Tag: Shelf life

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

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

Published:

01/12/2009

Authors:

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

Supported by:

Technology Development Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

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

The purpose of the experiments was to find the best storage conditions for fresh tilapia fillets by determining the shelf life by sensory evaluation, microbial counts and physical and chemical measurements. Nile tilapia (Oreochromis niloticus) raised in a renewable water cycle system was filleted and packed in 100% air and aerated packages 50% CO2: 50% N2 MA for storage at 1˚C and -1˚C. The development of the QIM rating scale and the sensory evaluation properties of fresh and cooked tilapia fillets and the use of the scale in shelf life testing are described. A linear relationship was found between the quality factor and the storage time (r> 0.93) for all storage groups. The results of sensory evaluation and microbial counts showed that fillets packed in air had a shelf life of 13-15 days at 1˚C and 20 days at -1˚C. At the end of shelf life in air packs, the total number of micro-organisms and the number of pseudomonads micro-logs were 7 CFU / g in meat. In fillets in aerated packages, the coating phase was longer and the total number of microorganisms was below log 4 CFU / g after 27 days of storage at both 1˚C and -1˚C. However, aerobic conditions adversely affected the color of the fillets shortly after packing, but the color of the fillets significantly affected buyers' choices. Chemical measurements such as TVB-N and TMA were not a good measure of damaged fillet fillets. The best storage conditions for tilapia fillets are air packing and storage at a constant low temperature of -1 ° C. This report is based on the main findings of Cyprian Ogombe Odoli's master's project.

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 negatively affected the color characteristics of the fillets soon after packaging (as from d6) but color is an important indicator of quality and a major factor in influencing retail purchase decisions. Chemical analyzes (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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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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Reports

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

Published:

01/09/2008

Authors:

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

Supported by:

AVS Research Fund, Rannís Technology Development Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

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

The purpose of this experiment was to evaluate the effect of aerated packaging (MAP) and supercooling on the quality changes and shelf life of cod pieces of fresh raw material that was processed and packaged after 2 and 7 days of fishing. The experiment was carried out in collaboration with Samherji, Dalvík and Norðlenska, Akureyri in October and November 2007. The fish was stored whole in ice until packing at -0.2 ± 0.1 ° C (2 days from fishing) and -0.2 ± 0.2 ° C (7 days from fishing). The neck pieces were cut in half and then packed (350-550 g) in an airtight container. The composition of the gas mixture was as follows: 50% CO2, 5% O2 and 45% N2. Packaged cod pieces were stored in cold storage at -0.6 ± 1.4 ° C and samples were taken over a 3-week storage period and evaluated by sensory evaluation, microbial and chemical measurements. The age of the raw material during packaging had a clear effect on the sensory evaluation of the pieces. Packing after 2 days led to a prolongation of the freshness symptoms in front of storage. In addition, signs of damage appeared much later than in bites packed 7 days after fishing. The shelf life of pieces after packing on day 7 can be roughly estimated at 4-8 days, but at least 19 days in pieces packed on day 2. This short shelf life of pieces from day 7 can be explained by the development of microbial flora and the formation of volatile pesticides as well as the temperature profile of whole fish before packaging. The effect of different packing dates had a significant effect on the microflora. Thus, the total number of microorganisms was much smaller in pieces packed after 2 days than on day 7 (log 3.7 vs 5.4 / g). This difference can largely be attributed to the varying number of Photobacterium phosphoreum (Pp) in the flesh immediately after packing, but it was not detected during the previous packing on the 3rd day of the experiment (below log 1.3 / g) and on day 8 the number was only log 2.4 / g. On that day, the number of Pp was 1000x higher in pieces packed on day 7 and they were predominant throughout the storage period in this group. On day 8, the number of other pests (H2S-producing bacteria and pseudomonads) was somewhat higher (Δ log 0.6-0.7 / g) in this group compared to the group packed on day 2. These results confirm that P. phosphoreum is one of the main damaging microorganisms in gas-packed cod pieces but also in chilled, whole cod. The results of TVB-N and TMA measurements were in good agreement with microbial measurements, but especially Pp. Low Field Nuclear Magnetic Resonance (LF-NMR) technology was used to measure relaxation times in samples over the storage period. Significantly higher "relaxation times" were measured in chunks packed after 7 days of fishing than in chunks packed 2 days after fishing. It indicates greater binding of water molecules to the environment in the 7-day bites. This is in line with the generally higher water resistance and water content of those samples over the storage period. Overall, the results show the importance of using the freshest ingredients for MA packaging, thus ensuring higher quality and longer shelf life, which should result in a higher price for the product.

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, ie 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 analyzes . 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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Reports

Combined Blast and Contact cooling - Effects on physiochemical characteristics of fresh haddock (Melanogrammus aeglefinus) fillets

Published:

01/06/2008

Authors:

Magnea Guðrún Arnþórsdóttir, Sigurjón Arason, Björn Margeirsson

Supported by:

Tækniþróunarsjóður, AVS

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Combined Blast and Contact cooling - Effects on physiochemical characteristics of fresh haddock (Melanogrammus aeglefinus) fillets

Skaginn hf. has a patent for new processing technology for the processing of fresh and frozen fillets based on so-called skin cooling before peeling. The purpose of this research project was to compare fillet processing with skin cooling and traditional fillet processing. The project compares fresh fillets and chilled fillets with regard to utilization, quality and shelf life. Two experiments were performed, on the one hand Experiment I where water resistance, quality, boiling efficiency and appearance were examined, and on the other hand Experiment II where these same factors were examined and the effect of erosive cooling on the shelf life of fresh and frozen haddock was examined. The experiments were carried out at Festi ehf. in Hafnarfjörður. The main results of these studies showed that fillet processing with skin cooling has more advantages than traditional fillet processing. The erosive cooling gives higher utilization and more valuable products with a longer shelf life. Increased shelf life of fresh fish provides increased opportunities for export, which is very important for the fishing industry.

The aim of the project was to compare a new processing technique, CBC, with traditional processing of haddock fillets. In the latter the fillets go through the process without additional refrigeration. In the new processing technique, CBC, the fillets, after filleting and pre-trimming, go through pre-cooler / fluid-ice followed by CBC super-chilling. Two trials were performed, a preliminary experiment (I) and a main experiment (II). In the preliminary experiment (I), water holding capacity, quality and cooking yield were examined. In the main experiment (II) these same factors were examined, in addition to the superchilling effect on extended shelf-life of fresh and frozen haddock fillets. After the pre-cooler step, the fillets gained weight with yields of 101.6% to 102.7%. After the CBC super-chilling the fillets had final yields of 100.3% to 101.2%. After skinning, the fillets without refrigeration (traditional processing) lost most weight. The highest value of cooking yield was obtained in CBC super-chilled fillets with skin. Skinless traditional and CBC super-chilled fillets showed similar cooking yield (P> 0.05). CBC super-chilling increased the total yield of the fillets. The difference between the traditional fillets and the super-chilled fillets was significant. The appearance of the CBC super-chilled fillets was much better and with less gaping than the traditional fillets. The traditional fillets had more ragged outlines, and the ratio of cut-offs after fine-trimming was therefore higher for the traditional fillets than the CBC super-chilled fillets. Appearance of the traditional fillets showed a little yellow tinge which increased during the storage time. The CBC super-chilled fillets had a whiter and more "fresh" appearance and were therefore more attractive. Examination of total bacterial count, and amount of TMA and TVN showed that the CBC super-chilling process can extend the shelf life of fresh haddock fillets.

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Reports

Effects of subcooling on salt uptake by pickling cod neck pieces (Gadus morhua)

Published:

01/06/2008

Authors:

Ragnhildur Einarsdóttir, María Guðjónsdóttir, Sigurjón Arason

Supported by:

Rannís Research Fund

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Effects of subcooling on salt uptake by pickling cod neck pieces (Gadus morhua)

Salt uptake and shelf life of skinless and boneless cod fillets (Gadus morhua) were studied at different temperatures. Salt uptake was examined at 0.5 ° C, -2 ° C and 5 ° C. The results indicate that fish muscle absorbs salt faster at -2 ° C than 5 ° C and salt uptake occurs most rapidly in the first 5 minutes. When looking for a final salt concentration of 0.6%, 4% brine is most desirable. In the shelf life test, the temperature was 0 ° C on the one hand and - 2 ° C on the other. Shelf life of fillets stored at -2 ° C was found to have a shelf life of 3-4 days longer than those stored at 0 ° C. Enzyme activity, more specifically trypsin-like protease activity, was examined in supercooled fish muscles. Fish muscle with a salinity of 0.5% stored at -2 ° C was found to have higher activity than other groups. The study suggests that it would be interesting to look more closely at the interaction between treatment, temperature and enzymes.

The salt uptake during brining and shelf life of skinless and boneless cod loins (Gadus morhua) was investigated at different temperatures. The salt uptake was studied at 0.5 ° C, -2 ° C and 5 ° C. The results show that the salt uptake of the cod muscle is faster at -2 ° C than at 5 ° C and that the salt uptake is fastest during the first 5 minutes. When aiming for a salt concentration of 0.6% in the muscle during brining it is optimal to use a 4% salt brine. In the shelf life study, samples were stored at 0 ° C and -2 ° C. The cod loins stored at -2 ° C showed 3-4 days longer shelf life than samples stored at 0 ° C. Enzymatic activity, or trypsin like protease activity to be more precise was studied in the superchilled muscle. Cod muscle with 0.5% salt and stored at -2 ° C showed higher activity than other groups. The study shows that there is a need for further studies on the combined effects of processing and storage temperatures on enzymatic activity.

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Reports

Shelf life tests on cod pieces: Effect of supercooling, pickling and gas packaging on quality changes and shelf life / Storage trials on cod loins: Effect of superchilling, brining and modified atmosphere packaging (MAP) on quality changes and sensory shelf-life

Published:

01/05/2007

Authors:

Hannes Magnússon, Hélène L. Lauzon, Kolbrún Sveinsdóttir, Ása Þorkelsdóttir, Birna Guðbjörnsdóttir, Emilia Martinsdóttir, Guðrún Ólafsdóttir, María Guðjónsdóttir, Sigurður Bogason, Sigurjón Arason

Supported by:

AVS Fisheries Research Fund, Technology Development Fund (Rannís)

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Shelf life tests on cod pieces: Effect of supercooling, pickling and gas packaging on quality changes and shelf life / Storage trials on cod loins: Effect of superchilling, brining and modified atmosphere packaging (MAP) on quality changes and sensory shelf-life

The aim of these experiments was to evaluate the effect of supercooling, aerated packaging (MAP) and brine on quality changes and shelf life of cod pieces. The effects of gas packaging and different storage temperatures on the growth of several pathogens and pointing organisms were also investigated. The experiment was carried out in October 2006 at Samherji in Dalvík. After storage (0.6 and 2% salt), the fish was trimmed and the neck pieces were packed in standard 3 kg foam packs (air packs) and in air-conditioned packaging. The gas mixture was adjusted to 50% CO2, 5% O2 and 45% N2. Three pieces (350- 550g) were placed in each tray with a drying mat. After packing, the samples were placed in Matís freezer simulators set at 0 ° C, -2 ° C and -4 ° C. The samples were examined over a four-week storage period. Sensory evaluation, microbial counts and chemical measurements were used to assess quality changes and shelf life. Pickled (2% salt) fish were stored shorter than uncooked (0.6% salt). A comparison of the number of micro-organisms the day after packing showed that the pickled fish contained ten times more cold-resistant micro-organisms than the non-pickled ones. According to sensory evaluation, the shelf life of the pickled fish at -2 ° C was 12-15 days in both air- and gas-packed pieces. In the blunt fish, the effects of gas packaging and supercooling were evident. The shelf life of air-packed pieces was about 11 days at 0 ° C and 14-15 days at -2 ° C. The shelf life of gas-packed pieces, on the other hand, was about 15 days at 0 ° C and about 21 days at -2 ° C. Supercooling of fresh uncooked fish products in air-conditioned packaging can therefore significantly increase shelf life. Gas packing significantly reduced the growth rate of pathogens and microorganisms at low temperatures. Salmonella was most affected, then Escherichia coli and Listeria monocytogenes the least. Under air conditions, L. monocytogenes grew at -2 ° C, but E. coli began to multiply at 5 ° C and Salmonella at 10 ° C.

The aim of these experiments was to evaluate the effect of superchilling, modified atmosphere packaging (MAP) and brining on the quality changes and sensory shelf-life of cod loins. The effect of MAP and different storage temperatures on some pathogenic and indicator bacteria was also tested. These experiments were initiated in October 2006 at Samherji, Dalvík. After brining (0.6 and 2% salt) the fish fillets were trimmed, and loins packed on one hand in 3 kg styrofoam boxes (air) and on the other in MA. The gas mixture used was 50% CO2, 5% O2 and 45% N2. Three pieces (350-550 g) were placed in each tray with an absorbent mat. After packaging the samples were placed in 3 coolers at Matís which were adjusted to 0 ° C, -2 ° C and -4 ° C. Samples were examined over a four-week period. Sensory analysis, microbial counts and chemical measurements were used to determine the quality changes and shelf-life. Brined loins had a shorter shelf-life than unbrined (0.6% salt). Comparison on numbers of microorganisms the day after packaging revealed that the brined pieces contained ten times more microbes than the unbrined ones. According to sensory analysis the shelf-life of the brined loins at -2 ° C was 12-15 days for both air- and MA-packed fish. In the unbrined loins the effects of superchilling and MAP were obvious. The shelf-life of air-packed loins was about 11 days at 0 ° C and 14-15 days at -2 ° C. The shelf-life of MA-packed loins was about 15 days at 0 ° C but 21 days at -2 ° C. Superchilling of unbrined fish under MA can therefore increase the keeping quality considerably. MA packaging clearly decreased the growth rate of pathogenic and indicator bacteria at low storage temperatures. Most effects were seen with Salmonella, then Escherichia coli but least with Listeria monocytogenes. In fact, L. monocytogenes could grow at -2 ° C under aerobic conditions, while proliferation of E. coli was first observed at 5 ° C but 10 ° C for Salmonella.

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