Reports

Effect of post ‐ slaughter time intervals on yield and quality of farmed cod

Published:

01/11/2011

Authors:

Kristín Anna Þórarinsdóttir, Aðalheiður Ólafsdóttir, Kolbrún Sveinsdóttir, Ásbjörn Jónsson, Hannes Magnússon, Kristján G. Jóakimsson, Sveinn K. Guðjónsson

Supported by:

AVS (R 11 006‐010)

contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

Effect of post ‐ slaughter time intervals on yield and quality of farmed cod

The purpose of the experiment was to investigate whether the waiting time (0, 2, 4 hours) from slaughter to processing had an effect on weight uptake during injection and the properties of frozen fillets. In addition, changes in thawed fillets during refrigerated storage were assessed. Changes in weight, chemical content, water resistance, microbial growth and levels of degradable substances were monitored, as well as the fillets were sensitized. For comparison, untreated fillets were used. Weight gain was greater as the waiting time became longer. Salting increased the water resistance of the fillets and reduced shrinkage during thawing and boiling compared to untreated fillets. The injected fillets were therefore also juicier. Higher water resistance of injected fillets is explained by the fact that a higher proportion of water was inside the muscle cells in the injected fillets, while the extracellular fluid was higher in untreated fillets and proportionally more water was loosely bound. The number of micro-organisms was higher in injected fillets, as expected, as the injection spreads micro-organisms throughout the muscle instead of being found only on the surface of the muscle after filleting. Damage symptoms therefore became more pronounced in injected fillets as the storage of thawed fillets progressed over a 2-week period, despite the fact that the fillets were not initially considered more relaxed. Desalination of salted fillets was higher according to TBA values, but its effect was not noticeable on sensory evaluation. Higher salt content was thought to increase the death stiffness of the injected fillets and give a rubberier and stiffer texture compared to untreated fillets. The appearance of injected fillets was poorer, they were a bit darker and more uneven than untreated fillets.

The aim of the experiment was to evaluate the effect of post ‐ slaughter time intervals on injection yield and characteristics of frozen cod fillets. In addition, to evaluate changes in thawed fillets during chilled storage. Weight gain by injection was higher as the waiting time was longer. Salting increased water retention during storage and cooking in comparison to untreated fillets. Therefore, the injected fillets were also juicier. The higher water retention of injected fillets was explained by a higher percentage of water within the muscle cells while the ration of intercellular fluid was higher in untreated fillets. Spoilage became more pronounced in injected fillets over 2 weeks of chilled storage of the fillets after thawing. Oxidation was higher in salted complex as expressed by higher TBARS ‐ values, but the effect was not observed in sensory analysis. Higher salt content seemed to increase rigor contraction in injected fillets and result in a more rubbery texture of the injected fillets, which were also slightly darker and more heterogeneous than untreated fillets.

Report closed until 01.01.2015

View report

Reports

Addition of collagen to heavy salted and lightly salted, chilled and frozen cod fillets

Published:

01/05/2011

Authors:

Kristín Anna Þórarinsdóttir, Hannes Magnússon, Irek Klonowski, Ásbjörn Jónsson, Frank Hansen, Egil Olsen, Sigurjón Arason

Supported by:

NORA

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Addition of collagen to heavy salted and lightly salted, chilled and frozen cod fillets

The effect of added gelatin extracted from fish was investigated on the utilization, chemical composition and quality of chilled, frozen and salted cod fillets. The gelatin was mixed into brine which was then injected into the fillets. Salted fillets were pickled after injection, then salted dry for 3 weeks and finally dehydrated. For comparison, fillets were sprayed only with brine. The main results were that the effect of gelatin on utilization and chemical composition was insignificant. Changes were mainly due to increased salt content. Another issue was the damage processes in chilled products. Microbial growth and degradation formation were higher in the fillets injected with gelatin. However, no visual difference in fillet appearance could be detected by brine composition. 

The effects of added fish gelatin on yield, chemical composition and quality of chilled, frozen and salted cod fillets were evaluated. The gelatin was mixed with salt brine and injected to the fillets. Salted fillets were brined after injection, dry salted for 3 weeks and finally rehydrated. Fillets injected only with salt brine were used as control. Effects of added gelatin on yield and chemical composition were not significant. Alterations were primarily due to the increased salt content by injection. Conversely, the growth of microorganisms and degradation within chilled fillets was accelerated by addition of gelatin. However, no significant differences were observed in visual appearance of the fillets. 

View report

Reports

The role and fate of added phosphates in salted cod products / Role and fate of added phosphate in salted fish

Published:

01/07/2010

Authors:

Kristín Anna Þórarinsdóttir, Sigurjón Arason, Guðjón Þorkelsson

Supported by:

AGS, AVS

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

The role and fate of added phosphates in salted cod products / Role and fate of added phosphate in salted fish

The aim of the project was to evaluate the fate of added phosphate in salted fish. It is clear that its amount decreases with effect and dehydration. The same goes for phosphates that are naturally present in fish muscle. Therefore, the total amount of phosphate in dehydrated products is usually lower than in fresh fish. However, it has been shown that added phosphates (di- and triphosphates) are found in both processed and dehydrated fish. However, it depends on the amount of phosphate added to the product and the salting processes used, ie. whether phosphate was added to the fish by injection or brine. Little or nothing is detected in dehydrated products if brine is used. Differences between processes can be due to the method of salting (spraying / pickling), the type and initial amount of phosphate added and the duration of action. Further research is needed to evaluate the effect of different salting processes on the fate of phosphate in salted cod muscles.

The aim of this study was to investigate the fate of added phosphates in salted cod products. The content of both added phosphates and naturally occurring phosphates, decreases during salting and rehydration. The final content in rehydrated fish (approx. 1-2.5% NaCl) is usually below values in the raw fish. However, di- and triphosphates are present both in salted and rehydrated products. The amount depends on the quantity of added phosphates in the product and on the salting procedures applied. It seems that lower contents are present in brined products than in injected products. Differences may depend on the method used for adding phosphates (injection / brining), phosphate type and, initial content of added phosphates in the muscle after pre-salting and finally on the curing time. Further studies are needed to get accurate information on the effects of different salting procedures on the fate of phosphates in salted cod products.

View report

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 Centre 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.

View report

Reports

Equalization - increased quality and improved properties of fish mince / Homogenization - increased value of fish mince

Published:

01/05/2009

Authors:

Kristín Anna Þórarinsdóttir, Magnea G. Arnþórsdóttir, Irek Klonowski, Arnljótur Bjarki Bergsson, Sindri Sigurðsson, Sigurjón Arason

Supported by:

AVS R 011‐08 / AVS R&D Fund of Ministry of Fisheries in Iceland TÞS 071321007 /Technology Development Fund, RANNIS ‐ Icelandic Centre for Research

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Equalization - increased quality and improved properties of fish mince / Homogenization - increased value of fish mince

The aim of the project was to develop a new production method for marrow mixture for injection into fish products based on leveling. The process gave good results in terms of stability, water resistance, appearance and sprayability of the mixture. The effects on micro-organisms varied according to the processes used and the raw materials, but they were not in all cases noticeable. The utilization and stability of the injected products increased significantly compared to untreated fillets and fillets injected with pure brine. Freezing significantly reduced the water resistance of the muscle. However, the benefit of the injection was in terms of total weight changes from processing until after thawing on the one hand and welding on the other. The report is a summary of experiments in the project "Membrane explosion - increased quality and improved properties of marrow". 

The aim of the project was to develop a process for homogenization of fish mince in solution for injection in fish products. The process was well suited for preparing a solution which had the right particle size, viscosity, water holding properties and stability for injection. The yield and stability of the protein injected fillets was increased compared to untreated fillets and fillets injected with pure salt brine. Freezing reduced water holding capacity but the yield was still higher than of untreated fillets, both after thawing and cooking.

View report

Reports

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

Published:

01/07/2007

Authors:

Kristín Anna Þórarinsdóttir, Þóra Valsdóttir, María Guðjónsdóttir, Sigurjón Arason

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 flat fish

Flat cod was processed according to different salting processes in order to assess the effect of pre-salting (injection, pickling and brine salting) and the composition of the injection brine (salt, phosphate, fish protein) on the action properties. Pre-salting improved efficiency and overall utilization at all stages, depending on efficacy, dehydration and drying. Brine was better than brine salting but had the most effect of spraying (followed by brine). All groups were post-salted after pre-salting. Products with added proteins came out best in the quality assessment, ie. higher percentage went in SPIG I than in other groups. Effects on microbial growth and degradation (TVN, TMA, TBA) were not significant. Efficacy characteristics assessed by sensory evaluation were similarly similar for all groups, regardless of the salting method.

Different pre-salting methods (injection, brine salting, pickle salting) were used as the initial step in heavy salting of cod. The effects of brine composition (salt, phosphate, fish proteins) were evaluated. Pre-salting increased yield and quality, brine salting was more effective than pickle salting, but the best results were obtained by injection (followed by brine salting. Dry salted was used as the main salting step for all groups. Higher ratio of products with added proteins were graded as the best class (SPIG I). Effects on microbial growth or formation of degradation compounds (TVN, TMA, TBA) were not significant.Sensory analysis showed that curing characteristics (taste, odor, appearance, texture) were not affected by the salting procedure.

View report
en_GBEnglish