Reports

The keeping quality of chilled sea urchin roe and whole urchins

Published:

20/09/2017

Authors:

Guðmundur Stefánsson, Aðalheiður Ólafsdóttir

Supported by:

Northern Periphery and Arctic Program 2014-2020

contact

Guðmundur Stefánsson

Head Research Group Leader

gudmundur.stefansson@matis.is

The keeping quality of chilled sea urchin roe and whole urchins

Sea urchins (Strongylocentrotus droebachiensis) are common off the coast of Iceland and are caught in small quantities and exported mainly as whole pots. Landings in 2015 were 280 tonnes. There are markets in Europe and Asia for sea urchin roe fresh, frozen or otherwise processed. In this study, the shelf life of fresh and pasteurized eggs stored at 0-2 ° C was assessed. The effects of freezing, both slow freezing (blow freezing at -24 ° C) and rapid freezing (nitrogen freezing) were studied as well as dextrin and alum treatment. It was also estimated how long the pots kept alive at 3-4 ° C were kept alive. The sea urchins were caught in Breiðafjörður with a plow and landed at Þórishólmur in Stykkishólmur where they were processed. Some of the sea urchins were opened, the eggs removed, cleaned and used in the experiments. Whole sea urchins were packed in plastic boxes in a similar way as when exported. The freshness characteristics of fresh sea urchin roe are the smell and taste of the sea, the smell of egg yolk and the taste and sweetness of the sea. The taste of pasteurized eggs was similar to that of fresh eggs but milder. In general, over time, the sweet, sea and egg yolk taste faded, but the metallic, kelp and chemical characteristics increased. The shelf life of fresh sea urchin eggs is limited by changes in texture - eggs dissolve and become unpalatable - and a shelf life of 0-2 ° C can be expected for one to four days. Sterilized eggs kept their freshness characteristics for at least 14 days and had a shelf life of 22 days or more at 0-2 ° C without any changes in texture. The freezing of fresh sea urchin eggs resulted in them becoming mushy during translation and there did not appear to be a difference between slow-freezing or rapid-freezing. After three months of storage at -24 ° C, thawed eggs developed a strong odor which rendered them unfit for consumption. Freezing pasteurized eggs had little or no effect on their texture or taste; however, after six months of cold storage, evidence of maladaptation was found. Aluminum treatment resulted in a strong odor that rendered the eggs unfit for consumption. The preservatives sorbate and benzoate resulted in a strong taste in the eggs and a metallic aftertaste, but treatment with dextrin did not appear to have much effect on sensory properties. All whole sea urchins were alive after 5 days from fishing but on day 9 one of the 18 vessels was dead but no damage was found. It can be assumed that a whole sea urchin stays alive at 3-4 ° C between five and nine days after fishing.

The green sea urchin (Strongylocentrotus droebachiensis) is commonly found in Iceland and is currently fished and exported mainly as whole urchins. The catch in 2015 was 280 tons. There are markets both in Europe and Asia for urchin roe, fresh, frozen or processed. In this study the shelf-life of fresh and pasteurized sea urchin roe, stored at 0-2 ° C was evaluated. The effect of freezing (blast freezing and freezing in liquid nitrogen), treatment with dextrin and alum was evaluated on both fresh and pasteurized roe. Further, the keeping quality of whole (live) sea urchins at 3-4 ° C was evaluated. The sea urchins were caught in the Breidafjordur area using a modified dredge, landed at Thorisholmi in Stykkishólmur, cleaned and the whole live sea urchin were packed in the same manner as that for export. Part of the sea urchins was opened up and the roe removed, cleaned and used for the experimental trial. The freshness characteristics of fresh sea urchin roe were found to be sea odor & flavor, egg yolk odor & flavor and sweet flavor. The flavor was similar but milder in pasteurized beet. In general, with time the sweet, egg yolk and sea flavors seemed to decrease but metallic, seaweed and chemical flavors increased. The shelf-life of fresh roe is limited by changes in texture - the roe liquefies - as indicated by sensory evaluation and can be expected to be between one and four days at 0-2 ° C. Pasteurised roe had a freshness period of at least 14 days and a shelf life of 22 days or more at 0-2 ° C, with no detectable changes in appearance or texture during that time. Freezing of fresh roe resulted in a porridge like texture at thawing and no difference was seen between freezing methods, blast freezing and liquid nitrogen freezing. After three months storage at -24 ° C frozen roe had developed a strong off-flavor and were considered unfit for consumption by the panelists. Freezing of pasteurized roe did not change the texture or flavor of the roe; however, after 6 months of freezer storage, the roe had a trace of an off-flavor. Treatment with alum gave all samples a strong off-flavor which made them unfit for consumption. Preservatives (a mix of sorbate and benzoate) gave a strong flavor and a metallic aftertaste but treatments with dextrin did not have a considerable effect on sensory characteristics. All whole sea urchins were alive after 5 days from catch, but on day 9 from catch, one urchin out of 18 had an open mouth but no spoilage odor was detected. It is estimated that the shelf life of live sea urchins is between five and nine days from catch at 3-4 ° C.

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Reports

Sub chilling of fish

Published:

17/07/2017

Authors:

Gunnar Þórðarson, Sigurjón Arason, Magnea Karlsdóttir

Supported by:

Technology Development Fund

contact

Gunnar Þórðarson

Regional Manager

gunnar.thordarson@matis.is

Sub chilling of fish

The aim of the project was to utilize the knowledge of supercooling of fish that has been developed in laboratories in recent decades; industrialize the concept and develop methods and equipment to control the cooling. It is important to cool the raw material below the freezing point or just below the temperature at which the first ice crystals form in the fish species in question, fast enough so that large crystals do not form in the muscles and cause cell damage. It is important to control the cooling correctly as well as to maintain a supercooled condition during storage and transport, but fluctuations in temperature can cause quality deterioration. The results of research show that ice-free transport and storage of super-chilled fish is a realistic solution that reduces the cost of fishing and processing as well as reducing the cost of transport and significantly reducing the footprint of fresh fish production. Fresh salmon has been transported ice-free but super-chilled for shorter and longer distances and stored for a week before processing with excellent results. In connection with the project, supercooling has been used on a large scale in Sauðárkrókur, where the trawler Málmey SK 1 has landed over 15 thousand tonnes in the past two years of supercooled catch and thus not used ice on board or for storage for production in fish processing.

The project objective was to utilize knowledge of sub chilling of fish developed in laboratories for the past decades; and to industrialize the concept and to develop methods and means for centralizing the process. The control of the chilling process is important, to chill raw material sufficiently without freeze out more than 20% of its water and without developing large ice crystals in the muscles. It is also important to keep storage temperature under control and stable and for the same reason temperature fluctuation can cause growth of ice crystals in the muscle. Based on results obtained in present project it can be concluded that sub chilling provides opportunities to use ice-free value chain for fresh fish, lowering cost of production, logistic and considerably the carbon footprint for the final products. Fresh salmon without any external refrigerant (ice) has been transported for long distance, by trucks and airplanes, and stored for long time with acceptable results. The trawler used in this project has landed over 15 thousand tonnes of sub chilled fish for the last two years without using any ice for chilling and storage. The fish is stored in the fish plant and processed without using any ice preservation.

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Reports

The effects of different packaging solutions on the shelf life of fresh cod loins - drainage holes, cooling media and plastic bags

Published:

22/03/2017

Authors:

Magnea G. Karlsdóttir, Björn Margeirsson, Sigurjón Arason

Supported by:

Tempra ehf, Útgerðarfélag Akureyringa ehf

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

The effects of different packaging solutions on the shelf life of fresh cod loins - drainage holes, cooling media and plastic bags / The effect of different packaging solutions on the shelf life of fresh cod necks
Boys' clothes, refrigerants and plastic bags

The aim of the study was to investigate the effect of different foam plastic boxes (with and without boys), the amount of coolant and plastic bags compared to plastic film in boxes on the quality of fresh cod necks. The age of the raw material during processing was about two days. Five different experimental groups were prepared and stored at -1.7 ° C for five days and subsequently stored at 2 ° C for 9 days, or the remainder of the storage period. Sensory assessment (Torry freshness assessment) and drip / water loss during storage were assessed 1, 7, 9, 12 and 14 days after packing. The results indicated that a neck piece packed under plastic wrap in a foam box without a boy and with the smallest amount (250 g) of refrigerant in the box was damaged significantly faster compared to other experimental groups. The longest shelf life from packing (12 days) was measured for products that were packed in a foam plastic box without boys, but were in a plastic bag inside the box and with a larger amount (750 g) of refrigerant (ice) outside the plastic bag. The results underlined the importance of maintaining a low and constant temperature throughout the storage period.

The aim of the study was to explore the effects of different expanded polystyrene (EPS) boxes (with and without drainage holes), cooling media and plastic bags compared to plastic films inside the boxes on the shelf life of fresh cod loins. The fish was caught two days before processing. Five experimental groups were prepared and stored at around - 1.7 ° C for five days followed by subsequent storage at around 2 ° C for nine days. Sensory (Torry score) and drip loss evaluations were performed 1, 7, 9, 12 and 14 days post packaging. The results indicated that loins packed under a plastic film in EPS boxes (without drainage holes) and with the lowest amount (250 g) of cooling medium spoiled faster compared with the other experimental groups. The longest shelf life from packaging (12 days) was obtained for loins packed in EPS boxes inside a plastic bag and covered with a larger amount (750 g) of ice. Furthermore, the sensory results were in accordance with the temperature profiles of the experimental groups, stating the advantages of a low and stable storage temperature.

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Reports

Effect of salt content in slurry ice on quality of fresh and thawed Atlantic mackerel (Scomber scombrus)

Published:

01/12/2015

Authors:

Paulina E. Romotowska, Björn Margeirsson, Gísli Kristjánsson, Sigurjón Arason, Magnea G. Karlsdóttir, Sæmundur Elíasson, Arnljótur B. Bergsson

Supported by:

AVS Fisheries Research Fund (R 12 029-12)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Effect of salt content in slurry ice on quality of fresh and thawed Atlantic mackerel (Scomber scombrus)

The aim of the experiment was to improve methods of cooling and storage of fresh produce in order to improve the quality of frozen mackerel products. A comparison was made of cooling in conventional ice scrapers and salt-improved ice scrapers. By adding salt to the ice scraper, it was hoped that the temperature of fresh mackerel could be lowered and thus its quality maintained longer. The fresh mackerel was stored for up to seven days after fishing. Another aim of the study was to investigate whether this different cooling of fresh mackerel affects the deterioration of the quality of frozen mackerel products. The results showed that the temperature distribution in the pots was related to salt concentration as lower temperatures were obtained in pots with higher salt content (3.3%). On the other hand, the cold storage had a much greater effect on the quality factors such as the freshness and release of the mackerel products compared to the effect of pre-cooling, as the effect of different salt concentrations in the ice scraper was negligible in terms of these quality factors.

The present experiment is part of the research project - Increased value of mackerel through systematic chilling. The aim of this study was to improve methods of chilling and storing of fresh products in order to obtain better quality of frozen mackerel products. This project was carried out to develop slurry ice mixture with addition of extra salt, with the intention of temperature decrease during chill storage up to seven days after catch. Secondary objective of this research was to investigate if different chilling condition of fresh fish has an effect on the quality assignment of long-term frozen mackerel products. The results showed that temperature distribution in the tubs was correlated to the salt concentration where lower temperature was obtained in the tub with higher salt content (3.3%). Furthermore, freshness, gaping and peritoneum deterioration have been affected by the storage process but not by different salt concentration in slurry ice during chilled storage. Due to high quality variation within the same group of the mackerel is needed to conduct more methods for quality evaluation such as oxidation analysis and sensory analysis.

Report closed until 01.01.2018

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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

Improved utilization of lumpfish

Published:

27/06/2013

Authors:

Gunnar Þórðarson (Matís), Skjöldur Pálmason (Fiskvinnslan Oddi), Ólafur Reykdal (Matís)

Supported by:

AVS V 11 020‐11

contact

Gunnar Þórðarson

Regional Manager

gunnar.thordarson@matis.is

Improved utilization of lumpfish

The Ministry of Fisheries and Agriculture's regulation, No. 1083/2010, made it obligatory to bring all grayling catch ashore after 2011. It was therefore necessary to react quickly and find a market for the grayling itself, but only the roe had been harvested and the rest thrown into the sea. . A great deal of entrepreneurship had taken place for several years, and it is worth mentioning the National Association of Small Boat Owners and the export company Triton in that context, which together built up a market for grayling in the Chinese market, with a bang and all. It should be noted that the roe is about 30% by the weight of the grayling, while the whale with the head and tail is about 55%, of which the fillets are only 14% of its total weight. There was a lot of work to be done and it is clear that there is great value in this underutilized fish species and great opportunities would be created in many coastal settlements for the production and export of grayling. At the same time, increased income for fishermen and the fishing industry, as well as the fact that the grayling was now mostly brought ashore, which created a lot of work for production parties. Cutting for the Chinese market is different from the traditional method and requires more complex procedures, but it requires better working conditions that do not exist on board small fishing boats. There was little information on the chemical and nutritional content of grayling, but such information is necessary when marketing products. A detailed report was prepared on the material and raw materials are used in many parts of the country. Shelf life tests were performed on frozen grayling. A conference was held in Patreksfjörður where stakeholders in the fishing, processing and export of grayling were invited to discuss the interests of the industry.

A new regulation from Minister of Fisheries and Agriculture, No. 1083/2010, require returning all lumpfish fished in Iceland, after 2011. A quick action had to be taken to find markets for lumpfish itself, but only the roes which have been processed but the rest of the fish have been discarded into the sea. With entrepreneurial activity for some years now new markets have been developed in China, by the National Association of Small Boat Owners in Iceland in cooperation with the export company Triton. It should be noted that the roes are only about 30% of the total weight of lumpfish, with head and tail about 70% of its total weight. There was much to be done to save value in the lumpfish business and great opportunities for small communities relying on this business and find a market for the lumpfish product and create extra value for stakeholders. Furthermore, increased income for fishermen and fishing communities by creating valuable work by processing the fish at shore. Gutting and trimming the lumpfish for the China market is different from the traditional approach and calls for more sophisticated self-administration, but it requires better working conditions that do not exist on board small fishing boats. Very little information on chemical composition and nutrient value has been available for lumpfish products. An in-depth report on this subject was prepared, using samples from different regions in Iceland. Self ‐ life experiments were prepared by this project. A work shop was held in Patreksfjordur in May 2013, with stakeholders from the lumpfish business participating.

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Reports

Effect of superchilled processing of whole whitefish - pre ‐ rigor / Effect of supercooling on spoilage processes and shelf life of whole fish and fillets

Published:

01/05/2012

Authors:

Aðalheiður Ólafsdóttir, Björn Margeirsson, Kolbrún Sveinsdóttir, Sigurjón Arason, Eyjólfur Reynisson, Emilía Martinsdóttir

Supported by:

AVS Fund of Ministry of Fisheries in Iceland (R 062‐11)

contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

Effect of superchilled processing of whole whitefish - pre ‐ rigor / Effect of supercooling on spoilage processes and shelf life of whole fish and fillets

The aim of the experiment was to investigate the effect of supercooling on the damage processes and shelf life of whole fish and fillets. A study was carried out on whole supercooled cod soon after fishing and also on the effect of supercooling on fillets made from supercooled cod and cod cooled in ice in the traditional way. Temperature measurements, sensory evaluation, chemical and microbial measurements were used to compare the following experimental groups, which were stored at –1.4 to –1.2 ° C average temperature:

1) NC: whole cod cooled in ice

2) SC: supercooled whole cod

3) NC-NC: traditional fillet processing from whole cod cooled in ice

4) NC ‐ SC: super-chilled fillets made from whole cod cooled in ice

5) SC-NC: traditional fillet processing from super-chilled whole cod

6) SC-SC: super-chilled fillets made from super-chilled whole cod

Sensory evaluation results suggest that supercooled processing of whole cod can extend its shelf life by two days. Supercooling of whole cod did not affect the acidity, water content, water resistance and microbial growth of whole fish compared to fish that were not supercooled during processing. According to sensory evaluation, there was little difference in the shelf life of different fillet groups. Shelf life was estimated at 16-18 days, which is quite a long time for cod fillets. However, the freshness period of the experimental group SC-SC seemed to be somewhat longer than the other groups. As with whole cod, there was little difference between the fillet groups in terms of microbial growth, chemical and physical properties. Limited differences between experimental groups can possibly be explained by stable and supercooled storage conditions. With this in mind, it is planned to carry out another similar experiment, which will simulate more typical environmental temperature processes in the transport of fresh fish products (0–4 ° C) than in this experiment (–1.4 to –1.2 ° C).

The main aim of the study was to study the effects of superchilled processing on storage life of both whole fish and fillets. The following experimental groups were evaluated by means of temperature monitoring, chemical and microbial measurements and sensory evaluation, which were stored at mean temperatures of –1.4 to –1.2 ° C:

1) NC: non ‐ superchilled whole cod

2) SC: superchilled whole cod

3) NC ‐ NC: non ‐ superchilled fillets from non ‐ superchilled whole cod

4) NC ‐ SC: superchilled fillets from non ‐ superchilled whole cod

5) SC ‐ NC: non ‐ superchilled fillets from superchilled whole cod

6) SC ‐ SC: superchilled fillets from superchilled whole cod

The results from the sensory evaluation indicate that superchilled processing of whole cod can extend shelf life by two days. Differences in values of pH, water content, water holding capacity and bacterial growth between the superchilled and non ‐ superchilled whole fish groups were minor. Differences in sensory scores between the fillet groups were small. Shelf life was estimated between 16 and 18 days which is quite long shelf life for cod fillets. However, the SC ‐ SC group seemed to retain freshness a little longer than other groups. As in case of the whole cod, the differences in bacterial count, chemical and physical properties between the fillet groups were small. Very similar fish temperatures between both the whole fish and the fillets groups resulting from the superchilled storage conditions applied may be the main reason for the small differences obtained. Thus, another study with more common temperature conditions during transport and storage of fresh fish (chilled but not superchilled) will be performed.  

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Reports

Development of QIM and shelf life of fresh mackerel (Scomber scombrus) / Development of QIM and shelf life of fresh mackerel (Scomber scombrus)

Published:

01/03/2012

Authors:

Aðalheiður Ólafsdóttir, Elvar Steinn Traustason, Ásbjörn Jónsson, Kolbrún Sveinsdóttir, Kristín Anna Þórarinsdóttir

Supported by:

AVS Fisheries Research Fund (R 11 037‐010)

contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

Development of QIM and shelf life of fresh mackerel (Scomber scombrus) / Development of QIM and shelf life of fresh mackerel (Scomber scombrus)

The aim of the project was to examine changes that occur in mackerel during ice storage. Develop a QIM scale for fresh mackerel and compare it with the results of cooked fish assessments and QDA (quantitative descriptive analysis) to determine the end of shelf life. Based on QDA results, it can be concluded that mackerel stored for 9 days on ice has reached the limit of shelf life. Taste and odor symptoms (fresh oil) are then reduced and damage symptoms (cravings and bitterness) take over.

The aim of the project was to look at the changes in mackerel at storage on ice. Develop a QIM spectrum for fresh mackerel and compare with cooked fish, QDA (quantitative descriptive analysis) to decide maximum shelf life. From the QDA results, one can conclude that maximum shelf life for fresh mackerel is 9 days on ice. At that time freshness in taste and odor are decreasing and characteristic of spoilage (rancidity and bitter) dominates.

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Reports

Germicidal effects of UV light on processing line surfaces and pork shelf life / Effect of UV light on microbial contamination of processing surfaces and shelf life of pork products

Published:

01/12/2011

Authors:

Sveinn Magnússon, Eyjólfur Reynisson, Viggó Marteinsson

Supported by:

Technology Development Fund

contact

Viggó Marteinsson

Group Leader

viggo.th.marteinsson@matis.is

Germicidal effects of UV light on processing line surfaces and pork shelf life / Effect of UV light on microbial contamination of processing surfaces and shelf life of pork products

The antimicrobial effect of UV radiation has been known for a long time, but UV radiation at 254nm (UV ‐ C) causes damage to the genetic material of cells and prevents microbial growth. The use of UV lighting for disinfection has increased, for example in the food industry - where UV radiation can be used to disinfect processing surfaces and food - thereby increasing safety and extending the shelf life of food. This report describes a test of the effect of UV exposure on the processing surface on the shelf life of meat products. The effect of UV exposure on the surface of meat processing - the conveyor belt and cutting board - on the shelf life of pork products was examined. The results of the study show that UV exposure has the effect of reducing the microbial content of processing surfaces. The results regarding the effect on shelf life were not decisive, but indicate that with a clean processing line and UV lighting on the processing surface, the shelf life of pork products from the processing line can be increased.

UV radiation at 254nm (UV ‐ C) causes damage to the genetic material of cells and prevents microbial growth. The use of UV light for disinfection is increasing eg in the food production industry - where UV radiation can be used for disinfection of food production surfaces and foods - and thereby increase food safety and extend product shelf life. This report describes the testing of the effects of UV lighting on surfaces in food processing facility on product shelf life. Effects of UV lighting on process line surfaces - conveyor belt and cutting boards - on the shelf life of pork was examined. The results of the study show that UV reduces the bacterial load on process line surfaces. Regarding the effects on pork shelf life the results were not significant but suggest that cleaner process lines and UV lighting on process line surfaces can increase the shelf life of pork products.

Report closed until 01.01.2014 / Report closed until 01.01.2014

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Reports

Effect of cooling and packaging methods on the quality deterioration of redfish fillets

Published:

01/09/2011

Authors:

Hélène L. Lauzon, Aðalheiður Ólafsdóttir, Magnea G. Karlsdóttir, Eyjólfur Reynisson, Björn Margeirsson, Sigurjón Arason, Emilía Martinsdóttir

Supported by:

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

contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

Effect of cooling and packaging methods on the quality deterioration of redfish fillets

The aim of the experiment was to evaluate the effect of slush ice cooling after filleting and / or packing in vacuum packaging on the deterioration of the quality of fresh redfish fillets. The fillets were stored at -1 ° C for 6 days to simulate well-executed sea transport in foam plastic boxes and then at 2 ° C, as happens after delivery abroad and storage in retail. Product and ambient temperature were monitored from packaging and sensory evaluation, microbial and chemical measurements were performed. The fish was caught in the spring and processed 6 days after fishing. The results show that the quality of the raw material was not the best during packaging as the development process (PV and TBARS) was well underway. This probably explains why none of these refrigeration methods led to an increase in shelf life. It was also found that there was no benefit in cooling the fillets unprotected in slush ice as the microbial growth and formation of TVB-N and TMA in the fillets was faster with further storage. However, it seems preferable to refrigerate vacuum packed fillets in ice cream as this method has led to slower growth of pest microorganisms, lower TMA levels and a slower development process. Photobacterium phosphoreum is important in the process of damaging fresh redfish fillets, regardless of the packaging method.

The aim of this study was to evaluate the effect of slurry ice cooling in process (post ‐ filleting) and packaging method (+/‐ oxygen) on the quality deterioration of skinned redfish fillets during storage in expanded polystyrene boxes simulating well ‐ performed sea freight transportation (6 days at ‐1 ° C) followed by storage at the retailer (2 ° C). Also, to assess the use of vacuum ‐ packaging to protect the fillets from direct contact with the cooling medium (slurry ice) and to achieve superchilling following extended treatment. Temperature monitoring as well as sensory, chemical and microbial analyzes were performed. The fish was caught in the spring and processed 6 days post catch. The results show that quality of the fillets was not optimal at packaging, due to the detection of primary and secondary oxidation products. This may have been the reason why shelf life extension was not achieved by any of the methods evaluated. Further, there was no advantage of cooling the fillets unpacked since this method stimulated microbial growth and formation of basic amines. On the other hand, slurry ice cooling of vacuum ‐ packaged fillets led to a slower microbial development, the lowest TMA level and delayed autoxidation. Finally, the importance of Photobacterium phosphoreum in the spoilage process of redfish fillets, independently of the packaging method, was demonstrated.

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