TVC og H2S myndandi) og mælt histamín í allt að 9 daga frá uppþíðingu. Niðurstaða rannsóknarinnar var QIM aðferðin fyrir þíddan makríl sem var þróuð og prófuð í geymsluþolsrannsókn. Gæðastuðull – QI (heildarsumma einkunna) jókst línulega með geymslutíma á ís. QIM aðferðin fyrir þíddan makríl byggir á mati á gæðaþáttum einsog útliti á roði, áferð, lit og formi augna, lit og lykt tálkna, útlit slíms í tálknum og tálknblaða og upplausn innyfla og getur heildarsumma fisksins orðið 19 að hámarki. Í verkefninu var einnig þróuð aðferð (general descriptive analysis-DA) til að meta soðinn makríl. Helstu einkenni makrílsins strax eftir þíðingu var lykt og bragð af ferskri olíu, málmlykt og sæt lykt/bragð sem dofnaði heldur með geymslutímanum. Það sem takmarkaði geymsluþolið voru skynrænir eiginleikar sem lýsa skemmdareinkennum, einsog þráalykt og –bragð sem getur verið áberandi í feitum fiski eftir lengri frystigeymslu. Samkvæmt skynmati á soðnum makrílflökum er geymsluþol þídds makríls eftir fimm mánaða frystigeymslu um 4-6 dagar. Heildarfjöldi örvera og H2S myndandi örvera var minni en yfirleitt sést við lok geymsluþols af völdum örvera. Histamín mældist ekki (< 5 ppm) í þíddum makríl á geymslutímanum sem var 9 dagar á ís.

The Quality Index Method (QIM) is an objective, rapid and reliable sensory method. The aim of the present study was to develop a QIM scheme for frozenthawed Atlantic mackerel (Scomber scombrus) stored in ice at 0°C and evaluate the scheme in a shelf life study. The mackerel was evaluated with sensory evaluation (QIM and generic descriptive analysis (DA)), microbial counts (Total viable counts (TVC) and H2S-producing bacteria) were estimated and histamine measured for up to nine days. The main result of this study vas the QIM scheme to evaluate freshness of frozen-thawed Atlantic mackerel storage in ice which was developed and tested in a shelf life study. The quality index – QI (sum of scores) increased linearly with storage time on ice. The QIM for thawed mackerel is based on the evaluation of quality parameters dealing with the appearance on back and belly side, texture, colour and form of eyes, mucus, colour and odour of gills and appearance of gill filaments and dissolution of viscera. The maximum sum of scores (QI) can be 19. A method to evaluate cooked mackerel was also developed (general descriptive analysis-DA). Newly thawed mackerel had fresh oil, metallic and sweet odours and flavours. The main limitation of length of shelf life in chilled storage after thawing were sensory characteristics describing spoilage such as rancid odour and flavour which can be prominent in fatty fish species after extended frozen storage. According to sensory evaluation of cooked mackerel, the shelf life of thawed mackerel after five months of frozen storage is around 4-6 days. Counts of TVC and H2S producing bacteria were relatively low at the end of shelf life. Histamine was not detected (< 5 ppm) in the thawed mackerel during the storage time of nine days on ice.

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Skýrslur

Geymsluþol reyktra síldarflaka í lofttæmdum umbúðum / Shelf life of vacuum‐packed smoked herring fillets

Útgefið:

01/06/2010

Höfundar:

Franklín Georgsson, Margeir Gissurarson

Styrkt af:

AVS rannsóknasjóður í sjávarútvegi

Geymsluþol reyktra síldarflaka í lofttæmdum umbúðum / Shelf life of vacuum‐packed smoked herring fillets

Markmið rannsóknarinnar var að kanna geymsluþol reyktra síldarflaka í lofttæmdum umbúðum og athuga hvaða áhrif það hefur á geymsluþol vörunnar ef rotvarnarefni er ekki notað sem og ef sorbat er notað í stað bensóats, sem notað er í hefðbundinni framleiðslu. Í þessari rannsókn kom fram að notkun rotvarnarefna hefur veruleg áhrif á lengd geymsluþols reyktra síldarflaka. Jafnframt kom fram að sorbat meðhöndlun síldarflaka veitti bestu rotvörn gegn örveruvexti og einnig reyndist sorbat meðhöndlun síldarflaka koma best út í óformlegu skynmati. Hvort þetta stafar af hindrun sorbatsins á örveruvöxt eða að það dragi úr hraða efna‐  og eðlisfræðilegra niðurbrotsþátta í samanburði við síldarflök með bensóati eða án rotvarnarefna þarfnast frekari rannsókna.

The object of this project was to evaluate the shelf life of vacuum packed smoked herring fillets and to evaluate whether the use of the preservatives benzoate or sorbate had any effect on the shelf life of the product Results showed that treatment of the smoked herring fillets with preservatives greatly affected the shelf life and that sorbate treatment of the herring fillets provided the best defence for bacteria growth and also gave best results in an informal sensory testing during the shelf life study. Whether this is due to inhibitory role of sorbate on bacteria growth or that sorbate slows down chemical and physical degradation in comparison to herring fillets with benzoate or without any preservatives needs further investigation.  

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The effect of cooling methods at processing and use of gel-packs on storage life of cod (Gadus morhua) loins – Effect of transport via air and sea on temperature control and retail-packaging on cod deterioration

Útgefið:

01/05/2010

Höfundar:

Emilía Martinsdóttir, Hélène L. Lauzon, Björn Margeirsson, Kolbrún Sveinsdóttir, Lárus Þorvaldsson, Hannes Magnússon, Eyjólfur Reynisson, Arna Vigdís Jónsdóttir, Sigurjón Arason, Maria Eden

Styrkt af:

EU (contract FP6-016333-2) Chill-on, AVS, R&D Fund of Ministry of Fisheries in Iceland, the Technology Development Fund at the Icelandic Centre for Research

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

The effect of cooling methods at processing and use of gel-packs on storage life of cod (Gadus morhua) loins – Effect of transport via air and sea on temperature control and retail-packaging on cod deterioration

Tilgangur tilraunanna var að kanna áhrif mismunandi kælingar við vinnslu og hitasveiflna í flutningi með og án kælimottu á geymsluþol þorskhnakka. Í vinnslu var borið saman að nota enga forkælingu fyrir flökun, vökvakælingu og roðkælingu (CBC) sem alltaf er með vökvakælingu. Áhrif hitasveiflna þar sem líkt var eftir í hitabreytingum í flutningi (RTS) voru borin saman við geymslu við stöðugt hitastig (-1 °C). Einnig voru metin áhrif þess að nota kælimottu í geymslu og flutningi. Sýni voru gæðametin með skynmati, örveru- og efnamælingum. Fylgst var með hitastigi með hitasíritum. Roðkældir þorskhnakkar í frauðplastkössum voru fluttir til Bremerhaven með flugi og skipi þar sem þeim var endurpakkað í loft og loftskiptar pakkningar (MAP) og þær geymdar við 1 °C. Gerðar voru efna- og örverumælingar til að fylgjast með gæðabreytingum. Hitastig roðkældra hnakka var lægra en hinna fyrstu 2 daga tilraunarinnar. Kælimotturnar höfðu ákveðin áhrif til lækkunar hitastigs þegar hitasveiflur voru í ferlinu og lægri hiti hélst gegnum allan geymslutímann. Samt sem áður hafði notkunin ekki áhrif á lengd ferskleikatíma eða geymsluþols samkvæmt skynmati. Örverufjöldi var heldur lægri ef hitasveiflur urðu í ferlinum en lítill munur var við stöðugt hitastig. Geymsla við stöðugt, lágt hitastig (-1 °C) lengdi geymsluþol um ca. 3 daga samkvæmt skynmati og var það í samræmi við örverutalningar og mælingar á TVB-N og TMA. Í tilraunum í Bremerhaven kom fram að örverufjöldi var yfirleitt lægri þegar notaðar voru loftskiptar umbúðir í samanburði við fisk í lofti. Þetta var sérstaklega áberandi í flugfiskinum. Fiskurinn sem fluttur var með skipi geymdist samt jafn lengi og fiskurinn sem fluttur var með flugi. Þetta orsakast af því að flugfiskurinn varð fyrir meiri hitasveiflum í flutningi og yfirborðshiti hans mældist 4 °C við komuna til Bremerhaven. Flutningstími með skipi var miklu lengri (+48 klst) en yfirborðshiti mældist undir 2 °C við móttöku. Notkun kælimotta hafði lítil áhrif á hitastigið í flutningi en samt sem áður var yfirborðshiti aðeins lægri í fiski með kælimottum við komuna til Bremerhaven bæði með flugi og skipi.

The main aim of the experiment was to investigate the effects of different cooling techniques during processing and temperature fluctuations during transport on the storage life of cod loins with and without gel packs. The following cooling techniques were studied: combined blast and contact (CBC) cooling (with liquid cooling prior to the CBC cooling), only liquid cooling and where no special cooling was used prior to deskinning and trimming. The effect of real temperature simulation (RTS) during storage was compared to a steady storage temperature of -1 °C. The samples were analysed with sensory, microbial and chemical methods. The temperature was monitored from packaging using temperature loggers. CBC cooled loins were transported to Bremerhaven via air and ship freight after packaging in EPS boxes. The fish was repacked in air and modified atmosphere and stored at 1 °C. Deteriorative changes were evaluated by microbial and chemical indicators. CBC cooling resulted in a lower temperature profile the first two days of the experiment. The use of gel packs lowered somewhat the temperature increase in the products when RTS was applied and lower temperature was maintained during the entire storage period. According to sensory evaluation, the use of gel packs did not result in prolonged freshness period or shelf life. According to microbial and chemical analysis no marked difference was seen whether gel packs were used or not in groups stored at a steady temperature. However, microbial counts were somewhat lower and slower formation of TVB-N and TMA occurred in RTS groups where gel packs were used compared to no gel packs. Storage at a steady -1 °C resulted in prolonged shelf life of three days according to sensory evaluation. This was confirmed by microbial and chemical analysis as lower microbial counts, TVB-N and TMA values were generally obtained in the steady temperature group than in the group receiving the RTS treatment. The storage studies carried out at Bremerhaven on modified atmosphere vs. air packed loins showed generally lower microbial counts, especially in the air transported fish. Deterioration process of air and sea freight fish was however similar. Re-packaging of sea freight fish at a later stage did not significantly affect its deteriorative process compared to re-packed air freight fish. This might be due to the fact, that the air freight fish was subject to high temperatures during transport and surface temperature reached over 4 °C. The sea freight fish had a much longer transport phase, but arrived with surface temperatures below 2° C. This shows that not only the time of re-packaging but also the temperature profile during transport are important factors influencing the deteriorative process and shelf life. Gel packs did not have significant cooling effect in this experiment. However the surface temperature in boxes with a gel pack was slightly lower than in boxes without a gel pack independently of transport mode used.

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Skýrslur

SSS PREDICTION Námskeið / SSS PREDICTION WORKSHOP

Útgefið:

29/04/2010

Höfundar:

Paw Dalgaard, Anna Kristín Daníelsdóttir, Steinar B. Aðalbjörnsson

Tengiliður

Anna Kristín Daníelsdóttir

Aðstoðarforstjóri / Rannsókna- og nýsköpunarstjóri

annak@matis.is

SSS PREDICTION Námskeið / SSS PREDICTION WORKSHOP

Námskeið í notkun á spáforritum í sjávarútvegi: SSS (Seafood Spoilage and Safety) Prediction version 3.1 2009 (http://sssp.dtuaqua.dk/), Combase (www.combase.cc) and Pathogen Modeling forrit (http://pmp.arserrc.gov/PMPOnline.aspx). Kennari er Dr. Paw Dalgaard frá Tækniháskólanum í Danmörku (DTU) og fer kennslan fram á ensku. Forritið nýtist vísindamönnum, yfirvöldum og iðnaði í sjávarútvegi.

Workshop on the practical use of computer software to manage seafood quality and safety. It includes presentations and hands-on computer exercises to demonstrate how available software can be used by industry, authorities and scientists within the seafood sector. Examples with fresh fish, shellfish and ready-to-eat seafood (smoked and marinated products) are included in the workshop. Special attention is given to: (i) the effect of storage temperature and modified atmosphere packing on shelf-life and (ii) management of Listeria monocytogens according to existing EU regulations (EC 2073/2005 and EC 1441/2007) and new guidelines from the Codex Alimentarius Commission. The presentations included in the workshop are given in English by Paw Dalgaard from the Technical University of Denmark. Participants will use their own laptop computers for the PC-exercises included in the workshop. Instruction for download of freeware will be mailed to the participants prior to the start of the workshop.

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The effect of different precooling media during processing and cooling techniques during packaging of cod (Gadus morhua) fillets

Útgefið:

01/04/2010

Höfundar:

Björn Margeirsson, Hannes Magnússon, Kolbrún Sveinsdóttir, Kristín Líf Valtýsdóttir, Eyjólfur Reynisson, Sigurjón Arason

Styrkt af:

AVS Fund of Ministry of Fisheries in Iceland, The Technology Development Fund at the Icelandic Centre for Research, University of Iceland Research Fund

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

The effect of different precooling media during processing and cooling techniques during packaging of cod (Gadus morhua) fillets

Tilgangur tilraunanna var að kanna áhrif mismunandi kælimiðla við forkælingu fyrir pökkun á hitastýringu, gæði og geymsluþol þorskflaka. Eftirfarandi kælimiðlar voru kannaðir og bornir saman við enga sérstaka forkælingu fyrir pökkun:

  1. pækill með lágu saltinnihaldi, 2) krapaís með lágu saltinnihaldi.

Auk þess voru könnuð áhrif þess að nota annars vegar ísmottur og hins vegar þurrís við geymslu flakanna. Fylgst var með breytingum á hitastigi með hitanemum á öllum stigum. Sýni voru gæðametin með skynmati, örveru- og efnamælingum í allt að 13 daga frá vinnslu og pökkun (16 daga frá veiði). Flökin voru geymd við ofurkældar aðstæður (undir 0 °C) mestan hluta geymslutímans. Lægra hitastig krapaíss en pækils leiddi til lægra hitastigs flaka við pökkun auk þess sem hiti vökvapækilsins reyndist hækka hratt þegar hlé var gert á vinnslu. Mismunandi meðhöndlun leiddi til sambærilegs ferskleikatíma samkvæmt skynmati. Hins vegar reyndist notkun vökvapækils við forkælingu fyrir pökkun leiða til 1 – 2 daga skemmra geymsluþols samanborið við enga forkælingu eða forkælingu með krapaís. Rekja má ástæður þessa til þess að pækillinn innihélt töluvert magn örvera, m.a. H2S-myndandi gerla sem eru virkir framleiðendur á trímetýlamíni (TMA). Samanburður á vökvakældu flökunum sýndi að notkun á þurrís lengdi geymsluþol um 1 dag í samanburði við ísmottur. Niðurstöður örveru- og efnamælinga voru í samræmi við þessar niðurstöður.

The aim of the experiment was to investigate effects of two cooling media during precooling at processing on temperature control, quality and storage life of cod fillets. The two cooling media compared to no special precooling during processing (NC) were: 1) liquid brine (LC) and 2) slurry ice (SIC). In addition, the influence of using either dry ice or ice packs during storage was studied. The samples were kept at superchilled conditions during most of the trial. The environmental and product temperature history of each group was studied using temperature monitors. The samples were analysed with sensory evaluation, microbial and chemical methods for up to sixteen days from catch (thirteen days from processing). Lower temperature of the slurry ice than the liquid brine resulted in lower fillet temperature at packaging and the liquid brine temperature increased rapidly during a processing break, which seems to be a weakness of the liquid brine tank. Results from sensory, microbial and chemical analysis all showed that immersing the skinless cod fillets in liquid cooling brine prior to packaging resulted in one to two days reduction of shelf life in comparison with fillets that were not immersed in liquid brine (no cooling) or in slurry ice. This could be attributed to the fact that the cooling brine carried considerable amounts of microbes including H2Sproducing bacteria which are active producers of trimethylamine (TMA). Comparison of the groups receiving liquid cooling showed that dry ice appeared to extend the shelf life of one day as compared to ice packs. The length of the freshness period was, however, similar in all experimental groups according to sensory evaluation. These results were confirmed by total volatile bases (TVB-N) and TMA analysis and microbial counts.

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Optimal storage conditions for fresh farmed tilapia (Oreochromis niloticus) fillets

Útgefið:

01/12/2009

Höfundar:

Emilía Martinsdóttir, Cyprian Ogombe Odoli, Hélène L. Lauzon, Kolbrún Sveinsdóttir, Hannes Magnússon, Sigurjón Arason, Ragnar Jóhannsson

Styrkt af:

Tækniþróunarsjóður

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

Optimal storage conditions for fresh farmed tilapia (Oreochromis niloticus) fillets

Tilgangur tilraunanna var að finna bestu geymsluaðstæður fyrir fersk tilapíuflök með því að ákveða geymsluþol með skynmati, örverutalningum og eðlis- og efnafræðilegum mælingum. Nílartilapía (Oreochromis niloticus) alin í endurnýtanlegu vatnshringrásarkerfi var flökuð og pökkuð í 100% lofti og loftskiptum pakkningum 50% CO2: 50% N2 MA fyrir geymslu við 1˚C og -1˚C. Lýst er þróun QIM-einkunnaskala og skynmatseiginleikum ferskra og soðinna tilapíuflaka og notkun skalans í geymsluþolstilraun. Línulegt samband fannst milli gæðastuðuls og geymslutíma (r > 0.93) fyrir alla geymsluhópa. Niðurstöður skynmats og örverutalninga sýndu að flök sem pakkað var í lofti höfðu geymsluþol 13-15 daga við 1˚C og 20 daga við -1˚C. Við lok geymsluþols í loftpakkningum var heildarörverufjöldi og fjöldi pseudomonads örvera log 7 CFU/g í holdi. Í flökum í loftskiptum pakkningum var lagfasi lengri og heildarfjöldi örvera var undir log 4 CFU/g eftir 27 daga geymslu bæði við 1˚C og -1˚C. Samt sem áður höfðu loftskiptar aðstæður slæm áhrif á lit flaka skömmu eftir pökkun en litur flaka hefur veruleg áhrif á val kaupenda. Efnafræðilegar mælingar eins og TVB-N og TMA voru ekki góður mælikvarði á skemmd tilapiuflaka. Bestu geymsluaðstæður fyrir tilapíuflök er pökkun í lofti og geymsla við stöðugt lágt hitastig -1°C. Skýrsla þessi er byggð á helstu niðurstöðum úr meistaraprófsverkefni Cyprian Ogombe Odoli.

The main aim was to establish optimal storage conditions for fresh tilapia fillets by determining its shelf life by sensory and microbiological evaluation, as well as monitoring its physical-chemical properties. Nile tilapia (Oreochromis niloticus) farmed in recirculation aquaculture system was filleted and packaged in 100% air and 50% CO2: 50% N2 MA prior to storage at different temperature; 1˚C and -1˚C. This report further describes the development of a Quality Index Method (QIM) scheme and a sensory vocabulary for fresh and cooked tilapia fillets accordingly and application in a shelf life study. The application of the QIM scheme for tilapia fillets showed a linear relationship between QIM scores and storage time (r > 0.93) for all samples. The results from sensory analysis of cooked samples as well as microbial growth indicated that fillets packaged in 100% air had a shelf life of 13-15 days during storage at 1˚C and 20 days during storage at -1˚C. At the end of shelf life in 100% air packaged groups, TVC and pseudomonads counts reached log 7 CFU/g in flesh. In MA packaged fillets, the lag phase and generation time of bacteria was extended and recorded total counts below the limit for consumption (< log 4 CFU/g) up to 27 days of storage at both 1˚C and -1˚C. However, MA packaging affected negatively the colour characteristics of the fillets soon after packaging (as from d6) but colour is an important indicator of quality and a major factor in influencing retail purchase decisions. Chemical analyses (TVB-N and TMA) were not good indicators of spoilage of tilapia fillets in the present study. 100% air packaging at -1˚C storage temperature is the optimal storage conditions for fresh tilapia fillets. The report is based on the master thesis of Cyprian Ogombe Odoli.

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Sprautun og pæklun tilapíuflaka / Injection and brining of tilapia fillets

Útgefið:

01/12/2009

Höfundar:

Kristín Anna Þórarinsdóttir, Kolbrún Sveinsdóttir, Þóra Valsdóttir, Irek Klonowski, Aðalheiður Ólafsdóttir, Hannes Magnússon, Arnljótur Bjarki Bergsson, Ragnar Jóhannsson, Emilía Martinsdóttir

Styrkt af:

Tækniþróunarsjóður Rannís / Technology Development Fund, RANNIS ‐ Icelandic Centre for Research

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

Sprautun og pæklun tilapíuflaka / Injection and brining of tilapia fillets

Markmið verkefnisins var að kanna áhrif sprautunar og pæklunar á nýtingu, geymsluþol og eiginleika tilapiuflaka. Framleiddir voru þrír afurðaflokkar: kældar afurðir, frystar afurðir (með óverulegum breytingum á saltinnihaldi) og léttsaltaðar, frystar afurðir. Við vinnslu kældra afurða voru flök með roði sprautuð með daufum pækli (1% salt) sem innihélt smækkaðan þorskmarning (2% prótein í pækli). Léttsöltuð flök voru í upphafi sprautuð með 4% saltpækli, síðan pækluð yfir nótt. Hluti flaka var frystur eftir pæklun en sambærilegt magn sprautað með próteinlausninni eftir pæklun. Nýting jókst við sprautun og pæklun, verulegur munur var þyngdarbreytingum á frystum flökum og léttsöltuðum flökum vegna mismunar í saltinnihaldi þessara tveggja afurðaflokka. Vatnsheldni flaka var lakari eftir frystingu heldur en eftir geymslu í kæli. Geymsluþol afurða var stutt og eru mögulegar ástæður fyrir því ræddar í skýrslunni. Örveruvöxtur og niðurbrotsferlar voru að mestu óháð sprautun og pæklun.

The objective of the project was to study effect of injection and brining on the yield, storage life and characteristics of tilapia fillets. Three different product groups were produced: chilled. Frozen (with small salt changes) and lightly salted products. During processing of chilled products fillets with skin were injected with brine containing minced cod (2%) protein in brine. Lightly brined fillets were at the beginning injected with 4% brine and then brined overnight. A part of the fillets was frozen after brining but similar part was injected with protein solution after brining. The yield increased with injection and brining, distinct difference was in the weight changes of frozen and lightly salted fillets because of the difference of the salt content of these two product groups. Water holding capacity of the frozen fillets was lower than for chilled fillets and the storage life was very short. Microbial growth was mostly not depending on the injection and brining.

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Skýrslur

The effect of liquid cooling at processing and different cooling techniques during transport of cod (Gadus morhua) fillets

Útgefið:

01/11/2009

Höfundar:

Hannes Magnússon, Lárus Þorvaldsson, Kolbrún Sveinsdóttir, Hélène L. Lauzon, Kristín Anna Þórarinsdóttir, Sigurjón Arason, Emilía Martinsdóttir

Styrkt af:

AVS R&D Fund of Ministry of Fisheries in Iceland, the Technology Development Fund at the Icelandic Centre for Research and EU (contract FP6-016333-2)

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

The effect of liquid cooling at processing and different cooling techniques during transport of cod (Gadus morhua) fillets

Tilgangur tilraunanna var að kanna áhrif mismunandi kælitækni og áhrif hitasveiflna á gæði og geymsluþol þorskflaka. Eftirfarandi kælitækni var könnuð: Vökvakæling í pækli við vinnslu miðað við enga kælingu og áhrif hitasveiflna við geymslu í samanburði við stöðugt hitastig (-1°C). Auk þess voru könnuð áhrif þess að nota annars vegar ísmottur og hins vegar þurrís við geymslu flakanna. Fylgst var með breytingum á hitastigi með hitanemum á öllum stigum. Sýni voru gæðametin með skynmati, örveru- og efnamælingum í allt að 14 daga frá veiði (11 daga frá vinnslu og pökkun). Mismunandi meðhöndlun leiddi til mismunandi ferskleikatíma og geymsluþols samkvæmt skynmati. Hópar sem voru vökvakældir við vinnslu höfðu um 2-3 daga skemmra geymsluþol en flök sem ekki voru kæld á þennan hátt. Rekja mátti ástæður þessa til þess að kælipækillinn innihélt töluvert magn örvera m.a. skemmdargerilinn Photobacterium phosphoreum sem er mjög virkur framleiðandi á trímetýlamíni (TMA). Samanburður á vökvakældu flökunum sýndi að notkun á þurrís lengdi geymsluþol um 1-2 daga í samanburði við ísmottur. Geymsla við -1°C hafði ekki merkjanleg áhrif á ferskleikatíma og geymsluþol í samanburði við flök þar sem hitasveiflum var beitt samkvæmt skynmati. Niðurstöður örveru- og efnamælinga voru í samræmi við þessar niðurstöður.

The aim of the experiment was to investigate the effects of different cooling techniques and temperature fluctuations on the storage life of cod fillets. The following cooling techniques were studied: liquid cooling in brine at plant as compared to no special cooling at processing. The effect of real temperature (RTS) simulation during storage was compared to a steady storage temperature at -1°C. Additionally, the influence of using either dry ice or ice packs during storage was studied. The temperature history of each group was studied using temperature loggings. The samples were analyzed with sensory evaluation, microbial and chemical methods for up to 14 days from catch (11 days from packaging). The different treatments of the groups resulted in different lengths of freshness period and maximum shelf life according to sensory evaluation. Liquid cooling resulted in a 2-3 days shorter maximum shelf life than the group that was not receiving liquid cooling. This could be attributed to the fact that the cooling brine carried considerable amounts of microbes including the spoilage bacterium Photobacterium phosphoreum which is an active producer of trimethylamine (TMA). Comparison of the groups receiving liquid cooling showed that dry ice appeared to extend the shelf life of 1-2 days as compared to ice packs. Storage at -1°C did not have much influence on the freshness period or maximum shelf life. These results were confirmed by total volatile bases (TVB-N) and TMA analysis and microbial counts.

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Skýrslur

The effect of different cooling techniques and temperature fluctuations on the storage life of cod fillets (Gadus morhua)

Útgefið:

01/08/2009

Höfundar:

Hannes Magnússon, Hélène L. Lauzon, Kolbrún Sveinsdóttir, Björn Margeirsson, Eyjólfur Reynisson, Árni Rafn Rúnarsson, María Guðjónsdóttir, Kristín Anna Þórarinsdóttir, Sigurjón Arason, Emilía Martinsdóttir

Styrkt af:

AVS R&D Fund of Ministry of Fisheries in Iceland, the Technology Development Fund at the Icelandic Centre for Research and EU (contract FP6-016333-2)

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

The effect of different cooling techniques and temperature fluctuations on the storage life of cod fillets (Gadus morhua)

Tilgangur tilraunanna var að kanna tvo kælimiðla um borð í veiðiskipi, að nota mismunandi kælitækni við vinnslu, m.a. svonefnda CBC (combined blast and contact) kælingu og kanna áhrif hitastigssveiflna við geymslu í samanburði við stöðuga geymslu við -1 °C. Lítill munur var á örveru- og efnamælingum hvort sem notaður var plötuís eða vökvaís fyrir vinnslu en samkvæmt skynmati reyndist hópurinn sem var kældur með vökvaís hafa eins dags lengri ferskleikatíma og geymsluþol. Hitastig var yfirleitt aðeins hærra í hópnum þar sem plötuís var notaður fyrir vinnslu yfir geymslutímann. Samkvæmt skynmati, örverutalningum og efnamælingum reyndist CBC kæling best til lengingar á ferskleikatíma og geymsluþoli. Hitastig reyndist vera lægra í þeim hópum þar sem CBC kæling var notuð. Örverufjöldi var svipaður í þeim tveimur hópum þar sem CBC kæling var ekki notuð við vinnsluna (vökvakæling og engin kæling). Þessar niðurstöður voru í samræmi við niðurstöður skynmats. TMA gildi voru aðeins hærri á geymsludögum 12-19 í hópnum sem var vökvakældur. Niðurstöður hitastigsmælinga yfir geymslutímann voru svipaðar. Svipaður örverufjöldi reyndist vera í hópum sem geymdir voru við stöðugt hitastig (um -1 °C) annars vegar og í hópum þar sem hitastigssveiflum var beitt fyrri hluta geymslutímans hins vegar. Fyrstu 15 daga geymslunnar reyndust TVB-N og TMA gildi vera svipuð í hópunum. Þeir hópar sem geymdir voru við stöðugt hitastig fóru ekki í skynmat. Örverumælingar sem gerðar voru með hinni fljótvirku aðferð qPCR voru í góðu samræmi við ræktunaraðferðir m.t.t. til Pseudomonas spp. og Photobacterium phosphoreum.

The purpose of this experiment was to examine two different cooling methods on board fishing vessel, to apply different cooling techniques during processing at fish plant including the CBC (combined blast and contact) cooling and to compare storage of packed cod fillets kept either at steady temperature (-1 °C) or under temperature fluctuations. No marked difference was seen in microbial and chemical measurements whether plate ice or liquid ice was used prior to filleting but according to sensory analysis, the experimental group where liquid ice was used had one day extension in freshness and shelf life compared to the group with plate ice. Temperature was usually slightly higher in the plate ice group than the liquid ice group during storage. According to sensory, microbiological and chemical analysis, the CBC cooling clearly resulted in longer freshness period and shelf life extension in comparison to the two groups where this technique was not applied during processing. Temperature was lower in these groups during the storage period. Similar microbial counts were found between the two experimental groups where CBC was not applied during processing (liquid cooling and no cooling). These results were in agreement with results from sensory analysis. TMA values were however higher on storage days 12 to 19 in the group with liquid cooling. Temperature measurements during storage of these two groups were very similar. No marked difference was seen in microbial counts between groups that were stored at a constant temperature around -1 °C compared to groups where temperature fluctuations were used during early phases of storage. During the first 15 days of storage, TVB-N and TMA values were very similar for these groups. Sensory analysis was not done on the two groups kept at -1 °C. The rapid qPCR analysis was generally in good agreement with the cultivation methods for Pseudomonas spp. and Photobacterium phosphoreum.

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Skýrslur

Effect of modified atmosphere packaging (MAP) and superchilling on the shelf life of fresh cod (Gadus morhua) loins of different degrees of freshness at packaging

Útgefið:

01/09/2008

Höfundar:

María Guðjónsdóttir, Hannes Magnússon, Kolbrún Sveinsdóttir, Björn Margeirsson, Hélène L. Lauzon, Eyjólfur Reynisson, Emilía Martinsdóttir

Styrkt af:

AVS Rannsóknasjóður, Tækniþróunarsjóður Rannís

Tengiliður

Kolbrún Sveinsdóttir

Verkefnastjóri

kolbrun.sveinsdottir@matis.is

Effect of modified atmosphere packaging (MAP) and superchilling on the shelf life of fresh cod (Gadus morhua) loins of different degrees of freshness at packaging

Tilgangur þessarar tilraunar var að meta áhrif loftskiptra umbúða (MAP) og ofurkælingar á gæðabreytingar og geymsluþol þorskbita af misfersku hráefni sem var unnið og pakkað eftir 2 og 7 daga frá veiði. Tilraunin var gerð í samvinnu við Samherja, Dalvík og Norðlenska, Akureyri í október og nóvember 2007. Fiskurinn var geymdur heill í ís fram að pökkun við -0.2 ± 0.1°C (2 dagar frá veiði) og -0.2 ± 0.2°C (7 dagar frá veiði). Hnakkastykki voru skorin í tvennt og þeim var síðan pakkað (350-550 g) í loftskiptar umbúðir. Samsetning gasblöndunnar var eftirfarandi: 50% CO2, 5% O2 og 45% N2. Pakkaðir þorskbitar voru geymdir í kæligeymslu við -0.6 ± 1.4°C og sýni tekin yfir 3ja vikna geymslutíma og metin með skynmati, örveru- og efnamælingum. Aldur hráefnis við pökkun hafði greinileg áhrif á skynmat bitanna. Pökkun eftir 2 daga leiddi til lengingar á ferskleikaeinkennum framan af geymslu. Auk þess komu skemmdareinkenni mun síðar fram en í bitum sem pakkað var 7 daga frá veiði. Geymsluþol bita eftir pökkun á 7. degi má gróflega áætla 4-8 dagar en a.m.k. 19 dagar í bitum pökkuðum á 2. degi. Þetta stutta geymsluþol bita frá 7. degi má skýra með þróun örveruflórunnar og myndun rokgjarnra skemmdarefna ásamt hitastigsferli á heilum fiski fyrir pökkun. Áhrif mismunandi pökkununardags hafði veruleg áhrif á örveruflóruna. Þannig var heildarörverufjöldi mun minni í bitum sem pakkað var eftir 2 daga heldur en á 7. degi (log 3.7 vs 5.4/g). Þennan mun má að miklu leyti rekja til mismikils fjölda Photobacterium phosphoreum (Pp) í holdi rétt eftir pökkun, en hann greindist ekki við fyrri pökkun á 3. tilraunadegi (undir log 1.3/g) og á 8. degi var fjöldinn aðeins log 2.4/g. Á þeim degi var fjöldi Pp 1000x meiri í bitum pökkuðum á 7. degi og voru þeir ríkjandi út geymslutímann í þessum hópi. Á 8. degi var fjöldi annarra skemmdarörvera (H2S-myndandi gerla og pseudomonads) nokkru hærri (Δ log 0.6-0.7/g) í þessum hópi miðað við hópinn sem pakkað var á 2. degi. Þessar niðurstöður staðfesta að P. phosphoreum sé ein af aðalskemmdarörverum í gaspökkuðum þorskbitum en einnig í kældum, heilum þorski. Niðurstöður TVB-N and TMA mælinga voru í góðu samræmi við örverumælingar en þó sérstaklega Pp. Low Field Nuclear Magnetic Resonance (LF-NMR) tækni var notuð til að mæla “relaxation times” í sýnum yfir geymslutímann. Marktækt hærri “relaxation times” mældust í bitum sem pakkað var eftir 7 daga frá veiði en í bitum sem pakkað var 2 daga frá veiði. Það gefur til kynna meiri bindingu vatnssameinda við umhverfið í 7 daga bitunum. Þetta er í samræmi við almennt hærri vatnsheldni og vatnsinnihald í þeim sýnum yfir geymslutímann. Í heildina sýna niðurstöður mikilvægi þess að nota sem ferskast hráefni til MA-pökkunar og tryggja þannig meiri gæði og lengra geymsluþol sem ætti að skila sér í hærra verði vörunnar.

The aim of this study was to evaluate the effect of modified atmosphere packaging (MAP) and superchilling on the shelf life and quality changes of fresh loins prepared from Atlantic cod (Gadus morhua) of different freshness, i.e. processed 2 or 7 days post catch. The study was performed in cooperation with Samherji (Dalvík, Iceland) and Norðlenska (Akureyri) in October and November 2007. The average fish temperature during storage prior to processing on days 2 and 7 was -0.2 ± 0.1°C and -0.2 ± 0.2°C, respectively. Cod loins (350-550 g) were packed in trays under modified atmosphere (50% CO2/ 5% O2/ 45% N2), stored at -0.6 ± 1.4°C and sampled regularly over a three-week period for sensory, microbiological and chemical analyses. The results show that the raw material freshness clearly influenced the sensory characteristics of packed loins. Processing 2 days post catch resulted in more prominent freshness sensory characteristics the first days of storage. In addition, sensory indicators of spoilage became evident much later compared to MApacked fillets from raw material processed 5 days later. The expected shelf life of the MA-packed cod loins could be roughly calculated as 4-8 days when processed 7 days post catch, but at least 19 days when the cod was processed 2 days post catch. This reduced shelf life of MAP products processed at a later stage was also explained by the temperature profile of the whole fish prior to processing, microbial development and volatile amine production observed. In fact, the day of packaging had a major effect on the microflora development, with lower total viable counts (TVC) in loins processed earlier in relation to time from catch (log 3.7 vs 5.4/g). This difference could be linked to large variations in levels of Photobacterium phosphoreum (Pp) in the flesh at processing times, being below detection (log 1.3/g) 2 days post catch but found to increase to log 2.4/g in early processed loins 6 days later, in contrast to 1000-fold higher Pp levels in loins processed later. Pp was found to quickly dominate the microflora of loins processed 7 days post catch. Similarly, slightly higher levels (Δ log 0.6- 0.7/g) of other spoilage bacteria, H2S-producing bacteria and pseudomonads, were found 8 days post catch in loins processed later. These results confirm that P. phosphoreum is one of the main spoilage organisms in cod, unprocessed as MA-processed. TVB-N and TMA production corresponded well to the microbial development, especially counts of P. phosphoreum. Low Field Nuclear Magnetic Resonance (LF-NMR) was used to measure the relaxation times of the samples during storage. The samples packed 7 days after catch showed significantly higher relaxation times than samples packed 2 days after catch. This indicates stronger bindings of the water molecules to their environment in samples packed at a later stage. This is in agreement with the generally higher water holding capacity and water content in the samples during storage. Finally, the results demonstrated that delaying processing of raw material is undesirable if it is intended to be MA-packed and sold as more valuable products.

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