Reports

Increased quality and stability of frozen herring products

Published:

01/11/2018

Authors:

Magnea Karlsdóttir, Huong Thi Thu Dang, María Guðjónsdóttir, Sigurjón Arason, Ásbjörn Jónsson

Supported by:

AVS R&D Fund (R 069-14)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Increased quality and stability of frozen herring products

Freezing and cold storage is an effective method of maintaining quality and extending the shelf life of seafood. The production of frozen products equals the supply of products where fishing is seasonal. There are many factors that can affect the quality and stability of frozen products. These include the condition of the raw material, processing methods and conditions for storage and transport, to name but a few. The aim of the study was to investigate the changes that take place in the chemical and physical properties of frozen herring fillets with regard to the condition of raw materials during processing and conditions in cold storage. Atlantic herring was processed before and after death solidification, and the fillets were stored under stable storage conditions (-25 ° C) and unstable conditions (at -25 ° C for 2 months, then -12 ° C for one month and then again at - 25 ° C for the duration of storage). To study the stability and physical properties of the products, water loss (drip), boiling efficiency and color were measured, in addition to which both light and dark fish muscles were measured for water resistance, pH, chemical composition, fatty acid composition, enzyme activity and evolution. The study showed that it is important for the fishing industry to ensure uniform and correct temperature control when products are stored in the freezer. Processing and freezing before death solidification, in parallel with stable storage conditions, has a positive effect on the quality and stability of herring falcons. In addition, the study confirmed that the fatty state of the herring muscle, often referred to as the dark muscle, is very sensitive to development. In order to extend the shelf life of frozen herring fillets, it is recommended that this muscle be removed in parallel with deep skinning.

Freezing and frozen storage has proven to be an effective method to preserve and prolong the storage life of seafood products. Production of frozen products provides all year around product availability although the catching is seasonal. There are several factors that can affect the quality and stability of frozen fish products, including the state of the raw material, processing methods and storage conditions. The aim of the study was to explore how physicochemical properties of frozen herring fillets are affected with respect to the state of the raw material during processing as well as storage conditions. Atlantic herring was processed and frozen pre- and post-rigor and stored at stable (-25 ° C) and abused storage conditions. To investigate the storage stability and physical properties of the fillets, thawing drip, cooking yield and color were evaluated, as well as proximate composition, fatty acid composition, pH and lipid degradation of the light and the dark muscle. The study demonstrated the importance of stable and controlled temperature during storage and transportation of frozen herring products. Processing and freezing pre-rigor, in combination with stable storage conditions, was shown to be beneficial in terms of preventing lipid oxidation, as well as reducing thawing loss and maintaining the cooking yield of the herring fillets.

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Reports

Impact of season, bleeding methods and storage temperature on the quality and stability of frozen cod climbs

Published:

01/04/2016

Authors:

Magnea G. Karlsdóttir, Sigurjón Arason, Ásbjörn Jónsson

Supported by:

AVS Fisheries Research Fund

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Impact of season, bleeding methods and storage temperature on the quality and stability of frozen cod climbs

The main goal of the project was to increase utilization and at the same time knowledge of the stability of cod climbing in frost according to the season. With increased knowledge of the effects of the season, the quality of raw materials and storage conditions on the stability of the liver in frost, it is possible to ensure that raw materials for further processing are available all year round. This report discusses the effects of the season, bleeding methods and storage temperature on the quality and stability of frozen cod climbs. Evaluation factors included enzymatic activity (free fatty acids) and evolution (primary and secondary subjects' evolution). Seasonality had a significant effect on the chemical composition and enzyme activity of the liver. This was reflected in higher fat content and higher levels of free fatty acids in the liver collected in July compared to liver from April. Frost stability also varied with the time of year as the liver from July was more susceptible to peroxide formation. Different bleeding methods (bleeding and gutting in one go (one step) and bleeding first and then gutting (two steps)) generally had little effect on the chemical composition and enzymatic activity of the liver. The haemorrhage methods, on the other hand, had a significant effect on the formation of a second-stage imagery of frostbite during storage, as the liver from fish bled in 2 steps was less craving compared to the liver from fish bled in one step. Storage temperature and time had a decisive effect on the stability of the livers in frost. Based on the available results, it is recommended to store frozen liver at -25 ° C rather than -18 ° C in order to slow down the damage process.

To our knowledge, there is limited information available regarding the effects of temperature, bleeding method, and seasonal variation on oxidation stability of cod liver during frozen storage. A profound knowledge of cod liver stability during frozen storage is needed to secure the available supply of cod liver for processing all year around. The objective of the present study was therefore to evaluate lipid deterioration during frozen storage of cod liver. The effects of temperature, storage time, bleeding method, and seasonal variation on lipid hydrolysis and oxidation were analyzed. Time of year significantly affected the chemical composition and enzymatic activity of the liver, which was reflected in a higher fat content and higher level of free fatty acids in the liver collected in July compared to liver collected in April. Stability during frozen storage also varied with season where liver from July was more vulnerable towards peroxidation. Different bleeding methods (bleeding and gutting in one step compared to bleeding first and then gutting (two steps)) had significant effect on the lipid oxidation where liver from fish bled in one step turned out to be more rancid compared to liver from fish bled in two steps. Storage temperature and time proved to be important factors with regard to lipid degradation of cod liver during frozen storage. Based on present results, in can be recommended to store frozen liver at - 25 ° C rather than -18 ° C in order to slow down these damage reactions.

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Reports

Effects of temperature fluctuations during storage and transport on quality and stability of frozen mackerel products

Published:

01/12/2015

Authors:

Magnea G. Karlsdóttir, Paulina E. Romotowska, Sigurjón Arason, Ásbjörn Jónsson, Magnús V. Gíslason, Arnljótur B. Bergsson

Supported by:

AVS Fisheries Research Fund (R 040-12)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Effects of temperature fluctuations during storage and transport on quality and stability of frozen mackerel products

The aim of the project "Maximizing the quality of frozen mackerel products" is to study the quality and stability of mackerel products in frost according to the seasons and the effects of different pre-cooling, freezing and storage conditions. By looking at the interplay of these factors, it is possible to maximize the quality and utilization of mackerel and therefore at the same time its value. This is the first report from the project and it deals with the effects of temperature fluctuations during storage and transport on the quality and stability of frozen mackerel products. Evaluation factors included release, enzyme activity and evolution. Containers were transported to Japan. Whole frozen raw materials provided in late July and early September were frozen and stored at -25 ° C for one month. During "transfer", the product was stored at -18 ° C ± 5 ° C for one month. The samples were measured before freezing, after the "transfer", and thereafter every 3 months in storage at -25 ° C. For comparison, samples were stored at a constant temperature (-25 ° C). In addition, whole frozen mackerel products were stored for up to 12 months at -18 ° C as well as -15 ° C to assess the effects of different storage conditions. There was a clear difference in the quality and stability of frozen mackerel products that were stored at low and stable temperatures compared to products that were subjected to heat stress, for example due to container transport. The results show that mackerel should not be stored above - 25 ° C.

The aim of the project “Quality optimization of frozen mackerel products” is to study the quality and stability of mackerel products during frozen storage as affected by season, different pre-cooling methods, freezing techniques and storage conditions. This is the first report from the project and describes the effects of temperature fluctuations during storage and transportations on quality and stability of frozen mackerel products. The main attributes investigated were eg gaping, enzymatic activity and rancidity. Container shipment were simulated. Whole mackerel caught late July and early September was frozen and stored at -25 ° C for one month. During “transportation”, the products were heat abused at -18 ° C ± 5 ° C for one month. Samples were analyzed after freezing, the transportation and with 3 months interval during subsequent storage at -25 ° C. For comparison, samples were stored at stable temperature (-25 ° C). Additionally, frozen mackerel products were stored for up to 12 months at -18 ° C and -15 ° C to further evaluate the effects of storage temperature. A significant difference in quality and stability were detected between products stored at stable and low temperature and products that underwent heat abuse during eg transportation. The results demonstrate that frozen mackerel products should not be stored at higher temperatures than -25 ° C.

Report closed until 01.01.2018

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Reports

Effect of brining and frozen storage on physicochemical properties of well-fed Atlantic mackerel (Scomber scombrus) intended for hot smoking and canning

Published:

01/12/2015

Authors:

Paulina E. Romotowska, María Gudjónsdóttir, Magnea G. Karlsdóttir, Sigurjón Arason, Ásbjörn Jónsson, Hörður G. Kristinsson, Telma B. Kristinsdóttir

Supported by:

AVS Fisheries Research Fund (R 040-12)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Effect of brining and frozen storage on physicochemical properties of well-fed Atlantic mackerel (Scomber scombrus) intended for hot smoking and canning

Mackerel (Scomber scombrus) is a relatively new species off the coast of Iceland. As mackerel is a fatty fish with a short shelf life, it therefore requires maximization of storage conditions and processing processes. In this project, changes in the chemical and physical properties of the heat treatment of salted and unsalted mackerel were studied. Prior to processing, the fish was stored for 6, 9 and 12 months at -18 ° C and -25 ° C with a view to examining how well Icelandic frozen mackerel is suitable as a raw material in canned and hot-smoked products. To examine the effect of heat treatment on the processing properties of mackerel, the samples were heated to 75 ° C (to simulate smoking) and 90 ° C (to simulate canning). Prolonged storage in the freezer had a negative effect on the raw material due to increased development and the fish stored at -18 ° C had a significantly poorer quality compared to fish stored at -25 ° C before processing. The results showed that a product heated to 75 ° C had a higher water content, higher water resistance and higher utilization and was also higher compared to a product heated to 90 ° C. Overall, the results indicate that a fat summer marker could be well suited for the processing of canned and hot-smoked products.

Atlantic Mackerel (Scomber scombrus) is a novel species in Iceland and as a fatty fish with a short shelf-life it requires optimization of storage and processing conditions. Physicochemical changes of brined and un-brined mackerel were analyzed during frozen storage (6, 9, 12 months) at -18 ° C vs. -25 ° C with the aim of investigating the suitability of using well-fed frozen mackerel as raw material for canned and hot-smoked products. Heat treatments to a core temperature of 90 ° C (representing canning) and 75 ° C (representing hot-smoking) were applied. Prolonged frozen storage showed negative effects on the raw material prior to heat processing due to an increased level of lipid oxidation, where fish stored at -18 ° C was of significantly poorer quality than fish stored at -25 ° C. Moreover, the results indicated that heat treatment resulting in a core temperature of 75 ° C showed higher water content, liquid holding capacity, heating yield as well as lower maximum shear force of texture compared to mackerel heated to a core temperature of 90 ° C. Overall, analyzes indicated that the fatty summer mackerel was well suited for the production of canned and hot-smoked products.

Report closed until 01.01.2018

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