Reports

Measurements of the characteristics of foal meat

Published:

03/07/2019

Authors:

Eva Margrét Jónudóttir, Guðjón Þorkelsson, Aðalheiður Ólafsdóttir, Óli Þór Hilmarsson, Kolbrún Sveinsdóttir

Supported by:

Agricultural Productivity Fund

Contact

Eva Margrét Jónudóttir

Researcher

evamargret@matis.is

Measurements of the characteristics of foal meat

Domestic horsemeat sales are only about half of production, and while meat consumption is growing with increased economic growth, this does not apply to horsemeat. Horses are generally not bred specifically for meat production, but the meat is a by-product of equestrian breeding and drug production from mare's blood. The popularity of equestrianism and the production of medicines are unlikely to decline in the next few years, so there is every reason to make horsemeat high and thus prevent further marketing problems in the future. Horse meat has been in a marketing campaign abroad in recent months, especially in Asia, but information is lacking about its characteristics. The main goal of the project was to gather and disseminate information that supports and facilitates the way of marketing and sales of horsemeat. Products from three foals slaughtered on 03.12.18 were examined. Thermostat was placed in the refrigerator and in the innermost muscles of the body. Acid syringes were inserted into their spinal muscles after slaughter. All carcasses were deboned in the slaughterhouse at Hella and weighed according to the division into muscle, processing material, bones and fat. Each muscle was divided into 4 parts. The first was in color measurement, the second in chemical measurement, the third in sensory evaluation and the fourth in surgical measurement and measurement of southern shrinkage. In addition, samples were sent for analysis of bacterial counts as well as Listeria bacteria. It took about 17 hours for acidity to fall into the spinal muscles after slaughter and it took about 24 hours in the refrigerator after slaughter for the carcass to reach a perfect ambient temperature at 5 ° C. Measurements on cooked muscle confirm that foal meat is tender meat. Sequence of increasing surgical force (viscosity) is: Puffs <ball steak <arch muscle <hip stitch <thigh tongue <vertebral muscle <lump <outer thigh <brisket <inner thigh muscle. Southern atrophy during cooking was about 25%. Listeria moinocytogenes was never measured and all samples were below microbial criteria. Flavor was generally low or not measurable but increases proportionally more with increasing intramuscular fat as it lasts during storage. According to color measurements, foal meat is similarly light but slightly redder and yellower than lamb and there was a nuance difference between the muscles. After 14 days of storage, the meat became slightly redder / yellower. Muscles used as whole muscle by carcass are only 34.7% of total dead weight. The raw material is 28.9%, which tells us that the proportion of what is normally used by the drop weight is 63.6%. Horse meat has everything to offer in order to be sold as a high-quality meat product, and there should be nothing to prevent it from making better use of this valuable resource.

The main objective was to gather and disseminate information that will support marketing of equine meat. Meat and offals from three foals were analyzed. Temperature was monitored in chiller and carcasses after slaughter and pH loggers were placed in the loin muscle (m. Longissimus dorsi). Yield was measured by cutting the carcasses into muscles, triminngs, fat and bone the day after slaughter. Each muscle was cut into 4 parts.The first was used for measuring CIELAB L, a, b * color. The second was analyzed for nutritional value. The third was cooked and analyzed for sensory properties and the fourth cooked and analyzed for Warner Bratzler shear force and cooking loss. In addition, samples were submitted for analysis of bacterial numbers as well as Listeria bacteria. It took about 17 hours for the pH to drop in the loin muscles after slaughter and it took about 24 hours for the carcasses to reach chiller temperature of 5 ° C. Shear force analysis confirmed the tenderness of foal meat. Cooking loss was about 25%. Listeria monocytogenes was not detected, and all samples were within acceptable limits for microbial counts. Generally, rancid flavor was little or not detected but increased proportionally with increasing intramuscular fat and storage time. Foal meat is similar to or lighter but more reddish and yellow than lamb met and there are slight differences between muscles. After 14 days of storage, the meat became slightly redder / yellower. Whole muscles were only 34.7% of carcass weight. Meat trimmings were 28.9%. The total yield was therefore 63.5%. Foal meat is a high-quality meat product and there are opportunities to market as such, and also to develop new products from the trimmings.

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Reports

The effects of insulated tub depth on the quality of iced Atlantic cod / Effect of insulated tub depth on the quality of frozen cod

Published:

01/04/2018

Authors:

Rúnar Ingi Tryggvason, Magnea Karlsdóttir, Björn Margeirsson, Sigurjón Arason, Aðalheiður Ólafsdóttir

Supported by:

AVS R&D Fund (R 17 016-17), Technology Development Fund (164698-1061)

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

The effects of insulated tub depth on the quality of iced Atlantic cod / Effect of insulated tub depth on the quality of frozen cod

The aim of the project was to investigate the quality of cod that had been gutted one day after fishing, frozen and packed in 12 different sized tanks, 4 × 250 L, 4 × 460 L and 4 × 660 L. Experimental fish were monitored at the top and bottom of each tank . The pots were stored in a temperature controlled environment at 1 ° C and measurements were made after 6, 10, 13 and 15 days after packing. To assess the quality of the cod, water loss was used in tanks after storage, processing utilization and sensory evaluation. The results showed that water loss was highest in 660 L pots and lowest in 250 L pots. There was no difference in processing efficiency. In all cases, there was less looseness in the bottom of the pot compared to the top, probably due to the different size of fish in the top and bottom. There was no difference in the results of the quality factor (QIM) evaluation between pots, but the existing sensory evaluation scales do not include the properties on which a clear difference was seen. There was a big difference between fish in the top layer and fish in the bottom layer in all cases, but ice vessels and marine fillets were more bulky on bottom fish. As a follow-up to the experiment, a new sensory evaluation scale will be designed in ongoing research on the quality of frozen and supercooled fish in different large tanks, which will address these factors, ie. let's go for ice cream and bruises in fillets.

The aim of this project was to examine the quality difference of Atlantic cod that had been iced and packed into 12 different sized food containers (tubs), 4 × 250 L, 4 × 460 L and 4 × 660 L. Each tub was split up into two groups, top-and bottom layer. Drip loss, processing yield, and sensory evaluation were used to evaluate the quality of the cod. The results showed that the greatest drip loss was in the 660 L tub, and the least in the 250 L tub. There was no difference in processing yield. Sensory evaluation showed no difference between tubs, except that the fillets from fish in the bottom layer of all containers had less gaping than fillets from the top layer of fish, most likely due to size differences of top-and bottom layer fish. No current sensory evaluation scales account for different amounts of ice marks and crushed fillets that was detected between fish in the top-and bottom layer of the tubs. The results of this project will be used in continuing research of iced and superchilled fish in different sized containers to develop a new sensory scale that will account for these qualities.

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Reports

Improved processing of dried fish proteins / Improved processing of dry fish proteins

Published:

01/05/2014

Authors:

Margrét Geirsdóttir, Aðalheiður Ólafsdóttir

Supported by:

AVS Nr. V 11 038‐11

Contact

Margrét Geirsdóttir

Project Manager

mg@matis.is

Improved processing of dried fish proteins / Improved processing of dry fish proteins

The aim of the project was to improve the production process of the start-up company Iceprotein. Iceprotein has worked on the utilization of unused proteins from fish with good results. However, it is necessary to improve the quality of dried products. The purpose of this project was to improve it and thereby ensure the continued development of this important growth point in Skagafjörður.

The aim of the project was to improve the processing of dry fish proteins at the company Iceprotein. Iceprotein is a development company that utilizes cut ‐ offs from fish processing for production of value added protein products. With this project, the aim was to improve their production and thereby strengthening this frontline company in use of fish by‐ products.

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Reports

Injection and brining of tilapia fillets

Published:

01/12/2009

Authors:

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

Supported by:

Tækniþróunarsjóður Rannís / Technology Development Fund, RANNIS - Icelandic Center for Research

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Injection and brining of tilapia fillets

The aim of the project was to investigate the effect of spraying and pickling on the utilization, shelf life and properties of tilapia fillets. Three product categories were produced: chilled products, frozen products (with insignificant changes in salt content) and lightly salted, frozen products. During the processing of chilled products, red fillets were injected with a weak brine (1% salt) containing a reduced cod base (2% brine protein). Lightly salted fillets were initially sprayed with 4% brine, then pickled overnight. Part of the fillet was frozen after pickling but a similar amount was injected with the protein solution after pickling. Utilization increased during spraying and pickling, there was a significant difference in weight changes in frozen fillets and lightly salted fillets due to differences in the salt content of these two product categories. The waterproofness of fillets was poorer after freezing than after storage in the refrigerator. The shelf life of products was short and possible reasons for this are discussed in the report. Microbial growth and degradation processes were largely independent of injection and brine.

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

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Reports

Processing in line boats / Processing in line boats

Published:

01/06/2009

Authors:

Róbert Hafsteinsson, Albert Högnason, Sigurjón Arason

Supported by:

AVS, Technology Development Fund

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Processing in line boats / Processing in line boats

This project is a collaborative project of the following companies; Matís, Brim, Samherji, Vísir and 3X Technology. The aim of the project is to improve the processing processes of longline vessels with a view to reducing the cost of processing, increasing work efficiency and product quality. The project includes the results of a voyage with the icefish trawler Stefni ÍS, where the goal was to perform different refrigeration and bleeding experiments on cod and thus find out what is the best processing method / processing treatment with regard to the quality of the product. The processing deck on longliners will be designed differently, but the same units are used to maximize the quality of the catch. Several groups were taken who received different processing treatments on board. The groups then went to the processing of Hraðfrystihús Gunnvarar where they underwent a sensory evaluation test in the color and release of the fillets. The main results of the project showed that bleeding in the sea, preferably with a lot of water change, before cooling, gives a better color - the meat quality of the wreck. There was no significant difference between the groups in terms of loss, as they all had similar results.

This project is a collaboration work between; Matis, Brim, Samherji, Vísir and 3X Technology. The object of this project is to improve the process in line boats, by reducing production costs, improve working conditions and product quality. This project includes payoff from voyage with the ice-fresh trawler Stefnir ÍS, where the objective was to carry out difference bleeding and cooling methods on cod and find out which methods is efficient regards to the quality of the product. The processing deck in line boats will be implement difference, but same unitary will be used to increase the quality of the catch. The primary conclusion from the research on board Stefnir, is that bleeding in sea before cooling the fish, gives better results regard to the color of the fillet. The research also shows that there was not a significant difference between groups regards to results in looseness of the fillet.

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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

Improved quality of herring for human consumption

Published:

01/12/2007

Authors:

Ásbjörn Jónsson, Hannes Hafsteinsson, Irek Klonowski, Valur N. Gunnlaugsson

Supported by:

Nordic Innovation Center

Contact

Valur Norðri Gunnlaugsson

Research Group Leader

valur.n.gunnlaugsson@matis.is

Improved quality of herring for human consumption

Herring is one of the most important fish species in the North Atlantic and the Baltic Sea. Although a large part of the catch goes to human consumption, about 85% of herring is processed into fish oil and flour. There is a general desire to increase the consumption of herring for human consumption. It was important to study the different factors that affect the quality of herring and especially how they are controlled by biological conditions. The main reason for the quality problems in herring is the high content of compounds that promote development, and affect the color and texture changes, as well as the loss of nutrients. Better quality results in increased competition for herring production in the Nordic countries, as well as a positive consumer attitude towards herring products. The main goal of the project was to improve the quality and quantity of herring, for consumption, by researching the quality of the raw material after fishing. Emphasis was placed on quality immediately after fishing and the quality of the raw material after varying periods of frost. Factors such as fishing location and fishing time did not affect the quality of the herring. However, freezing at -20 ° C had a significant effect on the quality of the raw material.

Herring is one of the most important fish species in the North Atlantic and Baltic Sea, with an annual catch exceeding 2 million tonnes. Although a large part of these fish is used for human consumption, as much as 85% of the herring is used for industrial production of fish meal and fish oil. There is a general wish to increase the utilization of herring for human consumption. Thus, it was important to study the various parameters which influence the quality of herring, and in particular how these paramenters are controlled by biological factors. A major reason behind quality problems arising during post-harvest handling of herring is its high content of compounds that efficiently catalyzes the development of rancidity, pigmentation, texture changes and loss of nutritional value. Improved quality will result in increased competitiveness of the Nordic fish processing industry and would improve the attitude among consumers towards herring products. The general objective of the project was to improve the quality and quantity of herring to be used for food production by investigating how natural variation in raw material characteristics affects post-harvest quality. Attention was given to the quality immediately after landing and the quality after period of frozen storage. The results indicated no clear differences in the quality of herring regarding catching place or season. The frozen storage for a prolonged time had the major influence on the quality of herring fillets.

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Reports

Shelf life tests on cod pieces: Effects of supercooling on salt and protein injected cod muscles

Published:

01/12/2007

Authors:

María Guðjónsdóttir, Kolbrún Sveinsdóttir, Hannes Magnússon, Sigurjón Arason

Supported by:

Rannís Research Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Shelf life tests on cod pieces: Effects of supercooling on salt and protein injected cod muscles

An integrated refrigeration study was performed on the effects of salting, protein injection and subcooling on the quality, chemical and physical properties of salt and protein injected cod muscles. The study shows that by injecting salt and protein into the muscle, utilization can be improved, drip reduced and the boiling efficiency of the muscle increased. On the other hand, the injection of salt and protein into muscles increases microbial growth and the formation of erratic alkalis, thus shortening the shelf life of the product. However, lowering the storage temperature could inhibit the growth of microorganisms and the formation of erratic alkalis. Decreased storage temperature, however, led to cell damage due to ice formation on the surface regardless of the salinity of the muscle. Therefore, it is not considered desirable to store fresh or lightly salted cod muscle at temperatures below -2 ° C. The effect of rinsing the samples in a brine bath after injection was also investigated. Such rinsing did not significantly affect the water and salinity or efficiency of the samples, but showed a reduction in the formation of erratic bases. It is therefore advisable to rinse fillets in brine after injection to prevent damage to the best extent possible. Sensory evaluation results showed that the properties of the muscle changed significantly with the injection of salt and protein into the muscle, but the injected groups lost their freshness characteristics until the fresh untreated control group.

A combined cooling experiment was performed on the effect of salting, protein injection and superchilling on the quality and physicochemical properties of brine and protein injected cod muscle. The study showed that brine and protein injections lead to increased processing and cooking yield, as well as decreased drip. Injection of salt and proteins increase on the other hand microbiological growth and the formation of volatile nitrogen bases, which in turn leads to shorter shelf life. By lowering the storage temperature this growth of microorganisms and volatile nitrogen bases could be decreased. If the storage temperature is kept too low this on the other hand led to cell damages due to ice crystallization on the muscle surface, independent on the salt content of the muscle. It is therefore not recommended to store fresh and light salted cod at temperatures below -2 ° C. The study also viewed the effect of brining the muscle after brine and protein injection. This brining had no significant effect on the salt or water content of the muscle but decreased the amount of volatile bases. It is therefore recommended that cod muscle is always washed in brine after injection to keep damaging processes at a minimum. Sensory analysis showed a significant difference between the characteristics of brine and protein injected samples to unprocessed cod muscle. The injected groups also lost their freshness characteristics earlier than the unprocessed control group.

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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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