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 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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