Tag: NMR

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.

View report

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.

View report

Reports

Shrimp - brine based on characteristics

Published:

01/07/2013

Authors:

Arnljótur B. Bergsson, Ásbjörn Jónsson, Gunnar Þórðarson, Lárus Þorvaldsson, María Guðjónsdóttir, Minh Van Nguyen, Sigurjón Arason

Supported by:

AVS Fisheries Research Fund

Contact

Gunnar Þórðarson

Regional Manager

gunnar.thordarson@matis.is

Shrimp - brine based on characteristics

The volume of imported frozen shrimp requires good care in the thawing of the raw material, as shrimp pickling is particularly important for the processing of the product produced from the raw material. Efforts were made to ensure that the best procedures for thawing and pre-packaging were shrimp in terms of raw material properties. Raw material properties were mapped using traditional certified measurement methods as well as low-range nuclear measurements and enhanced with near-infrared spectroscopy. Changes in shrimp that occurred during shrimp pickling were monitored. Processing conditions were mapped using alternate models. The effects of using phosphate as a technical aid were investigated. The correct proportions of shrimp and brine, as well as the temperature of the brine, are prerequisites for stability in pre-pickling so that the desired results are achieved. With proper application, phosphate increases the efficiency of shrimp processing but does not accompany shrimp in the packaging of consumer products. Maladjusted brine reduces utilization.

The volume of imported frozen shrimp demands optimal processes for defreezing the raw material. Brining is most important for the processing of the product that is produced from the raw material. Efforts were made to optimize defreezing and brining of shrimp depending on raw material quality attributes. Quality attributes of shrimp were mapped by accrecated methods as well as NMR and NIR measurments. Changes in shrimp were observed during the brining process. Processing conditions were charted with thermo ‐ models. Effect of usages of phosphate as technological adjuvants was observed. Porpotions of shrimp and brine, as well as temperature of brine are presumptions of stability during brining for expected results to be achieved. With correct application, phosphate increases processing performance and does not accompany shimp into packaged consumer product. Uncontrolled brining reduces product / raw material yield.

View report

Reports

Comparison of wild and farmed cod muscle characteristics

Published:

01/12/2008

Authors:

Valur Norðri Gunnlaugsson, Guðrún Anna Finnbogadóttir, María Guðjónsdóttir, Kolbrún Sveinsdóttir, Hannes Magnússon, Kristján Jóakimsson, Kristín Anna Þórarinsdóttir, Sigurjón Arason

Supported by:

AVS R26-06 / AVS R&D Fund of Ministry of Fisheries in Iceland

Contact

Valur Norðri Gunnlaugsson

Research Group Leader

valur.n.gunnlaugsson@matis.is

Comparison of wild and farmed cod muscle characteristics

The aim of the project was to make a comparison of the properties of cod products made from wild cod before and after dead-freezing and farmed cod before dead-freezing. Also experiment with storage in sludge, ice spray on brine and supercooling (-2.4 ° C) on farmed fish to investigate how the properties of the flesh change with different treatment. Mortality stiffness had a significant effect on weight gain and salt uptake during injection and storage. The uptake of pre-rigor samples was rather low while the uptake of post-rigor wild cod was significant. The pre-rigor fish had less than 5% uptake after pickling, while the wild post-rigor had almost 9% uptake. A similar pattern was seen after injection, where the longest uptake was obtained in wild post-rigor fish or 16.5%. The salinity of most samples ranged from 0.3-0.4%. No significant difference was observed between unsalted samples. In the saline-salted groups, there was only salt uptake in wild cod that was injected after death. On the other hand, salt intake in fish injected before death was insignificant and applied to both wild and farmed cod. The water content was higher in wild cod compared to farmed cod and also spray salting led to a higher water content. Measurements from NMR measurements indicated that there was a difference in the mobility of water molecules and the possible location of water, but this can affect the water - holding properties of the muscle. The fish fillets generally performed well in traditional quality assessments, whether they were injected fillets or untreated fillets. Discharges did not increase as much during the storage period as expected, although considerable discharges were made into the pre- and wild post on the thirteenth day of storage. In previous experiments, the color of farmed fish products has been very white, despite the fact that they have become unusable. On the other hand, yellow cod products turn yellow with shelf life. The results of this experiment did not confirm this difference between farmed cod and wild cod.

There was a great difference in the sensory properties of farmed cod and wild cod after boiling, primarily in texture where wild groups were much thicker, more mushy and softer. Breeding groups had a meaty mouth effect, were more gummy and stuttering, in addition to having a sweeter taste and a much more meaty taste and smell. Storage temperature generally had the effect of producing earlier symptoms of damage in products stored at + 1 ° C compared to -2.4 ° C. The shelf life of farmed cod stored at -2.4 ° C was at least 5 days longer than that of a comparable group stored at + 1 ° C. The effect of storage temperature was also observed in the number of microorganisms, which together with the injection salting led to a larger number of microorganisms. However, there was little difference in products in terms of whether processing took place before or after death solidification. The research was part of the project "Processing and quality control of farmed cod, more specifically a summary for work components 2 and 4.

Production of farmed cod is increasing rapidly, but quality appraisals show that farmed cod has different characteristic from wild cod. These different characteristics make traditional production methods not suitable for farmed cod and therefore it is necessary to analyze those characteristics and adjust production methods especially for farmed cod. Matis ohf has been involved in farmed cod research from its foundation and the company built its foundation on the work which was done by its predecessors. The aim of this project was to look at these different characteristics between farmed and wild cod, pre and post rigor. The aim was also to do experiments with injection of brine and superchilling (-2.4 ° C) and detect the impact of different methods. NMR was used to analyze difference in longitudinal relaxation time (T1), between the samples, farmed cod had lower values for T1 than wild one. Therefore the mobility of water indicates difference in structure between the samples. High levels of glycogen are usually found in farmed cod which results in sharp fall of pH after slaughter. This low pH affects texture, because of collagen degradation which results in gap formation. The low pH also affects water holding capacity of the farmed cod. Measurements have shown higher pH in wild cod and this difference continues through low temperature storage. Texture measurements after 2 days storage indicates that farmed cod is lower in firmness than wild one, regardless of whether the fish is filleted pre- or post rigor. Sensory panels have also detected difference between wild and farmed cod. Wild cod is more tender and mushier, while the farmed one has more meaty texture, is more rubbery and has a clammy texture. Also the farmed fish has sweeter taste and more meaty taste and smell. Farmed cod is different from wild cod in many aspects. Therefore it is necessary to know those aspects and adjust processes especially for production of consumer goods from farmed cod.

Report closed until December 2011 / Report closed until December 2011

View report

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.

View report

Reports

Shelf life tests on cod pieces: Effects of supercooling, pickling and gas packaging on the physical and chemical properties of cod muscles

Published:

01/12/2007

Authors:

María Guðjónsdóttir, Hannes Magnússon, Sigurjón Arason, Guðrún Ólafsdóttir, Sigurður Bogason

Supported by:

AVS, Rannís Technology Development Fund, Rannís Research Fund

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Shelf life tests on cod pieces: Effects of supercooling, pickling and gas packaging on the physical and chemical properties of cod muscles

An integrated refrigeration study was carried out on the effect of salting, different packaging methods and salting methods as well as the effect of subcooling on the quality and shelf life of cod muscles. The results show that storage is a more desirable salting method than injection salting from a microbiological point of view and with regard to drip and boiling efficiency. However, if the salinity during storage becomes too high, the muscle will gel. In the experiment, it was not considered to improve the quality of the fish to inject proteins into the muscle in addition to the salt. Microbial growth and the amount of wandering alkali decrease with decreasing temperature, so it is desirable to keep the temperature as low as possible, without the fish freezing. At -4 ° C, the surface of the fish in all groups, regardless of salinity, was frozen and the ice crystal formation increased with storage time. This ice crystal formation took place much more slowly at -2 ° C and is therefore considered a desirable storage temperature for lightly salted cod muscles. Air-packed packaging (MAP) also proved to be a more desirable storage method than foam packaging, as microbial growth and increase in erratic base was slower in the MAP packaging, which led to longer shelf life.

A combined cooling experiment was performed upon the effect of salting, different packaging and salting methods as well as the effect of superchilling on the quality and shelf life of cod muscle. The results show that brining is a better salting method that brine injection in terms of bacterial growth as well as increased yield. On the other hand, if the salt concentration becomes too high, gelation of the muscle proteins begins. The study also showed that injection of proteins along with salt injection did not improve the quality of the muscle. Microflora and the formation of volatile nitrogen bases decreased with lowering temperatures. It is therefore preferred to store fish at as low temperatures as possible, without letting the muscle water freeze. At -4 ° C the water at the muscle surface was frozen in all groups, independent of salt content, and the ice crystallization increased with storage time. This crystallization was much slower at -2 ° C and therefore this temperature is recommended for storage of light salted cod muscle. Modified Atmosphere Packaging (MAP) turned out to be a better packaging method than Styrofoam packaging, since the increase in bacterial growth and volatile nitrogen bases was slower in the MAP. This also lead to increased shelf life.

View report

Reports

Process control for fishing, processing and processing of salted fish. Effects of different salting methods on the effect of cod fillets

Published:

01/07/2007

Authors:

María Guðjónsdóttir, Þóra Valsdóttir, Ása Þorkelsdóttir, Kolbrún Sveinsdóttir, Hannes Magnússon, Sigurjón Arason, Kristín A. Þórarinsdóttir

Supported by:

AVS, Rannís Technology Development Fund

Contact

Þóra Valsdóttir

Project Manager

thora.valsdottir@matis.is

Process control for fishing, processing and processing of salted fish. Effects of different salting methods on the effect of cod fillets

A comparison was made of the effects of different salting methods on the utilization, quality and other properties of salted cod fillets. One group was only pre-salted but other groups were pre-salted in different ways, ie. by brine salting, spraying and / or pickling. Injured fish had a higher utilization and came out better in quality assessment than uninjected fish. However, the results indicated that the odor and taste of action were higher in unsprayed fish. The effect of phosphate use and spraying on drying properties due to higher water and salt content in products was investigated. It was found that injected fish lost less weight during drying. For the aforementioned reasons, the water content turned out to be higher after drying than in unsprayed fish. The fillets of the dried products varied according to whether the chemical content was based on drying or weight loss on drying. Therefore, the criteria for new salting processes need to be revised and drying processes need to be adapted to the changed properties of salted products.

The effects of different salting processes on yield, quality and other characteristics of salted and cured products were evaluated. Various combinations of salting steps were tested, one group was only dry salted but other groups were first pickle salted, brine injected and / or brine salted. The injected products had higher yield and higher quality than other products. The results indicated that the curing odor and flavor were stronger in products that were not injected. The water and salt content was higher in injected fillets which is important with regard to continuing processes, like drying and rehydration. Measurements during and after drying showed that injection resulted in lower drying rate and higher water content of the fillets. Dried products have been rated in different classes with regard to water content and weight changes during drying. Due to changes in the salting process and drying properties of the salted fish, these reference values have to be reconsidered.

View report
EN
IS EN