Reports

Comparison of packaging methods for bulk storage of fresh cod loins / Comparison of packaging solutions in foam packaging for storage of cod products

Published:

01/08/2013

Authors:

Hélène L. Lauzon, Aðalheiður Ólafsdóttir, Eyjólfur Reynisson, Björn Margeirsson

Supported by:

Promens Tempra ehf, Umbúðir og ráðgjöf ehf

contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

Comparison of packaging methods for bulk storage of fresh cod loins / Comparison of packaging solutions in foam packaging for storage of cod products

The main objective of the experiment was to compare packaging solutions for fish in terms of quality deterioration and product temperature during storage, which is similar to the conditions for export and distribution. The objectives were to compare cold storage of products packed (1) in 5-kg units in (H1) ship or (H2) air boxes; (2) in 3 ‐ kg units in (H3) airbags compared to H2; (3) with CO2 mats (H4) to reduce microbial growth in 5 kg units stored under 93% vacuum in EPS boxes. The results show that the lifespan of H1 was shorter, but there were smaller quality changes among the other groups. However, the freshness was longest and the lifespan of H4, which compares with slower TVB-N and TMA formation and microbial growth due to CO2 formation as well as lower product temperature. The fastest microbial growth was measured in H3 after 8 days of storage. There was no significant difference between the groups in terms of TVB-N and TMA values, which were highest in H1 and H3. Drip was at least half as high in H4 as in other groups.

The overall aim of the storage study was to compare the quality deterioration and temperature profile of cod loins differently packaged in expanded polystyrene boxes and stored under conditions mimicking distribution. The purpose of the study was threefold; to compare chilled storage (1) or 5 ‐ kg bulk fish packaged in sea freight (H1) or air freight (H2) boxes; (2) of 3 ‐ kg (H3) or 5 ‐ kg (H2) bulk fish packaged in air freight boxes; (3) with the use of CO2 ‐ emitting pads (H4) as a mean to slow down bacterial deterioration of cod loins (5 kg) packaged under partial vacuum and stored in EPS boxes. The results clearly indicated that group H1 had a shorter shelf life as it developed spoilage characteristics faster than the other three groups. Less difference was seen between the remaining three groups but group H4 retained its freshness slightly longer than groups H2 and H3. This can be explained by the CO2 present and the lower mean product temperature. More advanced microbial spoilage was detected in H3 group compared to H2, as shown by higher microbial counts in H3 being though insignificant. No significant differences were observed after 8 ‐ day storage in TVB ‐ N and TMA content of the four groups, despite the higher levels measured in H1 and H3. Drip loss was at least two times higher in H4 than the other groups.

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Reports

Effect of temperature control on the efficiency of modified atmosphere packaging of cod loins in bulk

Published:

01/06/2011

Authors:

Hélène L. Lauzon, Kolbrún Sveinsdóttir, Magnea G. Karlsdóttir, Eyjólfur Reynisson, Björn Margeirsson, Emilia Martinsdóttir

Supported by:

EU IP Chill ‐ on (contract FP6‐016333‐2)

contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Effect of temperature control on the efficiency of modified atmosphere packaging of cod loins in bulk

The aim of the experiment was to compare the freshness, quality and shelf life of sub-chilled (CBC) cod necks in air storage and in aerated packages (MAP) at controlled temperatures to simulate temperature fluctuations during transport and distribution in the European market. Changes in the composition of the gas in the packages were monitored and sensory assessments and microbial and chemical measurements were performed. The fish was caught in bottom trawls in the spring and processed three days after fishing. There was a two-day prolongation during the freshness period and one day for the shelf life of fish in aerated packages (2.7 kg in a tray) compared to air (3.1 kg) in foam plastic, despite a 0.5 ° C difference in the average temperature of the groups and the air group was stored at lower temperatures (‐0.3 ± 0.9 ° C). The greatest temperature fluctuations led to the greatest shortening of the freshness time in air-conditioned packages. Cod saddles stored subcooled at -1.1 ± 0.1 ° C had a shelf life of 13 days. The results of microbial counts and chemical measurements showed the importance of Photobacterium phosphoreum in the formation of TMA in the process of damaging cod necks during both air and air exchange packaging. MAP and subcooling slowed down and changed the damage process. MAP increased drip by 2% in the later stages of storage.

The aim of this study was to compare freshness, quality deterioration and shelf life of CBC (combined blast and contact) ‐treated cod loins packaged in bulk under different atmospheres (air or modified atmosphere, MA) and stored under different temperature profiles to mimic temperature changes during transport and distribution to European markets. Sensory, chemical, microbial and headspace gas composition analyzes were performed regularly. The fish was caught by trawler in the spring and processed 3 days post catch. Following simulation of current sea freight conditions and distribution to European markets, a 2 ‐ day and 1 ‐ day increase in freshness period and shelf life of MA ‐ packaged fish (2.7 kg in trays), respectively, was observed compared to air ‐ stored loins (3.1 kg in EPS boxes). This is despite a mean product temperature difference of 0.5 ° C between the products, being lower (‐0.3 ± 0.9 ° C) for air ‐ stored fish. Abusive conditions had the greatest impact on the reduction of the freshness period for MAP fish. Superchilled storage of MAP loins (‐1.1 ± 0.1 ° C) resulted in a 13 ‐ day shelf life. Evaluation of microbial and chemical indicators emphasized the importance of Photobacterium phosphoreum and TMA formation in the deterioration of cod loins stored in air or MA, while superchilled MAP storage delayed as well as modified the spoilage pattern. MAP increased drip loss by about 2% at late storage.

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Reports

Overview on fish quality research - Impact of fish handling, processing, storage and logistics on fish quality deterioration

Published:

01/11/2010

Authors:

Hélène L. Lauzon, Björn Margeirsson, Kolbrún Sveinsdóttir, María Guðjónsdóttir, Magnea G. Karlsdóttir, Emilia Martinsdóttir

Supported by:

AVS R&D Fund of Ministry of Fisheries in Iceland, Technology Development Fund and EU IP Chill-on (contract FP6-016333-2)

contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Overview on fish quality research - Impact of fish handling, processing, storage and logistics on fish quality deterioration

The short shelf life of fish is a limiting factor in the export of fresh fish products from Iceland. The initial quality of raw materials, methods of cooling, processing, packaging and conditions during storage and transport are discussed, as well as the effects of all these factors on the freshness and shelf life of fish products. Temperature control is very important to maintain the quality of the fish. Pre-processed fillets have been used to lower the pre-packing temperature. However, care must be taken that the pre-cooling technology does not endanger the microbial condition of the product and thus causes it to be damaged earlier after packaging. The synergistic effects of supercooling and aerated packaging (MAP) can significantly extend the freshness period and shelf life of fish products. Furthermore, packaging methods are examined, including new, more environmentally friendly packaging. Finally, the effect of transport routes of fresh fish products on their final quality to consumers in the market is discussed. This report provides an overview of the research of the Fisheries Research Institute and Matís ohf over the past three decades on the subject. Furthermore, it is discussed how these results can benefit the fishing industry.

The limited shelf life of fresh fish products is a large hurdle for the export of fresh products from Iceland. The influence of raw material quality, cooling methods, processing, packaging and storage conditions on freshness and shelf life extension is discussed. Temperature control is important to maintain fish quality. Pre-cooling of fillets in process has been used to lower the temperature prior to packaging. However, the cooling technique applied should not compromise the microbiological quality of the product and render it vulnerable to faster spoilage postpackaging. Synergism of combined superchilling and modified atmosphere packaging (MAP) can lead to a considerable extension of the freshness period and shelf life of fish products. Further, alternative and environmentally-friendly packaging methods are considered. Finally, the impact of transportation mode of fresh fish products on their resulting quality is examined. This report provides an overview of the findings on fish research carried out at Matís (Icelandic Fisheries Laboratories) over the last three decades and further discusses their practicality for the fish processing industry.

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Reports

The effect of different cooling techniques on the quality changes and shelf life of whole cod (Gadus morhua)

Published:

01/08/2010

Authors:

Hannes Magnússon, Kolbrún Sveinsdóttir, Lárus Þorvaldsson, María Guðjónsdóttir, Hélène L. Lauzon, Eyjólfur Reynisson, Árni R. Rúnarsson, Sveinn H. Magnússon, Jónas R. Viðarsson, Sigurjón Arason, Emilia Martinsdóttir

Supported by:

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

contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

The effect of different cooling techniques on the quality changes and shelf life of whole cod (Gadus morhua)

The purpose of the experiment was to investigate the effect of three different cooling methods on the shelf life of whole, gutted cod: (i) Cooling with crushed plate ice, (ii) cooling with liquid ice, (iii) pre-cooling with liquid ice and then cooling with crushed plate ice. Temperature processes were monitored with temperature sensors in all groups during the storage period. Samples were assessed by sensory evaluation, microbial and chemical measurements during the 10 days the fish was stored. The results of microbial and chemical measurements were generally in good agreement with the results of sensory evaluation. Comparison of experimental groups revealed that cod chilled with liquid ice had a shelf life of about two to three days shorter than the other two groups. The shelf life of the cod was considerably shorter than various previous studies have shown, especially in the group that was cooled with liquid ice (only 9-10 days). It is now clear that the cod that was cooled with liquid ice was vanished on board the fishing vessel compared to the other two groups. In addition, refrigerated storage after landing was not as good as might be considered, but the temperature fluctuated between 2-5 ° C. This could possibly explain the shorter shelf life of all groups compared to previous studies.

The aim of this experiment was to investigate the effect of three different cooling methods on the storage quality of whole, bled gutted cod: (i) Cooled with crushed plate ice, (ii) cooled with liquid ice, (iii) pre-cooled in liquid ice and then cooled with crushed plate ice. The temperature history of each group was studied using temperature loggers. The samples were analyzed with sensory, microbiological and chemical methods for up to 10 days from catch. The results from microbial and chemical measurements were generally in good agreement with the results from sensory evaluation. Comparison of the groups showed that the use of liquid ice instead of plate ice resulted in two to three days shorter shelf life than in the other two groups. The shelf life in this study was considerably shorter compared to previous studies with whole cod, especially in the experimental group where liquid ice was used for cooling (only 9-10 days). It is now known that the liquid iced group in this experiment was insufficiently iced on board the fishing vessel compared to the other two groups. Additionally, the ambient temperature in the cold room of the fish plant was relatively high and fluctuated between 2 - 5 ° C during the storage period. This could possibly explain the shorter shelf life of all groups compared to some earlier studies.

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Reports

Effect of improved design of wholesale EPS fish boxes on thermal insulation and storage life of cod loins - simulation of air and sea transport

Published:

01/08/2010

Authors:

Björn Margeirsson, Hélène L. Lauzon, Kolbrún Sveinsdóttir, Eyjólfur Reynisson, Hannes Magnússon, Sigurjón Arason, Emilía Martinsdóttir

Supported by:

EU (contract FP6-016333-2) Chill-on, AVS Fund of Ministry of Fisheries in Iceland (project no. R037-08), Technology Development Fund of the Icelandic Center for Research (project. No. 081304508), University of Iceland Research Fund

contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Effect of improved design of wholesale EPS fish boxes on thermal insulation and storage life of cod loins - simulation of air and sea transport

The aim of the experiments was to investigate how well two types of foam boxes protect cod neck pieces from the typical heat load in an air transport chain from a producer in northern Iceland to a buyer in Europe. Temperature measurements, sensory evaluation, chemical and microbial measurements were used to compare the foam boxes and examine the importance of the location of fillet pieces within the box (corner and center). Finally, the shelf life of neck pieces subjected to typical air transport temperature load was compared to the shelf life of neck pieces with stable -1 ° C storage, which is a viable option for container transport by ship. The new foam box, designed with the FLUENT heat transfer model, proved to be better than the older box in terms of thermal insulation. The temperature load on the first day of the experiment caused the highest product temperature in the corners to rise to 5.4 ° C in the older model but only to 4.5 ° C in the new model. The difference between the highest product temperature in the middle and the corners of the box was about 2 to 3 ° C. Sensory evaluation showed that storage in the new foam box led to a two to three day longer freshness period and one to two days longer shelf life with regard to storage in the older foam box. However, the differences between the boxes were not confirmed by chemical and microbial measurements. Position within the box (angle and center) did not significantly affect sensory evaluation results and there was only a small difference between placements in TVB-N and TMA measurements. Simulation of air and sea transport (temperature fluctuations and constant temperature) revealed that for well-cooled cod necks, one can expect one to five days longer freshness period and about three to five days longer shelf life in well-controlled sea transport compared to a typical air transport process from the North. As sea transport from Iceland often takes about four to five days longer than air transport (depending on, among other things, the day of the week and the location of the processing), this shows that sea transport is a viable option for Icelandic fresh fish producers. With the use of the new foam boxes in air transport, however, the fish will have a longer freshness period when it comes into the hands of buyers abroad than in shipping.

2nd edition, March 2011

In the previous version of the report, it was not considered clear enough that the environmental temperature trajectory that was to be simulated by sea transport was in fact based on more or less the best possible conditions in the sea transport chains of fresh fish products from Iceland. Temperature measurements in the cooling projects The simulation of cooling processes and Chill-on have shown that domestic transport is often accompanied by an undesirable temperature load for several hours. whether it is air or sea transport chains. This heat load was taken into account in the case of the airline chain and not the maritime transport chain in the first edition of the report. Most emphasis was on the length of shelf life in the previous edition of the report, but a discussion on the period of freshness is added in its new edition.

The aim of the study was to investigate the performance of two different types of EPS boxes in protecting pre-chilled, fresh fish products subject to temperature conditions, which are likely to occur during air- and land based, multimodal transport from a processor in North -Iceland to a wholesaler in Europe. The performance of the EPS boxes was evaluated by means of temperature monitoring, chemical- and microbial measurements and finally sensory evaluation. Furthermore, effect of fillet positions inside the wholesale fish packages (corner vs. middle) were investigated by means of the aforementioned methods. Finally, the shelf life of the air-transported simulation fish loins was compared to the shelf life of fish loins stored at around -1 ° C, which can be achieved during non-interrupted and well temperature-controlled, containerized sea transport. The new box, designed with a numerical FLUENT heat transfer model, proved to be better with regard to thermal insulation than the old box. The thermal load during the first day of the experiment caused the maximum product temperatures in the bottom corners of the top and second top to rise to 5.4 ° C and 4.5 ° C for the original and new boxes, respectively. The maximum temperature in the middle of the boxes was around 2 to 3 ° C lower than the maximum temperature in the bottom corners. According to sensory evaluation, storage in the new boxes resulted in approximately two to three days longer freshness period and one to two days longer shelf life than storage in the old boxes. The difference between the two box types is not as clear with regard to chemical and microbial measurements.

The sampling location (corner versus middle), did not significantly affect the sensory quality and only minor differences were noticed in TVB-N and TMA between sampling locations in the new box. Comparing the steady and dynamic storage in the old boxes it can be concluded that the increased freshness period (around 1-5 days) and shelf life (around 3-5 days) at steady temperature could compensate for the longer transport time by sea instead of air freight. This makes containerized sea transport a worthy choice for Icelandic fresh fish manufacturers depending on the week day and location of processing. However, for maximum remaining freshness period at the time of delivery to the buyer in Europe the results showed that air transport with the new boxes is the more advantageous transport mode relying on shorter transport time and improved thermal protection of the new boxes.

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Reports

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

Published:

01/05/2010

Authors:

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

Supported by:

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

contact

Kolbrún Sveinsdóttir

Project Manager

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

The purpose of the experiments was to investigate the effect of different cooling during processing and temperature fluctuations in transport with and without a cooling mat on the shelf life of cod necks. In processing, it was compared to use no pre-cooling for filleting, liquid cooling and skin cooling (CBC) which is always liquid-cooled. The effect of simulated temperature fluctuations in transport temperature changes (RTS) was compared with storage at a constant temperature (-1 ° C). The effects of using a cooling mat in storage and transport were also assessed. Samples were quality assessed by sensory evaluation, microbial and chemical measurements. Temperature was monitored with thermometers. Skimmed cod fillets in foam plastic boxes were transported to Bremerhaven by air and ship, where they were repackaged in air and aerated packages (MAP) and stored at 1 ° C. Chemical and microbiological measurements were performed to monitor quality changes. The temperature of the erythema necrosis was lower than in the first 2 days of the experiment. The cooling mats had a certain effect of lowering the temperature when temperature fluctuations were in the process and lower temperatures were maintained throughout the storage period. However, the use did not affect the duration of freshness or shelf life according to sensory evaluation. The number of microorganisms was somewhat lower if temperature fluctuations occurred in the process, but there was little difference at a constant temperature. Storage at a constant, low temperature (-1 ° C) prolonged shelf life by approx. 3 days according to sensory evaluation and it was in accordance with microbial counts and measurements of TVB-N and TMA. Experiments in Bremerhaven showed that the number of microorganisms was generally lower when using aerated packaging compared to airborne fish. This was especially noticeable in the flying fish. The fish transported by ship was still stored for as long as the fish transported by air. This is due to the fact that the flying fish experienced greater temperature fluctuations during transport and its surface temperature measured 4 ° C on arrival in Bremerhaven. The transport time by ship was much longer (+48 hours) but the surface temperature was below 2 ° C on receipt. The use of cooling mats had little effect on the temperature during transport, but nevertheless the surface temperature was slightly lower in fish with cooling mats on arrival in Bremerhaven both by air and by ship.

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 analyzed 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 extended 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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Reports

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

Published:

01/04/2010

Authors:

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

Supported by:

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

contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

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

The purpose of the experiments was to investigate the effect of different refrigerants in pre-cooling before packaging on temperature control, quality and shelf life of cod fillets. The following refrigerants were examined and compared with no special pre-packing pre-packing:

  1. brine with a low salt content, 2) ice cream with a low salt content.

In addition, the effects of using ice mats and dry ice on the storage of the wrecks were investigated. Temperature changes were monitored by temperature sensors at all levels. Samples were quality assessed by sensory evaluation, microbial and chemical measurements for up to 13 days from processing and packaging (16 days from fishing). The fillets were stored in supercooled conditions (below 0 ° C) for most of the storage time. Lower temperatures of slurry ice than brine led to lower fillet temperatures during packing, and the temperature of the liquid brine was found to rise rapidly during processing. Different treatment resulted in a comparable freshness period according to sensory evaluation. However, the use of a liquid brine during pre-packaging pre-packing proved to lead to a shorter shelf life of 1-2 days compared to no pre-cooling or pre-cooling with slush ice. The reasons for this can be traced to the fact that the brine contained a considerable amount of microorganisms, including H2S-producing bacteria which are active producers of trimethylamine (TMA). Comparison of liquid-cooled fillets showed that the use of dry ice prolonged shelf life by 1 day compared to ice mats. The results of microbial and chemical measurements were consistent with these results.

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 analyzed 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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Reports

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

Published:

01/11/2009

Authors:

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

Supported by:

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

contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

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

The purpose of the experiments was to investigate the effect of different refrigeration techniques and the effect of temperature fluctuations on the quality and shelf life of cod fillets. The following cooling technology was investigated: Liquid cooling in brine during processing based on no cooling and the effect of temperature fluctuations during storage compared to a constant temperature (-1 ° C). In addition, the effects of using ice mats and dry ice on the storage of the wrecks were investigated. Temperature changes were monitored by temperature sensors at all levels. Samples were quality assessed by sensory evaluation, microbial and chemical measurements for up to 14 days from fishing (11 days from processing and packaging). Different treatment resulted in different freshness times and shelf life according to sensory evaluation. Groups that were liquid-cooled during processing had a shelf life of about 2-3 days shorter than fillets that were not cooled in this way. The reasons for this can be traced to the fact that the cooling brine contained a considerable amount of microorganisms, including the destructive bacterium Photobacterium phosphoreum, which is a very active producer of trimethylamine (TMA). Comparison of liquid-cooled fillets showed that the use of dry ice prolonged shelf life by 1-2 days compared to ice mats. Storage at -1 ° C did not have a significant effect on freshness time and shelf life compared to fillets where temperature fluctuations were applied according to sensory evaluation. The results of microbial and chemical measurements were consistent with these results.

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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Reports

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

Published:

01/08/2009

Authors:

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

Supported by:

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

contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

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

The purpose of the experiments was to examine two refrigerants on board a fishing vessel, to use different refrigeration techniques during processing, including so-called CBC (combined blast and contact) refrigeration and to examine the effect of temperature fluctuations during storage compared to continuous storage at -1 ° C. There was little difference in microbial and chemical measurements, whether plate ice or liquid ice was used for processing, but according to sensory evaluation, the group that was cooled with liquid ice had one day longer freshness and shelf life. The temperature was usually slightly higher in the group as plate ice was used for processing during the storage period. According to sensory evaluation, microbial counts and chemical measurements, CBC cooling proved to be the best for prolonging freshness and shelf life. Temperatures were found to be lower in the groups where CBC cooling was used. The number of microorganisms was similar in the two groups where CBC cooling was not used in the processing (liquid cooling and no cooling). These results were consistent with the results of sensory evaluation. TMA levels were slightly higher on storage days 12-19 in the liquid-cooled group. The results of temperature measurements during the storage period were similar. A similar number of microorganisms were found to be in groups stored at a constant temperature (about -1 ° C) on the one hand and in groups where temperature fluctuations were applied during the first part of the storage period on the other hand. During the first 15 days of storage, TVB-N and TMA values were found to be similar in the groups. The groups stored at a constant temperature did not undergo sensory evaluation. Microbial assays performed by the fast-acting method qPCR were in good agreement with culture methods for Pseudomonas spp. and 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 below 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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