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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Reports

The effects of pre ‐ salting methods on salt and water distribution of heavily salted cod, as analyzed by 1H and 23Na MRI, 23Na NMR, low ‐ field NMR and physicochemical analysis and 23Na MRI, 23Na NMR, low range NMR and physical property measurements

Published:

31/03/2014

Authors:

María Guðjónsdóttir, Ásbjörn Jónsson, Magnea G. Karlsdóttir, Sigurjón Arason, Amidou Traoré

Supported by:

AVS Fisheries Research Fund (R45-12)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

The effects of pre ‐ salting methods on salt and water distribution of heavily salted cod, as analyzed by 1H and 23On MRI, 23Na NMR, low ‐ field NMR and physicochemical analysis / Impact of pre-salinization methods on salt and water distribution of fully salted cod products, analyzed by 1H and 23On MRI, 23Na NMR, low range NMR and physical property measurements

The effect of different pre-salting methods (injection salting with or without phosphate, pickling and brine salting) on the water and salt distribution in dry salted cod fillets (Gadus morhua) was investigated by proton and sodium NMR and MRI methods. In addition, the salt and water content were assessed, as well as water resistance. The results indicated that spraying with salt and phosphate resulted in a more uneven water distribution in the fillets compared to other pre-salting methods. On the other hand, brine-salted fillets had the least homogeneity in salt distribution. Fillets from all sample groups had stains with unsaturated brine, but such stains can increase the risk of microbial damage in the fillets during storage. The effect of the pre-salting methods remains throughout the processing process on both fully salted and dried products. As homogeneous water and salt distribution were not achieved with the pre-salting methods studied, further research into the salting process is needed.

The effect of different pre ‐ salting methods (brine injection with salt with / without polyphosphates, brining and pickling) on the water and salt distribution in dry salted Atlantic cod (Gadus morhua) fillets was studied with proton and sodium NMR and MRI methods, supported by physicochemical analysis of salt and water content as well as water holding capacity. The study indicated that double head brine injection with salt and phosphates lead to the least heterogeneous water distribution, while pickle salting had the least heterogeneous salt distribution. Fillets from all treatments contained spots with unsaturated brine, increasing the risk of microbial denaturation of the fillets during storage. Effects from the pre ‐ salting treatments remained throughout the processing line to both dry salted and dried products. Since a homogeneous water and salt distribution was not achieved with the studied pre-salting methods, further optimizations of the salting process, including the pre-salting and dry salting steps, must be made in the future.

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Reports

Water distribution in commercial Icelandic heavily salted Atlantic cod (Gadus morhua) / Water distribution in fully salted cod

Published:

31/03/2014

Authors:

María Guðjónsdóttir, Ásbjörn Jónsson, Magnea G. Karlsdóttir, Sigurjón Arason, Amidou Traoré

Supported by:

AVS Fisheries Research Fund (R45-12)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Water distribution in commercial Icelandic heavily salted Atlantic cod (Gadus morhua) / Water distribution in fully salted cod

Water distribution in a variety of products from Icelandic fully salted cod was analyzed using proton magnetic resonance imaging methods. The products were both flat and filleted, in addition to which they varied in terms of fishing methods, processing before or after death hardening, pre-salting methods (injection salting with / without phosphate, brine and brine salting) as well as the choice of injection machines. All products had an even water distribution, but the homogeneity depended on processing methods. Double injection of salt, as well as simple injection into a muscle before death, led to needle punctures in the muscle, which were even detectable after "kench" salting. Analysis of relaxation time indicated that brine salting led to high muscle protein depletion compared to other pre-salting methods. Injection salting led to a salt-inducing swelling in the muscle, and this effect was maintained even after the "kench" salting step. Multivariate analysis of all variables showed that the MR methods are powerful methods for evaluating the processing properties of products, as well as for maximizing processing methods.

The water distribution of various commercially available Icelandic heavily salted Atlantic cod) products were analyzed with proton magnetic resonance methods. The products varied in choice of catching method, in pre ‐ or post ‐ rigor processing, flattening or filleting cut, and pre ‐ salting technique (brine injection with salt with / without polyphosphates, brining and pickling) and choice of brine injection instruments. All products had a heterogeneous water distribution, but the level of heterogeneity was dependent on the handling during processing. Double brine injection and brine injection into pre ‐ rigor muscle lead to needle traces in the muscle, even after kench salting. Relaxation time analysis indicated that pickle salting leads to the highest degree of protein denaturation in the muscle of the analyzed pre ‐ salting methods. Brine injection lead to salt ‐ induced swelling, which effect remained after the kench salting step. The multi ‐ parametric analysis performed indicated how powerful the MR methods are for process and product characterization and optimization.

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Reports

Seasonal variations in quality and processing properties of whiting (Merlangius merlangus) by season

Published:

30/10/2011

Authors:

Ásbjörn Jónsson

Supported by:

Fisheries Project Fund

Seasonal variations in quality and processing properties of whiting (Merlangius merlangus) by season

The aim of the project was to build up a specific knowledge base for cod (Merlangius merlangus) and obtain information on the variability of its quality and processing properties (chemical and physical properties) according to the season. For comparison, information on haddock was used. The results showed that fillet utilization (processing utilization) was related to carcass production, as there was a positive correlation between fillet utilization and body mass index, which was noticeably highest in March. At the same time, there was less release in the fish compared to other seasons. The results of the project seem to indicate that it is not appropriate to fish for halibut around the spawning season, or in the middle of summer, in terms of processing, physical and other quality characteristics.

The aim of the project was to study seasonal variation in quality and processing properties of whiting (Merlangius merlangus). Haddock was used as a reference group. The results showed positive correlation between fillet yield and condition factor, with highest value in March. At the same time gaping was minor. The results indicated that during spawning time it is not suitable to catch whiting with regards to processing‐ and quality properties.

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